FM MULTIPLEX DETECTOR CIRCUITS

The FM stereo detector circuit shown in Fig. 22.4 (a), uses time-division multiplex detection. Basically, this system permits sampling of left and right information, each being channeled to its respective output circuit.

In operation, the 38 kHz signal from the secondary of the transformer is applied to the detector diode quad. This is a strong signal, some 30 times the level of the composite signal which comprises the other input to the detector. The 38 kHz switching signal causes the detector to conduct on alternate half cycles to each of the L and R outputs of the detector. Normal audio signals, (L+R), are simply interrupted at a 38 kHz rate; each output therefore contains equal amounts of (L+R) signal. In the ...

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