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Operating Manual

FSK Modem for the Peek ATC and 3000 Series Traffic Controllers

3/14/2011 p/n: 99-578 Rev 1

Copyright © 2011 Peek Traffic Corporation, a Signal Group company All rights reserved. Information furnished by Peek Traffic is believed to be accurate and reliable, however Peek does not warranty the accuracy, completeness, or fitness for use of any of the information furnished. No license is granted by implication or otherwise under any intellectual property. Peek reserves the right to alter any of the Company's products or published technical data relating thereto at any time without notice.

The information contained within this manual is intended to serve as a guide to users in the operation of the 3000E traffic signal controller FSK modem. An effort has been made to insure the accuracy of the information contained in this manual. However, the information is supplied without warranty of any kind. Further, there is no warranty of the applicability of the information to all cases.

The user is cautioned to fully program and thoroughly test the controller for its intended application prior to placing it in operational service. Peek Traffic reserves the right to add, delete, and/or modify the material in this manual at any time.

No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or via any electronic or mechanical means for any purpose other than the purchaser’s personal use without the expressed, written permission of Peek Traffic Corporation. Peek Traffic Corporation 2906 Corporate Way Palmetto, FL 34221 U.S.A. Trademarks ATC-1000, ATC-2000, GREENWave, M3000, 3000E Traffic Controller, and Peek FSK Modem for the 3000E are trademarks or registered trademarks of Peek Traffic Corporation, a Signal Group company, in the USA and other countries. Microsoft and Windows are trademarks or registered trademarks of Microsoft Corporation. Other brands and their products are trademarks or registered trademarks of their respective holders and should be noted as such.

FSK Modem Operating Manual iii

Contents

Table of Figures .................................................................................................................................. v

Chapter 1 — Introduction................................................................................................. 1 Overview .............................................................................................................................................1

Features...........................................................................................................................................2 Specifications...................................................................................................................................3

Chapter 2 — Installing the Modem .................................................................................. 7 Overview .............................................................................................................................................7

Preparing the FSK Modem for installation .......................................................................................7 Installing Into an ATC-1000 Controller................................................................................................8

Installation Procedure ......................................................................................................................9 Chapter 3 — Use and Operation .................................................................................... 15

Use and Operation............................................................................................................................15 Intersection Address ......................................................................................................................16 LED Indicators ...............................................................................................................................17 Port 3 Connector Pin-outs .............................................................................................................18 RTS CTS Delay - SW1................................................................................................................18 TC Level - SW2 .............................................................................................................................20 Default Jumper Settings - JP1-15..................................................................................................20 Mode Programming - SW3 ............................................................................................................22

Chapter 4 — Theory of Operation.................................................................................. 25 Overview ...........................................................................................................................................25

Digital Signal Processor (DSP)......................................................................................................25 Codec ............................................................................................................................................26 DSP-Codec Interface Operation ....................................................................................................27 Line Interface Section ....................................................................................................................28 Power Supply Section....................................................................................................................30 LED Indicator Drive Circuits...........................................................................................................30 Opto-Isolated PTT Circuit ..............................................................................................................31

iv FSK Modem Operating Manual

Chapter 5 — Interface Connectors................................................................................ 33 Overview........................................................................................................................................... 33

Ribbon Cable Interface ................................................................................................................. 33 Port 3 System Interface Connector ............................................................................................... 34 'D' Module Interface....................................................................................................................... 34 Option Headers ............................................................................................................................. 34 Configuration Jumpers .................................................................................................................. 35 Test Points..................................................................................................................................... 36

Chapter 6 — 9600 Baud Site Survey ............................................................................. 37 Site Survey - 9600 baud................................................................................................................... 37

Site Survey.................................................................................................................................... 38 Chapter 7 — Line Termination ....................................................................................... 45

Overview........................................................................................................................................... 45 Method One - Distributed Equivalent Termination @ each node .................................................. 46 Method Two - 600 Ohms/Mile Termination @ each node ............................................................. 50 Method Three - 600 Ohm Termination @ each node.................................................................... 54 Method Four - Termination @ Branch Ends Only ......................................................................... 55

Chapter 8 — Maintenance.............................................................................................. 59 Overview........................................................................................................................................... 59

Unit Replacement.......................................................................................................................... 59 Internal Diagnostics....................................................................................................................... 59 Fold Down Panel ........................................................................................................................... 59 Software Upgrading....................................................................................................................... 60 Integrated Circuit Removal & Replacement .................................................................................. 60 Surface Mount Technology............................................................................................................ 60 Manual Station............................................................................................................................... 60 Bench Repair................................................................................................................................. 61 Parts Lists...................................................................................................................................... 62 Parts List - FSK Modem Board TL-8884 ....................................................................................... 62 Parts List - FSK Modem Board TL-8884 ....................................................................................... 64 Schematic & Assembly Drawings.................................................................................................. 65

Chapter 9 — Termination of Lossy Twisted-Pair Multidrop Networks ....................... 67 Introduction....................................................................................................................................... 67

Modeling Propagation in Transmission Lines................................................................................ 68 Simulation Study ........................................................................................................................... 71 Field Study: Waldo Rd., Gainesville, FL ........................................................................................ 82 Summary....................................................................................................................................... 93

Glossary .......................................................................................................................... 95 Index .............................................................................................................................. 103

FSK Modem Operating Manual v

TABLE OF FIGURES

Figure 1 – FSK modem with and without the faceplate................................................................. 7 Figure 2 – Serial number label location on the ATC-1000 case.................................................... 8 Figure 3 – Unscrew and pull out the D Module ......................................................................... 9 Figure 4 – Unscrew and pull out the I/O module........................................................................... 9 Figure 5 – ATC-1000 Modem Blanking panel installed in the controller ..................................... 10 Figure 6 – Blanking panel mounting screws ............................................................................... 10 Figure 7 – Screws holding the interface module in place............................................................ 11 Figure 8 – J16 socket on the main controller board .................................................................... 11 Figure 9 – Power cables attached to the I/O module .................................................................. 12 Figure 10 – Data cable attached to the I/O module .................................................................... 12 Figure 11 – FSK to D module cable plugged into the FSK modem ............................................ 13 Figure 12 – FSK to D module cable plugged into the D module ................................................. 13 Figure 13 – Reinstalling the D module in the case (FSK cable not shown) ................................ 14 Figure 14 – Master at the End of the System.............................................................................. 16 Figure 15 – Master in the Middle of the System.......................................................................... 16 Figure 16 – LEDs on Port 3......................................................................................................... 17 Figure 17 — Command Transmission Line of cable network using distributed

termination scheme............................................................................................ 47 Figure 18 — Response Transmission Line of cable networks using distributed

termination scheme............................................................................................ 48 Figure 19 — Command Transmission Line of cable network using 600 ohms/mile

termination scheme............................................................................................ 51 Figure 20 — Response Transmission Line of cable network using 600 ohms/mile

termination scheme........................................................................................... 52 Figure 21 — Command Transmission Line of cable network using

Branch-end termination scheme. ....................................................................... 56 Figure 22 – Response Transmission Line of cable networks using Branch-End

termination scheme............................................................................................ 56 Figure 23 — Circuit approximation of a section of twisted pair cable.................................. 68 Figure 24 — Simulated cable network to illustrate the effectiveness of

distributed termination scheme .......................................................................... 71 Figure 25 — Response to a 1 volt, 100 μsec. pulse at nodes 3, 4, 5 and 6 of Figure 24 ........... 72 Figure 26 — Response to a 1 volt, 100 μsec. pulse at nodes 7 and 8 of Figure 24 ................... 72 Figure 27 — Pulse responses for nodes 3, 4, 5, and 6 for the doubly terminated line .............. 73 Figure 28 — Pulse responses for nodes 7 and 8 for the doubly terminated line ........................ 74 Figure 29 — Pulse shape at node 8 when the source impedance is

144 ohms and the termination is 28.8 ohms at node 8. There were no terminators in between .............................................................. 74

Figure 30 — Network with source located at an intermediate node............................................ 75 Figure 31 — Family of pulse responses when the source is located at

node 4 with a source impedance of 28.8 ohms as shown in Figure 30. ............ 75 Figure 32 — A doubly terminated network with distributed equivalent

terminators at both ends .................................................................................... 76 Figure 33 — Pulse amplitudes for the network of Figure 32 ....................................................... 76 Figure 34 — Pulse responses when the source impedance in Figure 32 is

reduced from 28.8 to 1 ohm............................................................................... 77 Figure 35 — Simulated Cable Network with a Star Junction Node and

Distributed Termination...................................................................................... 78 Figure 36 — Pulse Shape at Nodes 3 and 4 for the Network of Figure 35 ................................. 78 Figure 37 — Pulse Shapes for Nodes 5, 8 and 6 (listed in decreasing pulse

amplitude) for the Network of Figure 35............................................................. 79 Figure 38 — Pulse Shape at Node 7 for the Network of Figure 35............................................. 79

Features

vi FSK Modem Operating Manual

Figure 39 — Star Network in Which Only the Branch Ends are Terminated.............................. 80 Figure 40 — Pulse shapes at Nodes 3 and 4 for the Network of Figure 39 ............................... 81 Figure 41 — Pulse shapes at Nodes 5, 6, 8 and 7 for the Network of Figure 39 ....................... 81 Figure 42 — Transformer Equivalent Circuit Model Used in Simulations................................... 82 Figure 43 — Superposition of the Measured and Simulated Transformer Pulse Response ...... 83 Figure 44 — Waldo Rd. Master Station Command Transmission Line ...................................... 84 Figure 45 — Response to a 100 μs Pulse at 8th Ave.................................................................. 84 Figure 46 — Response to a 100 μs Pulse at 8th Ave.................................................................. 85 Figure 47 — Measured and Predicted Response at 8th Ave ...................................................... 86 Figure 48 — Measured and Predicted Response at 16th Ave in the Reverse Direction ............. 86 Figure 49 — Measured and Predicted Response at 23rd Ave in the Reverse Direction............. 87 Figure 50 — Improved Terminations for Waldo Rd .................................................................... 87 Figure 51 — Predicted Responses to the Terminations Shown in Figure 50............................. 88 Figure 52 — Pulse Response Circuit for Node 3 to Node 2 Transmission

and Proper Terminations ................................................................................... 89 Figure 53 — Pulse Response for Node 3 to Node 2 Transmission and Proper Terminations ... 89 Figure 54 — Response at Node 2 for Transmission from Nodes 3, 4, and 5 with

an 88 Ohm Source Impedance and a 75 Ohm Terminator at Node 2............... 90 Figure 55 — Response at Node 2 for Transmission from Nodes 3, 4, and 5 with

a 600 Ohm Source Impedance and a 600 Ohm Terminator at Node 2 (Non-transmitting nodes were open circuited) ..................................... 91

Figure 56 — Remote to Central Site Pulse Response ............................................................... 92 Figure 57 — Comparison of the Reponse at the Central Site from Node 8 ............................... 92

FSK Modem Operating Manual 1

Chapter 1 — Introduction

OVERVIEW

This is the manual for Peek’s in-controller FSK modem card. What is FSK? FSK stands for Frequency Shift Key, which is a form of digital frequency modulation, FSK is a communications method that employs discrete frequencies for specific tasks, such as sending particular signals (for example using one frequency range for marking signals.) The transmitter is changed from one frequency to another, keyed to represent a different information character with each frequency.

Peek's ATC and 'E' series Traffic Controller Units (such as the M3000E Master and 3000E Controllers can be upgraded with the addition of an FSK modem module. It provides those controllers with in-the-case connectors that provide remote communications. The Peek FSK modem is also occasionally refered to as a ‘DSP Modem’, as it uses a digital signal processor to enable the FSK functionality.

The FSK modem interfaces directly with both ATC and 'E' series Traffic Controller units via internal cables connected to the engine and D module boards When an FSK modem is installed, the controller is capable of full-duplex FSK 1200-baud data transmission using standard FSK methods, or full-duplex data transmission at 9600 baud using a proprietary communications scheme over a 4 wire twisted-pair cable. Either setup can be used to communicate with a system master in a closed-loop type system environment.

It is important to note that there are strict cable plant and line termination requirements for 9600-baud operation. It is therefore essential to strictly follow the guidelines of Chapter 5 (Site Survey - 9600 Baud) and Chapter 6 (Line Termination). Peek Traffic offers services to assist system operators with the installation and configuration of such systems.

There are 2 connectors on the communications module:

One 9 pin Line Interface Connector One 8 pin 'D' Module Interface Header

The FSK modem, in conjunction with a system master and a personal computer, provides the ability to receive system traffic commands and to use the computer, through the system master, to program the controller (download data) or to read data from the controller (upload data).

Features

2 FSK Modem Operating Manual

Features

Provides the communications link in these configurations:

– between an M3000E Master and 3000E Local Controllers

– between an M3000E master and an ATC-1000 Local Controller

– Between a 3000E independent local controller and a central system

– Between a Peek ATC series controller and a central system (such as IQ Central)

Self-contained plug-in module

Simple to install: No tools for a 3000E or M3000 installation, Just a screwdriver for an ATC installation.

Dual Mode operation. Operates at 1200 baud or 9600 baud.

Mode selection programmed using dip switches.

Ribbon cable serial interface to the controller.

Simple 5-wire interface to optional “D” modules.

Port 3 is a 9-pin metal shell ‘D’ subminiature connector as specified by NEMA.

Surface Mount Circuitry.

Operating temperature range -34oC +74oC. (-30°F to +165°F)

The modem uses transformers in the line interface circuit of the transmitter and the receiver to provide for common-mode noise rejection

MOV's to protect against transients on the line interface of the transmit and receive circuits.

Specifications


Specifications

The modem module functions in either a High Speed or Low Speed mode of operation. Mode selection is accomplished using a programmable dipswitch to select the mode of operation.

Low Speed Mode Interoperability Meets the requirements in Section 3.3.3 of the

NEMA TS2 Specification entitled: Port 3 System Interface, and interoperable in existing closed-loop systems using TA-5035 rev 4 or earlier FSK modem boards.

Digital Interface 1200 bps, asynchronous, bit serial, NRZ coding Transmission Method TDM using phase coherent frequency shift keying

(FSK) Line Interface Line Type Operates over an unconditioned Type 3002 voice

grade channel or customer owned cable (#19-24 AWG).

Maximum Distance 8 miles Maximum No. Drops 32 Line Impedance Transmitter TC On 600 Ohms TC Off 600 Ohms or ‘HI-Z’ Receiver 600 Ohms or ‘HI-Z’

Receiver Characteristics Receiver Input Sensitivity -34 dBm minimum Carrier Detect Hysteresis 3 dB Bit Error Rate 10-3 with 10 dB S/N ratio

Transmit Level +9, +6, +3, 0, -3, -6, -9, & -12 dBm Timing Characteristics RTS-CTS Delay 2.5 - 19.5 ms Carrier Detect 7 ms maximum SCTO Period 9 ms maximum

Duplex Mode 4-wire Systems Full or Half Duplex

Interface Connectors Controller interface (J1) 16-pin ribbon cable that interfaces to 'E' Series

controller Line interface (J2) 9-pin metal shell ‘D’ subminiature type connector 'D' module interface (J3) 8-pin header to route signals to an optional ‘D’

module.

