Combined parallel and sequential detection for GPS signal acquisition
First Claim
1. A signal acquisition process comprising:
- a) calculating a first set of correlations between a segment of a satellite signal received over a first time period and a reference signal over a set of phase offset values and carrier frequency values;
b) for each of the first set of correlations that exceeds a predetermined threshold value, identifying the carrier frequency value and the phase offset value associated with that correlation;
c) calculating a second set of correlations between a segment of the satellite signal received over a second time period with the reference signal using the frequency values and the phase offset values identified from the first set of correlations;
d) identifying the carrier frequency value and the phase associated with each of correlations that exceed the threshold value in the second set of correlations; and
e) calculating a third set of correlations between a segment of the satellite signal received over a third time period with the reference signal using the set of carrier frequency values and the phase offset values associated with the first set of correlations and the carrier frequency values and the phase offset values identified from the second set of correlations.
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Accused Products
Abstract
A two part signal acquisition process includes a parallel signal detection process and signal verification/false alarm rejection process. A massively parallel architecture of acquisition correlators search a large region of the time-frequency uncertainty during the parallel signal detection process to identify the most likely detections for each search dwell. Concurrent with the parallel signal detection process performed by the acquisition correlators, the current list of most likely detections is examined with additional search dwells in the verification/false alarm rejection process. The verification/false alarm rejection process is performed by a plurality of independent correlators or tracking channels. Under software control, the tracking channels perform repeated dwells on the most likely detections until they can be dismissed as false alarms or verified as the desired signal.
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Citations
10 Claims
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1. A signal acquisition process comprising:
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a) calculating a first set of correlations between a segment of a satellite signal received over a first time period and a reference signal over a set of phase offset values and carrier frequency values; b) for each of the first set of correlations that exceeds a predetermined threshold value, identifying the carrier frequency value and the phase offset value associated with that correlation; c) calculating a second set of correlations between a segment of the satellite signal received over a second time period with the reference signal using the frequency values and the phase offset values identified from the first set of correlations; d) identifying the carrier frequency value and the phase associated with each of correlations that exceed the threshold value in the second set of correlations; and e) calculating a third set of correlations between a segment of the satellite signal received over a third time period with the reference signal using the set of carrier frequency values and the phase offset values associated with the first set of correlations and the carrier frequency values and the phase offset values identified from the second set of correlations. - View Dependent Claims (2, 3, 4, 5)
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6. A signal acquisition device comprising:
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a first set of correlators adapted to repeatedly (a) perform over successive time intervals correlations over a predetermined range of phase offset values and carrier frequency values and (b) identify, for each time interval, a combination of phase offset values and carrier offset values corresponding to a predetermined number of largest correlations over that time interval; and a second set of correlators adapted to repeatedly perform correlations, for each of the successive time intervals, using the identified combination of phase offset values and carrier frequency values for that time interval and a selected subset of the phase offset values and the carrier offset values used in the immediately previous time interval. - View Dependent Claims (7, 8, 9, 10)
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Specification