Processing of signals to provide a delay Doppler map
First Claim
1. A method of processing a reflected signal R having a delay and a frequency shift relative to a reference signal D to obtain a delay Doppler map, the method comprising:
- a signal receiver receiving a sequence of samples xr(n) corresponding to the reflected signal R transmitted from a satellite and reflected to the signal receiver by a target area, and the signal receiver receiving a sequence of samples xd(n) corresponding to said reference signal D;
a signal processor obtaining a plurality of partial correlations z(n′
, k) between the sequence of samples xr(n) corresponding to the reflected signal and the sequence of samples xd(n) corresponding to the reference signal received by the signal receiver, across a set of delays, to provide a set of partial correlation samples for each delay, each partial correlation sample of a set corresponding to a different partial correlation for that delay, wherein obtaining a number of partial correlations of said plurality of partial correlations, providing one partial correlation sample for each delay, comprises;
obtaining discrete fourier transforms (DFTs) of at least a first and an associated second sequence of samples, the first sequence including at least one subsequence of the reflected signal and the second sequence comprising at least one associated subsequence of the reference signal, and obtaining an inverse DFT of a sequence of samples derived from at least a product of said DFTs of the first and second sequences;
the signal processor obtaining a DFT for each set of partial correlation samples to determine a correlation between sequences of samples across a plurality of frequency shifts at each delay of the set of delays; and
the signal processor outputting the delay Doppler map representing the energy received from the target area, which reflects the reflected signal R, transmitted from the satellite, to the signal receiver, as a function of delay and Doppler shift, using the determined correlation between the sequences of samples.
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Abstract
An apparatus is disclosed for processing a sequence of samples of a received signal R reflected by a target surface and having a delay and a frequency shift relative to a reference signal D to obtain a delay Doppler map for the reflected signal. A first correlation module can obtain partial correlations z(n′, k) between samples corresponding to the reflected signal R and a samples corresponding to the reference signal D, across a set of delays. An inverse discrete fourier transform (DFT) of a sequence of samples can be derived from at least DFTs of a first reflected signal sequence and second reference signal sequence.
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Citations
20 Claims
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1. A method of processing a reflected signal R having a delay and a frequency shift relative to a reference signal D to obtain a delay Doppler map, the method comprising:
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a signal receiver receiving a sequence of samples xr(n) corresponding to the reflected signal R transmitted from a satellite and reflected to the signal receiver by a target area, and the signal receiver receiving a sequence of samples xd(n) corresponding to said reference signal D; a signal processor obtaining a plurality of partial correlations z(n′
, k) between the sequence of samples xr(n) corresponding to the reflected signal and the sequence of samples xd(n) corresponding to the reference signal received by the signal receiver, across a set of delays, to provide a set of partial correlation samples for each delay, each partial correlation sample of a set corresponding to a different partial correlation for that delay, wherein obtaining a number of partial correlations of said plurality of partial correlations, providing one partial correlation sample for each delay, comprises;obtaining discrete fourier transforms (DFTs) of at least a first and an associated second sequence of samples, the first sequence including at least one subsequence of the reflected signal and the second sequence comprising at least one associated subsequence of the reference signal, and obtaining an inverse DFT of a sequence of samples derived from at least a product of said DFTs of the first and second sequences; the signal processor obtaining a DFT for each set of partial correlation samples to determine a correlation between sequences of samples across a plurality of frequency shifts at each delay of the set of delays; and the signal processor outputting the delay Doppler map representing the energy received from the target area, which reflects the reflected signal R, transmitted from the satellite, to the signal receiver, as a function of delay and Doppler shift, using the determined correlation between the sequences of samples. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. Apparatus for processing a sequence of samples of a reflected signal R reflected by a target surface and having a delay and a frequency shift relative to a reference signal D to obtain a delay Doppler map for the reflected signal, the apparatus comprising:
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a signal receiver for receiving a sequence of samples xr(n) corresponding to a reflected signal R transmitted from a satellite and reflected to the signal receiver by a target area, and a sequence of samples xd(n) corresponding to the reference signal D; a first correlation module for obtaining a plurality of partial correlations z(n′
, k) between the sequence of samples xr(n) corresponding to the reflected signal R transmitted from the satellite and reflected by the target area, and the sequence of samples xd(n) corresponding to the reference signal D, across a set of delays, the first correlation module being configured to obtain a number of partial correlations z(n′
, k) of said plurality of partial correlations, providing one partial correlation sample for each delay, by obtaining a discrete fourier transform (DFT) of at least a first sequence of samples and a DFT of at least a second sequence of samples, the first sequence including at least one subsequence of samples of the reflected signal R and the second sequence including at least one associated subsequence of samples of the reference signal D, and to obtain an inverse DFT of a sequence of samples derived from at least said DFTs of the first and second sequences;a memory for storing a plurality of sets of partial correlation samples, the samples of each set corresponding to the partial correlations for a different delay; and a second correlation module for obtaining a DFT of the samples in each set to determine the correlation between the sequences of samples of the reflected and the reference signals across a plurality of frequency shifts at each delay of the set of delays, and the second correlation module outputs the delay Doppler map representing the energy received from the target area, which reflects the reflected signal R, transmitted from the satellite, as a function of delay and Doppler shift, using the determined correlation between the sequences of samples. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification