sheet 1 of 1 activity b. references ct100hf c. …...trainee guide sheet 1 of 2 for training use...

TRAINEE GUIDE

Sheet 1 of 1

FOR TRAINING USE ONLY 1

INFORMATION SHEET 1-1

ACTIVITY

A. INTRODUCTION

In this lesson, you will learn about the TDR's purpose and function, safety, controls and indicators,

and operation. This activity is designed to stimulate prior knowledge and interest in the topics

covered in this lesson.

B. REFERENCES

1. Automated Metallic Time-Domain Reflectometers Operator's Manual, CT100 and

CT100HF

2. Navy Safety and Occupational Health (SOH) Program Manual for Forces Afloat, Volume

II, Surface Ship Safety Standards, OPNAVINST 5100.19 (series)

C. INFORMATION

For each item listed in the Topic column, write a brief statement in the Knowledge column that

describes what you know about the topic.

When you complete the activity, you will discuss your findings with the class.

No. Topic Knowledge

1 TDR purpose and function

2 TDR safety

3 TDR controls and

indicators

4 TDR operation

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Sheet 1 of 2


OUTLINE SHEET 1-2

OPERATE THE TIME-DOMAIN REFLECTOMETER (TDR)

A. INTRODUCTION

The TDR is a piece of electronic test equipment used to locate faults in metallic cables (e.g.,

coaxial cable). It is important to know how to operate the TDR to identify degraded cable

conditions, determine if a cable is impaired, and determine how far away the fault is.

B. OBJECTIVE

Upon successful completion of this section, you will be able to:

GIVEN APPLICABLE TECHNICAL DOCUMENTATION AND DIRECTIVES OPERATE

THE TIME-DOMAIN REFLECTOMETER (TDR) IAW ESTABLISHED SAFETY

REQUIREMENTS, APPLICABLE TECHNICAL DOCUMENTATION AND DIRECTIVES

C. SECTION OUTLINE

1. Section Introduction

2. Purpose and Function

3. Safety

4. Front Panel Controls and Indicators

5. Rear Panel Controls

6. Menus

7. Dialog Box Navigation

8. Cable Test Preparations

9. Relative Distance Measurement

10. Measuring VSWR

11. Common Cable Faults

12. TDR Procedures

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Outline Sheet 1-2 Sheet 2 of 2


13. Practice

14. Section Review

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Sheet 1 of 2



GLOSSARY

A. INTRODUCTION

The following is a list of acronyms, abbreviations, and key terms used in this lesson.

B. REFERENCES


CT100HF



C. INFORMATION

Term Definition

AC Alternating Current

BNC British Naval Connector; a miniature quick-

connect/disconnect RF connector used with

coaxial cable

CCW Counterclockwise

CG Guided Missile Cruiser

CIC Combat Information Center

CW Clockwise

H Horizontal function button

IS International System of Units; a system of

physical units based on the meter, kilogram,

second, ampere, kelvin, candela, and mole,

together with a set of prefixes to indicate

multiplication or division by a power of 10

LPO Leading Petty Officer

Mb Megabit

M-FUNC Multifunction

M-FUNCTION Multifunction

ns Nanosecond

PC Personal Computer

RF Radio Frequency

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Information Sheet 1-3 Sheet 2 of 2


Term Definition

RJ-45 Registered Jack-45

rVSWR Reflective Volts Standing Wave Ratio

TDR Time-Domain Reflectometer

USB Universal Serial Bus

V Vertical function button

VDC Volts Direct Current

VoP/Vp Velocity of Propagation

VSWR Volts Standing Wave Ratio

Δ Absolute distance measurement

Ω Ohms

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Sheet 1 of 1



PURPOSE AND FUNCTION

A. INTRODUCTION

The TDR is a piece of electronic test equipment that uses time-domain reflectometry to

characterize and localize faults in metallic cables used in microwave, RF, and digital systems.

B. REFERENCES


CT100HF

C. INFORMATION

The TDR can scan and detect subtle cable faults, which include:

1. Minor conductor or insulation damage

2. Water ingress

3. Loosened, corroded, or poor-quality interconnects

The TDR has an array of built-in software tools to simplify common measurements such as cable

length, local impedance (i.e., resistance of an electric circuit), and return loss.

