ON CHANNEL AGILE FM DEMODULATOR

摘要

An on channel frequency agile phase lock loop ("PLL") demodulator is provided using a precise and stable oscillator, such as a voltage controlled crystal oscillator ("VCXO") having its output frequency variable over a limited range. The output of the oscillator is multiplied by a multiplication factor to produce a mixing frequency. The multiplication factor scales the limited range of the oscillator to produce a proportionate mixing frequency deviation. A frequency synthesizer is used to enable the demodulator to detect signals on different channels. In one embodiment, the output of the frequency synthesizer is mixed with the scaled oscillator output to provide a mixing frequency having a fixed deviation for all channels. The demodulator can be used for detecting data transmitted over a cable television network.