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Processing of signals to provide a delay Doppler map

  • US 9,465,115 B2
  • Filed: 06/14/2013
  • Issued: 10/11/2016
  • Est. Priority Date: 06/15/2012
  • Status: Expired due to Fees
First Claim
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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:

  • 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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