The TDR tests cables for defects by creating and sending a signal down the cable and measures

the time it takes for the signal, or part of the signal, to return (i.e., reflection).

The signal’s reflection begins at the fault point of the cable. The more severe the flaw, the more

energy is reflected back, resulting in easier identification of imperfections.

The resulting measurement allows the operator to identify changes in impedance within the cable

that indicate the presence of a short, a partial short (crimps), an open, a partial open (nicks in the

cable), a defect in the shield or conductor, a foreign substance (e.g., water), or thermal damage.

The TDR allows the operator to save frequently used test configurations to minimize setup time.

The TDR can store waveforms for later analysis or historical comparison.

The TDR is especially helpful in locating defects in long, intricately routed, and inaccessible cable

runs.

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SAFETY

A. INTRODUCTION

Some electrical measuring instruments are used to measure electrical voltages or signals that can

be dangerous and may be fatal if you come in contact with energized circuits or equipment while

performing testing procedures. Exercise extreme caution when working with the TDR and

energized equipment.

B. REFERENCES


CT100HF



C. INFORMATION

General Safety

You must observe the following general safety precautions at all times:

1. Never work alone on energized electrical or electronic equipment.

2. Use the one-hand rule when turning on electrical equipment. Never operate a switch with the

other hand on a metal surface, which would provide a path to ground through the body.

3. Remove or snugly secure any loose clothing.

4. Remove all jewelry.

5. Never use outlets that appear to be burned or damaged.

6. Report all hazards. If at any time you detect a hazard, it is your responsibility to report the

hazard to ensure that it is corrected.

7. Make sure there is plenty of light in the work area. Never work with tools in dark areas where

you cannot see clearly.

8. Do not use any equipment that has a frayed cord, or a broken or damaged plug.

9. Do not touch a conductor until it is properly tagged out of service and tested, to be sure it is de-

energized or discharged.

10. Obey all warning signs; read equipment warning labels before use.

11. Always de-energize and tag out installed electrical equipment with red DANGER,

DO NOT OPERATE tags before starting any maintenance or repair. Test for energized

circuits.

12. Use an authorized voltage indicator to test if equipment or circuits are energized.

13. Do not use aluminum or metal portable ladders when working on electrical equipment.

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14. Always connect electrical equipment cords to the extension cord before the extension cord is

inserted into an energized receptacle.

TDR Safety

To avoid possible electric shock or personal injury, follow these guidelines when using the

TDR:

1. Only use the power cord supplied with the TDR, and then only if the cord is in good condition.

2. To reduce the risk of electric shock, disconnect all external cables before connecting the 24

VDC external power supply.

3. Never use the TDR to test any cable or device carrying a non-zero electrical potential relative

to earth ground, as this could cause an electric shock.

4. Upon loss of the protective-ground connection, all accessible parts, including the screen,

knobs, and connectors, can give an electric shock.

5. Do not operate the TDR in an explosive atmosphere unless your unit has been specifically

certified for that condition.

6. To avoid personal injury and risk of electric shock, do not open the TDR case, and do not

operate unless the case is fully intact.

7. The TDR should never be used to test any cable or device carrying live electrical signals, as

this carries a risk of electric shock.

8. Always properly ground the conductor(s) of any cable or wiring to remove any static charge

prior to connecting it to the TDR.

9. Do not proceed beyond a DANGER, WARNING, or CAUTION notice until the indicated

conditions are fully understood and met.

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DIAGRAM SHEET 1-6

FRONT PANEL CONTROLS AND INDICATORS

Front Panel Controls and Indicators

1 Power button 13 LIBRARY button

2 H1 function button 14 SELECT button

3 H2 function button 15 CURSOR button

4 H3 function button 16 SCAN button

5 H4 function button 17 AUTOFIT button

6 Menu button 18 M-FUNC button

7 VERTICAL POSITION knob 19 M-FUNCTION knob

8 VERTICAL SCALE knob 20 V1 function button

9 HORIZONTAL POSITION knob 21 V2 function button

10 HORIZONTAL SCALE knob 22 V3 function button

11 CABLE connector 23 V4 function button

12 Host USB port

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FRONT PANEL CONTROLS AND INDICATORS

A. INTRODUCTION

To accurately operate the TDR, it is essential that you are able to identify and understand the

function of the buttons, knobs, connectors, and ports on the TDR's front panel.