Specifications


Hi-Speed Mode Interoperability Only operable in systems using TL-8884 DSP modem

boards. Digital Interface 9600 bps, asynchronous, bit serial, NRZ coding Transmission Method TDM using a proprietary communications scheme Line Interface Line Type Operates over #19-24 AWG customer owned private line

metallic cable. Modem will not work over an unconditioned Type 3002 voice grade channel.

Maximum Distance 5 miles Maximum No. Drops 10 Line Impedance

Transmitter TC On 600 Ohms TC Off 600 Ohms or ‘HI-Z’ Receiver 600 Ohms or ‘HI-Z’ Receiver Characteristics Receiver Input Sensitivity -34 dBm minimum Carrier Detect Hysteresis 3 dB Bit Error Rate 10-5 with 15 dB S/N ratio

Transmit Level +9, +6, +3, 0, -3, -6, -9, & -12 dBm Timing Characteristics RTS-CTS Delay 10.4 - 36.5 ms Carrier Detect 3.0 - 36.5 ms Break Period 1.4 ms maximum

Duplex Mode 4-wire Systems Full or Half Duplex

Interface Connectors Controller interface (J1) 16-pin ribbon cable that interfaces to 'E' Series or ATC

controller Line interface (J2) 9-pin metal shell ‘D’ subminiature type connector 'D' module interface (J3) 8-pin header to route signals to an optional ‘D’ module.

Specifications


Line Interface In four-wire (4W) systems, two pairs of wires are required, one pair for the information transmitted from the master to the secondary and the second pair for information transmitted from the secondary to the master.

Each 'Pair' shall meet the following requirements:

#19-24 AWG copper wire twisted in pairs at least 12 turns per foot, all pairs enclosed in a shield. No other types of signals shall be present inside the shielded enclosure.

Total length not to exceed eight (8) miles. Impedance of 600 ohms resistive, balanced, and ungrounded. Envelope delay distortion shall be less than 1750 microseconds in the band from

800 to 2600 Hz. Frequency response referred to 1,000 Hz from 300 to 3000 Hz shall be flat -3, +12

dB. Response reference to 1000 Hz from 500 to 2500 Hz shall be flat -2, +8 dB. Insulation between any conductor and ground shall be at least 20 megohms DC

and 50 Kohms AC from 300 - 3000 Hz. Capable of transmitting a signal of no less that +10 dBm (average). Noise level shall be no more that -62 dBm. Non-linear (harmonic) distortion, fundamental to first harmonic of 25 dB minimum,

and fundamental to third harmonic of 30 dB minimum. Breakdown between any conductor and ground shall be greater than 1500 Vrms at

60 Hz.

Minimum receive level at most distant point shall be no less than -16 dBm at 0 dBm input power.

The following cable types are recommended for interconnection from the master - secondary or from the Central Office monitor to the master when user owned cable is installed:

Spec # Wire Gauge Use Fill Support REA PE-23* #19AWG DIRECT DRY BURIAL AIR CORE NONE** REA PE-39 #19AWG DIRECT BURIAL FILLED NONE** REA PE-22 #19AWG AERIAL DRY DUCT AIR CORE NONE** REA PE-38 #19AWG AERIAL AIR CORE W/Mesgr. CABLE *NOTE 1 - During the 1970's, PE-23 was superceded by PE-39. PE-39 cables are "filled" such that the entire cable assembly under the outer cable is 100% flooded (filled), thereby eliminating possible moisture migration or humidity changes due to ingress and/or outer jacket damage.

…"filled cables are often selected for wet duct or direct earth burial installation."

**NOTE 2 - For Aerial applications, cables with no support of their own must be supported by a separate messenger strand. Cables meeting the REA PE-38 specification are self-supporting, with their own messenger strand attached.

Specifications



Chapter 2 — Installing the Modem

OVERVIEW

The Peek FSK modem is installed directly into the case of the M3000E, 3000E, and ATC-1000 traffic controllers. It mounts on the right side of the case and provides what becomes ‘Port 3’ for the controller. The next section describes how to install the FSK modem into a Peek ATC controller.

Preparing the FSK Modem for installation

The FSK modem comes in two variants: one with a face plate and the other without. The version with the face plate is the one required for installation in an ATC-1000. The versions without a face plate are for installation in a 3000E or M3000E controller.

Figure 1 – FSK modem with and without the faceplate

Preparing the FSK Modem for installation


INSTALLING INTO AN ATC-1000 CONTROLLER

Before starting the installation of the modem, make sure that the controller has a version of the GREENWave firmware that will support the FSK modem. This means, for an ATC-1000, that you need to have GREENWave v3.7 or highter installed. Refer to the ATC-1000 controller Operating manual (81-1285) for instructions on checking the version of firmware installed in the device. If you must upgrade your firmware, refer to the GREENWave v3.7 Release Notes for installation instructions (99-545 Rev 4.)

Caution ATC-1000 beta test units were shipped with a standard complement of 16MB

of SDRAM. This is insufficient for the GREENWave v3.7 firmware, and installing the firmware on a beta version of the hardware can result in the controller becoming inoperable. Before upgrading to v3.7, verify that the Part Number/Serial Number label that is attached to the top of the controller (placed in the front right corner) does NOT show this text: PART NO: ATC1000 BETA If you see that text at the top of the label, you have a beta test unit of the controller and you MUST NOT INSTALL the v3.7 firmware.

Figure 2 – Serial number label location on the ATC-1000 case

The controller will also need to have both a field I/O module and a D module installed in order to accept all of the necessary cable connections from the FSK modem.

In order to install the modem, we will need to basically disassemble the entire controller (with the exception of the power supply module.) You will need a Philips-head screwdriver to perform the installation.

serial number label

Installation Procedure



Once you are certain of the proper firmware, follow these steps to install the modem:

1. Power down the ATC-1000 controller. For most versions of the controller, this means disconnecting the “A” connector cable from the front panel.

2. Locate the controller’s D Module. Unscrew the three front panel screws that hold the D module in place and pull the D module out from the controller case.

Figure 3 – Unscrew and pull out the D Module

3. On the cable at the back of the D Module, which attaches the D Module to the I/O module, press outward on the two plug latches to release the plug. Unplug the D module and set it aside.

4. Locate the four screws holding the I/O module to the controller case. Unscrew these screws and pull the I/O module out from the case.

Figure 4 – Unscrew and pull out the I/O module

5. Unplug three of the four cables from the back of the I/O module. (Leave the one at the right end plugged in; that’s the D module connection cable.) Set the I/O module aside.

D Module mounting screws

Screw mounting locations for an ATC Field I/O module



6. Locate the Modem ‘Blanking Panel’ on the front of the controller.

Figure 5 – ATC-1000 Modem Blanking panel installed in the controller

7. On the right side of the controller, locate the four blanking panel mounting screws. Unscrew these and remove the blanking panel from the controller. (Hold onto the panel while unscrewing the last screw, so the panel won’t drop to the bottom of the case.) Set the panel aside.

Figure 6 – Blanking panel mounting screws

modem blanking panel



8. Locate the six screws holding the interface module in place on the front of the controller (four along the top edge, and two along the bottom.)

Figure 7 – Screws holding the interface module in place

Remove the screws. (Hold the interface module while unscrewing the last two screws.)

9. Pull the interface module away from the case, rotating it out from the right end. Leave the two power cables attached at the left end and prop the module on the inside structure of the case and the work surface. You should be able to see the ATC engine board and the main controller board on the top side of the module if it is situated in this manner.

10. The FSK modem assembly has one cable running from the back. Attach the plug on that cable into the J16 socket on the main controller board. J16 is a vertical 16 pin male socket on the main board that if you look around to the front of the interface module and compare its position, is right behind the green up arrow button. There is only one orientation that the plug from the FSK modem can fit into this socket. Press the plug in place until it is firmly seated.

Figure 8 – J16 socket on the main controller board

J16 socket



11. Re-attach the interface module to the controller chassis. You will need to juggle the FSK modem, since it is now attached to the interface module. You can prop the FSK modem against the case side until you get the interface module attached. Re-install the six screws that hold the front interface module in place. (Be sure not to pinch any of the cables between the interface module and the chassis structure while doing this.)

12. Next, we need to reattach and re-install the I/O module. First, plug the two power cables into the left end of the I/O module. (J1 and J2)

Figure 9 – Power cables attached to the I/O module

13. Then, locate the data cable that is hanging down from the interface module. Plug that into the J4 socket on the right end of the I/O module.

Figure 10 – Data cable attached to the I/O module

Make sure the D Module cable attached to the I/O module doesn’t get pinched between the board and the chassis framework.

J4 socket



14. Re-attach the I/O module to the chassis. Make sure the D Module cable is visible through the D module opening of the case. Install the four I/O module screws.

15. The FSK Modem assembly with the front panel attached comes with a cable that is used to connec the modem to the D module. The FSK Modem to D Module cable assembly (TH-5171) is 15 inches long and has blue, white and black wires. Each end is unique, so there is no danger of connecting it in the wrong order. Plug one end of this cable into the plug on the side of the modem (socket J3).

Figure 11 – FSK to D module cable plugged into the FSK modem

16. Plug the other end of this cable into the J3 plug on the back, bottom corner of the D Module assembly.

Figure 12 – FSK to D module cable plugged into the D module

17. Position the FSK modem in the case, in the position where the modem blanking assembly had been installed. Install the four screws on the side of the controller that hold the modem in place.

18. Locate the I/O to D module cable. It should be visible near the right end of the I/O module. Plug this cable into the J2 socket on the D module. (Refer to Figure 13.) Press the plug firmly in place until the socket latch connectors click into place.

J3 socket on FSK modem

J3 socket on D module



19. Finally, re-install the D module in the controller case. Again, make sure that no cables get pinched or trapped between the module and the chassis brackets. Install the three screws that hold the D module in place.

Figure 13 – Reinstalling the D module in the case (FSK cable not shown)

20. Re-apply power to the controller. The unit should come up and immediately start operating normally. Verify that the I/O and D modules have been correctly identified by the firmware by going to the Revision Information screen and comparing the values displayed there for ‘IO Module’ and ‘IO D Module’ match the physical hardware installed. (The commands to reach that screen are Main Menu > 1.Status > 5.Revisions in GREENWave v3.7.)

21. Now we need to configure the new port through the firmware. We will set it up here to operate at 1200 Baud. (Please refer to the other pertinent sections of this manual if you wish to use the modem at 9600 baud. All of the requirements mentioned for the higher speed in an M3000/3000E environment also apply to the ATC-1000.) In the front panel interface, go to the Main Menu (MNU ) and then choose 2.Programming .

22. Select 1.Unit Conf igurat ion and then option 5.Comms and I /O Setup Menu . Command 2.Port 2-5 Parameters is where we need to make some changes.

23. Press - to enter edit mode, and then navigate to the fields under Port 3.

Set Enabled to 1 . Set Baud Rate to 1 . Press - again to save the new values. The other values shouldn’t need to be touched. (Parity should be set to None. Stop bits should be set to 1 and HW Flow should be set to 0 (‘None’).)

This completes the installation of the FSK Modem. If there are any screws left over at this point . . . such is life.

J2 socket


Chapter 3 — Use and Operation

USE AND OPERATION

The modem is designed to be used in Peek Traffic Systems 'E' Series Traffic Controller Units - the M3000E Master and 3000E Intersection controllers (NEMA Type I & II), and in Peek’s ATC-1000 and ATC-2000 line of advanced traffic controllers. A controller unit that is equipped with the FSK modem module is compatible with the following Peek systems:

In 4W full-duplex systems where PORT 3 provides 9600-baud data communications between the M3000E Master and 3000E type secondary controllers.

In 4W full-duplex systems where PORT 3 provides 1200-baud FSK data communications between a master and secondary controllers.

In 4W full-duplex UTCS-type systems where PORT 3 provides 1200-baud FSK data communications between the central modems and the secondary controllers.

Intersection Address


Intersection Address

Each local within the system must have its own unique address to allow the master to distinguish between otherwise identical secondary units.

The assignment of intersection numbers to intersections is generally an arbitrary process, but it is generally a good idea to number them sequentially away from the master as shown in figures 2-1(A) and 2-1(B).

Figure 14 – Master at the End of the System

Figure 15 – Master in the Middle of the System

Once assigned, the intersection numbers would then be recorded on a system diagram. Further references to detector assignments at the M3000E level or intersection monitoring at the central office monitor level would subsequently use this numbering system.

Each secondary in the system must be programmed with values for the MASTER TYPE, INTERSECTION ID, and MASTER IDENTIFICATION on the CLOSED LOOP Screen; BAUD RATE, PARITY, and DATA BITS on the PORT 3 SET-UP Screen; and MASTER (CL) PORT on the COMM SET-UP Screen. Refer to the Programming Instructions section of the Operating Manual for the 3000E Traffic Controller regarding data entry.

Master #1 #2 #3 #10

Master #4 #1 #3 #31 #2 #32

LED Indicators


LED Indicators

The FSK modem provides four LED status indicators located adjacent to Port 3 on 'E' Series controller units as shown in Figure 2-2. The LED's indicate the status of the TXD, RXD, RTS, and DCD signal lines in the modem. The function of the four indicators is as follows:

MASTER T: Transmit Data (TXD); "ON" whenever the modem transmits data.

MASTER R: Receive Data (RXD); "ON" whenever the modem is receiving data.

REPEATER T: Request-to-Send (RTS); "ON" whenever the modem is transmitting a carrier signal.

REPEATER R: Data Carrier Detect (DCD); "ON" whenever the modem detects a carrier signal.

Figure 16 – LEDs on Port 3

PORT 3

MASTER

REPEATER

T

R

T

R

COMM

Port 3 Connector Pin-outs


Port 3 Connector Pin-outs

The modem connector provides the hook-up of the 4-wire communications link between the master and secondary. The connector consists of two transmit and two receive terminations as follows:

PIN FUNCTION 1 TX+ (Transmit 1) 2 TX- (Transmit 2) 4 RX+ (Receive 1) 5 RX- (Receive 2) 6 Earth Ground 9 Earth Ground

Note: Pins 6 & 9 are provided for connection to an external cable shield, if appropriate.

The system communication lines would be wired such that the transmit output (TX+, TX-) at the M3000E master is connected to the receive terminations (RX+, RX-) of all secondaries. The transmit output (TX+, TX-) of all secondary controllers is connected to the receive inputs (RX+, RX-) on the M3000E master.

RTS CTS Delay - SW1

SW1 is an 8-position DIP switch that sets the RTS CTS delay time in the transmitter of the modem. The delay controls the period between when the modem initiates a transmit carrier (TC) and data (TXD) is sent. The controller asserts the Request-to-Send (RTS) signal when it has something to send, and waits for the Clear-to-Send (CTS) signal from the modem before sending any data. In most TDM systems, an RTS CTS delay is required at the transmitter before data transmission can begin. The function of the delay is to allow sufficient time for the receiver at the distant end to acquire the carrier signal and assert Data Carrier Detect (DCD). Typically this delay is set to a value greater than the maximum Carrier Detect time of the receiver. When the controller asserts the RTS signal, the transmitter immediately begins sending a carrier signal (TC). If data is sent immediately, the receiver at the distant end will not be ready to receive it since it did not yet detect a valid carrier signal, however, if data is delayed for a period longer than the maximum DCD time, valid data can be received. The following table shows the binary coding for SW1.

