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US 6,057,798 AGranted
Apparatus and method for frequency modulation
AssigneeRaytheon Company
InventorsRichard W. Burrier, James T. Hanson
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Abstract
A method and apparatus for frequency modulating a continuous wave signal is shown to comprise a voltage-controlled oscillator (VCO) having a first and a second control loop to maintain the carrier frequency of such VCO at a frequency determined by a crystal-controlled oscillator and to maintain the peak deviation of the FM modulation on such carrier frequency at a value equal to the deviation of the first Bessel null from the carrier frequency.
Claims3
An improved ranging standard generator for generating a frequency modulated waveform having a precise frequency deviation, such generator comprising:
- (a) a voltage controlled oscillator;
- (b) a divide-by-M frequency divider for dividing the output signal from the voltage-controlled oscillator;
- (c) a crystal-controlled reference oscillator;
- (d) a pair of divide-by-N frequency dividers for dividing the output signals from the divide-by-M frequency divider and the crystal-controlled reference oscillator;
- (e) an oscillator tuned to the modulating frequency;
- (f) means, responsive to the output signals from the oscillator tuned to the modulating frequency and the pair of divide-by-N frequency dividers, for frequency modulating the voltage-controlled oscillator;
- and
- (g) means, responsive to the undivided output signal from the crystal-controlled reference oscillator and the output signal from the divide-by-M frequency divider, for controlling the deviation of the frequency modulated output signal from the voltage-controlled oscillator.
5 more elements
Dependencies are inferred from the claim text.