Residual sideband amplitude modulator for sampled analogue or digital signals for television - has sampling circuit with over-sampling ratio of 2 or more, low pass filter, modulator, Nyquist filter and D=A converter

摘要

The modulator consists of a sampling circuit (1) with an over-sampling ratio of 2 or more and a primary low-pass filter (2) producing a baseband signal (x(k)). This is input to an amplitude modulator (3) together with a modulation signal (y0(k)). The output from the modulator (y1(k)) is input to a secondary Nyquist filter (4) to deliver a filtered, modulated signal (y2(k)). Finally, a digital analogue converter (5) converts this signal to a signal (y2(t)) which corresponds to a filtered, modulated carrier signal. USE/ADVANTAGE - E.g. for cable networks. Avoids problems due to distortion caused by weather, echos and temp.