1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 . TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU-!).4%.!.#%G0G0/b) the international sound connection (for supervising the programme effects circuit provided fortransmitting, for example, the background noises of a programme);c) the commentary connection (
2、for supervising the sound-programme circuit transmitting a commentary ina given language);d) the complete programme connection (for supervising the sound-programme circuit transmitting thewhole of the sound part of a programme).2 Provision of control circuits for sound-programme and television trans
3、mission1)The conditions governing the provisions and lease of control circuits for sound-programme and televisiontransmissions are given in Recommendation D.180 1.Reference1 CCITT Recommendation Occasional provision of circuits for International sound- and television-programmetransmissions, Vol. II,
4、 Rec. D.180._1)The CCITT has noted the fact that broadcasting organizations use a tone having a frequency of 1900 Hz 6 Hz and a level notexceeding 10 dBm0, for their signalling purposes on control circuits. Under the conditions of use specified in the CCITTRecommendations for control circuits, the CCITT has no objections to the use of this tone.
