Binary FM demodulator with self-adjusting resonant operating frequency according to demodulated binary output signal duty cycle
First Claim
1. A demodulator with a selectable resonant frequency of operation for demodulating a frequency-modulated signal comprising:
- demodulator means with an adjustable resonant frequency of operation for receiving and demodulating a frequency-modulated signal which has a signal carrier frequency associated therewith to produce a binary demodulated signal which has a duty cycle associated therewith, and for receiving a frequency control signal and in accordance therewith adjusting said adjustable resonant frequency of operation; and
controller means, coupled to said demodulator means for receiving and analyzing said binary demodulated signal duty cycle and in accordance therewith providing said frequency control signal.
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Abstract
A demodulator for demodulating a binary frequency-modulated signal includes a demodulator with a quadrature tank circuit and a duty cycle monitor circuit. The quadrature tank circuit has a voltage-controllable resonant frequency for compensating for shifts in the carrier frequency of the incoming signal and shifts in the tank circuit component values so as to allow the use of a high-Q tank circuit and thereby maximize use of the incoming signal energy. The quadrature tank circuit is a reactive circuit (with both inductive and capacitive elements) which includes a varactor diode having a voltage-controllable capacitance. The duty cycle monitor circuit measures the duty cycle of the demodulated binary output from the demodulator, and provides a control voltage to the quadrature tank circuit for adjusting its center frequency of operation.
28 Citations
33 Claims
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1. A demodulator with a selectable resonant frequency of operation for demodulating a frequency-modulated signal comprising:
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demodulator means with an adjustable resonant frequency of operation for receiving and demodulating a frequency-modulated signal which has a signal carrier frequency associated therewith to produce a binary demodulated signal which has a duty cycle associated therewith, and for receiving a frequency control signal and in accordance therewith adjusting said adjustable resonant frequency of operation; and controller means, coupled to said demodulator means for receiving and analyzing said binary demodulated signal duty cycle and in accordance therewith providing said frequency control signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A demodulator with a selectable resonant frequency of operation for demodulating a frequency-modulated signal, comprising:
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a demodulator with an adjustable resonant frequency of operation which receives and demodulates a frequency-modulated signal which has a signal carrier frequency associated therewith and produces a binary demodulated signal which has a duty cycle associated therewith, and which receives a frequency control signal and in accordance therewith adjusts said adjustable resonant frequency of operation; and a signal controller, coupled to said demodulator which receives and analyzes said binary demodulated signal duty cycle and in accordance therewith provides said frequency control signal. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A demodulation method for using a selectable resonant frequency of operation to demodulate a frequency-modulated signal, comprising the steps of:
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receiving and demodulating with an adjustable resonant frequency of operation a frequency-modulated signal which has a signal carrier frequency associated therewith to produce a binary demodulated signal which has a duty cycle associated therewith; receiving a frequency control signal and in accordance therewith adjusting said adjustable resonant frequency of operation; and analyzing said binary demodulated signal duty cycle and in accordance therewith providing said frequency control signal. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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Specification