Switch # S8 S7 S6 S5 S4 S3 S2 S1

Binary # 27 (MSB) 26 25 24 23 22 21 20

(LSB)

Decimal # 128 64 32 16 8 4 2 1

RTS(CTS Delay - SW1


Switch Setting: Add the decimal # for each switch that is in the "OFF" position.

SW1: S8 S7 S6 S5 S4 S3 S2 S1 ex: S8, S4, S1 OFF: OFF ON ON ON OFF ON ON OFF 128 + 000 + 000 + 000 + 008 + 000 + 000 + 001 = 137

RTS CTS Delay Formulas: Low-Speed Mode (1200 baud):

Delay = 2 x Ts x (32 + Switch Setting) Where Ts = 1/(29.3 kHz) Ex. 2 x 1/(29.3 kHz) x (32 + 137) = 11.54 ms

High-Speed Mode (9600 baud): Delay = Tb x (100 + Switch Setting) Where Tb = 1/(9.77 kHz). Ex. 1/(9.77 kHz) x (100 + 137) = 24.26 ms

Recommended RTS CTS Delay Settings: Low-Speed Mode (1200 baud): 7.99ms, SW1: S2, S4, S6, S8 = "ON" High-Speed Mode (9600 baud): 18.94ms, SW1: S2, S4, S6, S8 = "ON"

TC Level - SW2


TC Level - SW2

SW2 is an 8-position rotary switch that sets the reference level for the transmit carrier (TC) of the modem. The level is determined by the setting on rotary switch SW2, where:

Setting TC Level “0” + 9 dBm

“1” + 6 dBm

“2” + 3 dBm

“3” + 0 dBm “4” - 3 dBm

“5” - 6 dBm

“6” - 9 dBm

“7” - 12 dBm

Recommended TC Level Settings: Low-Speed Mode (1200 baud):

Master +9 dBm, SW2 = "0" Local 0 dBm, SW2 = "3"

High-Speed Mode (9600 baud):

Master +6 dBm, SW2 = "1" Local 0 dBm, SW2 = "3"

Default Jumper Settings - JP1-15

The DSP modem board has 15 different possible programming headers. Typically, only six headers are installed in the board, which require programming. The default settings configure the modem to terminate the transmit (TX) and receive (RX) pair either internal or external to the modem. The default settings are as follows:

Internal Termination: (Factory Defaults) JP7 Shorted. JP8 Open. JP10 Open. (Shorted sets impedance of transmitter to 600 ohms) JP11 Open. JP12 Open. (Shorted sets impedance of receiver to 600 ohms) JP13 Open.

Default Jumper Settings - JP1-15


External Termination: JP7 Shorted. JP8 Open. JP10 Open. Termination is provided externally across the

transmit pair. JP11 Open. JP12 Open. Termination is provided externally across the receive

pair. JP13 Open.

Note -The issue of line termination is very important. The termination value and method of termination can have a significant impact on system performance. Line termination is discussed in detail in the “Error! Reference source not found.” section, starting on page Error! Bookmark not defined. of this manual. It is recommended that all users of the FSK modem read this discussion thoroughly.

Mode Programming - SW3


Mode Programming - SW3 SW3 is an 8-position DIPswitch that determines the operational mode of the modem (i.e. Bell 202, V.23, Hi-Speed, PGM, Polled Carrier, and Constant Carrier). The DIP switch is organized as four groups of two switches each, and programs the MODE, RTS, RXD, & TXD functions. The following table describes the programming for each switch pair combination.

Switch # S8,S7 S6,S5 S4,S3 S2,S1 Function TXD RXD RTS MODE

Parameters

Connects TXD to DSP in low speed mode, etc. S8 S7 Off Off Enables Copyright/PGM Revision Level message. (See JP3,4 description). Off On Connects TXD to transmitter in low-speed modes of operation (Bell 202 and V.23). On Off Enables Programming and 9600 baud, Hi-Speed modes of operation. On On Prohibited, invalid switch setting.

Selects the source for receive data (RXD) from the modem. S6 S5 Off Off Nothing selected. The default for RXD from the modem is a constant mark Off On Selects RXD2 as the data source for RXD in low-speed operation. On Off Selects RXD1 as the data source for RXD in Hi-Speed operation. On On Prohibited, invalid switch setting.

Selects the source for the BRTS signal to the DSP that enables the transmitter. S4 S3 Off Off Nothing selected. The transmitter is never enabled. Off On GND selected. The transmitter is permanently enabled, (i.e. constant carrier operation). On Off RTS selected. The transmitter is enabled whenever RTS is low; (i.e. polled carrier operation). On On Prohibited, invalid switch setting.

Selects the operating mode of the modem (HS, Bell 202, V.23, or Pgm'g). S2 S1 Off Off Selects 9600 baud, Hi-Speed mode. Off On Selects 1200 baud, Bell 202 mode. On Off Selects 1200 baud, V.23 mode. On On Selects Programming mode.



Recommended Mode Settings: Low-Speed Mode (1200 baud, Bell 202):

Master (2.53 and prior) w/constant carrier SW3: S1, S3, S5, S7 = "On" Master/Local (2.76 and higher) w/polled carrier SW3: S1, S4, S5, S7 = "On"

High-Speed Mode (9600 baud): Master polled carrier only SW3: S2, S4, S6, S8 = "On" Local polled carrier only SW3: S2, S4, S6, S8 = "On"

Note – It is recommended that for Master Firmware (5581) Versions 2.53 and prior, “constant carrier” be used. For versions 2.76 and higher, “polled carrier” is recommended.


Chapter 4 — Theory of Operation

OVERVIEW

The modem board provides both M3000E Master and 3000E Secondary Controllers with a modem port. The modem interfaces to connector P215 on the control board via a 16-pin ribbon cable. The interface cable provides power, transmit data, receive data, and handshaking signals that control modem operation. Two IC's form the core of the modem, a Digital Signal Processor (DSP), and a CODEC.

Digital Signal Processor (DSP)

The DSP used is a high-performance static CMOS integrated circuit optimized for low-power operation. It contains on-chip FLASH Program Memory, 4.5K of RAM memory, and many on-chip peripherals integrated into the device. Flash memory provides reprogrammable, non-volatile storage, and eliminates the need for external EPROM. The DSP is packaged in a 100-Pin Quad Flat Pack (i.e. 100-Pin PQFP).

Codec


Codec

The codec is a complete Analog Front-End processor (AFE) containing a 16-bit A/D conversion channel and a 16-bit D/A conversion channel. The D/A channel drives the transmit circuit of the modem, and the A/D channel converts the receive signal to digital values for signal processing. The gains of the A/D and D/A conversion channels are independently programmable, and are dynamically adjusted during operation in order to maintain the TC LEVEL of the transmit circuit and sensitivity of the receiver.

The codec operates from a single supply voltage, however it utilizes independent analog and digital supply pinouts to minimize coupling between the analog and digital sections of the codec. The digital supply pins on the codec are DVDD and DGND, and the analog supply pins are AVDD1, AVDD2 and AGND1, AGND2, (i.e. U2 pins 12, 11, 3, 9, 4, & 10 respectively). The codec is packaged in a 20-Pin Small Outline IC (i.e. 20-Pin SOIC).

The codec communicates with the DSP over a full-duplex, bi-directional synchronous serial port (SPORT). The SPORT is used to send and receive digital data and control information to the codec. All data transfers over the SPORT occur at the serial clock rate (SCLK), with the MSB being transferred first, and are initiated by a Frame Sync (FS) signal from either the DSP or the codec itself.

The codec is interfaced to the DSP via the six-wire SPORT interface defined as follows:

U2 Pin 20: SPORT Enable (SE). Not used in this application. Tied high to permanently enable the SPORT.

U2 Pin 14: Serial Clock (SCLK). Clock signal from the codec that determines the serial transfer rate to/from the codec.

U2 Pin 17: Serial Data Output Frame Sync (SDOFS). The frame sync is one-bit wide and active one SCLK period before the first bit of each output word. Signal source is the codec.

U2 Pin 16: Serial Data Output (SDO). Serial data output from the codec. Clocked on the positive edge of SCLK. Signal is in three-state when no data is being transmitted.

U2 Pin 18: Serial Data Input Frame Sync (SDIFS). The frame sync is one-bit wide and valid one SCLK period before the first bit of each input word. Signal source is the DSP.

U2 Pin 19: Serial Data Input (SDI). Serial data input to the codec. Data is clocked on the negative edge of SCLK.

DSP-Codec Interface Operation


DSP-Codec Interface Operation

The codec is interfaced to the DSP via the 6-wire serial port (SPORT) on the codec described above. Both serial input and output data use an accompanying frame synchronization signal which is active high one clock cycle before the start of the 16-bit data word. The serial clock (SCLK) is an output from the codec used to define the serial transfer rate to the DSP's Tx and Rx ports. The configuration used connects the DSP's DT, FT, DR, and FR signals to the codec's SDI, SDIFS, SDO, and SDOFS signals respectively. This configuration decouples the transmission of input data from the receipt of output data.

There are three basic transfer processes that can occur between the DSP and the codec, initialization, transmit, and receive. The transmit and receive processes can occur simultaneously, and the transmit process can be a control or data word. The processes are described as follows:

Initialization Process This process uses the SDIFS and SDI signals on the codec. Following de-activation of [RESET] or [DTR], the DSP programs the codec. This establishes the SCLK rate for the SPORT, the sample rate, and several other codec parameters. This is a one-time process that occurs following de-activation of [RESET] or [DTR].

Receive Process

This process uses the SDOFS and SDO signals on the codec. It occurs once each sample period (i.e. 1 / sample rate). The A/D conversion channel in the codec performs an analog to digital conversion that converts the differential voltage present on the VINP and VINN pins of the codec into a 16-bit digital value. The resulting data word is placed in the output register of the codec, the codec asserts the SDOFS signal for one SCLK, and then transmits the data word to the DSP on the SDO pin at the SCLK rate. The codec repeats this process continuously at the sample rate.

Transmit process This process uses the SDIFS and SDI signals on the codec. Once each sample period (i.e. 1 / sample rate), the DSP calculates the next data value for the D/A conversion channel in the codec. The DSP asserts the SDIFS signal for one SCLK, and then transmits the next data word to the codec for the D/A conversion channel on the SDI pin at the SCLK rate. The D/A conversion channel uses the data value to set the differential voltage level on the VOUTP and VOUTN pins of the codec. This establishes the TC LEVEL on a continuous basis over time. The DSP repeats this process continuously at the sample rate.

Line Interface Section



Dedicated network installations generally consist of customer owned cable primarily used for data communications between the master and local controllers in a system. The line interface section of the modem provides the means to connect the modem to the network. The line interface section can be configured for either TWO-WIRE (2W) or FOUR-WIRE (4W) operation, although only 4W is supported.

Four-Wire Operation A four-wire network isolates the transmit signal from the receive signal, while allowing simultaneous communication in both directions (i.e. full duplex). The line interface section of the modem consists of a Transmit (TX) circuit, and a Receive (RX) circuit.

Transmit (TX) Circuit The transmit circuit interfaces the modem's Transmit Carrier (TC) signal to the network. The differential voltage generated by the codec between VOUTP and VOUTN is the source of the TC signal. The voltage changes each time the DSP writes a new data value to the D/A conversion channel in the codec.

Since the DSP is constantly writing new data values, the circuit includes an electronic switch used to turn the TC signal from the modem on and off. This is the function of transistors Q4 & Q5; they act as switches to turn the signal on and off. When the transistors are in the ON state, the differential voltage from the codec is connected to the primary side of transformer T1 (pins 1 & 3). The On/Off state of Q4,5 is controlled indirectly by the TXE signal from the DSP. When TXE is high, transistors Q4,5 are on. When TXE is low, transistors Q4,5 are off. Transistors Q2,3 buffer the TXE control signal from the DSP. Together they act as a switch, which controls the voltage level on the BASE of transistors Q4,5 turning them on and off.

VR2 protects the transmit circuit on the primary side of the transformer against any voltage transient between T1 pins 1 & 3.

The TC signal on the secondary of T1 (pins 6 & 4), is output on connector J2 pins 1 & 2, as TX+ and TX- respectively. As long as Q4,5 are on, a TC signal is present at connector J2.

Initial transient protection is provided by VR4, 6, and 7. They protect the transmit circuit in the modem against any Line-to-Line (L-L) and Line-to-Earth (L-E) voltage transients on the transmit lines TX+ and TX-. Resistor R47 and jumper JP10 provide the option to set the transmitter impedance to 600 ohms.

Receive (RX) Circuit In 4W operation, the receive signal from the network is input to the modem on J2 pins 4 & 5, as RX+ and RX- respectively. The input signal connects through series resistors R52,53 to the secondary of transformer T2, pins 6 & 4. The transformer provides DC isolation and rejection of any common-mode noise induced by the network into the input signal.



VR5, 8, and 9 protect the receive circuit in the modem against any Line-to-Line (L-L) and Line-to-Earth (L-E) voltage transients induced on the receive lines RX+ and RX-.

In 4W operation, the receive lines in the network must be properly terminated. This is generally done by installing a resistor directly across the receive pair, and is typically done either internal or external to the modem. Jumper JP12 provides the option to connect the termination resistor across the receive lines in the network internally. Potentiometer R48 and resistor R49 determine the termination resistance.

The resistance value is set between TP8 and TP9 by adjusting R48 with JP12 removed. The factory default setting is 600 ohms.

Jumper JP13 is an optional jumper that connects the center-tap of transformer T2 to chassis. It is normally installed is systems where the receive lines are differential with respect to chassis ground.

The receive signal on the secondary of transformer T2 generates a signal in the transformer primary on pins 1 & 3. Additional transient protection is provided by VR3, which protects the receive circuit against a voltage transient between pin 1 & pin 3.

The signal on T2 pin 1 & pin 3 connects to pin 3 on J5 & J6 respectively. Jumpers J5, J6 are optional, and when installed, allow the modem to be configured for either 2W or 4W operation. The default is 4W, as pin 2 is connected to pin 3 on each. Pin 2 on J5 and J6 is connected to DC blocking capacitors C29, C30.

Resistors R41, R42 and jumper JP9 are optional parts that lower the receive input impedance to 300 ohms when JP9 is installed.

The signal passes through DC blocking capacitors C29, C30, a low-pass filter (LPF) and to the codec on pins 5 & 6, as VINP and VINN respectively. This differential voltage is the input to the A/D conversion channel on the codec. The signal is passed through low pass filters (LPF) that bandlimit the signal prior to sampling by the A/D conversion channel in the codec. The LPFs are simple RC filters, where R38, C26 filter VINP, and R39, C27 filter VINN. Resistors R36, R37 provide a DC bias voltage for VINP and VINN that reference the dc level to the REFOUT pin on the codec.

Two-Wire Operation Two-wire networks use the same wire pair for transmit and receive signals, however, as opposed to four-wire, data transmission can occur in only one direction at a time (i.e. half-duplex). Additionally, two-wire operation requires special software in the master and local controllers to address problems relating to line turnaround timing and near-end/far-end echo. The line interface section of the modem consists of a Transmit (TX) circuit, and a Receive (RX) circuit.

Transmit (TX) Circuit The basic operation of the TX circuit is the same as described in four-wire operation, however, in 2W operation, transformer T1 provides the receive signal for the RX circuit.

