1、ITU-T RECMN*N-b2 93 486259L 0583969 2T5 II INTERNATIONAL TELECOMMUNICATION UNION ITU-T TE LECOMMUN ICATION STANDARDIZATION SECTOR OF ITU MAINTENANCE OF INTERNATIONAL TRANSMISSION CIRCUITS SOUND-PROGRAMME AND TELEVISION N.62 (03/93) TESTS TO BE MADE DURING A TELEVISION TRANSMISSION THE LINE-UP PERIOD
2、 THAT PRECEDES ITU-T Recommendation N.62 (Previously “CCITT Recommendation”) ITU-T RECMN*N-b2 93 D 4862591 0583970 TL7 FOREWORD The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the International Telecom- munication Union. The ITU-T is responsible for studying technica
3、l, 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, i
4、n their turn, produce Recommendations on these topics. ITU-T Recommendation N.62 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 (ITU), the CCI
5、T 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 Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector.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 Rec
6、ommendation, no change has been made in the text to references containing the acronyms “CCIIIT, 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 ITU structure. 2 teleco
7、mmunication administration and a recognized operating agency. In this Recommendation, the expression “Administration” is used for conciseness to indicate both a O ITU 1994 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechan
8、ical, including photocopying and microfilm, without permission in writing from the ITU. ITU-T RECMN*N-b2 93 I 48b2572 0583972 953 I CONTENTS ABSTRACT Keywords . 1 Introduction 2 Test signal source identification . 3 Test procedure 4 Tests to be made by the ITCs . 5 Abbreviations . References . Recom
9、mendation N.62 (03/93) Page 11 11 1 1 1 3 5 5 i ITU-T RECMNaN-bZ 93 I Y862591 0583972 87T I ABSTRACT This Recommendation provides test objectives for use by International Television Centres prior to a television transmission, for both circuit sections and links, using either satellite or terrestrial
10、 facilities or both. Keywords Insertion test signais, television transmission, test objectives. 11 Recommendation N.62 (03/93) ITU-T RECMN*N=b2 93 m 4862591 0583973 726 I Recommendation N.62 TESTS TO BE MADE DURING THE LINE-UP PERIOD THAT PRECEDES A TELEVISION TRANSMISSION (Published 1964; revised 1
11、968, 1972, 1980, 1984, 1988 und 1993) 1 Introduction International television circuits or national sections of such circuits may be provided either by Administrations or broadcasting organizations; both types of entities establish ITCs to carry out the functions given in Recommendation N.55 4. One o
12、f those functions is to test the international television circuitsAinks before they are handed over to the broadcasting organizations for programme transmission. International television circuits are: - - circuits with terrestrial sections only; circuits comprising a satellite section with national
13、circuit sections between each earth station and the ITC in the same country. Figure 1 shows an example of an intemational multiple destination television connection using circuits of both types. 2 Test signal source identification All full field test signals as described in this Recommendation shoul
14、d be superimposed with an identification which includes the point of origin and the name of the sending authority. It may be transmitted either in monochrome or in colour according to preference or to suit the technical requirements of the particular test signal being transmitted. If the local langu
15、age of the originating station is not an internationally recognized language, then the identification should be displayed not only in the local language of the station concerned but also in one of the internationally recognized languages. 3 Test procedure In accordance with Recommendation N.54 5, li
16、ning-up and testing of the national and international circuit sections should take place between H - 30 and H - 15 min, where H is the time at which the circuit should be handed over to the broadcasting organization. In practice, these tests normally take place: - between ITCs and earth stations; -
17、between earth stations; - between ITCs in adjacent countries linked by terrestrial circuits. The use of insertion test signals has been demonstrated to expedite the pre-transmission line-up testing of terrestrial and satellite circuit sections. Therefore, whenever possible, insertion test signals in
18、 accordance with CCIR Recommendations 567 i and 569 2 should be used together with appropriate automatic measuring equipment during the line-up period. Insertion test signals from the sending broadcasting organization should also be used during the preparatory period and subsequent transmission for