B. REFERENCES


CT100HF

C. INFORMATION

The TDR front panel controls and indicators provide the functionality to scan and filter cable

defects and characterize their failings. The table below describes the function of each control and

indicator on the TDR’s front panel.

Control/Indicator Function

Power button Selecting the power button applies power to the TDR

when the power switch on the rear panel is in the on

position.

Selecting the power button when power is applied to the

TDR displays the shutdown menu. The shutdown menu

options are as follows:

1. The Vacuum Database option cleans the unused

records from the TDR, freeing space in memory.

2. The Clean Shutdown option turns the TDR off and is

the preferred method for shutting down the TDR.

3. The Cancel option exits the shutdown menu.

CABLE connector This BNC allows you to attach the test cable to the TDR.

Ensure the test cable is properly grounded before

connecting to the BNC. This prevents electrostatic

damage to the internal circuitry of the TDR.

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Menu button The Menu button accesses and navigates through the

TDR’s internal menus.

The button activates the on-screen help function when

held down while selecting any other button on the TDR.

H1-H4 function buttons The H1 through H4 buttons provide different functions

based on the menu selected (e.g., set the horizontal

calibration by selecting button H4).

V1-V4 function buttons The purpose of these function buttons depends upon the

selected menu (e.g., set the vertical calibration by

selecting the V4 function button).

M-FUNCTION knob The M-FUNCTION knob implements the function

selected by the M-FUNC button.

M-FUNC button The M-FUNC button displays the current operation on

the screen. The function of the M-FUNCTION knob is

corrected by this button.

SCAN button The SCAN button displays a specialized soft-menu scan

and trace menus.

The SCAN button contains menus for saving, deleting,

hiding, and performing mathematical operations on

selected traces.

This button also allows you to perform automated scans

of an entire cable when detected by the AUTOFIT

button.

SELECT button The SELECT button is used to choose between traces on

the screen. Selecting the button has no effect if no

scanned traces are loaded.

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AUTOFIT button The AUTOFIT button displays the entire length of the

test cable and allows you to zoom in and inspect the

cable.

The TDR display will indicate terminations in the cable

caused by a short (e.g., crimps) or an open or break

(e.g., nicks), or the location of the last cursor position.

CURSOR button The CURSOR button allows you to toggle between the

two available on-screen cursors to display the distance,

return loss, or other measurements between the two

cursors.

By selecting and holding the CURSOR button for 1

second, you can move cursors that are not on the screen

to the display.

LIBRARY button The LIBRARY button opens the library menu, which

contains a database of previously named configurations,

saved cable records (scans), and the records of known

cable types.

Host USB port This USB 1.1 port allows the TDR to interface with USB

devices such as a barcode reader, keyboard, or thumb

drive.

VERTICAL controls The VERTICAL POSITION knob controls the vertical

position of the selected trace, moving it up or down.

The VERTICAL SCALE knob controls the display’s

vertical scale. It is displayed numerically on the bottom

of the screen.

HORIZONTAL controls The HORIZONTAL POSITION knob controls the

horizontal position of the cursor (i.e., left to right) and

the displayed trace relative to the start position of the

cable scan.

The HORIZONTAL SCALE knob controls the

horizontal scale of the displayed trace, and can be

displayed in either English or IS.

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DIAGRAM SHEET 1-8

REAR PANEL CONTROLS

Rear Panel Connectors and Switches

1 Power switch

2 Client USB connector

3 RJ-45 Ethernet port

4 External 14.4 VDC battery pack connector

5 24 VDC power adapter plug

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Sheet 1 of 1



REAR PANEL CONTROLS

A. INTRODUCTION

To accurately operate the TDR, it is essential that you are able to identify and understand the

function of each control on the TDR's rear panel.

