1、ITU-T RECMN*N=L 93 48b259L 0592447 030 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU MAINTENANCE OF INTERNATIONAL TRANSMISSION CIRCUITS SOUND-PROGRAMME AND TELEVISION N.l (03/93) DEFINITIONS FOR APPLICATION TO INTERNATIONAL SOUND-PROGRAMME AND TELEVISION
2、-SOUND TRANSMISSION ITU-T Recommendation N.l (Previously “CCITT Recommendation”) ITU-T RECMN*N.L 93 4862593 0592448 T77 = FOREWORD The ITU Telecommunication Standardization Sector (IT-T) is a permanent organ of the International Telecom- munication Union. The lTU-T is responsible for studying techni
3、cal, operating and 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,
4、 in their nim, produce Recommendations on these topics. ITU-T Recommendation N.l was revised by the ITU-T Study Group IV (1988-1993) and was approved by the WTSC (Helsinki, March 1-12, 1993). NOTES 1 As a consequence of a reform process within the International Telecommunication Union (IT), the CCm
5、ceased to exist 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 Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector. In order not to delay publication of this Recom
6、mendation, no change has been made in the text to references containing the acronyms “CCIlT, CCIR or IFRB” or their associated entities such as Plenary Assembly, Secretariat, etc. Future editions of this Recommendation will contain the proper terminology related to the new IT structure. 2 telecommun
7、ication administration and a recognized operating agency. In this Recommendation, the expression “Administration” is used for conciseness to indicate both a O IT 1994 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical,
8、 including photocopying and microfilm, without permission in writing from the I?zT. ABSTRACT This Recommendation provides definitions applicable to the maintenance of international sound-programme and television-sound transmissions, illustrated as required, and has an appendix on level, loss and noi
9、se units. KEY WORDS db designations, definitions, level, loss and noise units, sound-programme, television-sound, vocabulary. Recommendation N.l (OY93) i ITU-T RECMN*N-L 93 111 48b259L 0592450 625 W Recommendation N.1 DEFINITIONS FOR APPLICATION TO INTERNATIONAL SOUND-PROGRAMME AND TELEVISION-SOUND
10、TRANSMISSION). 2) (Published in 1964; Revised in 1968,1972,1976,1980,1988 and 1993) Ab brevia tiow For the purpose of this Recommendation, the following abbreviations apply: ISPC International Sound-Programme Cenre NSPC National Sound-Programme Centre PMI, Permitted Maximum Level The following defin
11、itions apply to the maintenance of international sound-programme ,transmissions. Other definitions are used for other purposes, e.g. an international sound-prograqme link and international multiple destination sound- programme link as defined in clauses 11 and 12 respectively below, are within the d
12、efinition of an international sound- programme circuit as defined by the CMIT. NOTES 1 2 it is intended that the definitions given in this Recommendation and Recommendation. N.51 7 should remain identical, so far as is practical, by use of only simultaneous amendments. A sound-programme circuit .sec
13、tion, circuit, link or connection is considered to be permanent -for maintenance purposes if ,it is always available for use when required; whether or not it is continuously in use. Such a circuit may be used for the purposes of occasional transmission, that is, transmissions of short duration, eg.
