Frequency deviation detector

专利名称：Frequency deviation detector

发明人：BEER MARCUS JOHN,SCHEMEL RAYMOND

ETIENNE

申请号：US118062申请日：19620420公开号：US3207995A公开日：19650921

摘要：908,209. Automatic frequency-control systems. STANDARD TELEPHONES &CABLES Ltd. May 11, 1961, No. 171/61. Class 40 (5). An F.M. signal f 1 is alternatelymixed with oscillations f 2 , f 3 whose mean frequency is equal to the centre frequency f 0of the FM signal to derive difference frequencies (# 1 - # 2 ) and (# 3 - # 1 ) applied to afrequency discriminator tuned to the frequency (f 0 - f 2 ) = (f 3 - f 0 ) so that a D.C output,of polarity dependent on the sense of any frequency error of the centre frequency f 0 ,and reversing at the switching frequency f 4 gating the oscillations f 2 , f 3 to the mixer 2,is applied to a synchronous detector 12 demodulating the phase sense of the outputwith respect to the frequency # 4 , to obtain an AFC voltage. Alternatively a frequency-shifted single oscillator may replace the oscillators f 2 , f 3 , f 4 and gates 6, 7 and a two-phase motor the detector 12. A limiter may precede the discriminator.

申请人：INTERNATIONAL STANDARD ELECTRIC CORPORATION

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