NT1Q Standard-Network-Terminationfor ISDN Basic Access

Echo Cancellation Method

SMD Technology

Integrated Power Supply

ETS 300 012, ITU-T I.430, TS 102 080

NT1QStandard-Network Terminationfor ISDN Basic Access

With the digitisation of thetelephone network and implementation of ISDN, it ispossible to transmit other databesides speech over an subscriberline.

The ISDN basic access providesthe subscriber with two independent 64-kbps channels B1 and B2 and one 16-kbpsD channel for signalling. Both B channels can be utilised simultaneously to carry individualcommunication services such asvoice, text, data and images todifferent users.

The signalling information andvarious features of the servicesused on the basic circuits aretransmitted on the D channel.The signalling method usedensures error-protected transmission of control information which can be performed at any time by eachterminal unit or by the exchange.Thus mutual interference ofuser information and controlinformation is impossible.

Both the network terminationNT1Q at the subscriber sideand the ISDN switch at theexchange of the network provider are required for therealisation of ISDN basic access.The NT1Q interfaces layer 1 ofline interface U and layer 1 ofthe user interface S/T within theOSI 7-layer reference model.

U Interface

On the two wire line interface U, the informationis transmitted in full duplex mode within commonfrequency band and time. Echo cancellation isused for direction separation. The net bit rate,which amounts to 144 kbps, is converted into aquaternary modulation rate of 72 kbaud as perthe 2B1Q coding method. With synchronisationword and overhead, a total modulation rate of 80kbaud is obtained.

Power supply

The NT1Q is remotely fed from the exchange viathe U interface. Both the internally required 5 Voperating voltage and the 40 V supply voltage forthe S/T interface are generated by a DC/DC converter which provides a short-circuit-proof output. The available power of 420 mW at the S/Tinterface manintains the basic functions of onetelephone set in the event of mains failure(restricted mode). During normal operation, thebuilt-in mains power supply circuit feeds the S/Tinterface with 40V/4.5 W and can thus be usedfor powering up to four ISDN telephone sets(normal mode). The NT1Q switches automaticallyfrom normal mode to restricted mode if the mainsvoltage drops below the lower limit of the nominal range. To indicate the restricted mode thepolarity of the feeding voltage at the S/T interfaceis reversed.

Electrical Safety

The NT1Q complies with the requirements of EN 41 003, EN 60 950, EN 300 047 and IEC 950. The electrical separation between U and S/T and Uor S/T towards the mains interface provides doubleinsulation.The mains power supply is designed tomeet the requirements of class II equipment.

Installation and Service

The NT1Q is installed at the subscribers premises.Its flat wall cabinet is made of self-extinguishingplastic material.The mechanical design complies with the electricaland mechanical requirements and offers practicaladvantages both for the service personnel of thenetwork provider and for the user:

Easy connection of the U interface wires bymeans of spring contact terminals which can be actuated manually without using ascrewdriver

are optionally equipped with a flexible cable toprovide a plug-in connection to the telecommunication network.

Easy connection to the S/T user-side installationusing spring contact terminals or two sockets(EN 28 877, ISO 8877, RJ45).

Setting of operational and test modes by switches.

Protection of the S/T interface against accidentalconnection with analogue telecommunicationnetwork voltages.

Protection against electric shock during servicingoperations by covering the bare parts of themains voltage circuit.

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Connection plan of the NT1Q with examples of subscriber terminal equipment

S/T interface

A maximum of eight ISDN user terminal equipments (TE1)which may support different services can be connected to the userinterface S/T via two copper twisted pair. Three basic configurations as per ITU-T I.430 must be distinguished:

Point-to-multipoint connection as a short passive bus Point-to-point connection Point-to-multipoint connection as an extended passive bus

With a wire diameter of 0.6 mm it is possible to achieve the rangesshown in the diagrams shown there. The ranges achieved in practiceare strongly dependent on the type of cable used and may thereforediffer from the values shown.

l1 l2low-capacitance cable 800 m 165 m

2000 m 55 mhigh-capacitance cable 400 m 75 m

1000 m 25 m

Short passive bus

Point-to-point connection

Extended passive bus

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TE1

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150 m to 320 m

TE1

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TE1

4

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1100 m to 2200 m

ISDNexchange

TA8

Data

Image

Voice

Non-ISDNuser terminals

Quante Netzwerke GmbHAhrensburger Str. 8D- 30659 Hannoverphone +49 511/740192-0fax +49 511/740192-100

www.quante-netzwerke.de

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NT1QTechnical data

Mains Interface

Mains voltage115 VAC 99 V 128 V230 VAC 195 V 253 V

Frequency115 VAC 48 Hz 63 Hz230 VAC 48 Hz 52 Hz

Current115 VAC type 80 mA*230 VAC type 40 mA*

*related to an output power of 4.5 W at S/T

Electrical Safety

- EN 41 003- ETS 300 047- ITC 950, EN 60 950

Environmental conditions

EMC as per CISPR 22, EN 50 022, IEC 801, ETS 300 386-1

Protection as per ETS 300 047 ITU-T (CCITT) K.12Storage as per ETS 300 019 class 1.2Transport as per ETS 300 019 class 2.3Operation as per ETS 300 019 class 3.2

General

Weight 0.6 kgDimensions (H W D) 150 mm 100 mm 45 mmMains cable length 2 meter

S/T Interface(as per ANSI T1.605, ETS 300 012, ITU-T I.430)

Transmission method 4-wire duplex transmissionChannel structure 2B + D + synchronisation

+ service dataLine code AMI, modifiedTotal bit rate 192 kbpsTransmit amplitude 750 mVp 10% at 50 Output and input impedance

20 kHz 106 kHz 2.5 kUnbalance

10 kHz 300 kHz 54 dB300 kHz 1 MHz 54 dB, decreasing at 20 dB/decade

User installation 2 balanced copper wire pairsRange

short passive bus 320 mpoint-to-point 2200 m

Power FeedingNormal mode 4.5 W from mains power supplyRestricted mode 420 mW from remote power supply

U Interface(as per ANSI T1.601, TS 102 080)

Transmission method 2-wire duplex transmissionwith echo cancellation

Channel structure 2B + D + synchronisation + service dataLine code 2B1QTotal modulation rate 80 kbaud

Transmit amplitudeSingle pulse 2.5 VS0 5 % at 135 Encoded signal 4 VSS 10% at 135

Internal impedance 135 Return loss 10 kHz 25 kHz 20dBLine Balanced copper wire pairRange for approximately 4200 metersBER 10-7 0.4 mm wire diameter

approximately 8000 meters0.6 mm wire diameterLoops 1 15 (ANSI)Loops 1 8 (ETSI)