ITU-T G.732-1988 工作在2048 kbit/s的基群脉冲编码调制(PCM)复用设备的特性 Characteristics of primary PCM multiplex equipment operating at 2048 kbit/s

pdf标准 ITU-T G.732-1988 工作在2048 kbit/s的基群脉冲编码调制(PCM)复用设备的特性 Characteristics of primary PCM multiplex equipment operating at 2048 kbit/s

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ITU-T G.732-1988 工作在2048 kbit/s的基群脉冲编码调制(PCM)复用设备的特性 Characteristics of primary PCM multiplex equipment operating at 2048 kbit/s  第 1 页 ITU-T G.732-1988 工作在2048 kbit/s的基群脉冲编码调制(PCM)复用设备的特性 Characteristics of primary PCM multiplex equipment operating at 2048 kbit/s  第 2 页 ITU-T G.732-1988 工作在2048 kbit/s的基群脉冲编码调制(PCM)复用设备的特性 Characteristics of primary PCM multiplex equipment operating at 2048 kbit/s  第 3 页 ITU-T G.732-1988 工作在2048 kbit/s的基群脉冲编码调制(PCM)复用设备的特性 Characteristics of primary PCM multiplex equipment operating at 2048 kbit/s  第 4 页 ITU-T G.732-1988 工作在2048 kbit/s的基群脉冲编码调制(PCM)复用设备的特性 Characteristics of primary PCM multiplex equipment operating at 2048 kbit/s  第 5 页
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INTERNATIONAL TELECOMMUNICATION UNION )45 4 ' TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU '%.%2!, !30%#43 /& $)')4!, 42!.3-)33)/. 3934%-3 4%2-).!, %15)0-%.43 #(!2!#4%2)34)#3 /& 02)-!29 0#-5,4)0,%8 %15)0-%.4 /0%2!4).' !4  KBITS )45 4 Recommendation ' (Extract from the "LUE "OOK) NOTES 1 ITU-T Recommendation G.732 was published in Fascicle III.4 of the Blue Book. This file is an extract from the Blue Book. While the presentation and layout of the text might be slightly different from the Blue Book version, the contents 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 a telecommunication administration and a recognized operating agency. © ITU 1988, 1993 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. Recommendation G.732 Fascicle III.4 - Rec. G.732 CHARACTERISTICS OF PRIMARY PCM MULTIPLEX EQUIPMENT OPERATING AT 2048 kbit/s (Geneva, 1972; further amended) 1 1.1 General characteristics Fundamental characteristics The encoding law used is the A-law as specified in Recommendation G.711. The sampling rate, load capacity and the code are also specified in that Recommendation. The number of quantized values is 256. Note - The inversion of bits 2, 4, 6, and 8 is covered by the encoding law and is applicable only to voicechannel time slots. 1.2 Bit rate The nominal bit rate is 2048 kbit/s. The tolerance on this rate is ± 50 parts per million (ppm). 1.3 Timing signal It should be possible to derive the transmitting timing signal of a PCM multiplex equipment from an internal source, from the incoming digital signal and also from an external source. Note - Further study is required on the effect of jitter of the incoming signal on the timing signal, and on the measures to be taken in case of loss of the incoming signal or the external source. 2 Frame structure Refer to §§ 3.3.1 and 3.3.2 of Recommendation G.704 for frame structure and use of derived channel time slots. Note - If channel time slot 16 which is assigned to signalling as covered in § 5 below is not needed for signalling it may be used for purposes other than a voice channel encoded within the PCM multiplex equipment. 3 Loss and recovery of frame alignment The strategy for the loss and recovery of frame alignment should be according to Recommendation G.706, § 4.1. 4 4.1 Fault conditions and consequent actions Fault conditions The PCM multiplex equipment should detect the following fault conditions: 4.1.1 Failure of power supply. Fascicle III.4 - Rec. G.732 1 4.1.2 Failure of codec (except when using single-channel codecs). As a minimum requirement this fault condition should be recognized when, for at least one signal level in the range -21 to -6 dBm0, the signal-to-quantizing noise ratio performance of the local codec is 18 dB or more below the level recommended in Recommendation G.712. 4.1.3 Loss of incoming signal at the 64 kbit/s input port (time slot 16). Note 1 - The detection of this fault condition is not mandatory when channel associated signalling is used and the signalling multiplex is situated within a few metres of the PCM multiplex equipment. Note 2 - The detection of this fault condition is not mandatory when contradirectional interfaces are used. 4.1.4 Loss of the incoming signal at 2048 kbit/s. Note - The detection of this fault condition is required only when it does not result in an indication of loss of frame alignment. 4.1.5 Loss of frame alignment. 4.1.6 Excessive bit error ratio detected by monitoring the frame alignment signal. 4.1.6.1 With a random bit error ratio of ≤ 10-4, the probability of activating the indication of fault condition within a few seconds should be less than 10 -6. With a random bit error ratio of ≥ 10-3, the probability of activating the indication of fault condition within a few seconds should be higher than 0.95. 4.1.6.2 With a random bit error ratio of ≥ 10-3, the probability of deactivating the indication of fault condition within a few seconds should be almost 0. With a random bit error ratio of ≤ 10-4, the probability of deactivating the indication of fault condition within a few seconds should be higher than 0.95. Note - The activating and the deactivating period specified as "a few seconds" is intended to be in the order of 4 to 5 seconds. 4.1.7 Alarm indication received from the remote PCM multiplex equipment (see § 4.2.3 below). 4.2 Consequent actions Further to the detection of a fault condition, appropriate actions should b

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