The differences between FM and AM are: different frequencies, different sound quality and different working principles. Use AM when listening to band 4.

First, the frequency difference

1, FM: FM microwave transmission, with high signal quality, low transmission cost, low transmission power, small coverage and great influence by geographical factors, is generally the first choice for urban broadcasting. For example, your hometown city station can generally listen to it through FM.

2.AM: AM medium wave transmission, with stable signal quality, high transmission cost, large transmission power, wide coverage and great influence by weather conditions, is generally the first choice for long-distance transmission.

Second, the sound quality is different.

1, FM: The influence of FM jamming signal on the amplitude of broadcast signal can be eliminated by limiter, so it has strong anti-jamming ability and almost no noise.

2.AM: AM has poor anti-interference ability and poor sound quality due to its narrow bandwidth.

Third, the working principle is different.

1, FM: FM is a kind of information expressed by the instantaneous frequency change of carrier wave, and the frequency of electromagnetic wave is adjusted and changed with the amplitude of sound wave.

2.AM: AM realizes the purpose of transmitting information by changing the amplitude of the output signal, and adjusts the amplitude of electromagnetic waves to change with the amplitude of sound waves.