Direct AM Stereo Detection by a PLL Synthesized Synchronous Carrier Generator
It is now possible to combine a PLL frequency synthesizer and a PLL synchronous detector to form a new demodulation system. In this circuit the crystal oscillator phase, which is the reference for the PLL frequency synthesizer, is controlled by the dc output voltage of the quadrature detector. Received frequencies are detected directly, without the need for superheterodyne conversion. This detection system incorporates very few inductors and can be produced in an integrated circuit. The system yields high-fidelity AM reception and is easily adapted for AM stereo.
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