19、monitoring and fault location purposes. An example of the circuits and circuit sections to be tested during the first half of the line-up period is shown in Figure 1. Priority should be given to verifying the continuity and that the send and received levels are correct. Table 1 gives a suitable time
20、table of the sequence of measurements to be made during the line-up period. Recommendation N.62 (03/93) ITU-T RECMN*N.b2 93 4862592 0583974 662 Test Test At H - 15 min precisely, the circuit sections are interconnected to form international circuits and the international circuits interconnected to f
21、orm international links which could be multiple destination. Tests are carried out from the sending ITC for each international link or international multiple destination circuit (see the example given in Figure 1). Again, priority is given to the continuity of each international circuit or link and
22、the send and received levels. B-C C-D Satellite Broadcasting organizations I / I I I2 T._ ITC * * -. - I / .A E r- -+o/ I I G- J Broadcasting I station D J organization , o Broadcasting /” /” Organizations H- 15 min. to H A - B and G N-OandP P-B H IMDTC established from sending broad- casting organi
23、zation to all receiving broadcasting organizations by action at A, B, C, D, E, J and by broadcasting organization fed from B NOTE - His the time from which the broadcasting organization has ordered the connection. FIGURE 1N.62 Example of an international multiple destination television connection At
24、 H precisely, or a few minutes beforehand if the pre-transmission tests have been completed, the ITCs extend the international circuits/links to the broadcasting organization so that the intemational television connection from the sending broadcasting organization to the receiving broadcasting organ
25、ization(s) can be verified. Any interconnections required in the premises of the broadcasting organizations will also be made at this time. International television connections should be made available to the broadcasting organizations on time, even if all tests have not been completed, provided tha
26、t the continuity and levels have been verified. There is a need for broadcasting organizations to assess subjectively the quality of the television picture as per Table UN.64. If colour bar signals1) are used for this purpose, the composite signal (colour bars plus captions, etc.) must not exceed 1
27、volt (peak-to-peak) in order to preclude interference with adjacent video channels, particularly on half transponder satellite operation. As defined in 3. 2 Recommendation N.62 (03/93) ITU-T RECMN*N-b2 93 4862591 0583975 5T9 Item I Timing Signal a) TABLE 1N.62 Sequence of measurements Measurement la
28、 lb Luminance bar amplitude error and short period vanations 2T pulse-to-bar ratio B2 or B3 and BI (pulse signai b, H - 30 to H - 25 H- 15 to H- 10 and bar) Or Bar tilt or base line distodion C) 2a 2b Signal-to-weighted-random-noise ratio d, H- 25 to H- 23 H - 10 to H - 8 No input signal or “quiet l
29、ine” H - 23 to H - 21 3b 3a I H-8 toH-6 Field-time waveform distortion A (field bar) a) b, c, dl e) Signals A, BI, B2 and B3 are defined in CCIR Recommendation 567 i. To be inserted in appropriate lines of a video signal with a mean average picture level (APL). Bar tilt or base line distortion may b
30、e measured by mutual agreement of the Administrations concerned. Where an ITC has equipment for measuring the signal-to-weighted-noise ratio on the “quiet” line it should take that measurement during the first five minutes of the test sequence if insertion test signals are received. In accordance wi
31、th Recommendation N.54 5 conection may be made to the broadcaster by an ITC during this period. Connection may also be made to the sending broadcaster provided the sending ITC is receiving a video signal from the broadcaster originating the transmission. 4a 4b 4 Only 15 minutes is allowed for each o
32、f the series of tests referred to in clause 2. This period is more than adequate if modem test equipment is used. The measurements to be carried out are defined in CCIR Recommendations 567 i or 569 2. Before the commencement of the line-up period the staff of the ITCs should ensure that the test gen
33、erator(s) and measuring equipment are in good working order. It is particularly important that impeccable test signals should be sent so as to prevent receiving ITCs from concluding, on the basis of their measurements, that a circuit is faulty when that is not the case. If difficulty is experienced