Power Supply Section


Receive (RX) Circuit The main circuit difference, as discussed under four-wire operation, is that jumpers J5 and J6 are programmed differently. The trace connecting pin 2 to pin 3 is cut, and pin 1 is shorted to pin 2. In this configuration, transformer T1 serves as the interface to the network for the TX and RX circuits. Transformer T2 is not used in this configuration. The remainder of the RX circuit from the blocking capacitors C29 & C30 to the codec, functions the same as described under four-wire operation.

Power Supply Section

The modem board requires +8VDC and +24VDC supply voltages as input to the board. A third supply voltage, +5VDC is also required, but is generated on the board from the +8VDC supply by VR1, a 7805 linear voltage regulator. Capacitors C1, C2, C3, and C4 provide supply filtering at the regulator and diodes CR1 and CR2 provide transient suppression.

The +24VDC supply is used to power the opto-isolated RX_SHIELD circuit. The +8VDC supply is used in three places, to generate +5VDC, to power the LED indicator drive circuits, and as the supply voltage for the control circuit of the electronic switch in the transmit circuit (i.e. transistors Q4, Q5).

The modem board is a 4-layer PCB, and as such, employs split power and ground planes to maintain separation between the analog and digital sections of the modem. The layout is such that the separation passes through the middle of the codec (U2). Both analog and digital supply voltages are connected to the codec. The digital supply (DVDD and DGND), connect to the codec (U2) on pins 12 and 11 respectively, while the analog supply (AVDD1,AVDD2, AGND1, & AGND2), connect to pins 3, 9, 4, and 10 respectively.

Inductor L2 is a ferrite bead inductor that ties the analog (AGND) and digital (DGND) grounds together. Inductor L1 (a wire jumper) ties the analog (AVDD) and digital (DVDD) supplies together. Capacitors C21 and C22 provide filtering for the digital supply voltage (DVDD) at the codec, while capacitors C23 and C24 provide filtering for the analog supply voltage (AVDD).

Inductor L3 and capacitors C19 & C20 filter the +8V supply. The filtered voltage is used in the TXE control circuit that controls the electronic switch in the transmit circuit.

LED Indicator Drive Circuits

The modem has four LED indicators (DS1-4), which indicate the status of the data and control lines. The function of the four indicators is as follows:

DS1: Transmit Data. This indicator is "ON" whenever the TXD line to the modem is low. It indicates the modem is receiving data from the controller for it to transmit.

Opto-Isolated PTT Circuit


DS2: Receive Data. This indicator is "ON" whenever the RXD line from the modem is low. It indicates the modem is receiving data from the network and is sending it to the controller.

DS3: Request-to-Send. This indicator is "ON" whenever the BRTS line is low. It indicates that the modem is sending a transmit carrier (TC) signal.

DS4: Data Carrier Detect. This indicator is "ON" whenever the DCD line is low. It indicates that the modem's receiver is detecting a carrier signal.

The operation of the transistor drive circuit is the same for DS1-4. Circuit operation is described using the drive circuit for DS1 as an example. The biasing resistors are omitted to simplify the description.

The TXD signal is connected to the base of transistor Q6. If TXD is high, transistor Q6 will turn-on. This causes the collector voltage on Q6 to go low (i.e. DGND), which will turn-off transistor Q7. With transistor Q7 off, no collector current can flow. Since no current flows through the LED (DS1), it turns the LED "Off".

If TXD is low, transistor Q6 will turn-off. This causes the collector voltage on Q6 to go high (i.e. +8V), which will turn-on transistor Q7. With transistor Q7 on, a collector current will flow. Since the collector current flows through the LED (DS1), it turns the LED "ON".


The modem provides an optoisolated output circuit. The TXE signal from the DSP activates the circuit by turning on transistor Q1. This causes current to flow in the optoisolator input diode, which will turn-on the optoisolator output transistor. While the output transistor is "ON", it shorts RX_SHIELD to TX_SHIELD. A typical application for this circuit is activation of the Press-To-Talk (PTT) circuit in a radio, where the PTT signal is used to "Key" the transmitter in the radio to the "ON" state.


Chapter 5 — Interface Connectors

OVERVIEW

The modem contains three interface connectors (J1-3), three option headers (J4-6), fifteen programming jumpers (JP1-15), and nine testpoints (TP1-9).

Ribbon Cable Interface

J1 is a 16-pin ribbon cable interface connector. It is used to connect the modem to connector P215 on the control board in both an M3000E Master or a 3000E Secondary controller. Pinouts for the ribbon cable are as follows:

Pin Function 1 TCLK1 (NOT USED) 2 RCLK1 (NOT USED) 3 TXD 4 RESET 5 RXD 6 DTR 7 BRG1 (NOT USED) 8 RTS 9 DCD 10 CTS 11 CHASSIS 12 +24VDC 13 +8VDC 14 +8VDC 15 DGND 16 DGND

Port 3 System Interface Connector


Port 3 System Interface Connector

J2 is a 9-pin 'D' connector with male pins. This connector functions as the "Port 3" system interface connector as specified in Section 3.3.3 of the NEMA TS2 Specification - "Port 3 System Interface". Connector pinouts for J2 are as follows:

Pin Function 1 TX+ 2 TX- 3 Reserved 4 RX+ 5 RX- 6 CHASSIS 7 RX_SHIELD (Reserved) 8 TX_SHIELD (Reserved) 9 CHASSIS

Note - Pins 7 & 8 are "Reserved" pins in the NEMA TS2 Specification. The FSK modem uses pins 7 & 8 as outputs from the optoisolated PTT circuit.

'D' Module Interface

J3 is an 8-pin interface header that is used to connect the modem signals to an optional 'D' module in the controller. It is provided so that the 3000E controller can maintain compatibility with existing cabinet wiring that utilizes the interface connector on the 'D' module to connect to the communication lines. Pinouts for the header are as follows:

Pin Function 1 RX+ 2 CHASSIS 3 RX- 4 RX_SHIELD 5 TX- 6 Reserved 7 TX+ 8 TX_SHIELD

Option Headers

J4 Optional debugging header. This header is not installed.

J5, 6 Selects 2W or 4W operation. The headers are not installed. The default (in copper) is 4W.

Configuration Jumpers


Configuration Jumpers

JP1 Optional jumper to force /RESET low during isolated (i.e. stand-alone) operation. Normally open.

JP2 Optional jumper to force /DTR low during isolated (i.e. stand-alone) operation. Normally open.

JP3 A jumper (in copper) which shorts DSP pin 39 to ground. When cut, it enables the Copyright/PGM message mode. Must be shorted for normal operation.

JP4 A jumper (in copper) which shorts DSP pin 40 to ground. When cut, it enables the Copyright/PGM message mode. Must be shorted for normal operation.

JP5 Jumpers used to select alternate TC Level configuration of modem. Normally open.

JP6 Jumpers used to select alternate TC Level configuration of modem. Normally open.

JP7 This jumper must be shorted in normal operation. Selects alternate TC circuit configuration of modem.

JP8 This jumper is used to select alternate line interface configuration of modem. Normally open.

JP9 This jumper must be shorted in normal operation. Selects alternate RC circuit configuration of modem.

JP10 This jumper sets impedance of transmitter to 600 ohms, with installation being dependent on the system.

JP11 This jumper connects the center tap of transformer T1 to CHASSIS ground. Normally open.

JP12 This jumper sets impedance of receiver to value set by R48+R49. Factory default is 600 ohms. Jumper installation is dependent on the system.

JP13 This jumper connects the center tap of transformer T2 to CHASSIS ground. Normally open.

JP14 Optional jumper to connect /RESET to SE pin on CODEC. Normally open.

JP15 Optional jumper to ground pin 17 on DSP. Normally open.

Test Points


Test Points

The DSP Modem Board has 9 testpoints. Six are assigned a permanent function, and 3 are reserved for diagnostic purposes.

TP1 Ground Reference (DGND)

TP2 Reserved

TP3 RTS signal to modem, active low.

TP4 DCD signal from modem, active low.

TP5 CTS signal from modem, active low.

TP6 Reserved

TP7 Reserved

TP8 Set termination resistance of receiver, (R48 + R49).

TP9 Set termination resistance of receiver, (R48 + R49).


Chapter 6 — 9600 Baud Site Survey

SITE SURVEY - 9600 BAUD

In Hi-Speed mode (i.e. 9600 baud), the FSK modem utilizes a proprietary communications scheme that may not provide satisfactory performance over existing communication lines (i.e. cable plant) unless the network configuration is modified. The following questionnaire was developed to help identify any problems where an existing system is upgraded to run at 9600 baud.

Site Survey


Site Survey

System Location: .

Basic Layout of System: Attach drawing (sketch).

SYSTEM QUESTIONS: 1. How many locals will be connected (i.e. # drops)?

2. Where is the master in the system?

3. What is the end-to-end length of the cable?

4. Is the system configuration 4W, with the TX and RX pairs balanced?

Site Survey


5. Are the TX and RX pairs terminated?

6. Are impedance-matched power splitters used?

7. Are Loading coils used in the system?

8. Are there any Line Equalizers on the TX or RX pair?

9. Are any Line/Repeater Amplifiers used?

Site Survey


10. Are any of the drops "Leased" lines?

CABLE PLANT QUESTIONS:

11. What is the age of the cable plant?

12. What is the Physical condition of the cable plant?

13. What is the cable Manufacturers part number(s)?

14. What is the gauge of the wires?

Site Survey


15. How many pairs are in the cable?

16. Are there any spare pairs in the cable?

17. How are the spare pairs terminated?

18. Are there any cable splices?

19. On Aerial runs, is the Messenger cable strand grounded?

Site Survey


20. Do any of the pairs carry AC/DC Power?

21. Does the cable run in the same conduit as a high voltage power cable?

22. What cable shield grounding method is used - Single Point or Grounded Sections?

Site Survey


CABINET QUESTIONS: 23. Do the communication lines terminate directly in the cabinet?

24. What is the Communication Line Transient Suppressor?

TEST QUESTIONS: (OPTIONAL)

25. What level of 60Hz "Hum" is present on the cable pairs?

26. What is the signal level caused by "Crosstalk" between cable pairs?

27. What is the noise floor on the TX and RX pairs?

Site Survey


28. What is the signal level at the last controller in each direction from the master?

29. What is the signal level at the master from the last controller in each direction?


Chapter 7 — Line Termination

OVERVIEW

Termination of the network lines is one of the most important issues in properly setting up a system. Proper line termination will compensate (i.e. equalize) the lines to minimize the distortion of a signal transmitted over twisted-pair wires. This is especially important at data transmission speeds greater than 1200 baud. Signal distortion occurs for many reasons, amplitude distortion, echo, phase changes, noise, etc, to name just a few.

Appendix I contains a white paper entitled "Termination of Lossy Twisted-Pair Multidrop Networks" which discusses line termination in some detail. The user is encouraged to read this paper to help develop a better understanding of the importance of proper line termination. The paper investigates the effect of termination resistance on the quality of received signals transmitted across twisted pair lines organized in a multidrop, point-to-multipoint network.

The following four methods are recommended based on the findings of this paper.

Method One - Distributed Equivalent Termination @ each node

Method Two - 600 Ohms/Mile Termination @ each node

Method Three - 600 Ohm Termination @ each node

Method Four - Termination @ Branch Ends Only




This method places shunt termination resistors at each node in the network. The value of each termination resistor depends on the length of the run between nodes. The modem is configured to use EXTERNAL termination (i.e. JP10, JP12 are open).

First calculate Rs, the shunt resistance per unit length, using formula Rs = L/RC, where values for R, L, & C depend on the wire gauge of the cable in the system. Typical values for Rs based on wire gauge are as follows:

Wire Gauge Rs R L C

19 AWG: 143.94 ohms/mile 83.7 ohms/mile 1 mH/mile 83nF/mile 22 AWG: 72.02 ohms/mile 167.3 ohms/mile 1 mH/mile 83nF/mile 24 AWG: 45.38 ohms/mile 265.5 ohms/mile 1 mH/mile 83nF/mile 26 AWG: 28.15 ohms/mile 428.0 ohms/mile 1 mH/mile 83nF/mile

Then, for each node in the system, calculate Rn (node shunt resistance), using formula Rn = Rs/y, where y is segment length from last node.

EXAMPLE:

The following example illustrates the method for determining the value of the termination resistors in a system that consists of a master and five local controllers. The following assumptions apply:

Cable is #19 AWG (Rs = 144 ohms/mile).

System is 4W full duplex.

EXTERNAL termination is employed.

Master is in same cabinet as local #1.

Segment length y is cable length, not distance between intersections.

Resistors R1-5 are shunt terminators on the command transmission line.

Resistors R6-10 are shunt terminators on the response transmission line.



3/8 mi 1/4 mi 3/4 mi 1/2 mi

R1 R2 R3 R4 R5Rxmt

1 2 3 4 5

Figure 17 — Command Transmission Line of cable network using distributed termination scheme

Rxmt: This is the impedance of the transmit circuit in the modem. It has two states as follows:

"ON" State: Nominal value 88 ohms.

"OFF" State: Hi-Z (> 24K ohms), w/ JP10 open.

Rrcv: This is the impedance of the receive circuit in the modem. It has one state w/ JP12 open: Hi-Z (> 24K ohms).

R1: To calculate the value for R1, the segment length y is the distance between the master and the local in the same cabinet = 20'.

5280201441 =R = 38K ohms not required (provided by Hi-Z impedance of local

#1 receiver)

R2: To calculate the value for R2, the segment length y is the distance from node 1 2 = 3/8 mile.

375.01442 =R = 384 ohms 390 ohms (5%)


250.01443 =R = 576 ohms 620 ohms (5%)




750.01444 =R = 192 ohms 200 ohms (5%)


500.01445 =R = 288 ohms 300 ohms (5%)

Rrcv

2 1/4 mi

R788

3 3/4 mi

R888

51/2 mi

R1088

1 3/8 mi

R688 R988

4

Figure 18 — Response Transmission Line of cable networks using

distributed termination scheme





R6: The value for R6 is calculated assuming node 2 is transmitting. The segment length y is therefore the distance from node 2 1 = 3/8 mile.



375.01446 =R = 384 ohms 390 ohms (5%)

R7: The value for R7 is calculated assuming node 3 is transmitting. The segment

length y is therefore the distance from node 3 2 = 1/4 mile.

250.01447 =R = 576 ohms 620 ohms (5%)



750.01448 =R = 192 ohms 200 ohms (5%)



500.01449 =R = 288 ohms 300 ohms (5%)

R10: The value for R10 is calculated assuming node 4 is transmitting. The

segment length y is therefore the distance from node 4 5 = 1/2 mile.

500.014410 =R = 288 ohms 300 ohms (5%)

Advantages Provides closest approximation to a distortionless transmission line.

The method is based on the wave equation and yields superior results to any of the other three methods.

Signal is insensitive to source impedance variations.

Less susceptible to induced noise than other methods.

Disadvantages More difficult to implement. Two values must be calculated and installed at each

node.



Shunt termination across each remote transmitter reduces the output level.

Lowest output TC level.

Transmit for shorter distances for given receiver sensitivity.


This method places shunt termination resistors at each node in the network. The value of each termination resistor depends on the length of the run between nodes. The modem is configured to use EXTERNAL termination (i.e. JP10, JP12 are open).

