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Method for processing transmitted and reflected signals for removing unwanted signals and noise from wanted signals

  • US 5,144,313 A
  • Filed: 04/24/1991
  • Issued: 09/01/1992
  • Est. Priority Date: 10/27/1988
  • Status: Expired due to Term
First Claim
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1. A method in an identification system, wherein a radar signal is transmitted from a transmitter, said signal is arranged to be received by a mobile, bit-coded identification transponder which returns a coded signal that is received by a receiver;

  • the received coded signals are processed in order to remove unwanted signals and noise from the reflected, coded and wanted signals, wherein a pseudo-random bit sequence is used, characterized by comprising the steps of;

    phase modulating the radar signal with a pseudo-random bit sequence,dividing the modulated radar signal in time slots, forming a pulse train, which is transmitted,passively reflecting from the transponder the transmitted pulse train signal, said transponder being encoded with binary coded information, and the reflected pulse train is modulated with the binary code of the transponder,said receiver receiving and demodulating the reflected, coded pulse train signal using the same pseudo-random bit sequence and same time slots as were used at transmission, both of which being time delayed in order to demodulate the reflected pulse train signal to store, average and process the identification code from the bit-coded transponder for individual recognition.

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