The frequency range of FM radio is 87.5-108 MHz, which is also commonly used for the radio function of car audio system. In the wireless TV signal, the image is in AM format, and the sound is in FM format. The modulation method of FM signal is to load the audio signal on the "frequency" of high-frequency carrier for Transmission. Specifically, the change of audio signal will cause the corresponding change of high-frequency carrier frequency, while the amplitude of the carrier remains unchanged, so that the FM signal containing audio information is sent into the air. Imagine that there are countless invisible "information elves" floating in the air-they are the FM signals that carry the broadcast content. When these invisible electromagnetic waves meet the Car Radio Antenna, like magic, a weak current is excited in the FM AM Antenna. These currents seem ordinary, but they are actually carriers of "information secrets", waiting to be interpreted. Next, the signal began its wonderful adventure inside the radio. The tuning circuit is like a gatekeeper with "frequency super power". In the complicated signal torrent, the specific frequency signal we want to hear is accurately screened out and escorted into the central amplifier. Here, the weak signal gets "energy supply" and becomes a powerful "signal messenger". Then, the frequency discriminator circuit appeared, which, like a skilled translator, restored the "password" of frequency change in FM signal to the original audio signal word by word. Finally, the low-frequency amplifier circuit injects "the last force" into the audio signal, driving the speaker to vibrate and make sound, and those sounds and music from the radio station will flow out of this small machine, bringing us an auditory feast. AM stands for amplitude modulation band, and amplitude modulation broadcasting is to modulate audio signals to the "amplitude" of high-frequency carriers for transmission. That is to say, the change of audio signal will make the amplitude of high-frequency carrier change correspondingly, while the frequency of carrier remains stable, and the modulated amplitude-modulated signal is emitted into the air. AM radios usually use a magnetic rod Walkie Talkie Antenna to receive signals. The magnetic rod antenna consists of a magnetic rod and a coil wound around the magnetic rod. It can gather the magnetic field energy in the surrounding space and induce the amplitude modulation signal into the coil to form a weak current signal. These signals also pass through the high-frequency tuning circuit to screen out the amplitude modulation signals with specific frequencies, and then enter the central amplifier for amplification. The amplified signal is demodulated by the detection circuit, and the detection process is the process of extracting the original audio signal from the amplitude modulation signal. Finally, the audio signal is further processed and amplified by the audio amplifier circuit, and the loudspeaker is driven to restore the broadcast program content. Through the cooperative work of Car Antenna and a series of subsequent circuits, we can transform the radio signals spread in the air into pleasant sounds and enjoy colorful radio programs. How does the FM radio antenna restore the sound step by step after receiving the signal? The antenna of FM radio first receives FM signals of 87.5-108 MHz, which are transmitted into the air after modulating audio signals to the frequency of high-frequency carriers. After receiving the signal, the antenna separates the audio signal from the high-frequency carrier by tuning the central amplifier-frequency discriminator circuit. Finally, the audio signal is amplified to a suitable power by low-frequency amplification and output to the speaker, thus restoring the sound. What are the characteristics of the signal received by AM radio antenna? How is it demodulated? AM radio antenna receives the signal that modulates the audio signal to the "amplitude" of high frequency carrier. After receiving the AM broadcast signal in the air, the antenna demodulates the audio signal modulated on the high-frequency carrier through the high-frequency tuning center amplification detection circuit, and then restores the broadcast program content through the audio amplification circuit.