Circuit for reception of TV audio multiplex signal - includes two FM discriminators for output from mixer delivering frequencies irrespective of multiplex carrier signal pairs

摘要

Pairs of audio multiplex carrier signals at the input (1) are band-pass filtered (11) and mixed (12) with output of a local oscillator (13) controlled by, e.g. 16.2 and 16.958 MHz crystals (14a,14b). The IF prod. is divided between parallel combinations of band-pass filters (15,16) and discriminators (17,18) whose outputs are switched (S2,S3) alternately to terminals (2,3) in synchronism with the switching (S1) of the crystals by a control signal (4). USE/ADVANTAGE - Esp. for the dual-carrier audio multiplex systems of Germany, Poland, the Czech Republic and Slovakia, simplified circuit with only two FM demodulators takes up less space.