1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 * TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU4%,%6)3)/.G0G0!.$G0G03/5.$G0G042!.3-)33)/.,).).G0G13G050G0G0!.$G0G0-/.)4/2).!.G0G0).4%2.!4)/.!,G0G03/5.$G0G13G002/2!-%#/%#4)/.)45G134G0G0RecommendationG0G0* (Extract from the “LUEG0“OOK)NOTES1 ITU-T Recommend
2、ation J.15 was published in Fascicle III.6 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 identical to the Blue Book version and copyright conditions remain
3、 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 this publication may be reproduced or utilized in any form or b
4、y any means, electronic ormechanical, including photocopying and microfilm, without permission in writing from the ITU.Fascicle III.6 - Rec. J.15 1Recommendation J.15Fascicle III.6 - Rec. J.15LINING-UP AND MONITORING AN INTERNATIONALSOUND-PROGRAMME CONNECTION(former Recommendation J.14; amended at G
5、eneva, 1972 and 1980, and at Melbourne, 1988)For the alignment of international sound-programme connections the CCIR, in Recommendation 661,recommends a three-level test signal.This test signal is based on the test signal definitions given in CCIR Recommendation 645 and specifies a testsignal which
6、should be used on sound-programme circuits generally. A common alignment procedure for peakprogramme meters and VU-meters using the three-level test signal can be found in Annex I of CCIRRecommendation 645. From this information it can be seen what indicators will be produced by the three-level test
7、signal on the different types of peak programme meters and volume meters.To comply with the provisions of Recommendation J.14, the lining-up and monitoring of an internationalsound-programme connection should ensure that, during the programme transmission, the peak voltage at a zerorelative level po
8、int will not exceed 3.1 volts, which is that of a sinusoidal signal having an r.m.s. value of 2.2 volts. Themethods for achieving this condition as well as the relevant performance requirements are given in RecommendationsN.10 to N.18 (see references 1 to 8).Some indication of the volume or of the p
9、eaks of the signals during programme transmission may be obtainedby monitoring at the studio, in the repeater stations, or at the transmitter. One of the instruments, the characteristics ofwhich are summarized in Table 1/J.15, may be used.Since there is no simple relation between the readings given
10、by two different instruments for all types ofprogramme transmitted, it is desirable that the broadcast organization controlling the studio and the telephoneAdministration(s) controlling the sound-programme circuit should use the same type of instrument so that theirobservations are made on a similar
11、 basis.In general the telephone Administration and the broadcast organization of a country agree to use the same typeof instrument. It is desirable to reduce to a minimum the number of different types of instrument and to discourage theintroduction of new types which only differ in detail from those
12、 already in service. The unified use of the peakindicator specified in reference 9 is under study.During programme transmission, the signal level at the output of the last amplifier controlled by the sendingbroadcast organization (Point A of Figure 3/J.13) should be monitored to see that the meter d
13、eflection of the measuringinstrument is always lower than the peak voltage for the overall line-up, allowance being made for the peak factor ofthe programme involved.It should be remembered that the amplitude range from a symphony orchestra is of the order of 60 to 70 dB,while the specification for
14、sound-programme circuits is based on a range of about 40 dB. Before being passed to thesound-programme circuit, therefore, the dynamic ratio of the studio output needs to be compressed.2 Fascicle III.6 - Rec. J.15TABLE 1/J.15Principal characteristics of the various instruments used for monitoring th
15、e volume or peaksduring telephone conversations or sound-programme transmissionsType of instrumentRectifiercharacteristic(Note 1)Time to reach 99%of final reading(milliseconds)Integration time(milliseconds)(Note 2)Time to returnto zero(value and definition)(1) Vu meter (United Statesof America)1.0 t
16、o 1.4 300 165 (approx.) Equal to the integrationtime(2) Vu meter (France) 1.0 to 1.4 300 10% 207 30 300 ms 10% from thereference deviation(3) Peak programme meter, used bythe Netherlands1 Not specified 10 ms for 1 dB5 ms for 2 dB0-4 ms for 15 dB0 to 20 dB: 1-5 s0 to 40 dB: 2-5 s(4) Programme level m
17、eter (Italy) 1 Approx. 20 ms Approx. 1.5 ms Approx. 1.5 ms from100% to 10% of the reading inthe steady state(5) Peak indicator forsound-programme transmissionsused by the British BroadcastingCorporation (BBC peakprogramme meter)110(Note 3)3 s for the pointer tofall 26 dB(6) Maximum amplitude indicat
18、orused by the Federal Republic ofGermany (type U 21)1 Around 80 5 (approx.) 1 or 2 s from 100% to10% of the reading inthe steady state(7) OIRT Programme levelmeter:Type A sound meterType B sound meterFor both types:less than 300 msfor meters withpointer indication,andless than 150 msfor meters withl
19、ight indication10 560 10For both types:1.5 to 2 s from the 0 dBpoint which is at 30% ofthe length of theoperational section ofthe scale(8) E.B.U. standard peakprogramme meter(Note 4)1 10 2.8 s for the pointer tofall 24 dBNote 1 The number given in the column is the index n in the formula V(output)=
20、V(input)napplicable for each half-cycle.Note 2 The “integration time” was defined by the CCIF as the “minimum period during which a sinusoidal voltage should beapplied to the instrument for the pointer to reach to within 0.2 neper or nearly 2 dB of the deflection which would be obtained if thevoltag
21、e were applied indefinitely”. A logarithmic ratio of 2 dB corresponds to 79.5% and a ratio of 0.2 neper to 82%.Note 3 The figure of 4 ms, that appeared in previous editions, was actually the time taken to reach 80% of the final reading with ad.c. step applied to the rectifying integrating circuit. I
22、n a new and somewhat different design of this programme meter usingtransistors, the performance on programme remains substantially the same as that of earlier versions and so does the response to anarbitrary, quasi-d.c. test signal, but the integration time, as defined in Note 2, is about 20% greate
23、r at the higher meter readings.Note 4 This meter is intended specifically for use in monitoring sound signals transmitted internationally, and thereforeincorporates a scale conforming to CCITT Recommendation N.15 5, calibrated in dB from 12 to +12 relative to a level marked“TEST” corresponding to 0
24、dBm at a zero relative level point. In addition to the normal mode of operation having the characteristicsshown above, the meter may be operated temporarily in a “slow” mode faciliting the comparison of observations made at widelyseparate points. The peak values indicated in this mode have no absolu
25、te significance, and may only be used for such comparisons.Fascicle III.6 - Rec. J.15 3References1 CCITT Recommendation Limits for the lining-up of international sound-programme links and connections,Vol. IV, Rec. N.10.2 CCITT Recommendation Essential transmission performance objectives for internat
26、ional sound-programmecentres (ISPC), Vol. IV, Rec. N.11.3 CCITT Recommendation Measurements to be made during the line-up period that precedes a sound-programme transmission, Vol. IV, Rec. N.12.4 CCITT Recommendation Measurements to be made by the broadcasting organizations during the preparatoryper
27、iod, Vol. IV, Rec. N.13.5 CCITT Recommendation Maximum permissible power during an international sound-programmetransmission, Vol. IV, Rec. N.15.6 CCITT Recommendation Identification signal, Vol. IV, Rec. N.16.7 CCITT Recommendation Monitoring the transmission, Vol. IV, Rec. N.17.8 CCITT Recommendation Monitoring for charging purposes, releasing, Vol. IV, Rec. N.18.9 IEC Publication 268-10A.
