GPS system for navigating a vehicle
First Claim
1. A spread spectrum receiver, comprising:
- a multi-bit digital correlator for correlating each sequential segment of a spread spectrum signal with at least one series of differently time delayed code replicas; and
matrix means responsive to the correlator to derive code source specific information.
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Abstract
A terrestrial C/A code GPS receiver system digitally samples, filters and stores a segment of 11 half chips of the received composite as a binary number and multiplexes this number for parallel correlation with each of a series of multibit code replicas for the satellites to be tracked. Each of the time delay specific correlation products are accumulated in a cell of a memory matrix so that at least twenty two delays for each satellite may be evaluated each code period providing fast reacquisition, even within a city intersection, as well as correction of multipath tracking and multipath interference. All cells of the memory matrix may be used for a acquisition of a single satellite in about 4 ms. Two satellite tracking, in addition to altitude hold, uses cross track hold alternating with clock hold to update the cross track estimate. Single satellite tracking uses cross track and clock hold together. Navigation data is updated with detected changes in motion including turns.
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Citations
110 Claims
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1. A spread spectrum receiver, comprising:
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a multi-bit digital correlator for correlating each sequential segment of a spread spectrum signal with at least one series of differently time delayed code replicas; and
matrix means responsive to the correlator to derive code source specific information. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69)
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70. A GPS system for navigating a vehicle, comprising:
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means for tracking at least one GPS satellite to provide on-track information related to progress of the vehicle along a selected track;
means for providing an estimate of cross track information related to motion of the vehicle perpendicular to the track; and
means for providing vehicle navigation data from the on-track and the cross track estimate. - View Dependent Claims (71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87)
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88. A method of operating a GPS C/A code receiver, comprising the steps of:
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forming x multibit digital segment values per C/A code period, each representing a sequential segment of a received composite of satellite signals;
correlating each digital segment value with n satellite specific sets of m differently time delayed segments of C/A code modulation to form at least n times m time delay specific correlation values; and
determining navigation information from the correlation values. - View Dependent Claims (89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110)
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Specification