System for determining position over a network
First Claim
1. A system for determining position utilizing signals of opportunity transmitted by at least three transmitters with known locations, the system comprising:
- a base receiver with a clock and a known position that calculates ranges to at least three of the transmitters and samples the signals of opportunity, time tags the signal samples with a time of receipt, a time of transmission or both and sends respective series of the time-tagged signal samples over a communications network;
one or more remote receivers that receive information over the communications network, each remote receiversaving and time-tagging samples of signal segments of the signals of opportunity,correlating the time-tagged series of signal samples received over the communications network with the saved time-tagged samples of signal segments,determining for each of the at least three transmitters an associated time offset as a difference in the time of receipt at the remote receiver and either or both of the time of transmission by the transmitter or the time of receipt at the base receiver, anddetermining a position by determining pseudoranges to the at least three transmitters based on the time offsets.
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Accused Products
Abstract
A system to determine position, frequency and clock offsets over a network utilizing signals of opportunity transmitted by one or more transmitters with known locations, the system includes a base receiver with a clock and a known position that determines ranges to the transmitters, takes a series of samples of the signals of opportunity and time tags the series with times of receipt, calculated times of transmission based on the calculated ranges, or both. The base receiver transmits the time tagged series and, as appropriate, computed ranges to the remote receivers. A given remote receiver saves and time tags samples of the signals of opportunity, correlates the time-tagged series with the saved samples, and calculates a time offset as a time difference of the times of receipt at the remote receiver and either the time of receipt at the base receiver or the time of transmission calculated at the base receiver. The remote receiver calculates position based on the time offsets, and as appropriate, the ranges provided by the base receiver. The elevations of the remote receivers may be calculated as part of the position calculations, determined iteratively based on constraining the Z coordinate to an average elevation, or determined from differences in air pressure sensor readings at the base and remoter receivers.
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Citations
25 Claims
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1. A system for determining position utilizing signals of opportunity transmitted by at least three transmitters with known locations, the system comprising:
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a base receiver with a clock and a known position that calculates ranges to at least three of the transmitters and samples the signals of opportunity, time tags the signal samples with a time of receipt, a time of transmission or both and sends respective series of the time-tagged signal samples over a communications network; one or more remote receivers that receive information over the communications network, each remote receiver saving and time-tagging samples of signal segments of the signals of opportunity, correlating the time-tagged series of signal samples received over the communications network with the saved time-tagged samples of signal segments, determining for each of the at least three transmitters an associated time offset as a difference in the time of receipt at the remote receiver and either or both of the time of transmission by the transmitter or the time of receipt at the base receiver, and determining a position by determining pseudoranges to the at least three transmitters based on the time offsets. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of determining position utilizing signals of opportunity transmitted by at least three transmitters with known locations, the method including the steps of
calculating ranges from a known location to at least three of the transmitters; -
sampling the signals of opportunity at the known location and time tagging series of signal samples with times of receipt, times of transmission or both; sending respective series of the time-tagged signal samples over a communications network; at one or more unknown locations saving and time-tagging samples of the signal segments of the signals of opportunity, correlating the time-tagged series of signal samples received over the communications network with the saved time-tagged samples of signal segments, determining for each of the at least three transmitters an associated time offset as a difference in the time of receipt at the unknown location and either or both of the time of receipt at the known location or the time of transmission by the transmitter, and determining a position by determining pseudoranges to the at least three transmitters based on the time offsets. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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Specification