For each node in the system, calculate Rn (node shunt resistance), using formula Rn = Rs/y, where y is segment length from last node, and the value for Rs is assumed to be 600 ohms/mile.

EXAMPLE:


Cable is #19 AWG (except Rs = 600 ohms/mile).





Resistors R1-5 are shunt terminators on the command transmission line.

Resistors R6-10 are shunt terminators on the response transmission line.



3/8 mi 1/4 mi 3/4 mi 1/2 mi

R1 R2 R3 R4 R5Rxmt

1 2 3 4 5

Figure 19 — Command Transmission Line of cable network using 600 ohms/mile termination scheme.





R1: To calculate the value for R1, the segment length y is the distance between the master and the local in the same cabinet = 20'.

5280206001 =R = 158.4K ohms not required (provided by Hi-Z impedance of

local #1 receiver)


375.06002 =R = 1600 ohms 1.6K ohms (5%)




250.06003 =R = 2400 ohms 2.4K ohms (5%)


750.06004 =R = 800 ohms 820 ohms (5%)


500.06005 =R = 1200 ohms 1.2K ohms (5%)

Rrcv

2 1/4 mi

R788

3 3/4 mi

R888

51/2 mi

R1088

1 3/8 mi

R688 R988

4

Figure 20 — Response Transmission Line of cable network using 600 ohms/mile termination scheme





R6: The value for R6 is calculated assuming node 2 is transmitting. The segment length y is therefore the distance from node 2 1 = 3/8 mile.



375.06006 =R = 1600 ohms 1.6K ohms (5%)



250.06007 =R = 2400 ohms 2.4K ohms (5%)



750.06008 =R = 800 ohms 820 ohms (5%)



500.06009 =R = 1200 ohms 1.2K ohms (5%)



500.060010 =R = 1200 ohms 1.2K ohms (5%)

Advantages Provides acceptable termination to approximate a distortionless transmission line.

Signal is relatively insensitive to source impedance variations.

Highest output TC level.

Termination most accurate with #19AWG wire.

It is a distributed scheme, so it yields less distortion than end termination scheme.

Disadvantages: Two values must be calculated for each node.

Not a true "Distortionless" transmission line, because it ignores wire gauge, assumes Rs = 600 ohms.

Benefit of 600 ohm/mile termination decreases with increasing wire gauge.




This method places shunt termination resistors at each node in the network. The value of each termination resistor is 600 ohms. The modem is configured to use INTERNAL termination (i.e. JP10, JP12 are closed).

Advantages Provides better approximation to distortionless transmission line than method two.

Signal is insensitive to source impedance variations.

Simplest termination scheme, modem provides the termination.

It is a distributed scheme, so it yields less distortion than end termination scheme.

Disadvantages: Shunt termination across each remote transmitter reduces the output level.

Intersections spaced close together will effectively shunt line with a low termination value.

Due to attenuation losses, distance limited to five miles.




This method utilizes shunt termination of the communications lines at the branch-ends only.

This method places shunt termination resistors at the end of each branch in the network. The value of each termination resistor depends on the length of the run. The modem is configured to use EXTERNAL termination (i.e. JP10, JP12 are open).

First calculate Rs, the shunt resistance per unit length, using formula Rs = L/RC, where values for R, L, & C depend on the wire gauge of the cable in the system. Typical values for Rs based on wire gauge are as follows:

Wire Gauge Rs R L C

19 AWG: 143.94 ohms/mile 83.7 ohms/mile 1 mH/mile 83nF/mile 22 AWG: 72.02 ohms/mile 167.3 ohms/mile 1 mH/mile 83nF/mile 24 AWG: 45.38 ohms/mile 265.5 ohms/mile 1 mH/mile 83nF/mile 26 AWG: 28.15 ohms/mile 428.0 ohms/mile 1 mH/mile 83nF/mile

Then, for each branch-end in the system, calculate Rn (branch-end shunt resistance), using formula Rn = Rs/y, where y is length displacement from source.

EXAMPLE:


Cable is #19 AWG (Rs = 144 ohms/mile).





Resistor R1 is a shunt terminator on the command transmission line.

Resistor R6 is a shunt terminator on the response transmission line.



3/8 mi 1/4 mi 3/4 mi 1/2 mi

R5Rxmt

1 2 3 4 5

Figure 21 — Command Transmission Line of cable network using

Branch-end termination scheme.





R5: To calculate the value for R5, the termination resistor at the branch-end, the segment length y is the distance from node 1 5 = 3/8 + 1/4 + 3/4 + 1/2 mile = 17/8 miles

875.11445 =R = 76.8 ohms 75 ohms (5%)

Rrcv

2 1/4 mi

88

3 3/4 mi

88

51/2 mi

88

1 3/8 mi

R688 88

4

Figure 22 – Response Transmission Line of cable networks using Branch-

End termination scheme



R6: The value for R6 is calculated assuming node 5 is transmitting. The segment length y is therefore the distance from node 5 1 = 1/2 + 3/4 + 1/4 + 3/8 mile = 1 7/8 miles

875.11446 =R = 76.8 ohms 75 ohms (5%)

Advantages Approximates performance of a "Distributed" scheme by using an equivalent

termination at the branch-ends.

Transmitter output level not reduced by shunt resistance at intermediate nodes.

Only two values to determine in a system with N nodes.

Disadvantages Intermediate nodes suffer a higher level of distortion than branch end node.

Exhibits more distortion than a true "Distributed" scheme.


Chapter 8 — Maintenance

OVERVIEW

Unit Replacement

The FSK modem, if faulty, should be removed from the controller and replaced with a known good unit.

Internal Diagnostics

The 'E' series controller units have a diagnostic program. Activation and operation of the diagnostic routine is described in the "'E' Series Controller Diagnostic Manual", that can be ordered from your distributor or from Peek. Note that the diagnostic program is not intended as a field troubleshooting procedure, but as a shop test. A special cable is required and the outputs and indications do not operate normally. Also, once executed, the unit must be restarted to exit the diagnostic routine.

Fold Down Panel

To access the 3000E circuitry, fold down the front panel after pressing the latch on the top of the unit. This will expose all boards, which are fastened by retaining clips. Disconnect the interface ribbon cable plugged into connector P215 on the control board, and the optional 'D' modules interface harness if it is installed. To remove the FSK modem board, depress the catch on the top most standoff post, and gently lift the board clear of the top two posts. Gently pull the board until it is free of the bottom two support posts, and can be lifted out of the controller.

Software Upgrading


Software Upgrading

The FSK modem program can be upgraded when a revision is necessary. The DSP is a "Flash" based processor, and was designed to be easily upgraded using a proprietary flash loader program in order to upgrade the modem program without requiring removal of any parts on the board. Program upgrades, when necessary, utilize the 16-pin ribbon cable interface, and must be performed at the factory.

Integrated Circuit Removal & Replacement

An IC is not a discrete component but a functional circuit (or circuits) within itself. Furthermore, since an IC cannot be repaired it is only necessary to determine:

1. That the IC is defective, generally by replacement with one known to be good.

2. That the defect was not caused by some other circuit malfunction. If it has been shown definitely that an IC is defective it must be replaced.

Surface Mount Technology

The FSK modem board predominantly uses surface mounted IC components. Although this technology provides benefits on reliability, size, and performance, it does require different techniques in removing and replacing these components. The following equipment is required as a minimum to repair surface mount assemblies.

Manual Station

This workstation is the minimum required and would consist of a well-lighted work area, grounded to prevent static electricity damage to the electronic components, and a set of tools similar to the list below.

Tweezers Small tip soldering ion Temperature indication lacquer Braided solder wick Solder paste syringe dispenser RMA flux Hot air repair station Heat shields

Several sizes of tweezers will be required to handle all packages, from small chip components to the 100-pin QFP DSP IC. Some irons have special de-soldering tips that can be used for almost all-small SMC's in addition to standard soldering tips. Also, there are individual de-soldering tools that appear to be the equivalent of "Hot tweezers" that are designed to remove a specific size of SMC.

Temperature indicating lacquers are useful for safe removal of a defective component. A temperature on the low side (184oC) is preferable, as the body heats a little slower

Bench Repair


than the leads. The braided solder wick is a standard item sold by most electronic shops.

Bench Repair

The major factor is the ability to remove and replace a defective component. The tools listed under the manual station will be necessary. The best procedure to follow for removal and replacement is listed below. Step 11 would be accomplished by using the repair station with due care to monitor the solder reflow, removing the heat immediately after the solder has achieved a thorough reflow. In an emergency situation, a component can be attached by using tweezers, soldering iron, and solder paste. Careful application of heat and solder is still the important issue. Clean up can be achieved by using an aerosol spray can of appropriate solvent.

Procedure

1. Correctly identify the defective component.

2. Paint a small amount of temperature sensitive lacquer on the defective component.

3. Setup the repair station and adjust the temperature controls according to board size and component mass.

4. Place the board on the repair station, centering the component under the hot air outlet.

5. Place a heat shield over the adjacent components or place the vacuum collet on the defective component.

6. Begin applying heat.

7. When the temperature sensitive lacquer gives a positive indication, remove the unit with tweezers and remove hot air from the board. On semi-automatic stations, the vacuum collet will lift the unit and redirect the hot air.

8. The footprint must be cleaned of excess solder with a soldering iron and solder wick to achieve smooth, planar lands.

9. Use the solder syringe dispenser to put a proper and even amount of solder paste on each component land.

10. Place the component with care to get it correctly aligned.

11. Reflow and clean by using the reflow and clean-up equipment.

12. Inspect the solder connections for bridging, poor solder joints, etc. Touch-up as required.

Parts Lists


Parts Lists

A parts list is provided for most component parts including Peek part number as well as manufacturer's part number. Most are available from standard electronic supply houses, except for those specified as Peek only. For those listed by a specific manufacturer's part number, please exercise caution when obtaining "substitute" or "equivalent" parts other than the part and manufacturer listed. Only those manufacturers and part numbers approved by Peek are suitable. Suffice it to say that all parts are not created equal. The design characteristics and performance of individual parts do make a difference, and in many cases we do choose specific parts from specific manufacturers for a reason. When in doubt, consult your distributor or Peek Traffic Systems Inc.

Parts List - FSK Modem Board TL-8884

Part Number Description Comp Mfr's Part Number Reference Designator Capacitors 121C25-475 CAP TANT SMD 4.7UF 20V Sprague 293D475X9020C2T C1 121C23-226 CAP TANT SMD 22UF 16V Sprague 293D226X9016D2T C3,19 121C01-104 CAP SMT .1UF 50V CER(1206) Murata Erie GRM42-6Y5V104Z050BD C2,4,7-18,20,22,24,25,28 121C03-060 CAP CER SMT 6PF 50V Murata Erie GRM42-6COG060D50V C5,6 121C23-106 CAP TANT SMT 10UF 16V Sprague 293D106X9016B2 C21,23 121C02-102 CAP SMT 1000PF 50V CER Murata Erie GRM42-6X7R102K050BD C26,27 121C25-335 CAP TANT SMT 3.3UF 20V Sprague 293D335X9020B2 C29,30 121C26-475 CAP TANT SMT 4.7UF 35V Sprague 293D475X9035C2 C31 Resistors 121E02-104 RES SMT 4.7K OHMS (1206) KOA RM73B2BT472J R24,26,38,39,45,56,60,64,68 121E02-112 RES SMT 10K OHMS (1206) KOA RM73B2BT103J R3-8,40,43,44,54,55 121E02-064 RES SMT 100 OHMS (1206) KOA RM73B2BT101J R1,2,10 121E02-088 RES SMT 1K OHMS (1206) KOA RM73B2BT102J R22,34,35,59,63,67,71 121E02-048 RES SMT 22 OHMS (1206) KOA RM73B2BT220J R28,30,32,33 121E02-136 RES SMT 100K OHMS (1206) KOA RM73B2BT104J R36,37 121E06-3010 RES SMT 301 OHMS 1% (1206) KOA RK73H2BT3010F R41,42 121E04-098 RES SMT 2.7K OHMS (2010) KOA RM73B2BT272J R46 121E06-6040 RES SMT 604 OHMS 1% (1206) KOA RM73H2BT6040F R47 121E02-076 RES SMT 330 OHMS (1206) KOA RM73B2BT331J R49 1416 RES FILM 22 OHM .5W 5% R50-53 120K72-501 POT MULTI TURN 500 OHMS Bourns 3260W-1-501 R48 121E02-096 RES SMT 2.2K OHMS (1206) KOA RM73B2BT222J R25,57,61,69 121E02-080 RES SMT 470 OHMS (1206) KOA RM73B2BT471J R27 121E02-072 RES SMT 220 OHMS (1206) KOA RM73B2BT221J R9,11-21,23



9680A RES O (ZERO) OHMS (1206) KOA RM73Z2BT R29,31 121E03-075 RES SMT 300 OHMS (1210) KOA RM73B2E301J R58,62,66,70 Resistor Networks 121E51-104 RES NTWK SMT 4.7K 8-ISO Bourns 4816P-001-472 RN1 121E51-112 RES NTWK SMT 10K 8-ISO Bourns 4816P-001-103 RN2,3 Inductors 043303 INSULATED JUMPER WIRE Vestal Electronics IN1057 L1 120J07-001 INDUCTOR FERRITE BEAD Murata Erie BL01RN1-A62 L2,3 Integrated Circuits 9646 CHIPSET FOR FSK MODEM Peek part number U1 9647 CODEC FOR DSP CHIPSET Peek part number U2 120G08-001 OSCILLATOR SMT 15MHZ Saronix NTHA6HC-15.0000 U3 2544 MOC8050 OPTO DARLINGTON Motorola MOC8050 U4 Transistors 120E35-002 TRANSISTOR NPN MMBTA06 Motorola MMBTA06 Q1-13




Part Number Description Comp Mfr's Part Number Reference Designator Indicators 9676A INDICATOR, LED SMT RED Dialight 597-3001-207 DS1-4 9677A LIGHTPIPE, PLASTIC SINGLE Dialight 515-1001 OLP1-4 Diodes 121D50-4005 DIODE SMD 1N4005 (SOD87) Amperex BYD17J CR1,2 2340 ZENER 1N5364 33V 5W 5% Motorola 1N5364B CR3 Miscellaneous 120P34-007 5 HEADER SGL ROW STRAIGHT Amp 87224-5 TP1-5 120P34-008 SINGLE TESTPOINT 1X1 Amp 103185-1 TP8,9 3477 XFMR P600 OHM S600 OHM Dale TA-10-04 T1,2 120G06-001 SMT XTAL 40MHZ Saronix SRX6210 Y1 2580 REGULATOR +5V 7805 Motorola MC7805CT VR1 3478 VAR 5.5VDCM 100A@ 8X20US General Electric 08Z1 VR2-5 3480 VAR 200VDCM 4KA @ 8X20US General Electric V150LA10A VR6-9 8255A RIBBON CABLE 3000E COMM Peek part number J1 5160 D-SUB 9PIN MALE R/A METAL Amp 747840-2 J2 5155 HEADER 2X4 SHROUDED Amp 102618-2 J3 120P33-014 HEADER 2 X 7 .100 Amp 87227-7 J4 4118 PRGM HEADER 3P SGL ROW Amp 102885-3 J5,6 9678A SWITCH, DIP SMT 8 POS Bourns SDMR-08-T SW1,3 9679A SWITCH, ROTARY BIN SMT 8 Bourns 7743G-001-008 SW2 060463 HEADER SIP 2P .100SP GLD- Amp 87224-2 JP7,8,10-13 4120 PROGRAM JUMPER .100 Amp 531220-7 JP7,8,10-13 3667 D-SUB LATCH BLOCK Amp 208101-8 J2 1281 SCREW PNHD 4-40 .375" SS J2 2063 WASHER SPLIT LOCK #4 SS J2,VR10 1672 SCREW PNHD 4-40 .250" SS VR1 1286 NUT, HEX 4-40 SS VR1 1708 RIVET, POP .125 X .250" Pop Fasteners AD43ABS 8243A 3000E DSP FILLER BRKT Peek part number 8883 FSK MODEM CIRCUIT BOARD Peek part number

Overview


Schematic & Assembly Drawings

Schematic Diagrams

TX-8883 Sh1 Schematic Diagram, 3000E FSK modem Board (DSP)

TX-8883 Sh2 Schematic Diagram, 3000E FSK modem Board (Codec)

Assembly Drawing

TL-8884 Board Assembly, 3000E FSK modem Board

Schematic & Assembly Drawings


Introduction


Chapter 9 — Termination of Lossy Twisted-Pair Multidrop Networks

INTRODUCTION

This paper investigates the effect of termination resistance on the quality of received signals transmitted across twisted pair lines organized as a multidrop, point-to-multipoint network. Among other applications, such networks are typically in traffic control systems where twisted pair wires, usually of telephone cable quality, are used as a means of communication between a central site and distributed control stations. The motivation behind this investigation is to determine to what extent termination resistors can enhance the effective communication bandwidth by equalizing the received signal. This would have the effect of minimizing the training interval, which is especially important, when communication consists of short bursts of data.

