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System for direct acquisition of received signals

  • US 7,224,721 B2
  • Filed: 10/11/2002
  • Issued: 05/29/2007
  • Est. Priority Date: 10/11/2002
  • Status: Active Grant
First Claim
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1. A signal processing architecture (SPA) for acquiring a received direct sequence spread spectrum (DSSS) signal, comprising:

  • means for sampling the received DSSS signal at a predetermined sampling rate;

    means for cross-correlating, in a parallel fashion, time and frequency shifted versions of the sampled DSSS signal with samples of a locally generated replica of a pseudo random noise (PN) code sequence used to spread the spectrum of the received DSSS signal in order to obtain cross-correlation values;

    a Doppler compensator coupled to the cross-correlating means for processing the obtained cross-correlation values in order to compensate for misalignment effects resulting from time-companding of the received DSSS signal;

    an integrator for non-coherently integrating groups of the compensated cross-correlation values representing corresponding time and frequency offsets of different time segments of the received signal and replica code sequence in order to obtain correlation metrics; and

    a detector for detecting whether a sum of the magnitudes of the correlation metrics exceeds a detection threshold,wherein the cross-correlating means further comprises;

    a bank of code matched filters for computing short-time correlations (STCs) entirely in parallel; and

    means for calculating the cross-correlation values utilizing discrete-time Fourier analysis of the computed STCs.

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