B. REFERENCES


CT100HF

C. INFORMATION

The table below describes the function of each control on the TDR’s rear panel.

Control Function

Power switch The power switch turns the TDR off and

prevents it from powering on.

Client USB connector The client USB connector allows you to

connect the TDR to a host computer for data

transfer and PC control.

RJ-45 Ethernet port The 10/100 Mb RJ-45 Ethernet port can be

used for data transfer and remote PC control.

External 14.4 VDC battery pack connector The external 14.4 VDC battery pack connector

allows you to select whether the external

battery or the internal battery is charged. By

default, the internal battery is preferred for

charging. The secondary battery will be

charged when the preferred battery is detected

to be at full charge.

24 VDC power adapter plug The 24 VDC power adapter plug allows you to

connect the 24 VDC AC adapter.

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PROBLEM SHEET 1-10

CONTROLS AND INDICATORS ACTIVITY

A. INTRODUCTION

Troubleshooting a cable to ensure it is performing as expected and meets the desired specifications

is a critical task. The TDR allows you to identify subtle changes in cable impedance that indicate a

fault. Properly setting up the TDR is essential in this task.

B. EQUIPMENT

None

C. REFERENCES


CT100HF

D. DIRECTION

Identify and define each of the controls and indicators numbered in the graphics below.

E. PROBLEM

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Problem Sheet 1-10 Sheet 2 of 3


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1. Name:

Function:

2. Name:

Function:

3. Name:

Function:

4. Name:

Function:

5. Name:

Function:

6. Name:

Function:

7. Name:

Function:

8. Name:

Function:

9. Name:

Function:

10. Name:

Function:

11. Name:

Function:

12. Name:

Function:

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Sheet 1 of 2



MENUS

A. INTRODUCTION

Key TDR functions are presented in a menu format. Interpreting the menus will assist you in

successfully operating the TDR.

B. REFERENCES


CT100HF

C. INFORMATION

The TDR features an array of built-in menus and analysis tools that allow the operator to locate

cable faults. The table below describes the TDR’s menus and their functions.

Menu Function

CABLE LEN menu The CABLE LEN menu allows you to select

predefined short, medium, and long cable

lengths while measuring the pulse period of

the cable.

Display menu The Display menu turns on-screen display

items on or off using the soft-menu

buttons to show or remove a variable. For

some items, selecting the button once shows

the display item, and selecting it again hides

the item. Some items may disappear

automatically when scanned traces are

selected.

Power menu The Power menu allows you to adjust the

power save options, power display, and

battery charging preference.

Connections menu The Connections menu allows you to change

the way the TDR connects to an external

source.

Measurement menu The Measurement menu allows you to change

units, Vp control, and reflection coefficient

calculation methods.

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Menu Function

Diagnostics menu The Diagnostics menu allows you to obtain

information on the software and hardware

versions for the TDR and diagnose potential

performance issues.

Info menu The Info menu provides you with information

regarding the TDR and its installed software.

Math menu The Math menu contains frequently used

mathematical operations.

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DIALOG BOX NAVIGATION

A. INTRODUCTION

Recognizing the different dialog boxes and their functions will facilitate operating the TDR and

prompt a faster response time.

B. REFERENCES


CT100HF

C. INFORMATION

Use the M-FUNCTION knob to scroll through the different entry boxes.

1. With an entry box selected, press the Keyboard menu option to call up an on-screen keyboard.

2. Select the desired characters with the M-FUNCTION knob, selecting the Select menu option

for each one.

3. Select the Shift menu option to get more characters.

4. To delete a character, use the Back menu option.

5. With the on-screen keyboard open, accept the current entry with the OK menu option, or return

to the original entry with the Cancel menu option.

6. With the keyboard off the screen, select the OK menu option to accept all changes to the

current dialog box and close the dialog box.

7. Select the Cancel menu option to clear all changes.

With a USB keyboard attached, entries can be changed directly by using the following steps:

1. Use the Tab key to scroll down through entry boxes; hold down Shift and select Tab to scroll

up through entry boxes.