This paper is divided into five sections. The second section derives equations for the propagation of electromagnetic waves over transmission lines. Signal pulse dispersion is primarily attributed to different frequencies traveling at different rates over long transmission lengths. This results in pulse dispersion. Conditions are derived which enable all frequencies within the band of interest to propagate at the same rate and thereby eliminate this type of dispersion. While these conditions cannot be strictly achieved in most situations, attempting to approximate these conditions leads to some rules of thumb for determining the value of termination resistors in a multidrop twisted pair network.

The third section uses simulation of some network topologies to demonstrate the effectiveness of the termination scheme. The fourth section compares the result of simulations to field measurements. The fifth section provides summarizes our results.

Introduction


Modeling Propagation in Transmission Lines

The behavior of signals through such cables can be simulated through the use of an LCRG approximation:

L/2 L/2 R/2R/2

C G

Figure 23 — Circuit approximation of a section of twisted pair cable. L is the inductance per unit length, C is the capacitance per unit length, G is the conductance per unit length between the wires and R is the series resistance per unit length.

Analog simulation programs based on Berkeley's Spice3f4 contain a cable model based on Figure 23 as an integral part of the package. The conductance, G, which is on the order of 0.1 microsiemens per mile (10 MΩ), is ignored without a significant impact on the accuracy of the model. For telephone cable, C is standardized during manufacture to be 66 or 83 nF per mile with 83 nF being the most common [1]. L is approximately 1 mH per mile but decreases to about 70% of this value as frequency increases from 50 kHz to 1 MHz due to a phenomena known as skin effect wherein higher frequencies travel closer to the surface of a conductor. R is dependent on the gauge of the twisted wire and is 83.7, 167.3, 265.5 and 428.0 ohms/mile for 19, 22, 24, and 26 gauge wire, respectively.

A typical traffic system’s communication network is composed of several miles of twisted wire cable interconnected in an ad hoc fashion. A cable may be tapped at any point to form a star or a network of branches of various lengths. In many cases, impedance matched power splitters are not used for interconnection. For Bell 202 communication at 1200 baud, typical source and destination impedance terminators are 600 ohms. Such high resistance values are not necessarily optimal for communicating at rates greater than or equal to 9600 baud. It is unknown to what extent the traffic system vendor is able to influence communication system practices but it is expected that the less labor intensive the requested changes in procedure, the more likely is their adaptation. For example, it is expected to be easier to influence how signal sources and cable branches are terminated than it is to require retrofitting interconnect junctions with impedance matched power splitters.

The current simulation study was initiated with two major goals in mind. The first was to obtain some rules of thumb for terminations that could be used in the field, which would result in acceptable signal quality in most situations. The second was to obtain qualitative and quantitative estimates of the pulse response at various points of an

Modeling Propagation in Transmission Lines


adhoc traffic network, with and without correct terminators, to assess their suitability for communication.

The characteristic impedance of the twisted pair cable, whose model is shown in Figure 23, is given by the relation:

Z0 = R + jωLG + jωC (1)

Here, it must be recalled that the parameters R, L, G and C are distributed throughout the line. Over the communication distances (~ 5 miles) and frequencies of interest, we would like to establish an equation which describes the propagation of waves of various frequencies along the line. As we shall see, the most significant effect for lossy lines whose impedance is given by (1) is that different frequency components travel at different velocities. However, a distributed termination scheme, one which is well suited to a multi-drop network, ameliorates the situation tremendously.

Let V(z) and I(z) be the voltage and current at a position z along a transmission line. At a fixed time instant, the change in voltage with respect to a change of position along the line is given by the relation:

dV(z)

dz = (R + jωL)I(z) (2)

Similarly, at a fixed time instant, the change in current with respect to a change in position along the line is given by the companion relation:

dI(z)dz = (G + jωC)V(z) (3)

The wave equation is obtained by taking the derivative of (2) and substituting (3) into the resulting equation to yield:

d2V(z)

dz2 = (R + jωL)(G + jωC)V(z) (4)

This second order differential equation has a solution of the form:

V(z) = V0 e−ρz (5)

Introduction


which, when substituted into (4) yields the well known dispersion relation:

ρ2 = (R + jωL)(G + jωC) (6)

where ρ, which is called the propagation constant, is complex. The significance of (6) is that it tells us the attenuation of various frequency components along the line. By rewriting ρ in the form

ρ(ω) = α(ω) + jβ(ω) (7)

and substituting back into (5), it is clear that if α is a function of frequency then, in general, different frequency components will be attenuated by different amounts. Since pulses used to communicate signals are composed of many frequency components, they can become severely distorted when different constituent frequency components are attenuated differently. Thus, the first step to reducing pulse distortion is to force the real part of ρ, i.e., α, to be independent of frequency. To see how to do this, let us rewrite (6) in the form:

ρ = jω LC ⎝⎜⎛

⎠⎟⎞1 +

RjωL

⎝⎜⎛

⎠⎟⎞1 +

GjωC (8)

From (8), it is evident that if

RL =

GC (9)

then

ρ = jω LC ⎝⎜⎛

⎠⎟⎞1 +

RjωL

⎝⎜⎛

⎠⎟⎞1 +

RjωL = R

CL + jω LC) (10)

and a comparison with (7) indicates that α is now independent of frequency.

In a traffic cable network, shunt elements are easier to control than series elements since the latter would require adding elements in series with the cable either periodically or at branch points while the former simply requires controlling the shunt termination at a distribution point or terminal. Since, for the telephone grade cables of interest, R/L is greater than G/C, the condition implied by (9) requires us to increase G, the conductance per unit length. This can approximately be achieved by periodically

Simulation Study


shunting the cable with a resistor. In this approximation the desired distributed conductance is integrated over the span of a cable segment and converted into a lumped equivalent shunt conductance at one or both ends of the segment. Thus, if the desired conductance is G per unit length l, then, for a cable segment having a negligible conductance over its span, an approximate equivalent conductance can be realized for a segment of length y by placing a resistor whose value is 2l /Gy at both ends or l /Gy at one end of the span. The value of the resistor is dependent on the length of the run between nodes. Obviously, the quality of this approximation deteriorates with the length of the span between shunt terminations. For extremely long spans, this rule results in shunts of high conductance and commensurately high signal attenuation. Such spans should be driven with as low an impedance as possible at their source and terminated at the destination with approximately 120 ohms. For 19 gauge cable with 83nF/mile distributed capacitance, G = 1/144Ω and the resulting attenuation per mile is 6.7 dB. We now illustrate the use of this termination technique with simulations in the following section:

Simulation Study

A five mile span of 19 gauge twisted pair cable fed at one end by a voltage source which generates a 100 microsecond pulse is illustrated in Figure 24. (For simplicity of illustration

1 mi 1/4 mi 1/4 mi 1/2 mi 2 mi 1 mi

144 144 576 576 288 72 144

2 3 4 5 6 7 8

Figure 24 — Simulated cable network to illustrate the effectiveness of distributed termination scheme

the twisted pair cable is drawn as a coax with a ground reference for the sheath). With the typical parameters R = 83.7Ω/mile, C = 83 nF/mile, and L = 1 mH/mile and G ≈ 10−7 siemens/mile, we find that a shunt of 144 ohms each mile is required to force the conditions derived in (9) above. This implies that a value four times greater than this for a run length of ¼ mile (576Ω), a value of 288Ω for ½ mile, and a value of 72Ω for a two mile run. A Spice simulation of Figure 24 was conducted. The resulting waveforms, with a 1 volt, 100 microsecond pulse as an input, are shown in Figure 25 and Figure 26.

Introduction


0.0 0.1 0.2mS time-0.1

0.1

0.3

V

v(3) v(4) v(6)

v(5)

Figure 25 — Response to a 1 volt, 100 μsec. pulse at nodes 3, 4, 5 and 6 of Figure 24

time0.0 0.1 0.2mS-10

0

10

20

30

40

mV

v(7) v(8)

Figure 26 — Response to a 1 volt, 100 μsec. pulse at nodes 7 and 8 of Figure 24

Simulation Study


As expected, there is an increase in attenuation with increasing distance from the source (note the difference in voltage scale between Figure 25 and Figure 26). The pulse distortion, on the other hand, is quite small considering the wide range of frequency components. Furthermore, with the source on one end of a single cable span as shown in Figure 24, the pulse distortion seen at the nodes is quite insensitive to the source impedance which only affects the pulse amplitude. Thus, the signal amplitude can be maximized by minimizing the source impedance with minimal effect on pulse distortion. This result is not unexpected since the effect of distributed terminators effectively is to make the cable “self terminating”.

Increasing the cable length between successive shunt terminators results in increasing pulse distortion. An examination of the pulse waveform for node 7 in Figure 26, which represents two miles between terminators, shows a slight increase in pulse distortion. To dramatize the effect, we graph the pulse shapes that result from a doubly terminated five mile cable span. That is, for the full five mile span, we use a source resistance of 144Ω/5 = 28.8Ω, a terminating resistance of 28.8Ω, and an infinite shunt impedance at intermediate nodes. The results are shown in Figure 27 and Figure 28. Note that most of the pulse distortion is due to the filtering of higher frequency components by the cable. If a communication system can tolerate this pulse distortion then it may be that the doubly terminated line is preferable to distributed termination. Note especially the minimal distortion of the pulse seen at the end of the span. One caveat here is that, unlike for more distributed termination, the pulse distortion is quite sensitive to value of the source terminator. The pulse at the end (node 8) of the doubly terminated line with a source resistance of 144Ω and a node 8 terminator of 28.8Ω is shown in Figure 29 .

time0.0 0.1 0.2mS-0.1

0.1

0.3

0.5

0.7

0.9

V

v(3) v(4) v(5) v(6)

Figure 27 — Pulse responses for nodes 3, 4, 5, and 6 for the doubly terminated line

Introduction


time0.0 0.1 0.2mS-0.1

0.0

0.1

0.2

0.3

0.4

V

v(7) v(8)

Figure 28 — Pulse responses for nodes 7 and 8 for the doubly terminated line

time0.0 0.1 0.2mS0

10

20

30

40

50

60

mV

v(8)

Figure 29 — Pulse shape at node 8 when the source impedance is 144 ohms and the termination is 28.8 ohms at node 8. There were no terminators in between

Next, we investigate the effect of relocating the source to the center of the line. What should the source termination be in this case? We have already mentioned that for the case of distributed termination, the pulse shape is relatively insensitive to source impedance variations. Thus, when transmitting, providing maximum power to the loads for a given maximum source voltage requires us to minimize the source impedance.

Simulation Study


However, for practical considerations, (e.g., circuit protection) it should not be zero but may be as high as 50 to 100 ohms. The network in Figure 30 was simulated.

1 mi1/4 mi 1/4 mi 1/2 mi 2 mi 1 mi

144576 576 288 72 144

2 3 4 5 6 7 8

28.8

Figure 30 — Network with source located at an intermediate node

time0.0 0.1 0.2mS

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

V

v(2) v(4) v(5) v(6) v(7) v(8)

Figure 31 — Family of pulse responses when the source is located at node 4 with a source impedance of 28.8 ohms as shown in Figure 30.

The pulse responses, in order of decreasing amplitude, are for nodes 4, 5, 6, 2, 7, and 8.

Suppose now the network of Figure 30 is doubly terminated with the distributed equivalent termination at both ends (we still assume a 28.8Ω source impedance) and infinite impedance at intermediate nodes as shown in Figure 32. The impedance of the destination ends is referenced with respect to their displacement from the source – 3¼ miles and 1¼ miles. The family of node pulse responses is shown in Figure 33. Once

Introduction


again, it is clear that distributed termination achieves less pulse distortion. As before, the least distorted pulse shape occurs at the nodes with the terminators.

1 mi1/4 mi 1/4 mi 1/2 mi 2 mi 1 mi

115 44

2 3 4 5 6 7 8

28.8

Figure 32 — A doubly terminated network with distributed equivalent terminators at both ends

time0.0 0.1 0.2mS

-0.1

0.1

0.3

0.5

0.7

0.9

V

v(2) v(4) v(5) v(6) v(7) v(8)

Figure 33 — Pulse amplitudes for the network of Figure 32

In decreasing amplitude, as measured at the center of each pulse, the responses are for nodes 4, 5, 6, 2, 7, and 8.

Simulation Study


time0.0 0.1 0.2mS

v(2) v(4) v(5) v(6) v(7) v(8)

-1

0

1

V

Figure 34 — Pulse responses when the source impedance in Figure 32 is reduced from 28.8 to 1 ohm

Next, we would like to consider an ad hoc type of cable network. This network is characterized by “T” junctions or star junctions at random locations along a five mile span. How should the junction nodes and branch ends be terminated? Once again we conjecture that the best termination would be one which approximates the optimum distributed equivalent shunt terminator as dictated by Eq. (9). When several branches are joined at a single node, they create an impedance which is less than that dictated by (9). For the purpose of calculating the distributed equivalent termination impedance for adjacent nodes, this lower impedance node may be treated as a low impedance virtual source as we now demonstrate.

Consider the network shown in Figure 35. Here, we have simply followed heuristic rules for the in-line cable in selecting the shunt resistors. Figure 36, Figure 37, and Figure 38 show that there is relatively little pulse distortion caused by the star distribution at node 5. This is because from the standpoint of nodes adjacent to node 5, node 5 has a low enough impedance that it may itself be considered as the signal source. Any reflections which occur at this node are quickly absorbed by the shunt resistors at adjacent nodes.

