1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU J.27 (ex CMTT.661) (06/90) TELEVISION AND SOUND TRANSMISSION SIGNALS FOR THE ALIGNMENT OF CONNECTIONS INTERNATIONAL SOUND-PROGRAMME ITU-T Recommendation 5.27 (Formerly Recommendation ITU-R CMTT.661) COPYRIGHT
2、 International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesFOREWORD The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the International Telecom- munication Union. The ITU-T is responsible for studying technical, operating and
3、 tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, established the topics for study by the ITU-T Study Groups which, in their turn, pr
4、oduce Recommendations on these topics. IT-T Recommendation J.27 (formerly Recommendation ITU-R CMTT.66 1) was elaborated by the former IT-R Study Group CMTT. See Note 1 below. NOTES 1 As a consequence of a reform process within the Intemational Telecommunication Union (ITU), the CCITT ceased to exis
5、t as of 28 February 1993. In its place, the ITU Telecommunication Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRi3 have been replaced by the Radiocommunication Sector (ITU-R). Conforming to a joint decision by the World Telecomm
6、unication Standardization Conference (Helsinki, March 1993) and the Radiocommunication Assembly (Geneva, November 1993), the ITU-R Study Group CMTT was transferred to ITU-T as Study Group 9, except for the satellite news gathering (SNG) study area which was transferred to ITU-R Study Group 4. 2 tele
7、communication administration and a recognized operating agency. In this Recommendation, the expression “Administration” is used for conciseness to indicate both a O ITU 1990 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mech
8、anical, including photocopying and microfilm, without permission in writing from the ITU. COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesRecommendation 5.27) SIGNALS FOR THE ALIGNMENT OF INTERNATIONAL SOUND-PROGRAMME CONNECTIONS (1986;
9、 revised 1990) The CCIR, CONSIDERING that Recommendation 645 defines three test signals to be used on international sound-programme connections; that no level information can be derived from a single-level test signal concerning its relationship to the levels that many impairments in international p
10、rogramme exchanges can be traced to misinterpretations of the that the test signals in Recommendation 645 could be used to align sound-programme commentary (4 (b) defined in Recommendation 645; (c) single-level test signals; (4 connections on the switched telephone network which cannot accommodate h
11、igh level sinusoidal test signals, UNANIMOUSLY RECOMMENDS that international sound-programme connections should be identified and aligned using the definitions in 5 1, the test signal format in Q 2 and the measurement methods in Q 3 of this Recommendation. 1. Definitions 1.1 Source identification as
12、 short as possible. It is suggested that such an announcement contain at least the following information: - name of originating organization, - location, - country. peaks only rarely exceed the peak amplitude of the permitted maximum (sine-wave test) signal. An announcement should be used to identif
13、y the originating point of the test signals and should be preferably The sound-programme signal should be controlled by the sending broadcaster so that the amplitudes of the 1.2 Test signal und level definitions 1.2.1 Alignment signal (AS) Sine-wave signal at 1 kHz2) at a level of O dBmOs, which is
14、used to align the international sound-programme connection. Sine-wave signal at 1 kHz2) at a level 12 dB below the alignment signal level, which should be used for long-term measurements and measurements at all frequencies. Sine-wave signal at 1 kHz2), 9 dB above the alignment signal level, equivale
15、nt to the permitted maximum programme-signal level. 1.2.2 Measurement signal (MbJ 1.2.3 Permitted maximum signal (PMS) Formerly Recommendation ITU-R CMTT.66 1. 2, This frequency is nominal, and 1020 Hz recommended by CCITT Recommendation 0.33 may be used. Recommendation 5.27 (06/90) 1 COPYRIGHT Inte
16、rnational Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services2. Test signal format 2.1 A three-level sinusoidal test signal at a reference frequency of 1 kHz3) should be used to check the alignment of international sound-programme connections. These three levels
17、should be combined with the source identification and be repeated cyclically as specified in the format shown in Fig. 1 for monophonic and stereophonic connections. tA IS - 2s + 9 dBmOs O dBrnOs -12 dBm0s + 9 dBrn0s O dBm0s as 2s 3s 2s I 1- 1 -12 dBmOs FIGURE 1 - Format for the three-revel fest sign
18、al for sound programme connections Cycle duration = f + 18 s Q: station announcement t : duration of the station announcement. It varies depending on the length of the message P : signal pauses dOl-sc 3, This frequency is nominal, and 1020 Hz recommended by CCITT Recommendation 0.33 may be used. 2 R
19、ecommendation 5.27 (06/90) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services - STD-ITU-T RECMN J-27-ENGL 1990 4862591 Ob3008b 22 2.2 loading or crosstalk into other channels may be produced. These test signals should not be connected dir
20、ectly to the switched telephone network as excessive channel 2.3 Some organizations may not have automatically generated test levels as defined in 9 2.1. In these cases, the alignment level of O dBmOs at 1 kHz (see Note) should be used for the alignment of international sound-programme connections.
21、Note - This frequency is nominal, and 1020 Hz recommended by CCIM Recommendation 0.33 may be used. 3. Measurement methods The fundamental concept of the test signals defined in this Recommendation is to provide organizations with accurate and well-defined levels Thiele, 19841. These levels are inten
22、ded to provide rapid identification of level errors as well as to allow operational personnel sufficient time to make the necessary level adjustments at the appropriate points in the international sound-programme connection. Alignment of the connection is made by adjusting the alignment signal to th
23、e appropriate point on the programme level meter as defmed in Annex I to Recommendation 645. Identification of left and right channels is provided as shown in Fig. 1. Organizations should give consideration to Reports 292 and 820 when establishing measurement procedures. The three-level test signal
24、defined in 9 2.1 makes provision for a brief subjective and/or objective noise measurement in the signal pauses (P) as shown in Fig. 1. These measurement pauses are not intended to replace the maintenance practices defined in the CCITT Series N Recommendations but rather to confirm that there are no
25、 gross noise or cross-talk impairments on the circuit. REFERENCES THIELE, A. N. September, 19841 Three-level-tone test signal for setting audio levels. AES Australian Convention, Melbourne, Australia. Recommendation 5.27 (06/90) 3 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services
