Apparatus for estimating a line of sight signal propagation time using a reduced-multipath correlation function
First Claim
1. A positioning signal processing system which receives from a transmitter a data carrying carrier modulated with a pseudo random noise signal, and processes the received data carrying signal to determine a propagation time τ
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0 indicative of the time it takes the received data carrying signal to propagate directly from the transmitter to the positioning signal processing system, the system comprising;
a signal source for providing a reference signal;
means for performing a correlation operation on the received data carrying signal with said reference signal in order to provide a measure of the shape of the correlation function Rx (τ
) of the received data carrying signal;
means for iteratively estimating the multipath-induced contribution to the correlation function and subtracting said estimated multipath-induced contribution from the correlation function to obtain an estimated line of sight contribution to the correlation function; and
means for calculating the propagation time τ
0 from said estimated line of sight contribution to the correlation function.
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Accused Products
Abstract
A method and device for processing a signal are described, wherein an estimate of a multipath-induced contribution to a demodulated navigation signal is calculated and subtracted from said demodulated navigation signal to obtain an estimated line of sight contribution to said demodulated navigation signal, and a propagation time τ0 is calculated from the thus calculated line of sight contribution to said demodulated navigation signal, such that a very accurate propagation time τ0 of said navigation signal can be calculated.
93 Citations
14 Claims
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1. A positioning signal processing system which receives from a transmitter a data carrying carrier modulated with a pseudo random noise signal, and processes the received data carrying signal to determine a propagation time τ
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0 indicative of the time it takes the received data carrying signal to propagate directly from the transmitter to the positioning signal processing system, the system comprising;
a signal source for providing a reference signal; means for performing a correlation operation on the received data carrying signal with said reference signal in order to provide a measure of the shape of the correlation function Rx (τ
) of the received data carrying signal;means for iteratively estimating the multipath-induced contribution to the correlation function and subtracting said estimated multipath-induced contribution from the correlation function to obtain an estimated line of sight contribution to the correlation function; and means for calculating the propagation time τ
0 from said estimated line of sight contribution to the correlation function. - View Dependent Claims (2)
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0 indicative of the time it takes the received data carrying signal to propagate directly from the transmitter to the positioning signal processing system, the system comprising;
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3. A signal processing system which receives from a transmitter and processes a data carrying carrier modulated with a pseudo random noise signal, the system comprising:
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means for receiving the transmitted signal and providing a received data carrying signal; a signal source which provides a reference signal; means for performing correlations on said received data carrying signal with said reference signal at a plurality of points along the correlation function Rx (τ
) of said received data carrying signal to provide a measure of the shape of the correlation function Rx (τ
);means for estimating a multipath-induced contribution to the correlation function; means for subtracting said estimated multipath-induced contribution from the correlation function to obtain an estimated line of sight contribution to the correlation function; and means for calculating a propagation time τ
0 for said signal propagating between the transmitter and said signal processing system, said propagation time τ
0 being calculated from said estimated line of sight contribution to the correlation function. - View Dependent Claims (4, 5, 6)
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7. A GPS receiver which receives from a transmitter a data carrying carrier modulated with a pseudo random noise signal, and processes the received data carrying signal to determine an estimated propagation time τ
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0 indicative of the time it takes the received data carrying signal to propagate directly from the transmitter to the receiver, the receiver comprising;
means for providing a plurality of delayed reference signals wherein each of said delayed reference signals has been delayed in time by a different mount; means for performing, for each of said plurality of delayed reference signals, a correlation operation with said received data carrying signal and for providing a plurality of correlation signal values indicative thereof; means for estimating multipath-induced correlation signal values for each of said plurality of correlation signal values; means for subtracting each of said estimated multipath-induced correlation signal values from its associated one of said plurality of correlation signal values to obtain an estimated line of sight signal correlation contribution for each of said plurality of correlation signal values; and means for calculating the estimated propagation time τ
0 from said estimated line of sight signal correlation contributions. - View Dependent Claims (8)
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0 indicative of the time it takes the received data carrying signal to propagate directly from the transmitter to the receiver, the receiver comprising;
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9. A GPS receiver which receives from a transmitter a data carrying carrier modulated with a pseudo random noise signal, and processes the received data carrying signal to determine an estimated propagation time τ
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0 indicative of the time it takes the received data carrying signal to propagate directly from the transmitter to the receiver, the receiver comprising;
a signal source which generates and provides a reference signal; a time delay network responsive to said reference signal, for providing a plurality of delayed reference signals wherein each of said delayed reference signals has been delayed in time by a different amount; a plurality of correlators, each responsive to an associated one of said plurality of delayed reference signals, for performing a correlation operation with said received data carrying signal and providing a plurality of correlation signal values indicative thereof; and a processor which estimates a multipath-induced correlation contribution for each of said plurality of correlation signal values, subtracts each of said estimated multipath-induced correlations from its associated one of said plurality of correlation signal values to obtain an estimated line of sight signal correlation contribution for each of said plurality of correlation signal values, and calculates the estimated propagation time τ
0 from said estimated line of sight signal correlation contributions. - View Dependent Claims (10, 11)
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0 indicative of the time it takes the received data carrying signal to propagate directly from the transmitter to the receiver, the receiver comprising;
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12. A GPS signal processing system which receives from a transmitter a data carrying carrier modulated with a pseudo random noise signal, and processes the received data carrying signal to determine an estimated propagation time τ
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0 indicative of the time it takes the received data carrying signal to propagate directly from the transmitter to the GPS signal processing system, the system comprising;
means for providing a plurality of delayed reference signals wherein each of said delayed reference signals has been delayed in time by a different amount; means for performing, for each of said plurality of delayed reference signals, a correlation operation with said received data carrying signal and providing received correlation signal values indicative thereof; means for providing an initial estimate of a line of sight signal contribution to said received correlation signal values, and providing initial estimated line of sight signal values indicative thereof; means for estimating, subtracting and calculating until a stop criterion has been satisfied, comprising means, responsive to the estimated line of sight signal values, for estimating multipath-induced correlation signal values for each of said plurality of received correlation signal values; means for subtracting each of said estimated multipath-induced correlation signal values from its associated one of said plurality of received correlation signal values to obtain a new estimated line of sight signal correlation contribution for each of said plurality of received correlation signal values; and means for calculating the estimated propagation time τ
0 from said new estimated line of sight signal correlation contribution. - View Dependent Claims (13, 14)
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0 indicative of the time it takes the received data carrying signal to propagate directly from the transmitter to the GPS signal processing system, the system comprising;
Specification