1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 . TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU-!).4%.!.#%G0G0/&G0G0).4%2.!4)/.!,3/5.$G0 G002/2!-%G0G0!.$G0G04%,%6)3)/.42!.3-)33)/.G0G0#)2#5)43-!).4%.!.#%G0G0-%!352%-%.434/G0G0“%G0G0-!$%G0G0/.G0G0).4%2.!4)/.!,3/5.$G0 G002/2!-%G0G0#)2#5)43)45G134G0G02ECOMM
2、ENDATIONG0G0. (Extract from the “LUEG0“OOK)NOTES1 ITU-T Recommendation N.23 was published in Fascicle IV.3 of the Blue Book. This file is an extract from theBlue Book. While the presentation and layout of the text might be slightly different from the Blue Book version, thecontents of the file are id
3、entical 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 reserved. No part of
4、 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 IV.3 - Rec. N.23 1Recommendation N.23Fascicle IV.3 - Rec. N.23MAINTENANCE MEASUREMENTS TO BE MADEON INTERNAT
5、IONAL SOUND-PROGRAMME CIRCUITS1 GeneralIn Tables 1/N.23 to 5/N.23 maintenance limits for international sound-programme circuits are specified. Ifthese limits are exceeded, the control station1)for the circuit should decide the appropriate action to be taken to bring thecircuit back within these limi
6、ts.2 Routine measurementsRoutine measurements should be made every six months and the circuit realigned to meet the limits given inRecommendation N.21. The control station should agree with other stations, the date and time of routine measurementsand the parameters to be included. It is recommended
7、to use an automatic measuring equipment (see RecommendationsO.31 1, O.32 2, O.33 3). The test procedures and frequencies to be used are detailed in Recommendation N.21. Ifno automatic measuring equipment is available, measurements shall normally be restricted to loss/frequency distortionand weighted
8、 noise. For the stereophonic pairs, the parameters Nos. 12, 13, 14 and 15 of Table 1/N.23 shall also bemeasured.3 Release of circuit for routine measurementsEven if there is a general understanding with a renter of a permanently leased circuit on the time when routinetests are to be carried out, the
9、 SIPCO should always confirm with the renter that the circuit can be released for thesetests._1)For the functions and responsibilities of the circuit control stations see Recommendation N.5.2 Fascicle IV.3 - Rec. N.23TABLE 1/N.23Limits for international 15 kHz sound-programme circuitsItem Parameter
10、Unit Limits1 Insertion gainAdjustement error dB 0.5Variation during 24 h dB 0.50.04 to 0.125 kHzdB + 0.5dB 20.125 to 10 kHz dB 0.52 Loss/frequency distortion 10 to 14 kHzdB + 0.5referred to 0.8 ou 1 kHzdB 214 to 15 kHzdB + 0.5dB 30.04 kHz ms 553Groupe delay/frequencyresponse referred0.075 kHz ms 24t
11、o minimum14 kHz ms 815 kHz ms 124 Weighted noiseIdle channel dBq0ps 44Programme-modulated dBq0ps 325 Single tone interference level + dBm0s 736 Disturbing modulation by power supply dB 457 Total harmonic0.04 to 0.125 kHz % 1distortion0.125 to 7.5 kHz % 0.58 3rd order difference tone at 0.18 kHz % 0.