14、less than 24 hours, or it may b used for a long duration, i.e. one day or more. A permanent sound-programme connection between broadcasting organizations premises may be used at any time, except only for periods of maintenance as agreed between the Administrations and broadcasting organizations conc
15、erned. A sound-programme circuit section, circuit, link or connection is considered to be temporary for maintenance purposes when it has no existence outside the period of transmission (including line-up and testing time) for which it is required. 1 intemational sound-programme transmission: The tra
16、nsmission of sound signals over the international telecommunication network for the purpose of interchanging sound-programme material between broadcasting organizations in different countries. 2 broadcasting organization: A broadcasting organization is an organization which is concerned with either
17、or both sound and television broadcasting. Most of the customers ordering facilities for sound-programme and television transmission are broadcasting organizations. For convenience, the term broadcasting organization is used to denote the activity of any user or customer and, where so used, it is eq
18、ually applicable to any other customer requiring sound- programme or television transmissions. 3 broadcasting organization (send): The broadcasting organization at the sending end of an international sound-programme transmission. 4 broadcasting organization (receive): The broadcasting organization a
19、t the receiving end of an international sound-programme transmission. 5 international sound-programme centre (ISPC): A centre at which at least one international sound- programme circuit (see clause 9) terminates and in which international sound-programme connections (see clause 13) can be made up b
20、y the interconnection of international and national sound-programme circuits. The responsibility of an ISPC is given in Recommendation N.5 8. 6 circuits terminate and at which national sound-programme circuits may be interconnected. national sound-programme centre (NSPC): A centre at which two or mo
21、re national sound-programme i) Definitions in this Recommendation apply both to analogue and digital systems. *) Annex A gives definitions and designations for units of measurements for sound-programme and television-sound transmission. Recommendation N.l (0-3) 1 ITU-T RECMN*N*L 93 4862591 0592453 5
22、61 7 mutd=programme circuit secth: The unidirectional national or international sound-programme transmission path between two stations at which the programme is accessible at audio frequencies. The transmission path may be established via terrestrial or single destination satellite routing. (See Not
23、e 2 above and Figures 1 and 3.) 8 intemamal multiple destiantion sound-programme cira64 sectian: The uniddonai sound-programme transmission path from one frontier station to two or more of the frontier stations at which interconnection is made at audio frequencies. (See Note 2 above and Figure 4.) 9
24、 internatmal sound-pmgmmme Circuit: The transmission path between two ISpCs which comprises one or more sound-programme circuit sections (national or international), together with any necessary audio equipment. The transmission path may be established via terrestrial or single destination sateliite
25、routing. (See Note 2 above and Figures 1 and 3.) 10 internatid mdtiple destination sound-programme circuit: The unidirectional transmission path from one ISPC to two or more other ISPCs comprising sound-programme circuit sections (national or international) one of which is an international multiple
26、destination circuit section, together with any necessary audio equipment. (See Note 2 above and Figure 4.) 11 intemational sound-programme icnk: The unidirectional transmission path between the ISPCs of the two terminal countries involved in an international sound-programme transmission. The interna
27、tional sound-programme link comprises one or more international sound-programme circuits (see Figures 1 and 3 below) interconnected at intermediate ISPCs. It can also include national sound-programme circuits in transit countries. (See Note 2 above and Figure 2.) 12 intemational mdtiple desthaion so
28、und-prognmme link: The unidirectional transmission path between the ISPCs of the terminal countries involved in an intemationai multiple destination sound-programme transmission. The international multiple destination sound-programme link comprises international sound-programme circuits, one of whic
29、h is an international multiple destination sound-programme circuit. (See Note 2 above and Figure 5.) 13 international sound-programme connedon: The unidirectional transmission path between the broadcasting organization (send) and the broadcasting organization (receive) comprising the international s
30、ound-programme link extended at its two ends over national sound-progrimme circuits to the broadcasting organization. (See Note 2 above and Figure 2.) 14 international multiple destination sound-programme connection: The unidirectional transmission path between the broadcasting organization (send) a
31、nd two or more broadcasting organizations (receive) comprising the international multiple destination sound-programme link extended at its ends over national sound-programme circuits to the broadcasting organizations. (See Note 2 above and Figure 5.) 15 send teerence station: The transmit sub-contro