2. Use the Backspace key to delete a character, and use the arrow keys to move the cursor left or

right.

3. Select Enter for OK or Escape for Cancel.

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Some dialog boxes present a list of selectable items. Use the M-FUNCTION knob to highlight

individual items for selection. Then, use the Select option to choose the highlighted item.

Where appropriate, multiple items can be marked for selection using the options on the right-side

menu:

1. Toggle selected

2. Clear all

3. Mark all

4. Toggle all

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CABLE TEST PREPARATIONS

A. INTRODUCTION

The TDR is a useful tool in finding and examining cable faults. To prepare a cable for testing, you

must navigate through several layers of TDR menus.

B. REFERENCES


CT100HF

C. INFORMATION

When testing a cable, you must perform several preliminary steps before beginning the cable trace.

Determining Vp

Vp, also sometimes abbreviated VoP, is the measure of the velocity of an electrical signal within a

cable expressed as a fraction of the speed of light in a vacuum.

Vp can be set in ranges between 0.25 and 1.0.

An accurate Vp is necessary for accurate cable length and distance-to-fault measurements.

The current setting for Vp appears on the lower center of the screen.

For cables of a known type, you can approximate the Vp by using the minimum Vp for that cable

type. To find that Vp value, use the TDR’s built-in library of cable types.

You can also approximate the Vp by testing a known cable of the same length and type as the one

you want to test.

Changing Vp

To change the Vp, select the M-FUNC button until the top-center information indicator reads Vp.

Two Vp indicators, Coarse Vp and Fine Vp, will be separately available:

1. Coarse Vp allows for the modification of the first three significant digits.

2. Fine Vp allows for the modification of the last three significant digits.

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Measurements and traces are automatically updated on the display to reflect the new Vp.

Finding an Unknown Vp

Follow these steps to find the Vp for a cable under test where the Vp is entirely unknown. It

requires a sample cable of the same type that can be measured physically.

Step Number Step

1 Measure the length of the test cable. Make sure the test cable is of the same

type as the cable for which you need to determine the Vp. If there are any

adapters used while connecting the cable, include their length in the

measurement or set one of the cursors at the end of the adapter before

attaching the cable.

2 Attach the test cable to the CABLE connector.

3 Select the AUTOFIT button. The TDR will now show the beginning and the

end of the test cable.

4 Position the active cursor (the last cursor selected) at the end of the test

cable. Use the HORIZONTAL SCALE knob to zoom in on the end of the

cable and get an accurate placement.

5 Adjust the Vp until the TDR distance measurement to the active cursor

equals the physical measurement. The final Vp value is the true Vp value of

the cable.

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RELATIVE DISTANCE MEASUREMENT

A. INTRODUCTION

To reduce time and expense, the TDR can accurately measure the relative distance to a fault.

B. REFERENCES


CT100HF

C. INFORMATION

The TDR displays the absolute distance from cable start and the relative distance from the passive

cursor to the active cursor.

The Vp must be set accurately for the section of cable between the cursors in order for the TDR to

accurately measure relative distance.

To measure the relative distance between two points in a cable, perform the following:

1. Access and set the Display menu to distance and ns.

a. Select the menu button.

b. Select the Display button.

c. Select the Distance ns button. The data appears in the top right corner of the display.

2. Exit the menu.

a. Select the menu button. The Display menu closes and the top-level menu appears.

b. Select the menu button. The top-level menu closes.

3. Select the AUTOFIT button. The TDR will now show the beginning and the end of the test

cable.

4. Select the CURSOR button to change the active cursor.

5. Turn the HORIZONTAL POSITION knob to move the active cursor to the beginning of the

section to be measured.

6. Turn the HORIZONTAL POSITION knob to move the newly active cursor to the end of the

section to be measured.

The TDR displays the distance measured between the two cursors as a Delta value below

the absolute distance measurement.

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MEASURING VSWR

A. INTRODUCTION

The Navy requires its cables to meet or exceed performance standards at a certain level across a

broad spectrum of operating frequency ranges. The TDR uses these specifications, which include

VSWR, to determine if the cable passes or fails its performance requirements.

