A radio is a machine constructed from mechanical devices, electronic devices, magnets, etc., which uses electrical energy to convert radio signals and can listen to audio signals emitted by broadcasting stations. Also known as radio, broadcasting, etc. The emergence of DSP technology radio marks the gradual withdrawal of traditional analog radio from the historical stage. The digital age of radio has arrived. A sound machine is a receiver for radio broadcasting. The high-frequency modulated weak signal input by the receiving antenna is amplified, converted, and detected to be restored to an audio signal. According to different needs, radios can be combined using different components and wiring methods. Early radios used electronic tubes, but now transistors and integrated circuits are widely used. A simple circuit regenerative radio only uses one crystal transistor, while a complex circuit superheterodyne AM FM radio often requires multiple integrated circuits. The reception principle is to demodulate the high-frequency signal received from the antenna and restore it to an audio signal, which is then sent to the headphones or speakers to become sound waves. Due to technological advancements, there are many radio waves of different frequencies in the sky. If these many radio waves are all received, the audio signal will be like being in a busy market, with many sounds mixed together, resulting in nothing being heard clearly. In order to try to choose the desired program, there is a selective circuit after receiving the antenna. Its function is to select the desired signal (radio station) and filter out the unwanted signal to avoid interference. This is the "select station" button we use when listening to the radio. The output of the selective circuit is to select the high-frequency amplitude modulation signal of a certain radio station. It is not feasible to use it to directly push the earphone (electroacoustic device), and it must also be restored to the original audio signal. This restoration circuit is called demodulation, which sends the demodulated audio signal to the earphone to receive the broadcast