1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 . TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU-!).4%.!.#%G0G0/&G0G0).4%2.!4)/.!,3/5.$G0G13G002/2!-%G0G0!.$G0G04%,%6)3)/.42!.3-)33)/.G0G0#)2#5)43-%!352%-%.43G0G04/G0G0“%G0G0-!$%G0G0$52).4(%G0G0,).%G0G13G050G0G00%2)/$G0G04(!4G0G002%#%$%3!G0G03/5.$G0G13G002
2、/2!-%G0G042!.3-)33)/.)45G134G0G0RecommendationG0G0. (Extract from the “LUEG0“OOK)NOTES1 ITU-T Recommendation N.12 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 v
3、ersion, thecontents of the file are identical 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 198
4、8, 1993All rights reserved. No part of 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.12 1Recommendation N.12Fascicle IV.3 - Rec. N.12MEASUREM
5、ENTS TO BE MADE DURING THE LINE-UP PERIODTHAT PRECEDES A SOUND-PROGRAMME TRANSMISSIONAfter the connection of the various circuits to form the international sound-programme link (conforming to thelevel diagrams of these circuits) it is necessary to verify, by means of an automatic measuring equipment
6、 (seeRecommendations O.31 1, O.32 2 and O.33 3) or by measurements at individual frequencies, that the received levelat the distant incoming terminal ISPC is at the correct value (see Recommendation N.10) at the following frequencies:for an international sound-programme link composed entirely of 15-
7、kHzsound-programme circuits . 40, 800 and 15 000 Hzfor an international sound-programme link composed entirely of 10-kHzsound-programme circuits 50, 800 and 10 000 Hzfor an international sound-programme link comprising at least one7 kHz sound-programme circuit . 50, 800 and 7 000 Hzfor an internatio
8、nal sound-programme link comprising at least one6.4 kHz sound-programme circuit . 50, 800 and 6 400 Hzfor an international sound-programme link comprising at least one5 kHz sound-programme circuit . 100, 800 and 5 000 Hzfor an international sound-programme link comprising at least oneordinary teleph
9、one circuit . 300, 800 and 3 400 Hz1)The send level during these measurements should be 12 dBm0.In the case of 15-kHz sound-programme links forming a stereophonic pair, it is necessary to verify theinterchannel parameter limits specified in Table 4/N.10.A measurement of other parameters such as nonl
10、inear distortion and noise should be measured on all links andthe results recorded. At the present time the limits cannot be specified.The national sound-programme circuits should be so adjusted that, when they are connected to theinternational sound-programme link, the level diagrams of the interna
11、tional sound-programme circuits are respected. Inthis regard, a useful and quick method which Administrations could use to verify the correct alignment of sound-programme links is given in Annex A of Recommendation N.13.Any necessary adjustments having been made, the national circuits are connected
12、to the international sound-programme link at the terminal ISPCs. This is the end of the line-up period and the beginning of the preparatory periodand is the instant when the complete connection is placed at the disposal of the broadcasting organizations.The latter then proceed to measure and adjust
13、as necessary.References1 CCITT Recommendation Automatic measuring equipment for sound-programme circuits, Vol. IV, Rec. O.31.2 CCITT Recommendation Automatic measuring equipment for stereophonic pairs of sound-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._1)Or the frequency appropriate to the telephone-type circuit used.