12、59 Error in reconstituted frequency Hz 10.04 kHz dB 5010 Intelligible crosstalk ratio 0.5 to 5 kHz dB 7415 kHz dB 6011 Error in amplitude/amplitude response dB 0.5Fascicle IV.3 - Rec. N.23 3TABLE 1/N.23 (cont.)Item Parameter Unit Limits0.04 to 0.125 kHz dB 1.512 Difference in gain0.125 to 10 kHz dB
13、0.8between A and B channels10 to 14 kHz dB 1.5Additionalparameters14 to 15 kHz dB 3for stereotransmission0.04 to 0.125 kHz degree 3013 Phase difference0.2 to 4 kHz degree 15between A and B channels14 kHz degree 3015 kHz degree 4014 Intelligible crosstalk ratio A/B dB 5015 Crosstalk ratio (intermodul
14、ation) A/B dB 60Note The limits given in this table are applicable both for analogue and digital transmissions.4 Fascicle IV.3 - Rec. N.23TABLE 2/N.23Limits for international 10 kHz sound-programme circuitsItem Parameter Unit Limits1 Insertion gainAdjustment error dB 0.4Variation with time dB 0.40.0
15、5 to 0.1 kHzdB + 1.3dB 3.30.1 to 0.2 kHzdB + 1.3dB 22Loss/frequency distortion referredto 0.8 or 1 kHz0.2 to 6 kHz dB 1.36 to 8.5 kHzdB + 1.3dB .28.5 to 10 kHzdB + 1.3dB 3.30.05 kHz ms 543Group delay/frequency response referredto minimum0.1 kHz ms 1310 kHz ms 5.44 Weighted noise (Idle channel)a)dBq0
16、ps 415 Single tone interference level + b)dBm0s 736 Disturbing modulation by power supply dB 477 Total harmonic distortion0.05 to 0.1 kHz % 2.30.1 to 10 kHz % 1.58 3rd order difference tone at 0.18 kHz % 1.59 Error in reconstituted frequency Hz 0.810 Intelligible crosstalk ratioc)dB 7611 Error in am
17、plitude/amplitude response dB 0.4a)For circuits on carrier systems, it is not always possible, in absence of special precautions, to meet these limits (see Annex IIto CCIR Recommendation 504 4).b)Or 20 dB below measured weighted noise level, whichever is higher.c)It is in some cases difficult or imp
18、ossible to meet these limits (see 3.8, Note 2, in Annex I to CCIR Recommendation 5044).Fascicle IV.3 - Rec. N.23 5TABLE 3/N.23Limits for international 7 kHz sound-programme circuitsItem Parameter Unit Limits1 Insertion gainAdjustment error dB 0.4Variation during 24 h dB 0.40.05 to 0.1 kHzdB + 0.8dB
19、2.32 Loss/frequency distortion referredto 0.8 or 1 kHz0.1 to 6.4 kHz dB 0.86.4 to 7 kHzdB + 0.8dB 2.30.05 kHz ms 54Group delay/frequency response0.1 kHz ms 133 referred to minimum6.4 kHz ms 3.47 kHz ms 6.74 Weighted noiseIdle channel dBq0ps 46Programme-modulated dBq0ps 345 Single tone interference l
20、evel + dBm0s 756 Disturbing modulation by power supply dB 477 Total harmonic distortion0.1 kHz % 1.18 3rd order difference tone at 0.18 kHz % 1.19 Error in reconstituted frequency Hz 0.80.05 kHz dB 5510 Intelligible crosstalk ratio 00.5 to 3.2 kHz dB 766.4 kHz dB 7011 Error in amplitude/amplitude re
21、sponse dB 0.4Fascicle IV.3 - Rec. N.23 7TABLE 5/N.23Limits for international 5 kHz sound-programme circuitsReferences1 CCITT Recommendation Automatic measuring equipment for sound-programme circuits, Vol. IV, Rec. O.31.2 CCITT Recommendation Automatic measuring equipment for stereophonic pairs of so
22、und-programmecircuits, Vol. IV, Rec. O.32.3 CCITT Recommendation Automatic equipment for rapidly measuring stereophonic pairs and monophonicsound-programme circuits, links and connections, Vol. IV, Rec. O.33.4 CCIR Recommendation Performance characteristics of 10 kHz type sound-programme circuits, V
23、ol. XII,Recommendation 504, ITU, Geneva, 1982.Item Parameter Unit Limits1 Insertion gainAdjustment error dB 0.4Variation during 24 h dB 0.40.07 to 0.2 kHzdB + 0.8dB 2.32 Loss/frequency distortion referred to0.8 or 1 kHz0.2 to 4 kHz dB 0.84 to 5 kHzdB + 0.8dB 2.33 Group delay/frequency response0.07 k
24、Hz ms 40referred to minimum5 kHz ms 104 Maximum weighted noise level dBq0ps 345 Single tone interference level + dBm0s 756 Disturbing modulation by power supply dB 477 Total harmonic distortion0.1 kHz % 1.18 3rd order difference tone at 0.18 kHz % 1.19 Error in reconstituted frequency Hz 0.80.07 kHz dB 5910 Intelligible crosstalk ratio 00.5 to 3.2 kHz dB 765 kHz dB 7211 Error in amplitude/amplitude response dB 0.4
