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Apparatus and method for range detection using the analytic signal identified from the received signal

  • US 4,837,578 A
  • Filed: 10/29/1981
  • Issued: 06/06/1989
  • Est. Priority Date: 10/29/1981
  • Status: Expired due to Fees
First Claim
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1. A pulse-echo or passive listening response system for indentifying one or more closely spaced interfaces of a target wherein an unprocessed signal is received by the system'"'"'s receiver either after a pulsed signal from the system has struck the target and has been reflected by one or more of the target'"'"'s interfaces, or by passive reception, wherein the response system is characterized by the received signal being a multi-frequency signal which occupies a given bandwidth, which received signal is then processed by said system to identify a particular portion of the processed signal which is useful for locating the target interface (s), the system comprising:

  • (1) a signal receiving means at the system'"'"'s receiver for receiving said unprocessed signal, which received signal contains information proportional to the rate of arrival of energy at the receiver and is indicative of the location of said target'"'"'s interface (s);

    (2) a signal processing means, connected to said signal receiving means, for processing said received unprocessed signal by a constant phase-shift while leaving the relative amplitude of all phase-shifted frequency components of the multifrequency signal unchanged and to produce therefrom a pair of signals which together represent the complete complex analytic signal from which the location of the target interface(s) can be identified;

    said signal processing means comprising;

    (a) a signal separation means connected to receive said unprocessed signal for separating said received signal into two signals in two channels;

    (b) phase shifting means connected to receive both of said separated signals in said channels for subjecting the signal in each channel to a constant phase shift (i.e., a phase shift which is the same for all frequency components in that channel), the constant phase shift differing between the two channels by 90 degrees and therefore resulting in the processed signals of the two channels being Hilbert transforms of each other; and

    (3) means forming a representation of said analytic signal from said processed signal in order to identify said particular portion from the representation whereby the target interface(S) may be located.

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