Digital frequency modulation system and method
AssigneeMotorola, Inc.
InventorsDonald L. Linder, William R. Murphy
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Abstract
There is disclosed a new and improved frequency modulation system and method for providing a frequency modulated signal which varies in frequency from a center frequency in response to the amplitude of an analog modulating signal. The system and method utilizes a frequency shift synthesizer to provide the frequency modulated signal and digital techniques for quantizing the amplitude modulating signal and providing dividing factors to the frequency shift synthesizer responsive to the amplitude quantization.
Claims29
In a frequency modulation system of the type which transforms an analog modulating signal to a signal substantially constant in amplitude by varying in frequency from a center frequency responsive to a characteristic of said analog modulating signal, the improvement comprising:
- frequency synthesizer means including an output and not more than one frequency control input for receiving digital frequency control signals and for varying the output frequency at said output by an amount related to said digital frequency control signals;
- and
- digital frequency control signal generating means coupled to said frequency control input for providing said frequency control input with said digital frequency control signals in response to said characteristic of said analog modulating signal;
- and
- means for synchronizing said digital frequency control signal generating means with said frequency synthesizer means.
A method of providing a signal varying in frequency from a center frequency by an amount related to a characteristic of an analog modulating signal, said method comprising the steps of:
- providing a frequency synthesizer of the type having an output and not more than one frequency control input which varies the output frequency in response to digital frequency control signals received at said control input;
- generating said digital frequency control signals in response to said characteristic of said modulating signal;
- and
- conveying said digital control signals to said control input;
- and
- synchronizing said digital frequency control with said frequency synthesizer.
Dependencies are inferred from the claim text.