ISB is short for Independent sideband, so ISB modulation is independent sideband modulation. Independent sideband modulation is used in some AM radio transmissions. Suppressed Carrier ISB is used in short wave (HF) point-to-point (often overseas) radiotelephones and radioteletypewriters. In military usage, ISB generally refers to a tight pair of FSK radio teletype channels that can be demodulated by a single receiver and used for fleet broadcast, point-to-point, and HF and UHF between larger ships and shore stations.
Like VSB, ISB is also a modulation method between double sideband (DSB) and single sideband (SSB). ISB is a new type of signal modulation that still sends double sideband signals. The two sideband signals of the modulated signal can be signals of different frequencies. Compared with amplitude modulated signals, single sideband modulated signals, and double sideband modulated signals, among them The two sideband signals are exactly the same, and its information transmission capability is stronger, and the channel utilization rate is higher. It can save frequency resources for the increasingly crowded short-wave frequency band, and has high engineering application value.