How to determine the modulation bandwidth of analog signals

拜月潇湘

How to determine the modulation bandwidth of analog signals [Copy link]

How to determine the modulation bandwidth of an analog signal? I've seen people say that the modulation bandwidth of an analog signal refers to the maximum bandwidth of the output (or loaded) analog signal. So here comes the question: How do you calculate "loaded"? To what extent can a signal be distorted to be considered "loaded"? Urgently seeking advice from professionals, thank you!

gmchen

This statement is not entirely accurate. If it is ordinary amplitude modulation, then the bandwidth of the modulated wave is twice the highest frequency component of the modulating signal. If it is single-sideband amplitude modulation with suppressed carrier, then the bandwidth of the modulated wave is the bandwidth of the modulating signal. The bandwidth of the modulated wave of these two types of modulation has nothing to do with distortion. If it is an angle-modulated signal, then the bandwidth of the modulated wave is theoretically infinite, but since the power of the sideband signal attenuates as the frequency deviation increases, the signal is actually limited to a limited frequency band. When the modulation index is small, it is often considered that the bandwidth of the modulated wave is equal to twice the highest frequency component of the modulating signal. At this time, the signal distortion is related to the modulation index.

maychang

It depends on which modulation method you use. For the same modulation signal, the bandwidth occupied by amplitude modulation and frequency modulation is different.