Introduction


1 mi 1 mi 1 mi 1 mi

25 144 144 144

2 3 4

5

61 mi

7

1 mi8

1 mi9

1 mi10

144 144

144

144

144

Figure 35 — Simulated Cable Network with a Star Junction Node and Distributed Termination

time0.0 0.1 0.2mS-0.1

0.0

0.1

0.2

0.3

0.4

V

v(4) v(3)

Figure 36 — Pulse Shape at Nodes 3 and 4 for the Network of Figure 35

Simulation Study


time0.0 0.1 0.2mS-10

0

10

20

30

40

50

60

mV

v(5) v(6) v(8)

Figure 37 — Pulse Shapes for Nodes 5, 8 and 6 (listed in decreasing pulse amplitude) for the Network of Figure 35

Responses at nodes 9 and 10 are identical to node 8.

time0.0 0.1 0.2mS-10

0

10

20

mV

v(7) Filtered

Figure 38 — Pulse Shape at Node 7 for the Network of Figure 35

Also shown is pulse response filtered by an RC lowpass whose response is −3dB at 20 kHz.

Introduction


Next, we would like to compare the performance of the network with distributed terminators shown in Figure 35 to one which only has terminators at the most remote (with respect to the source) branch ends as shown in Figure 39. Note that because node 5 represents a low impedance, unlike the case of the inline cable, the terminators for the branches are calculated as if node 5 were the source. Although, for some nodes, the pulse distortion is greater than for the network of Figure 35, the pulse shapes are quite good. Furthermore, the pulse amplitudes are 10dB greater at the nodes most distant from the source – a fact which might outweigh the significance of the increased distortion.

We close this section with a remark about higher gauge cables having increased distributed series resistance R. In general, the greater the series resistance, the greater the benefit of distributed termination. Even though pulse shapes might be well preserved, the larger the value of R, the smaller the value of the distributed shunt resistance (L/RC) for a given length of cable and, consequently the greater the attenuation per unit length. Eventually, a threshold is reached at some distance beyond which the signal level becomes less than the system is capable of detecting. It is unremarkable that the larger the value of R, the shorter the maximum transmission distance.

1 mi 1 mi 1 mi 1 mi

25

2 3 4

5

61 mi

7

1 mi8

1 mi9

1 mi10

144

144

144

72

Figure 39 — Star Network in Which Only the Branch Ends are Terminated

Simulation Study


time0.0 0.1 0.2mS-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

V

v(4) v(3)

Figure 40 — Pulse shapes at Nodes 3 and 4 for the Network of Figure 39

time0.0 0.1 0.2mS0.0

0.1

0.2

V

v(8) v(6) v(7) v(5)

Figure 41 — Pulse shapes at Nodes 5, 6, 8 and 7 for the Network of Figure 39

Introduction


Field Study: Waldo Rd., Gainesville, FL

Central Site to Remote Station Communication A sketch of the topology of the command line for the Waldo Rd. Installation is shown in Figure 44. This system uses 22 gauge wire for which the series resistance per loop mile is 171 ohms. The long span of the lines made measurements virtually impossible without the use of isolation transformers of the type typically used for practical signaling. In order to provide a more realistic comparison between simulation and measurements, it was necessary to first derive a circuit model for the transformer using a variety of measurement techniques. The resulting model is shown in Figure 42. To demonstrate the validity of the model, a signal generator (having a source impedance of 50 ohms) was connected across the primary and the oscilloscope connected across the secondary of the transformer. The signal generator was configured to produce a periodic 100 μs pulse. The recorded oscilloscope trace is superimposed onto the results of its circuit-equivalent Spice simulation output in Figure 43.

1 7

8

2

9

103

4

5

6

11

12

13

14

14

14

14

14

2.7nF

2.7nF

0.83H

0.83H

2.1nF

2.1nF

0.64H

0.64H

10

10

10

10

k=0.99963 between all inductors

Figure 42 — Transformer Equivalent Circuit Model Used in Simulations



x 10

1

time0.0 0.2 0.4mS-1

0

1

2

V

The irregular oscillation just prior to the falling edge is due to plot aliasingin the Spice simulation program.

Figure 43 — Superposition of the Measured and Simulated Transformer Pulse Response

To ascertain the accuracy and capability of the overall circuit simulation model, several pulse response measurements of the Waldo Rd. traffic system were made. In each of these, a signal generator with a 50 ohm source impedance was configured to produce a one volt pulse. This was connected to the primary port of a transformer (whose circuit equivalent is shown in Figure 42) through a 600 ohm resistor. Measurements taken at each remote were also taken by an oscilloscope through a transformer. We present here a comparison of simulation results with the results of some of these measurements. One of the measurements was configured as shown in Figure 44 with the measurement being taken at 8th Ave. (node 5). The transformers, located at node 2 and node 5 are not shown for ease of illustration. A comparison of the predicted and measured response is shown in Figure 45 and Figure 46. This pulse has not reached its maximum step response amplitude in 100 μs and its base width in this figure is in excess of 200 μs. Thus, we can expect there to be significant inter-symbol interference for signaling with a 100 μs NRZ pulses using the existing termination scheme.

To double the transmission length, a spare twisted pair was connected to the signal pair at 8th Ave and looped back. In both the forward and reverse direction twisted pairs, a 120 ohm shunt resistor was placed across the twisted pair at each node. The net source impedance remained at 650 ohms. A comparison of the predicted and measured

Introduction


responses for the nodes most distant from the source is shown in Figure 47, Figure 48, and Figure 49. As can be seen, there is quite good agreement between the predicted and measured results. For the most part, discrepancies can be attributed to noise and accumulated component tolerances not being commensurate with in approximations used in the Spice model. The discrepancies are small enough to give us confidence to use the Spice model to predict behavior in cases where measurements are too time consuming to be practical.

0.9375 mi 0.6106 mi 0.5850 mi

600

2 3 4

600

39th Av 23rd Av 16th Av 8th Av

5

Figure 44 — Waldo Rd. Master Station Command Transmission Line

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4-0.05

0

0.05

0.1

0.15

0.2

0.25

0.3

timemS

V

Figure 45 — Response to a 100 μs Pulse at 8th Ave

This is an overlay of predicted and measured responses. The net source impedance at the source (39th Ave.) was 650 ohms and the termination resistance at 8th Ave. was 600 ohms. The simulated response (red) is the one which is truncated early.



time0.0 0.2 0.4mS-10

0

10

20

30

40

50

60

70

80

90

100

mV

Figure 46 — Response to a 100 μs Pulse at 8th Ave

This is an overlay of predicted and measured responses. The net source impedance (at 39th Ave.) was 650 ohms and the termination resistance at 8th Ave. was 120 ohms.

time0.0 0.2 0.4mS-1

0

1

2

3

4

5

6

7

8

mV

9

10

11

Introduction


Figure 47 — Measured and Predicted Response at 8th Ave

All nodes, in both forward and reverse directions had a 120 ohm shunt across the twisted pair.

time0.0 0.2 0.4

mS-1

0

1

2

3

4

mV

Figure 48 — Measured and Predicted Response at 16th Ave in the Reverse

Direction


time0.0 0.2 0.4

mS0

1

mV

2



Figure 49 — Measured and Predicted Response at 23rd Ave in the Reverse Direction


Finally, we use the heuristic termination rules derived in the previous section to select more optimal termination impedances for the Waldo Rd. traffic control system. Scaling the termination resistances according to their distance from the previous source as explained in the discussion following Eq.(10), we get the terminations shown in Figure 50. The 88 ohm source resistor was chosen to approximate 22 ohms in series with each terminal of both the primary and secondary windings of a transformer which couples a differential transmitter to the line. The response predicted by the model is shown in Figure 51. It can be observed that the resulting pulse responses are sharp and suffer almost no distortion. It should be noted that no reverse direction twisted pair was assumed in this particular simulation.

In the next subsection, we use our model to predict the pulse response of each of the remotes transmitting to the master station.

0.9375 mi 0.6106 mi 0.5850 mi

88

2 3 4

75 120 120


5

Figure 50 — Improved Terminations for Waldo Rd

Introduction


time0.0 0.2 0.4mS

-0.1

0.0

0.1

0.2

V

v(3)v(4) v(5)

Figure 51 — Predicted Responses to the Terminations Shown in Figure 50



Remote to Master Station Communication The terminators derived using the above analysis for a remote station transmitter at node 3 and the master station receiver at node 2 are shown in Figure 52 with the resulting response at node 2 plotted in Figure 53.

0.9375 mi 0.6106 mi 0.5850 mi

88

2 3 4

75 120 120


5

Figure 52 — Pulse Response Circuit for Node 3 to Node 2 Transmission and Proper Terminations

time0.0 0.2 0.4mS

-0.1

0.0

0.1

0.2

V

v(2)

Figure 53 — Pulse Response for Node 3 to Node 2 Transmission and Proper Terminations

Peek’s existing transformer interface design causes the transmitter terminals to present an infinite impedance when a remote’s transmitter is not active. To achieve the

Introduction


termination shown in Figure 52 would require a line termination to be present even when the remote is not transmitting. Since this termination is not necessarily equal to the desired source impedance when the remote is transmitting, it complicates the design. This justifies examining alternative termination schemes for the twisted pair which is shared by the remote transmitters. One approach is to use the existing scheme but decrease the terminators used. Accordingly, Figure 54 shows the pulse response at the master station from each remote node when the transmitter source impedance is 88 ohms, and the master station receiver is terminated with 75 ohms. All non-transmitting nodes were open circuited (i.e., had no terminating resistor).

time0.0 0.2 0.4mS

0.0

0.1

0.2

0.3

V

from node 4from node 3 from node 5

Figure 54 — Response at Node 2 for Transmission from Nodes 3, 4, and 5 with an 88 Ohm Source Impedance and a 75 Ohm Terminator at Node 2

Non-transmitting nodes were open-circuited.

For comparison, we show the pulse response at the master station from each of the remotes if 600 source and termination resistors are used. The resulting wave forms, shown in Figure 55, indicate that with these higher impedances, high speed data transmission would suffer significant inter-symbol interference. On the other hand, if lower impedance terminators are used, the signal level is lower but no equalization is necessary.



time0.0 0.2 0.4mS0.0

0.2

0.4

V

from node 4from node 3 from node 5

Figure 55 — Response at Node 2 for Transmission from Nodes 3, 4, and 5 with a 600 Ohm Source Impedance and a 600 Ohm Terminator at Node 2 (Non-transmitting nodes were open circuited)

An alternative scheme is to have a relatively large shunt resistance (e.g., 600 ohms) always left to shunt the twisted pair at each node regardless of whether the remote transmitter is active. Then, if the remote’s transmitter has a low source impedance (e.g., 88 ohms) when it is active, this shunt causes negligible signal loss. In the following simulation, we consider a longer span for Waldo Rd. (with forward and reverse cables connected together at 8th Ave). Thus, in addition to the node number shown in Figure 52, we add node 6 which is 16th Ave. in the reverse direction, node 7 which is 23rd Ave in the reverse direction, and node 8 which is 39th Ave. in the reverse direction. Each of the nodes is treated as a remote transmitting to the central site at 39th Ave (node 2). Each remote transmitter is made to always shunt the line with 600 ohms. In addition, when it becomes active, its signal source has an 88 ohm source impedance which drives the shunt and the line. The predicted response from each remote at the central site, when the central site is terminated in 600 ohms is illustrated in Figure 56. Note that this small degree of pulse distortion is acceptable and permits the use of the larger value of termination at the central site to increase signal voltage. For comparison, Figure 57 shows the effect of reducing the terminating resistor from 600 ohms to 120 ohms. In this case, since the change in pulse shape is small, the larger signal amplitude is preferable and a 600 ohm terminator can be used.

Introduction


time0.0 0.2 0.4

mS-0.1

0.0

0.1

0.2

0.3

0.4

V

from node 3from node 4from node 5

from node 6from node 7from node 8

Figure 56 — Remote to Central Site Pulse Response

Each remote shunts the transmit line with 600 ohms when it is inactive and has an 88 ohm source impedance when it becomes active. The central site’s receive transformer is also terminated with 600 ohms.

time0.0 0.2 0.4mS

-10

0

10

20

30

40

50

60

mV

600 ohms 120 ohm

Figure 57 — Comparison of the Reponse at the Central Site from Node 8

All other nodes were terminated with 600 ohms. The comparison shows the signal when the central site employs a 600 ohm terminating resistor and when it uses a 120 ohm resistor.

Summary


Summary

From the wave equation for propagation in a lossy transmission line, we have derived heuristic rules to calculate terminating resistors. This first method relies on approximating a distributed shunt admittance that causes all frequency components in a pulse to be attenuated equally. This approximation is carried out by using distributed shunt terminators whose value is calculated using Eq.(9) and the length of the line segment to the upstream node. The approximation hinges on lumping together at its end points, all of the admittance which should have been distributed throughout a line segment. In the case of a star distribution topology, the common point where cables meet is treated as a low impedance virtual source. A second method was studied in which the only terminators are at the remote branch ends. This method does not yield pulse shapes of as high a quality but it is simpler to implement and may be acceptable for many network topologies. The validity of our modeling method was verified against field measurements taken at Waldo Rd. We have also investigated remote to central site transmission. While, the termination method based on the wave equation yielded superior results in this case, it presents a more difficult termination problem since the network topology is dynamic and requires impedances to change depending on which particular remote is active. Nonetheless, simulations demonstrated that a common distributed termination resistor value works well enough in this topology. What is clear is that each installation needs to be analyzed individually and after termination values are selected, the network should be simulated to verify the signal integrity and adjust termination values to obtain acceptable performance.

[1] Whitham D. Reeve, Subscriber Loop Signaling and Transmission Handbook - Analog, IEEE Press, N.Y., N.Y., 1992.

Introduction



Glossary

3000 Series — A line of traffic controller hardware produced by Peek Traffic Corporation.

AC — Alternating Current

Actuated — Identifies a type of controller which responds to calling signals generated by the actions of either vehicles or pedestrians. See also Semi-actuated and Fully-actuated.

Adaptive Split Control — A means of intersection split selection based on vehicular activity.

Advance Call Detector — A detector located a considerable distance upstream from an intersection which calls the green to that approach.

Advance Warning — A per-movement output used to give advance notice of an upcoming yellow or red indication. Typically used at hidden intersections with “prepare to stop” indicators. This is a term used with the LMD-40 controller.

ASCII — American standard code of information interchange. A standard code that assigns eight-bit codes to individual alphanumeric characters.

Auto/Manual Switch — A cabinet switch, when operated, discontinues normal signal operation and permits manual operation.

Back Panel — A board within the controller cabinet upon which are mounted field terminals, fuse receptacles or circuit breakers, and other components of controller operation not included in the controller unit itself, or its ancillary devices. Such back panels are typical in older traffic control cabinets.

Barrier — A logical term to describe a line of compatibility in a multi-ring signal plan in which all rings are interlocked. Barriers assure that there will be no concurrent selection and timing of conflicting phases for traffic phases on different rings.

Glossary


Barrier — A logical term to describe a line of compatibility in a multi-ring signal plan in which all rings are interlocked. Barriers assure that there will be no concurrent selection and timing of conflicting phases for traffic phases on different rings.

Baud rate — The data transfer rate of data transmission to a communications channel, usually expressed in ‘bits per second’.