B. REFERENCES


CT100HF

C. INFORMATION

VSWR is defined as the maximum reflected voltage over the minimum reflected voltage at a given

frequency.

To understand what VSWR is, consider this example: A voltage wave is traveling down a cable to

an antenna. In some cases, part of this voltage wave is reflected back down the cable in the reverse

direction toward the source. The VSWR is a measure of what is happening to the forward and

reverse voltage waveforms and how they compare in size.

A VSWR value of 1.2:1 denotes a maximum standing wave amplitude that is 1.2 times greater

than the minimum standing wave value. For example, a 50 Ω coax cable would have 9% of its

voltage reflected and 0.8% of its power reflected.

If there is no reflection, VSWR will be 1.

If all energy is reflected, VSWR goes to infinity.

The TDR displays two different VSWR values:

1. The first VSWR value is calculated from the total reflection relative to the output impedance

of the TDR (50 Ω).

2. The second VSWR value, labeled rVSWR, is calculated as the reflection between the two

cursors.

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COMMON CABLE FAULTS

A. INTRODUCTION

When a possible cable fault occurs (e.g., a break, a short circuit, moisture, or a bad connector),

signal power is compromised and the cable falls below specified performance specifications.

Knowing the different types of cable faults is crucial to locating faults in all cable systems aboard

ship.

B. REFERENCES


CT100HF

C. INFORMATION

Faults are mostly found at cable terminations and joints, or other locations where there has been

disruption in the cable’s route.

Each change in a signal has a different effect on the trace displayed on the TDR. A positive

reflection shows a higher impedance (i.e., the trace curves up); a lower reflection shows a lower

impedance (i.e., the trace curves down).

Examples of common cable faults:

1. A short shows as a curved negative trace to the bottom of the screen.

2. An open conductor shows a large positive trace to the top of the screen.

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3. A cable splice or joint shows a small positive trace followed by a small negative trace.

4. A T-joint shows a negative trace followed by a long positive trace.

5. A bridge tap shows a small positive trace followed by, after a short distance, a small negative

trace.

6. A split shows a short positive trace followed by a negative trace.

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7. A wet splice in water shows a short positive trace followed by a negative trace.

8. Water ingress shows a long, irregular trace.

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INITIALIZATION PROCEDURE

A. INTRODUCTION

It is important to know how to set up and verify proper operation of the TDR to accurately

measure cable lengths, troubleshoot, and identify faults on cables.

B. REFERENCES


CT100HF

C. INFORMATION

Follow the steps below to initialize the TDR:

1. Select the power button and observe the display.

2. Attach the cable to be tested to the CABLE connector.

3. Set the Vp to match the Vp of the cable under test.

a. Select the LIBRARY button.

b. Select the H2 function button to select the Cable Types menu. The Cable Type menu

appears.

c. Turn the M-FUNCTION knob CW or CCW to select the cable type.

d. Ensure the cable type of the cable under test is highlighted in the Cable Type menu.

e. Select the H3 function button to select the Select button. The Cable Type menu closes.

4. Exit the menus.

a. Select the menu button. The top-level menu appears.


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MEASURING CABLE LENGTH

A. INTRODUCTION

The ability to quickly measure cable length helps to ensure efficient test measurements during

troubleshooting procedures. Precise measurements also provide quantitative confirmation of

adherence to the Navy's cabling standards.

B. REFERENCES


CT100HF

C. INFORMATION

Follow the steps below when using the TDR to measure cable length:

1. Perform the TDR Initialization Procedure.

2. Select the AUTOFIT button to ensure the entire length of the cable fits on the display.


a. Select the menu button. The top-level menu opens.

b. Select the V2 function button to select the Display menu.

c. Select the V3 function button to select the Distance ns menu. The distance is displayed in

the upper right corner of the display.

d. Select the V3 function button to select *Distance* *ns*.

4. Exit the menus.



5. Select the CURSOR button to position the active cursor.

6. Access the Display menu to close the distance function.



c. Select the V3 function button to select *Distance* ns.

d. Select the V3 function button to select Distance *ns*.

