About radio frequency

Traditionally, FM is used to refer to general FM broadcasting (76- 108MHz, 87- 108MHz in China and 76-90MHz in Japan). In fact, FM is also a modulation method. Even in the short wave range of 27-30MHz, FM is used as the frequency band for amateur radio, space and satellite communication applications. FM radio is FM radio.

2. AM: AM. Amplitude modulation, also known as medium wave, ranges from 530 to 1600 kHz. AM is an electrical signal that changes from sound level to amplitude.

When the radio turns right, both values increase. The frequency of carrier frequency is not constant, but varies with the modulation signal in a certain range, and its amplitude is constant. Accordingly, amplitude modulation means that the frequency of carrier frequency is constant and its amplitude changes with the modulated signal. The greater the frequency of the received electromagnetic wave.

4. The propagation of electromagnetic waves does not need medium, and the propagation speed of electromagnetic waves with the same frequency in different media is different. When electromagnetic waves with different frequencies propagate in the same medium, the higher the frequency, the greater the refractive index and the smaller the speed.

Extended data:

Radio band:

From the frequency band, it is basically divided into FM and MW dual-band radio, short-wave and FM dual-band radio, short-wave and MW dual-band radio, 3-4 multi-band radio (FM | MW | 1-2 short wave), 5- 14 multi-band radio (FM | MW |3- 12 short wave), and There are few single-band and dual-band radios in the market, and there are many multi-band radios integrating FM, medium wave and short wave.

References:

Baidu encyclopedia _FM

Baidu encyclopedia _ Zhong Bo

Baidu Encyclopedia _ Electromagnetic Wave

Baidu encyclopedia _ radio station