32、l station of an international multiple destination sound- programme circuit section (see clause 8). circuit (see clause 10) or link (see clause 12). (See Figures 4 and 5.) 16 effectively transmitted signais in sound-programme transmission: For sound-programme transmission, a signal at a particular f
33、requency is said to be effectively transmitted if the nominal overall loss at that frequency does not exceed the nominal overall loss at 1020 Hz by more than 4.3 di3. This should not be confused with the analogous definition concerning telephone circuits given in the Recommendation G.151 i. For soun
34、d-programme circuits, the overall loss (relative to that at 1020 Hz) defining effectively transmitted frequency is 1.4 dEi, i.e. about one third of the allowance. 17 types of sound-programme circoit3): The various types of international sound-programme circuit or sections of such circuits should be
35、referred to by quoting the top nominal frequency, in kHz, effectively transmitted. Example: 10-kHz sound-programme circuit. 3, To reduce problems in ordering and charging for sound-programme circuits, Shidy Group II has a classification of circuits based on their approximate bandwidth (see the Recom
36、mendation cited in Recommendation D.180 121). 2 Recommenaon N.1 (0-3) ITU-T RECMNrN.1 93 = 4862591 0592452 4TB = 18 international television-sound transmission: The transmission of television-sound signals over the international telecommunications network for the purpose of interchanging television-
37、sound material between broadcasting organizations in different countries. Country A Country 6 National International National sourdprogramme sour where Z, = lo00 ohms reference impedance and Z = impedance of the circuit under test. Absolute voltage levels, for which terminal impedance is not defined
38、, are more rarely used. As a correction, power level may be calculated for impedances other than 600 ohms, with respect to 1 mW. The power level thus calculated would be equal to that measured in a correctly terminated system. A.2.2 relative power (dBr) and relative voltage (mur) levels: The relativ
39、e power level of a point in a transmission system, where the transmission plan is based on power, is the nominal power gain at the reference frequency from a reference point to the point considered. Values of the relative power level are usually characterized by the unit designation dBr. The relativ
40、e voltage level in a transmission system, where the transmission plan is based on voltage, is the nominal voltage gain at the reference frequency from a reference point to the point considered. Values of the relative voltage level are usually characterized by the unit designation mur. For sound-prog
41、ramme circuits, the zero relative level point is the origin of the sound programme connection as defined in Recommendation 5.14 5. A.2.3 power level referred to a zero relative level point (dBmO) and voltage level referred to a zero relative level point (dBuO): The power level referred to a point of
42、 zero relative level point is provisionally called “load level” (L,o). The load level with respect to 1 mW is the absolute power level (&) with respect to 1 mW minus the relative power level (LJ: Lm0 = L, - L, The voltage level with respect to 0.775 V referred to a zero relative level point (bo) is
43、the absolute voltage level with respect to 0.775 V (L,) minus the relative voltage level (LW): Lo = Lu - L”, For a given signal within a given transmission system a level referred to a zero relative level point is the same along a transmission line. Recommendation N.1 (03/93) 7 A.2.4 Designation of
44、weighted noise measurement uni For noise measurements made with a weighting filter a ?P?) is added to the unit designation, e.g. dBmOp and dBmp. Unlike telephony, ?p? for sound-programme does not identify the type of weighting filter that has been used. A.2.5 Designation of quasi-peak noise measurem
45、ent units For noise voltage level measurements (reference voltage: 0.775 V) made with a quasi-peak instrument (in accordance with CCIR Recommendation 468 6) instead of an instrument showing r.m.s.-values, the letter ?q? is used similarly to the letter ?m?, e.g. dBqOps. A.2.6 Designation of sound-pro
46、gramme transmission units Unit designations associated with sound-programme transmission contain a supplementary ?s? (s for sound), e.g. dBrs, dBmOs, dBm0ps and dBqOps. The ?s? indicates that the bandwidth used in the measurement is related to sound- programme transmission so as to prevent confusion
47、 when differing measurement techniques, weighting filters or meters are used. .3 Practical problems There is a wide range of measuring instruments used at different measurement points, so that differences are always bound to appear. A state which every Administration is prepared to define is the per
48、mitted maximum level (PML). Despite different relative power levels, depending on the systems, a direct relation can now be indicated between the value of the level to be measured and the PML. If, for instance, a signal of 21 dB below the PML is sent as a measurement signal, it must also be received
49、 as a signal 21 dB below PML, independently of local relative levels, which may differ according to systems and Administrations. References CCITT Recommendation General performance objectives applicable to all modern international circuits and national extension circuits, Rec. G. 15 1 (Note 1, clause 1). CCI? Recommendation Occasional provision of circuits for Intemtional sound- and television-programme transmissions, Rec. D. 180 (clause 3). CCIT Recommendation Use of the decibel and neper in telecommunications, Rec. B.12. CCIR Recommendation Use ofthe decibe
