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US 2008/0159438 A1Published application
Methods and apparatus for multi-mode frequency shift keying
AssigneeCustom One Design, Inc.
InventorsJoseph M. Kulinets, Peter R. Nuytkens
Life of this patent
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Abstract
Methods and apparatus for signal transmission utilizing directly modulated frequency shift keying. Embodiments of the present invention provide a fractional (non-integer) N oscillator to directly modulate a baseband signal for transmission using a programmable digital raised cosine generator, providing a tunable Gaussian FSK transmitter.
Claims21
A modulator comprising:
- a phase detector receiving a reference signal and a feedback signal and providing a phase difference output;
- a charge pump receiving the phase difference output from the phase detector and providing the phase difference output to the filter;
- a filter receiving the phase difference output from the phase detector and providing the phase difference output to a voltage-controlled oscillator;
- a voltage-controlled oscillator receiving the phase difference output and providing a divider input signal;
- and
- a divider receiving the divider input signal and a modulation signal and providing the feedback signal,
- wherein the modulation signal is varied between consecutive integer values using stitched together parabolic curves so as to realize a divider input signal that is a non-integer multiple of the reference frequency.
4 more elements
A method for direct modulation, the method comprising:
- converting a reference signal and a feedback signal into a phase difference output signal using a phase detector and applying this signal to a charge pump;
- supplying the output signal of the charge pump to a low-pass filter;
- controlling a voltage-controlled oscillator (VCO) with the output signal from the low-pass filter;
- providing an output frequency signal from the VCO as a divider clock signal;
- applying to a divider the divider clock signal and a modulation signal serving as a changing division ratio coefficient;
- supplying the end of division signal as the feedback signal to the phase detector;
- and
- varying the modulation signal between consecutive integer values so as to realize a divider with division ratio that on the average is a non-integer multiple of the reference frequency,
- wherein the modulation signal is derived by adding the constant value representing the integer part of non-integer N to the changing value from the output of a sigma-delta modulation of a sum of a constant, representing the fractional part of a non-integer N, and another digital signal changing according to an approximation of a raised cosine law using two stitched-together parts of parabolas that are in a point symmetry to each other.
6 more elements
A method for direct modulation, the method comprising:
- converting a reference signal and a feedback signal into a phase difference output signal using a phase detector;
- providing a divider input signal from the phase difference output using a voltage-controlled oscillator;
- converting the divider input signal and a modulation signal into the feedback signal using a divider;
- and
- varying the modulation signal between consecutive integer values using stitched together parabolic curves so as to realize a divider input signal that is a non-integer multiple of the reference frequency.
2 more elements
Dependencies are inferred from the claim text.