What does the radio am mean?
This article will explain in detail what the radio am refers to. Xiaobian thinks it is quite practical, so share it with you for reference. I hope you can gain something after reading this article.
AM in radio means Amplitude Modulation, i.e. amplitude modulation; AM is also commonly referred to as medium wave, ranging from 530-1600KHz; AM is an electrical signal that changes from the height of sound to the amplitude; The transmission distance is relatively long, but it is greatly affected by weather factors, suitable for inter-provincial radio broadcasting.
AM on the radio is Amplitude Modulation. FM on the radio is Frequency Modulation.
AM Amplitude Modulation (AM) is amplitude modulation. Amplitude modulation is also commonly referred to as medium wave, ranging from 530--1600KHz. Amplitude modulation is an electrical signal that changes from the height of a sound to its amplitude. Transmission distance is longer, but affected by weather factors, suitable for inter-provincial radio broadcasting. Early VHF band mobile communication stations mostly use amplitude modulation mode, because channel fading will make analog amplitude modulation produce additional amplitude modulation, resulting in distortion, in the transmission process is also easy to be eavesdropped, has been rarely used. At present, there are simple communication equipment used, such as radio AM band is amplitude modulation wave, sound quality and FM band FM wave is relatively poor.
FM (Frequency Modulation) is frequency modulation. FM is customarily used to refer to general FM broadcasting (76-108MHz, 87-108MHz in China, 76-90MHz in Japan), in fact FM is also a modulation mode, even in the short-wave range between 27-30MHz, as amateur radio, space, satellite communication application bands, there are also FM (FM) mode. FM radio is FM radio.
extended information
Amplitude modulation classification:
1, double sideband amplitude modulation
The double-sideband AM signal contains only two sidebands, no carrier component, and its bandwidth is still twice the frequency of the modulated signal.
2. Single sideband amplitude modulation
A SSB AM signal contains only one sideband.
3. Residual sideband modulation
Residual sideband amplitude modulation refers to the amplitude modulation method that includes a complete sideband, carrier and a small part of another sideband in the signal transmission signal.
The basic combination of complex frequency modulation:
1. Additive carriers with one modulator
This combination consists of two or more simple FM instruments operating simultaneously, and the effect obtained is the sum of the outputs of each FM instrument (in the legend abbreviations, al denotes the amplitude of carrier 1, fl denotes the frequency of carrier 1, d1 denotes the frequency offset of modulator 1, i.e. the amplitude of modulator 1, f1 denotes the frequency of modulator 1, a denotes the carrier amplitude, and other abbreviations are identified accordingly).
Additive carriers with one modulator
The effect it achieves is the sum of the outputs of each carrier.
Single carrier with parallel modulators
Single carrier with serial modulators
5. Self-modulating carrier
The so-called self-modulated carrier is to modulate its own frequency with the output of a signal oscillator. The oscillator output signal is multiplied by a feedback factor (denoted fb), adding a frequency value (fm) before being re-input to its own frequency input. The feedback factor (denoted fb) can be seen here as a modulation index.
Since the self-modulating processing technique always works in a frequency ratio of 1:1, a sawtooth waveform is always generated. The amplitude of the harmonic component varies in proportion to the feedback factor value (fb).
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