1、Rec. 216-2 SECTION 10A-2: SOUND BROADCASTING IN THE-TROPICAL ZONE 107 RECOMMENDATION 216-2 PROTECTION RATIO FOR SOUND BROADCASTING IN THE TROPICAL ZONE (Report 302, Question 45/10, Study Programme 45E/10) f (1951-1953-1956-1978-1982) The CCIR, CONSIDERING I (a) that it is necessary to establish a va
2、lue for the protection ratio for sound broadcasting within the shared bands in the Tropical Zone; (b) that the operation of sound broadcasting transmitters with 10 kHz separation makes it difficult to measure the protection ratio with a receiver having an audio-frequency cut-off in excess of 5 kHz;
3、c) . that more information concerning noise values in various parts of the Tropical Zone is necessary to arrive at a more accurate value of minimum field strength to which the protection ratio should be maintained; however, this minimum, field strength should provide satisfactory reception at the l
4、imit of the broadcast station coverage area, as provided by No. 2666 of the Radio Regulations, UNANIMOUSLY RECOMMENDS 1. that, for the present, and wherever practicable, in the Tropical Zone, the ratio of median-wanted sound broadcasting carrier to median-unwanted carrier shall be 40 dB, to provide
5、a signal-to-interference ratio of not less than 23 dB for at least 90% of the hours and 90% of the days (taking into consideration the effect of short- and long-term fading - see Recommendation 41 1); 2. having an audio-frequency cut-off of 5.0 kHz; that the protection ratio thus defined should be m
6、easured at the output of a receiver provided with a filter 3. that, for the present, the protection ratio, as defined in Q 1, should be maintained throughout the broadcast coverage area in the Tropical Zone to a minimum field strength of 200 pV/m or any lower value consistent with satisfactory recep
7、tion; 4. that the conditions of operation required for sound broadcasting in the Tropical Zone should be compatible with the protection ratio required for other services outside the Tropical Zone, in accordance with Number 346 of the Radio Regulations. COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling Services
