SYSTEM AND METHOD FOR FAST CODE PHASE AND CARRIER FREQUENCY ACQUISITION IN GPS RECEIVER
First Claim
1. A method for detecting code phase in a GPS signal, comprising:
- collecting a multiple millisecond portion of a GPS signal in a GPS receiver;
partitioning the multiple millisecond portion of the GPS signal into a plurality of one millisecond segments;
converting each of the one millisecond segments to the frequency domain;
multiplying each of the converted one millisecond segments by a frequency domain representation of a Gold code corresponding to a GPS satellite to generate a plurality of products;
converting each of the plurality of products to the time domain to obtain convolution signals between each one millisecond segment and the Gold code; and
combining said convolution signals to determine a correlation peak that is reflective of a code phase of the GPS signal.
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0 Petitions
Accused Products
Abstract
A GPS receiver acquires carrier frequency and Gold code phase using short segments of a received GPS signal. In one embodiment, a 1-ms segment of the GPS signal is transformed to the frequency domain. This is multiplied by a frequency representation of the Gold code. The resulting product is converted to the time domain, and a peak is detected. The location of the peak corresponds to the code phase. If no peak is located, the carrier frequency is changed. Full- and half-bin steps in carrier frequency are considered. Processing gain is achieved by using longer segments of the input signal, for example 4 or 16 ms and integrating 1-ms segments. Considerations are provided for compensating for the effects of a transition, should it occur in the short segment of the GPS signal being processed. Integrations can be performed using non-coherent and coherent techniques. Adjustments are made for non-integral millisecond segment lengths.
79 Citations
16 Claims
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1. A method for detecting code phase in a GPS signal, comprising:
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collecting a multiple millisecond portion of a GPS signal in a GPS receiver; partitioning the multiple millisecond portion of the GPS signal into a plurality of one millisecond segments; converting each of the one millisecond segments to the frequency domain; multiplying each of the converted one millisecond segments by a frequency domain representation of a Gold code corresponding to a GPS satellite to generate a plurality of products; converting each of the plurality of products to the time domain to obtain convolution signals between each one millisecond segment and the Gold code; and combining said convolution signals to determine a correlation peak that is reflective of a code phase of the GPS signal. - View Dependent Claims (2, 3, 4)
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5. A method for detecting code phase in a GPS signal, comprising:
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partitioning a multiple millisecond portion of a GPS signal into a plurality of one millisecond segments; generating a plurality of products, each product representing a multiplication of a frequency domain representation of a one millisecond segment of the GPS signal with a frequency domain representation of a Gold code corresponding to a GPS satellite that produced the GPS signal; converting each of the plurality of products to the time domain to obtain convolution signals between each one millisecond segment of the GPS signal and the Gold code; and combining said convolution signals to determine a correlation peak that is reflective of a code phase of the GPS signal. - View Dependent Claims (6, 7, 8, 9, 10)
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11. A computer-readable medium that stores a program for controlling a computer device to perform a method for detecting code phase in a GPS signal, the method comprising:
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partitioning a multiple millisecond portion of a GPS signal into a plurality of one millisecond segments; generating a plurality of products, each product representing a multiplication of a frequency domain representation of a one millisecond segment of the GPS signal with a frequency domain representation of a Gold code corresponding to a GPS satellite that produced the GPS signal; converting each of the plurality of products to the time domain to obtain convolution signals between each one millisecond segment of the GPS signal and the Gold code; and combining said convolution signals to determine a correlation peak that is reflective of a code phase of the GPS signal. - View Dependent Claims (12, 13, 14, 15, 16)
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Specification