Single-sideband modulation#Vestigial sideband .28VSB.29

The residual sideband modulation is a variation of the amplitude modulation. It allows a transfer with less bandwidth at higher signal quality and simple circuitry for the demodulator. This is suppressed in the transmitter through a filter after the modulator of one of the sidebands to a residual. The carrier wave is transmitted with reduced power and the second side band is not attenuated. Thus, they can be called " partially " single sideband will be described (for the single sideband sideband and the carrier is fully filtered ).

The main reason for this variant are the simpler filter after the modulator, because these need not have the rectangular passage curves to exactly " cut " the unwanted sideband.

The residual sideband modulation is used, for example in the transmission of analog television signals, because the sidebands are located very close to the carrier frequency. This occurs when the lower to the carrier frequency modulated signal components contains frequency or DC components ( while watching TV: average brightness of the image) to be transferred.

In conjunction with a receiver in use band-pass filter with a special edge shape ( Nyquist slope ), the signal processing, especially at low modulation frequencies can be simplified. An application is, for example, the amplitude-modulated image signal at television broadcasting.

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