34、in performing the required tests, as a minimum, the circuit continuity should be established and the send and received levels checked, with the assistance of the sending broadcasting organization. If colour bar signals are used for this continuity check, the amplitude should be checked and applicati
35、on must be in accordance with clause 3. Table 2 lists the parameters and test objectives for international television circuitsAinks. Tests to be made by the ITCs Chrominance-luminance gain inequality Peak differential phase - 21 to - l9 Insertion test signais b, Peak differential gain H-6 tOH-4 Reco
36、mmendation N.62 (03/93) 3 H- 19 to H- 15 5b H-4 toHe) B2 Or B3 and B1 Or insertion test signaisb) Verification of continuity and line-up ITU-T RECMN*N.b2 93 I 48b259L 0583776 435 I Parameter (1) TABLE 2N.62 Test objectives a) International circuits Circuit sections Terrestrial lus g Earth station/ e
37、arth station b, Terrestrial only satellite lTC/earth station Half 525-line 625-line 525-line 625-line transponder transponder (2) (3a) (3b) (4) (5) I I - f 0.5 dB or 5% or 5 IRE units Luminance bar amplitude error f0.25 dB f 0.25 dB f 1 dB fldB or 2.5% or 2.5% or 11% or 11% or 2.5 IRE units or 2.5 I
38、RE units or 11 IRE units or 11 IRE units & 0.3 dB fO.l dB fO.l dB k 0.3 dB or3% I or1% I or1% I or3% Short period variations of luminance bar error (1 s) or 3 IRE units or 1 IRE unit or 1 IRE unit or 3 IRE units f 0.4 dB or 4% or 4 IRE units Bar tilt Base line distortion 2T pulse-to-bar ratio Signal
39、-to-weighted-random- noise ratio Field time waveform distortion f 1% I1.5% f 1% fl% f3% f2% f4% f 1% (Note) (Note) fl% f3% (Note) f 6% f 6% f 6% I6% f8% f12% f10% 56 dB 54 dB 59 dB 56 dB 52-54 dB f 2% f 2% f 1% f2% f6% f4% f6% C) Peak differential gain I f10% I +lo% 1 k10% I f10% I +8% I f15% +lo% f
40、 10% f 10% Chrominance-luminance gain inequality +- f10% +12% f15% - 11% - 20% In principle, the test objectives for terrestrial circuitsflinks apply to those having a length of about 1250 km. Test objectives given in columns 3a, 3b and 5 are examples of temporary circuit sections and circuits estab
41、lished by one satellite system (INTELSAT VI) and relate to expected performance in global beam utilizing earth stations having G/T of 40.7 dB(K-) and elevation angles of 10“. Different values would be appropriate when other satellites, earth station sizes and elevation angles are employed. The terre
42、strial plus satellite signal-to-weighted-random-noise ratio will be additive according to the power summation rules. The satellite (earth station to earth station) signal to noise will be determined by the performance data provided by the satellite operating authority for the specific satellite and
43、earth stations (earth station locations relative to satellite beam center and earth station G/T). Example: S/N(ter. + sat.) = 10 loglo 1 ci tern - 1 + . a ter i 10 10 Peak differential phase 1 1 = lOlog, r I3“ f 4“ I3“ f 3“ f 5“ f 6“ & 8“ where a sat = S/N of the satellite section Transmission of MA
44、C signals requires that the elements which could clamp the signal be withdrawn. On the other hand, a larger bandwidth, up to about 8.5 MHz, should be used in order to take advantage from MAC transmissions. These signal-to-weighted-noise ratio values should be obtained with composite systems. The use
45、 of better quality circuits for MAC family signals is under study. For MAC signals, limited values for clamp noise are under study. They should be less restrictive for T-MAC than for other MAC systems. a ter = SM of the ITC/earth station section. NOTE - Under study. 4 Recommendation N.62 (03/93) ITU
46、-T RECMN*N-b2 93 I 4862.593 0583977 373 = 5 Abbreviations ITC International Television Centre MAC Multiplexed analogue components IMDTC International multiple destination television connection APL Average picture level T-MAC Transmission-MAC References r 11 CCIR Recommendation 567 Television perform
47、ance of television circuits designed for use in international connections. r21 CCIR Recommendation 569 Definitions of parameters simplified for automatic measurement of television insertion test signals. WEAVER (L.E.): Video measurement and the correction of video circuits, EBU (European Broadcastin
48、g Union) Technical Monograph 31 16, Appendix 3, sections 5,6,7 and 8, 1978. Recommendation N.55 Organization, responsibilities and functions of control and sub-control ITCs, control and sub-control stations for international television connections, links, circuit and circuit sections. Recommendation N.54 Definition and duration of the line-up period and the preparatory period. 31 141 151 Recommendation N.62 (03/93) 5
