FM RECEIVER INCLUDING FM DISCRIMINATOR FOR GENERATING OUTPUT SIGNAL WITH AMPLITUDE DEPENDENT ON FREQUENCY OF RECEIVED FM SIGNAL

摘要

PURPOSE: To make an FM receiver small-sized and make it possible to use a smaller battery by converting an FM signal into a series of discrete rectangular wave pulses having the same amplitude as the FM signal and a repetition rate varying with a frequency of the FM signal, integrating the rectangular wave pulses and generating an output signal. CONSTITUTION: An RF carrier frequency is shifted to an intermediate frequency so that an FM signal is received by an antenna 10, passed through an input- stage amplifier 12, supplied to a demodulator 13 and controlled by an oscillator 14. The output of the demodulator 13 is supplied to a high-speed comparator 16 and converted into a series of discrete rectangular wave bipolar pulses having a repetition rate varying with a frequency of the received FM signal. The rectangular pulses from the comparator 16 are supplied to a differentiator circuit 17 and converted into bipolar spike-shaped pulses. Consequently, it is made possible to use a smaller battery and/or exchange it at a shorter interval.