ARRANGEMENT FOR DEMODULATING A VESTIGIAL SIDEBAND SIGNAL

摘要

An arrangement is described for demodulating a vestigial sideband signal component contained in an amplitude-modulated frequency signal, and preferably in a vision intermediate-frequency signal derived from a television signal. What distinguishes the invention is that there are provided two parallel, preferably identical, mixing stages (8a, 8b) that operate at a phase shift of substantially, and preferably exactly, 90°, of which mixing stages a first one (8a) produces from the frequency signal a first output signal and a second one (8b) produces from the frequency signal a second output signal that is phase shifted by substantially, and preferably exactly, 90° relative to the first output signal, a downstream phase-shifter (12) that causes a phase shift between the first and second output signals from the mixing stages (8a, 8b) of substantially, and preferably exactly, a further 90°, an adder (14) that adds together the output signals from the phase shifter (12), which output signals have been phase shifted relative to one another by substantially, and preferably exactly, 180°, a local oscillator (10) that drives the mixing stages with a phase shift of substantially, and preferably exactly, 90°, and a setting device for setting the frequency and phase of the local oscillator (10), the setting device setting the frequency and phase of the local oscillator (10) substantially, and preferably exactly, to the frequency and phase of the frequency signal.