| 摘要 |
PURPOSE:To perform AM and FM demodulation without switching time constants nor using and changeover switch by converting the frequencies of an AM and an FM signal to the same intermediate frequency, and installing a phase-locked loop which is locked at the intermediate frequency. CONSTITUTION:The AM and FM signals are converted to the intermediate frequency f0 and then amplified by an amplification part 6 and supplied to the common phase-locked loop 14 constituting a demodulation circuit. An FM demodulation output appears at the output side of a filter 18 and is supplied to a frequency mixer circuit 12 for the FM signal. On the other hand, it is passed through a filter 24 to obtain a sensor output. The output of a VCO20 is delayed by pi/2 through a phase circuit 26 and inputted to a synchronous AM detecting circuit 28 together with the output of the amplification part 6, obtaining an AM demodulation output S0. The output S0 is supplied to a mixer circuit 4 as an automatic gain adjustment signal. |
