| 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 ( 8 a, 8 b) 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 ( 8 b) 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 ( 8 a, 8 b) 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, an 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.
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