Method and apparatus for performing signal correlation
AssigneeGlobal Locate, Inc.
InventorCharles Abraham
Life of this patent
Estimating the term…
Abstract
A method and apparatus for computing a convolution between an input GPS signal and a C/A code reference by generating the convolution result in real time without storing unprocessed signal samples. The apparatus comprises a vector multiplier running at high speed to achieve the same result as a vector multiplier sized to process an entire epoch. Additionally, the input samples to, and the output samples of, the vector multiplier can be quantized to reduced circuit complexity.
Claims17
A receiver of global positioning system (GPS) signals comprising:
- a decimation circuit for producing a subsampled in-phase (I) signal and a subsampled quadrature (Q) signal from received GPS signals;
- a quantizer for producing quantized I and Q samples from the subsampled I and Q signals;
- a convolution processor for producing I and Q correlations.
The receiver of claim 2 wherein the quantized I and Q samples are represented using two bits.
A method of receiving global positioning system (GPS) signals comprising:
- decimating received GPS signals to produce a subsampled in-phase (I) signal and a subsampled quadrature (Q) signal;
- quantizing the subsampled I and Q signals to produce quantized I and Q samples;
- multiplying a C/A reference code with the quantized I and Q samples to produce I and Q correlations.
A receiver of global positioning system (GPS) signals comprising:
- a decimation circuit for producing a subsampled in-phase (I) signal and a subsampled quadrature (Q) signal from received GPS signals;
- a convolution processor for producing I and Q correlations;
- a divider for reducing the number of bits of precision of the I and Q correlations to produce quantized I and Q correlations;
- a signal normalizer for normalizing the quantized I and Q correlations to produce complex magnitude values;
- and
- a magnitude accumulator for summing the complex magnitude values.
A receiver of global positioning system (GPS) signals comprising:
- a decimation circuit for producing a subsampled in-phase (I) signal and a subsampled quadrature (Q) signal from received GPS signals;
- a convolution processor for producing I and Q correlations;
- a magnitude approximation circuit for normalizing the I and Q correlations to produce complex magnitude values;
- and
- a magnitude accumulator for summing the complex magnitude values.
A receiver of global positioning system (GPS) signals comprising:
- a decimation circuit for producing a subsampled in-phase (I) signal and a subsampled quadrature (Q) signal from received GPS signals;
- a convolution processor for producing I and Q correlations;
- a signal normalizer for normalizing the quantized I and Q correlations to produce complex magnitude values;
- a magnitude accumulator for summing subsets of the complex magnitude values;
- and
- a minimum value register for storing a minimum magnitude value for each of the subsets of complex magnitude values to produce an offset, and for subtracting the offset from the complex magnitude values.
Dependencies are inferred from the claim text.