Method and apparatus for digital modulation using concurrent pulse addition and subtraction
AssigneeMotorola, Inc.
InventorsPeter Nanni, Bradley M. Hiben, Leslie D. Mutz
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Abstract
A method and apparatus for generating an output signal (616) having a pre-determined frequency shift relative to the frequency of a reference signal from a reference frequency generator (202) comprise a digital phase-locked loop (206) coupled to the reference signal for generating the output signal (616). The method and apparatus further comprise adding pulses to the reference signal in a pulse addition circuit (304), the pulses recurring at a first cyclical rate determined by a microprocessor (702). The method and apparatus further comprise concurrently subtracting pulses from the reference signal in a pulse subtraction circuit (302) at a second cyclical rate.
Claims20
A method of generating an output signal having a pre-determined frequency shift relative to the frequency of a reference signal in a system comprising a digital phase-locked loop coupled to the reference signal for generating the output signal, the method comprising the steps of:
- (a) adding pulses to the reference signal, the pulses recurring at a first cyclical rate;
- and
- (b) concurrently subtracting pulses from the reference signal at a second cyclical rate.
An apparatus for generating an output signal having a pre-determined frequency shift relative to the frequency of a reference signal in a system comprising a digital phase-locked loop coupled to the reference signal for generating the output signal, the apparatus comprising:
- pulse addition means coupled to the reference signal for adding pulses recurring at a first cyclical rate to the reference signal;
- and
- pulse subtraction means coupled to the reference signal for concurrently subtracting pulses at a second cyclical rate from the reference signal.
A wireless communication transmitter comprising a frequency synthesizer for generating an output signal having a pre-determined frequency shift relative to the frequency of a reference signal in the synthesizer comprising a digital phase-locked loop coupled to the reference signal for generating the output signal, the frequency synthesizer comprising:
- a pulse adder coupled to the reference signal for adding pulses recurring at a first cyclical rate to the reference signal;
- and
- a pulse subtracter coupled to the reference signal for concurrently subtracting pulses at a second cyclical rate from the reference signal.
Dependencies are inferred from the claim text.