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US 7,843,228 B2Granted
Half bin linear frequency discriminator
AssigneeQUALCOMM Incorporated
InventorJoel Brenner
Life of this patent
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Abstract
Frequency discriminator based on a variant of the DFT transform in which the usual twiddle factors are replaced with twiddle factors as for a DFT on a number of points which is the double as the actual number of sample points. The DFT so modified allows half-bin frequency discrimination, with few added computational burden. Two DFT shifted of half bin with respect to the zero frequency provide a linear response of the discrimination and good immunity to noise. The discriminator is particularly useful in FLL for tracking signals in a GPS receiver.
Claims57
A method comprising:
- obtaining an input signal based, at least in part, on one or more signals received by a receiver;
- extracting a first spectral component of the an input signal at a first frequency that is less than a reference frequency by a first specified frequency difference and a second spectral component of the input signal at a second frequency that is greater than the reference frequency by a second specified frequency difference, wherein the first and second specified frequency differences are each less than a frequency span between integer values associated with adjacent bins of digital data as sampled from the input signal at a specified sampling rate;
- calculating a frequency error value based, at least in part, on the first and second spectral components, wherein the frequency error value relates a fundamental frequency of the input signal and the reference frequency;
- and
- providing one or more signals representing the frequency error value to an apparatus that is operatively affected by the one or more signals representing the frequency error value.
2 more elements
An apparatus comprising:
- means for extracting a first spectral component of an input signal at a first frequency that is less than a reference frequency by a first specified frequency difference;
- means for extracting a second spectral component of the input signal at a second frequency that is greater than the reference frequency by a second specified frequency difference, wherein the first and second specified frequency differences are each less than a frequency span between integer values associated with adjacent bins of digital data as sampled from the input signal at a specified sampling rate;
- means for calculating a frequency error value based, at least in part, on the first and second spectral components, wherein the frequency error value relates a fundamental frequency of the input signal and the reference frequency;
- and
- means for providing one or more signals representing the frequency error value to an apparatus.
2 more elements
An apparatus comprising:
- one or more processors programmed to act as a discriminator module to:
- obtain one or more signals representing an input signal from a receiver;
- extract a first spectral component of the input signal at a first frequency that is less than a reference frequency by a first specified frequency difference;
- extract a second spectral component of the input signal at a second frequency that is greater than the reference frequency by a second specified frequency difference, wherein the first and second specified frequency differences are each less than a frequency span between integer values associated with adjacent bins of digital data as sampled from the input signal at a specified sampling rate;
- calculate a frequency error value based, at least in part, on the first and second spectral components, wherein the frequency error value relates a fundamental frequency of the input signal and the reference frequency;
- and
- generate one or more signals representing the frequency error value for use by at least one other apparatus.
4 more elements
An article comprising:
- a storage medium having software code stored therein that is executable by one or more processors in a computer device to:
- extract a first spectral component of an input signal at a first frequency that is less than a reference frequency by a first specified frequency difference;
- extract a second spectral component of the input signal at a second frequency that is greater than the reference frequency by a second specified frequency difference, wherein the first and second specified frequency differences are each less than a frequency span between integer values associated with adjacent bins of digital data as sampled from the input signal at a specified sampling rate;
- calculate a frequency error value based, at least in part, on the first and second spectral components, wherein the frequency error value relates a fundamental frequency of the input signal and the reference frequency;
- and
- generate one or more signals representing the frequency error value for use by an apparatus.
3 more elements
A method comprising:
- calculating at least two discrete spectral components of an input signal based, at least in part, on a Half-bin Discrete Fourier Transform (HDFT);
- determining a frequency error value between the input signal and a reference signal based, at least in part, on the at least two discrete spectral components;
- and
- providing one or more signals representing the frequency error to at least one locked loop circuit.
1 more element
An apparatus comprising:
- means for calculating at least two discrete spectral components of an input signal based, at least in part, on a Half-bin Discrete Fourier Transform (HDFT);
- means for determining a frequency error value between the input signal and a reference signal based, at least in part, on the at least two discrete spectral components;
- and
- means for providing one or more signals representing the frequency error to at least one locked loop circuit.
1 more element
An apparatus comprising:
- a frequency discriminator to calculate at least two discrete spectral components of an input signal based, at least in part, on a Half-bin Discrete Fourier Transform (HDFT), determine a frequency error value between the input signal and a reference signal based, at least in part, on the at least two discrete spectral components, and generate one or more signals representing the frequency error for use by at least one locked loop circuit.
An article comprising:
- a storage medium having software code stored therein that is executable by one or more processors to:
- calculate at least two discrete spectral components of an input signal based, at least in part, on a Half-bin Discrete Fourier Transform (HDFT);
- determine a frequency error value between the input signal and a reference signal based, at least in part, on the at least two discrete spectral components;
- and
- establish one or more signals representing the frequency error for use by at least one locked loop circuit.
2 more elements
Dependencies are inferred from the claim text.