7. Exit the menus.



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MEASURING DISTANCE TO A FAULT AND IDENTIFYING THE FAULT

A. INTRODUCTION

Many components can cause problems for electrical systems. Cable lines are typically the most

common failure point. These failures can cause unwanted signal reflections. Using the TDR, the

root cause of an RF problem can be identified and isolated, thereby saving time and expense.

B. REFERENCES


CT100HF

C. INFORMATION

Follow the steps below when using the TDR to measure distance to and identification of a fault:






c. Select the V3 function button to select the Distance ns menu.

d. Select the V3 function button to select *Distance* *ns*.

4. Exit the menus.



5. Select the CURSOR button to position the active cursor.

6. Measure the distance to the fault and identify the fault.

a. Rotate the HORIZONTAL POSITION knob CW or CCW to move the active cursor to the

beginning of the first fault.

b. Rotate the VERTICAL SCALE knob CW or CCW to zoom in and identify the fault.

c. Rotate the HORIZONTAL SCALE knob CW or CCW to get an accurate distance

measurement to the fault.

d. Identify the type of fault.

7. Access the Display menu to close the distance function.



c. Select the V3 function button to select *Distance* ns.

d. Select the V3 function button to select Distance *ns*.

8. Exit the menus.


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Note: Repeat step 6 if the distance for additional faults is needed.

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MEASURING VSWR

A. INTRODUCTION

Measuring VSWR is important in understanding the efficiency of a system and how well the

components of the RF network are matched in impedance. When impedance is improperly

matched, you lose signal power, which results in weak transmissions, poor reception, or both.

B. REFERENCES


CT100HF

C. INFORMATION

Follow the steps below when using the TDR to measure the VSWR:



3. Access and set the Display menu to VSWR.


b. Select the V2 function button to select the Display menu. The Display menu appears.

c. Select the V4 function button to display more menu functions. Page 2 of the Display menu

appears.

d. Select the V1 function button to select VSWR.

4. Exit the menus.



5. Turn the HORIZONTAL POSITION knob CW or CCW to move the active cursor along the

cable trace.

6. Access the Display menu to close the VSWR function.



c. Select the V4 function button to display more menu functions. Page 2 of the Display menu

appears.

d. Select the V1 function button to select *VSWR*.

7. Exit the menus.

e. Select the menu button. The Display menu closes and the top-level menu appears.

f. Select the menu button. The top-level menu closes.

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PROBLEM SHEET 1-21

OPERATE THE TDR PRACTICE

A. INTRODUCTION

This exercise allows you to practice operating the TDR. You will set up the TDR, measure cable

length and VSWR, and identify and measure distance to a fault.

B. EQUIPMENT

None

C. REFERENCES


CT100HF

D. DIRECTION

For each scenario, use the job and information sheets in your Trainee Guide to practice performing

the procedures to operate the TDR. Record your test measurements in the spaces provided.

E. PROBLEM

During pre-underway check-offs, your LPO assigns you the task of troubleshooting a possible cable

fault on a newly installed RG-58/U cable. You are to measure the length of the RG-58/U cable.

Measuring Cable Length

Measurement Answers

Cable lengths 1. ft

2 ns

3. ∆ft

4. ∆ns

TRAINEE GUIDE



Your LPO suspects one or more faults in an RG-58/U cable. You are to troubleshoot for a possible

fault. If a fault(s) is found, you are to measure the distance to the fault(s) on the cable and identify

the type of fault.

Measuring Distance to a Fault and Identifying the Fault

Measurement Answers

Distance to fault #1 1. ft

2. ∆ft

Distance to fault #2 3. ft

4. ∆ft

Type of fault 5.

Vp 6.

The LPO needs to know the reflection of an RG-58/U cable used in a single antenna installation.

You are to measure the VSWR and rVSWR of the RG-58/U cable.

Measuring VSWR

Measurement Answers

VSWR 1. VSWR

rVSWR 2. rVSWR

sheet 1 of 1 activity b. references ct100hf c. …...trainee guide sheet 1 of 2 for training use...

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