FM Demodulation Based on FM to PWM Conversion With Voltage Gain Control

This paper attempts to present the FM demodulation based on FM to PWM conversion with voltage gain control (VGC). The proposed scheme is based on the basic principle of zero crossing (ZC) for conversing FM to PWM. The PWM-signal is filtered by low pass filter (LPF). The result is the message signal (speech, music, etc.). The outstanding feature of this method is that the pulse width of PWM signal influences the amplitude of demodulated signal. It can be adjusted by VGC affecting the gain of a message signal. The proposed circuit has relatively simple and efficient. It consists of monostable multivibrator and low pass filter (LPF). The experimental and synthesis results from MATLAB confirm the mathematics analysis.