BIU — Bus Interface Unit, required to interface a TS-2, Type 1 controller to any type of cabinet hardware.

Buffer — A device or section of memory used to compensate for differences in data transfer flow speeds or variable latencies in a communications channel.

CA — Controller Assembly

Cabinet — An outdoor enclosure for housing controller units, master units, detector electronics and other associated equipment.

Call — The result of a detector or signal activation by either a pedestrian or a vehicle. A signal to the controller indicating that a vehicle or pedestrian is present and is ‘requesting’ the right-of-way.

Capacity — The maximum number of vehicles that can pass over a given lane or roadway during a given period, under prevailing traffic conditions.

CBD — Central business district. The portion of a municipality in which the dominant land use is intense business activity.

Checksum — A numerical value that is calculated by applying a predefined algorithm to a set of data. It is used to determine if a portion of memory or a message has been corrupted in any way.

Clearance Interval — The interval from the end of the right-of-way of one phase to the beginning of a conflicting phase.

CLMATS — A software package created and maintained by Peek Traffic Corporation that allows traffic management personnel to interact with and control a variety of Master and Controller hardware. Stands for Closed Loop Multi-Arterial Traffic Control System.

Closed Loop System — A software and hardware system in which a computer controls an external process using information received from the process. For example, the closed loop in a traffic control system is from the computer to the controllers and then from the detectors back (through the controller) to the computer.

CLR — Phase Clearance. Includes Ped Clearance times for CNA phases.

CNA — Call to Non-Actuated. Provides a method of phase timing where vehicle and pedestrian detectors are not required to serve the associated phases, with operation as defined by NEMA. An actuated controller feature in which the associated phase will always serve the Walk plus Ped Clear time, regardless of detector inputs.

Compatibility Line — The dividing line crossing both rings (in dual ring operation) that separates compatible phase combinations. Usually, it divides phases associated with North/South from those associated with East/West. Also known as the Barrier.

Glossary


Conditional Service — A dual-ring feature which allows re-service to an odd phase (i.e. a left turn phase) once the opposite ‘through’ phase has gapped out. The service is conditional upon the time remaining in the adjacent ‘through’ phase’s Max timer.

Conflict Monitor — A device used to continually check for the presence of conflicting signal indications coming from the controller, and to provide an output in response to the conflict (usually All Flash).

Conflicting Phases — Two or more traffic flows which would result in interfering traffic movements if operated concurrently.

Controller — A device which, through software and firmware programming, manages the sequence and duration of traffic signals.

Coordination — The state where two or more intersections are configured to communicate with each other in order to time their signals in some manner that improves the greater system performance, rather than being timed independently at each intersection. This independent operation, by contrast, is known as Free operation.

Coordination — The state where two or more intersections are configured to communicate with each other in order to time their signals in some manner that improves the greater system performance, rather than being timed independently at each intersection.

CRC — Cyclic Redundancy Check

Critical Intersection — A selected, heavily traveled intersection within a coordinated traffic artery. This intersection would be employed to dynamically control the split at other intersections within the artery, based on its vehicle detector inputs.

CVM — Controller voltage monitor. An open collector output that is maintained ‘low’ by the controller as long as the internally generated operating voltages are within tolerances. This output is used by a conflict monitor to place the intersection in Flash, should all voltages fail in the controller.

Cycle — The total time required to complete one complete set of signal states around an intersection. In basic, pre-timed control, the cycle length is fixed. In actuated systems the cycle length can be increased up to a predetermined maximum, based on the continued detection of vehicles.

Cycle Zero Point — See ‘Time Reference Point’

Cyclic Redundancy Check — When transferring data back and forth between the computer and controllers, CLMATS uses a standard Cyclic Redundancy Check on transmitted data to verify that the same string that is transmitted is received at the other end. Basically, the CRC method uses the bit-by-bit contents of each packet of the message (or ‘frame’) to come up with a unique Frame Check Sequence (the FCS, or what we are calling the CRC number) that is then added to the end of the frame. The combination of the frame and the FCS is created in such a way that it is exactly divisible by a predefined binary polynomial. These CRC tests utilize a commonly used 8-bit polynomial called the CRC-CCITT polynomial, which looks like this: X16+X12+X5+1, which corresponds to these two bytes of binary data: 10001000 00010001. For more

Glossary


details about the CRC check used by CLMATS, refer to the MIZBAT Protocol Manual (p/n 81-1001).

Database — The CLMATS and Peek controller system environment uses two distinctly different meanings for the term ‘database’. The first is the typical one used in most computer systems: CLMATS stores all of the information it gathers from the field and maintains about all connected controllers in a set of database files on the central computer. The second meaning of database is the complete set of operating parameters stored in a single controller or master controller. This is why the terminology in CLMATS used to discuss the programming of individual controllers uses phrases such as ‘Open the controller database and edit it. Then download the database to the controller.’

DCMATS — The software predecessor to CLMATS, originally only communicated with single controllers

Density — A measure of the concentration of vehicles in an intersection, stated as the number of vehicles per mile (space density) or as the flow volume divided by the average speed (point density.)

Detection Zone — The area of the roadway in which a vehicle will be detected by a vehicle detector.

Detector — A device that senses the presence or absence of a vehicle in a particular area (the Detection Zone). Vehicle detection methods include inductance detecting loops (the most common type), piezo pressure sensors, light beam sensors, radio ID sensors, air tube sensors, and mechanical switches.

Detector Failure — A detector which fails to indicate that vehicle is present when it is, or fails to go off when a vehicle is absent. Types of failures include non-operation, chattering, and erroneous signaling.

Detector Memory — A feature of some controllers in which the actuation of a detector is retained in memory until the corresponding phase is serviced.

Dimming — This feature of some controllers allows the brightness of selected traffic signal indicators to be lowered during night time operation, typically by lowering the voltage applied to the output.

DLL — A dynamically linked library file. In the Windows environment, programs store data, graphics, and other resources in these linked libraries. CLMATS, TOPS, Z-Link and most other Windows applications use them.

Dual Entry — A mode of dual-ring operation in which one phase in each ring must be in service. If a Call does not exist in a ring when the controller crosses the barrier to activate a phase within the ring, a phase is selected in that ring to be activated in a predetermined manner.

Duplex — Two-way communications over a single communications link.

EEPROM — Electronically erasable/programmable read-only memory, the programmable memory storage area on the LMD-40 and several other traffic control components.

Glossary


EGB — Extended Green Band

EP — End of Permissive

EPP — End of Pedestrian Permissive

FO — Force Off

FOM — Fiber Optic Modem, a device that modulates a signal appropriately for transmission over fiber optic cables

Force Off — Action taken by an external source which generates a signal to the intersection controller, causing termination to begin in the phase currently exhibiting the right-of-way. Used in Preemption and Coordinated operation.

FSK — Frequency shift key, A form of digital frequency modulation employing discrete frequencies for specific signals, for example for marking signals. The transmitter is changed from one frequency to another, keyed to represent a different information character with each frequency.

Fully-actuated — Identifies a type of intersection control in which every phase has a vehicle detector input capability

Green Band — The time, in seconds, elapsed between the passing of the first vehicle and the last possible vehicle in a group of vehicles moving in accordance with the designed speed of a progressive traffic control system.

Greenband Analysis — a method of analyzing the amount of green light time available in a set of coordinated traffic intersections.

Hz — Hertz, a unit of frequency indicating cycles per second

INIT — Initial or Initialization

Intersection — The location where two roadways meet or cross, or a Controller assigned to such a location.

Interval — A unit of time that is assigned a certain of controller behavior and signal output in a time-based (non-NEMA) controller.

ITS — Intelligent traffic systems

Lead/Lag Operation — A feature of some traffic controllers which makes it possible to reverse the phase sequence on a phase-pair basis. When the phase pairs (such as 1-2, 3-4, 5-6, 7-8) are reversed, the odd phase will lag the even phase instead of leading it as it does in normal operation.

Local — Connection to a Controller unit

M3000 — The model number of a master unit manufactured by Peek Traffic Corporation. Often used in conjunction with Peeks’ Series 3000 and Series 3000E Traffic Controllers

MCE — Manual Control Enable

MIZBAT — This is a communications protocol that is proprietary to Peek traffic controllers and system software. It provides a method for traffic devices and software to

Glossary


transfer data back and forth reliably. For more details about MIZBAT, refer to the MIZBAT Protocol Manual (p/n 81-1001).

MMU — Malfunction Management Unit

MOE — Methods of efficiency

MSCLR — Main Street Clearance

NEMA — National Electrical Manufacturers Association. The industry group that has designed one of a couple of competing standards for intelligent traffic control systems.

PA — Phase Allocation

PE — Preemption

Ped — Pedestrian or Pedestrian phase

PED CLR — Pedestrian Clearance Interval

Phase — a single traffic movement. NEMA compatible controllers typically manage the intersection in terms of phases, while earlier controllers use intervals and circuits instead.

PTSI — Peek Traffic Systems Inc., now known as Peek Traffic Corporation, a Quixote company.

RAM — Random Access Memory. The main memory of a computer while power is on. Typically does not maintain its memory when power is turned off.

RGB — Reduced Green Band

ROM — Read Only Memory, hard written memory in a computer that is maintained even when power is removed. Typically used to store basic OS code and firmware programs.

Semi-actuated — Identifies a type of intersection control that has one or more phases that lack a vehicle detector input capability.

SP — Start Permissive Period

SPL — Split, in a coordinated traffic system, each intersection in an artery must have the same cycle time. So instead of set times for each phase, a coordinated intersection has a split assigned to each phase. A split is a percentage of the total time available in the cycle.

SPP — Start Pedestrian Permissive Period

T/F — Terminal and Facilities

TCP/IP — The most common pair of protocols used to send data across an Ethernet or the Internet. Each component in such a system is assigned a unique IP address. IP addressing is used by the various components of CL-MATS.

Time Reference Point — A point in time which serves as the time reference for an entire artery or region of traffic flow. For example, in the timing diagram for a single street, each intersection has a time offset between the start of its cycle and one arterial

Glossary


signal which serves as the Time Reference Signal. The start of the Green time reference signal in this system is known as the Time Reference Point.

TOD — Time of Day

WALK — Walk Interval Time

WRM — Walk Rest Modifier

Glossary


Index


Index

3 3000 Series .........................................................95

8 8p D module interface header.................................1

9 9600 baud mode......................................................1 9p line connector.....................................................1

A AC .........................................................................95 Actuated ...............................................................95 Adaptive Split Control........................................95 Advance Call Detector........................................95 Advance Warning ...............................................95 ASCII....................................................................95 assembly drawings ................................................65 Auto/Manual Switch ...........................................95

B Back Panel ...........................................................95 Barrier..................................................................95 barriers ..................................................................96 Baud rate..............................................................96 bench repair...........................................................61 binary polynomial .................................................97 bit error rate.............................................................3 BIU........................................................................96 breakdown...............................................................5 Buffer....................................................................96

C CA......................................................................... 96 cabinet................................................................... 96 cable types .............................................................. 5 calculating CRC.................................................... 97 Call ....................................................................... 96 Capacity ............................................................... 96 carrier detect ........................................................... 3 CBD ...................................................................... 96 CCIT polynomial .................................................. 97 Checksum ............................................................ 96 Clearance Interval .............................................. 96 CL-MATS............................................................. 96 Closed Loop System............................................ 96 CLR....................................................................... 96 CNA...................................................................... 96 codec ..................................................................... 26 Compatibility Line.............................................. 96 Conditional Service............................................. 97 Conflict Monitor ................................................. 97 Conflicting Phases............................................... 97 Controller ............................................................ 97 controller interface.................................................. 3 coordination

definition.......................................................... 97 Coordination ....................................................... 97 CRC ...................................................................... 97 Critical Intersection............................................ 97 CVM ..................................................................... 97 Cycle ..................................................................... 97 Cycle Zero Point ................................................. 97

Glossary


D D module interface................................................34 D modules ...............................................................2 Database ...............................................................98 DCMATS..............................................................98 default jumper settings ..........................................20 Density ..................................................................98 Detection Zone .....................................................98 Detector ................................................................98 Detector Failure...................................................98 Detector Memory ................................................98 diagnostics.............................................................59 digital interface........................................................3 Dimming ...............................................................98 distortion..................................................................5 DLL .......................................................................98 DSP........................................................................25 Dual Entry............................................................98 dual mode ................................................................2 Duplex...................................................................98

E EEPROM .............................................................98 EGB.......................................................................99 EP 99 EPP ........................................................................99

F FCS........................................................................97 feature list ................................................................2 FO..........................................................................99 fold down panel.....................................................59 FOM ......................................................................99 Force Off ..............................................................99 four wire operation................................................28 FSK .......................................................................99 Fully-actuated ......................................................99

G glossary ................................................................95 Green Band ..........................................................99 greenband analysis ................................................99

H hi-speed mode .........................................................4 Hz 99

I IC removal.............................................................60 impedence................................................................3 INIT .......................................................................99 input sensitivity .......................................................3 insulation .................................................................5

interface connectors ..............................................33 interoperability........................................................3 Intersection ..........................................................99 intersection address...............................................16 interval ..................................................................99 introduction .............................................................1 ITS.........................................................................99

J jumpers..................................................................20

L Lead/Lag Operation ...........................................99 LED indicator........................................................30 LED indicators ......................................................17 line impedence ........................................................3 line interface........................................................3, 5 line interface section .............................................28 line termination .....................................................45 local .......................................................................99 low speed mode.......................................................3

M M3000 ...................................................................99 maintenance ..........................................................59 manual station .......................................................60 master LED ...........................................................17 maximum distance ..................................................3 maximum drops ......................................................3 MCE ......................................................................99 MMU...................................................................100 mode programming...............................................22 MOE....................................................................100 MOVs......................................................................2 MSCLR ...............................................................100

N NEMA

definition ........................................................100 noise level ...............................................................5

O opto-isolated PTT circuit ......................................31 overview..................................................................1

P PA........................................................................100 parts lists ...............................................................62 PE 100 ped .......................................................................100 PED CLR ............................................................100 phase

Glossary


definition ........................................................100 port 3 .....................................................................34 port 3 connector ....................................................18 power supply.........................................................30 PTSI ....................................................................100

R RAM....................................................................100 receive circuit........................................................28 repeater LED.........................................................17 replacement ...........................................................59 RGB ....................................................................100 ROM....................................................................100 RTS .......................................................................18 RTS-CTS delay.......................................................3

S schematics .............................................................65 SCTO period ...........................................................3 selection of mode ....................................................2 Semi-actuated ....................................................100 site survey .............................................................37 software upgrade...................................................60 SP 100 specifications...........................................................3 SPL .....................................................................100 SPP......................................................................100

surface mount.................................................... 2, 60

T T/F....................................................................... 100 TC level ................................................................ 20 TCP/IP ................................................................ 100 temperature range ................................................... 2 termination............................................................ 67 termination methods ............................................. 45 termination requirements........................................ 1 theory of operation................................................ 25 Time Reference Point ....................................... 100 TOD .................................................................... 101 transformers ............................................................ 2 transmission method............................................... 3 two-wire operation................................................ 29 TX circuit.............................................................. 28

U use and operation .................................................. 15

W WALK ................................................................ 101 wire gague............................................................... 5 WRM .................................................................. 101

Glossary


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