1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 1 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU%.%2!,G0G02%#/-%.$!4)/.3G0G0/.G0G04%,%0(/.%37)4#().G0G0!.$G0G03).!,).#,!53%3G0G0!00,)#!“,%G0G04/G0G0)45G134G0G034!.$!2$3934%-3490)#!,G0G042!.3-)33)/.G0G02%15)2%-%.43&/2G0G03).!,G0G03%.$%23G0G0!.$G0G02%#%)6%23
2、)45G134G0G0RecommendationG0G01 (Extract from the “LUEG0“OOK)NOTES1 ITU-T Recommendation Q.114 was published in Fascicle VI.1 of the Blue Book. This file is an extract fromthe Blue Book. While the presentation and layout of the text might be slightly different from the Blue Book version, thecontents
3、of the file are identical to the Blue Book version and copyright conditions remain unchanged (see below).2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both atelecommunication administration and a recognized operating agency. ITU 1988, 1993All rights re
4、served. No part of this publication may be reproduced or utilized in any form or by any means, electronic ormechanical, including photocopying and microfilm, without permission in writing from the ITU.Fascicle VI.1 - Rec. Q.114 1Recommendation Q.114Fascicle VI.1 - Rec. Q.1142.3 TYPICAL TRANSMISSION
5、REQUIREMENTS FOR SIGNALSENDERS AND RECEIVERS2.3.1 In-band line signal receivers (including the buffer amplifier or equivalent device), in 2.3.2 to 2.3.7 below,apply only in the case where the signal receiver is a 4-terminal device (“quadripole“) and where the nominal circuitimpedance is 600 ohms.2.3
6、2 Input and output impedanceThe nominal value of the input and output impedances of the signal receiver is 600 ohms.ZEand ZS, which are respectively the measured values of the input and output impedance of the signalreceiver, should meet the following condition throughout the 300 to 3400 Hz frequen
7、cy band:In making these measurements the free terminals should be looped by a resistance of 600 ohms and thevoltage applied must not overload the equipment.2.3.3 AttenuationAt 800 Hz, the insertion loss of the signal receiver, measured with a generator and a receiver of internalresistance of 600 ohm
8、s, must be between the limits:A 0.5 decibelThe value A is to be determined from the level diagram of the circuit according to the point of the circuit atwhich the signal receiver should be connected.The measurement is made with a 1 mW generator having an internal impedance equal to a pure resistance
9、 of600 ohms and having an e.m.f. of 2 x 0.775 volt (so-called “standard generator“). The e.m.f. of the generator will beadjusted to take into account the relative level of the point of the circuit at which the signal receiver is connected.If n is the relative level at the signal receiver input, the
10、e.m.f. of the generator will therefore be:2.3.4 Attenuation distortionThe variation in insertion loss of the signal receiver in the 300-3400 Hz frequency band, measured under theconditions of 2.3.3 above, should not exceed the limits shown in Figure 1/Q.114.As in certain cases Systems No. 5, and R1
11、may be applied to circuits in transmission systems with a channelspacing of less than 4 kHz, the 300 Hz lower limit shown above may be replaced by 200 Hz for System No. 5.2 Fascicle VI.1 - Rec. Q.1142.3.5 Nonlinear distortionThe curve representing the variation (as a function of power) of the output
12、 level of the signal receiver, withreference to the nominal value of the output level, should be within the limits shown in Figure 2/Q.114 over therelevant frequency range.2.3.6 BalanceThe input and output of the signal receiver should have a high degree of balance to earth, the admittance ofeach te
13、rminal to earth being very low.The same clause should apply to the signal sender.2.3.7 Crosstalk between adjacent signal receiversThe crosstalk ratio between two adjacent signal receivers should not be less than 74 dB in the relevantfrequency band.2.3.8 During the register signalling period no speech transmission takes place. It is not essential therefore for theregister signalling equipment of systems having separate equipment for that purpose to take account of 2.3.2 to 2.3.7above but it is desirable to adopt appropriate clauses for efficient signalling performance.
