ITU-R BS 468-4-1986 Measurement of Audio-Frequency Noise Voltage Level in Sound Broadcasting - Section 10C - Audio-Frequency Characteristics of Sound-Broadcasting Signals《声音广播中音频噪声.pdf
《ITU-R BS 468-4-1986 Measurement of Audio-Frequency Noise Voltage Level in Sound Broadcasting - Section 10C - Audio-Frequency Characteristics of Sound-Broadcasting Signals《声音广播中音频噪声.pdf》由会员分享,可在线阅读,更多相关《ITU-R BS 468-4-1986 Measurement of Audio-Frequency Noise Voltage Level in Sound Broadcasting - Section 10C - Audio-Frequency Characteristics of Sound-Broadcasting Signals《声音广播中音频噪声.pdf(7页珍藏版)》请在麦多课文档分享上搜索。
1、,- CCIR VOLUME*X-1 90 Y855212 0504044 1 H Rec. 468-4 167 RECOMMENDATION 468-4 * MEASUREMENT OF AUDIO-FREQUENCY NOISE VOLTAGE LEVEL IN SOUND BROADCASTING (Question 50/10) (1970-1974-1978-1982-1986) The CCIR, CONSIDERING (a) sound-recording systems and on sound-programme circuits; (b) that it is desir
2、able to standardize the methods of measurement of audio-frequency noise in broadcasting, in that such measurements of noise should provide satisfactory agreement with subjective assessments, UNANIMOUSLY RECOMMENDS that the noise voltage level be measured in a quasi-peak and weighted manner, using th
3、e measurement system defined below: 1. Weighting network of the passive network shown in Fig. la. Table I gives the values of this response at various frequencies. equipment, comprising the amplifier and the network, are shown in the last column of Table I and in Fig. 2. The nominal response curve o
4、f the weighting network is given in Fig. lb which is the theoretical response The permissible differences between this nominal curve and the response curve of the measuring Z= 600 600 fi 12.88mH 33.06 nF 26.49rnH . D FIGURE la - Weighting network, simple form (A constant-resistance realization is de
5、scribed in Annex I) A tolerance of at most 1 % on the component values and a Q-factor of at least 200 at 10 000 Hz are sufficient to meet the tolerances piven in Table I. (The difference between the responses at 1000 Hz and 6300 Hz may be adjusted more precisely by a smaii adjustment of the 33.06 nF
6、 capacitor or by a different approach using an active filter CCIR, 1982-86al.) This Recommendation should be brought to the attention of the CMT. 168 CCIR VOLUME*X-l 90 4855232 05040Y5 3 M Rec. 468-4 12 8 4 O -4 -8 -12 s 2 -16 8 -20 2 -24 -28 -32 -38 -40 -44 -48 5 IO* 2 2 5 Frequency (Hz) FIGURE lb
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- ITURBS46841986MEASUREMENTOFAUDIOFREQUENCYNOISEVOLTAGELEVELINSOUNDBROADCASTINGSECTION10CAUDIOFREQUENCYCHARACTERISTICSOFSOUNDBROADCASTINGSIGNALS

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