2018 Electronic Competition Question F-Wireless Microphone Amplification System (Harbin Engineering University)

This system is a wireless microphone amplification system. Specifically, it can be divided into pre-voice signal processing circuit and analog FM modulation circuit. The system mainly uses the phase-locked loop chip ADF4001 to realize analog frequency modulation with a carrier frequency between 88MHz and 108MHz. It can modulate and transmit audio signals with a frequency of 40 Hz~15 kHz with an external 0.5m high-frequency transmitting antenna, and the communication distance can reach 30m. The RDA5820 transmitter-receiver chip is used to automatically detect the channel occupancy when the microphone is turned on, and then automatically select the carrier frequency to avoid interference signals. The receiver back-stage circuit uses an LM386 audio power amplifier to improve the load capacity of the demodulated audio signal and achieve 0.5W audio output power into 8Ω load. The microcontroller part uses TI's high-performance MCU-TM4C1294 to control the PS2 keyboard and LCD display. The entire system uses TFT liquid crystal for display, and parameter settings are entered using the keyboard and displayed on the liquid crystal in real time. The system implements a wireless microphone amplification system with controllable carrier frequency and automatic detection of channel occupancy.