TELEVISION RECEIVER WITH DIGITAL WORKING LEVELS

摘要

This unit only contains a single A/D converter (aw) and thus only a single interface (s) between analog and digital section following the intermediate-frequency stage (z). The A/D converter (aw) is clocked at approximately 20 MHz. In the video channel (vk), the band-pass filter (bp) with a pass band of 1 MHz to 6 MHz is located at the input, which, directly and via the 90 DEG -phase shifting circuit (ps), feeds the first amount forming circuit (b1), at the output of which the digital composite colour television signal (fb) occurs. In the audio channel (ak), the quadrature mixer (qm) (mixing frequency 7 MHz to 7.5 MHz) is located at the input, the two output signals of which are conducted by one decimating circuit (d1, d2) each to the second amount forming circuit (b2) and to the angle forming circuit (wb). Its output supplies the frequency-modulated audio signal (fa) via the differentiating stage (dt). The amplitude-demodulated audio signal (aa) occurs at the output of the second amount forming circuit (b2). …IMAGE…