Monopulse FM-CW radar system with improved axis stability

  • US 4,656,480 A
  • Filed: 11/15/1984
  • Issued: 04/07/1987
  • Est. Priority Date: 11/23/1983
  • Status: Expired due to Fees
First Claim
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1. A monopulse FM-CW radar system comprising a first transmitting antenna and a transmitter coupled thereto for effecting transmission of a radar signal toward a target, first and second spaced-apart receiving antennas for producing respective echo signals in response to reflections of the radar signal from the target, first and second mixers each coupled to the transmitter and to a respective one of the receiving antennas for producing respective first and second beat signals, and signal processing means coupled to the first and second mixers for producing from the first and second beat signals respective first and second summation signals representing target information, characterized in that said radar system further comprises:

  • (a) simulated-echo producing means for producing a simulated target echo signal representing a target at a predetermined range which is outside a selected surveillance range interval of the radar system;

    (b) a second transmitting antenna, coupled to the simulated-echo producing means and located at a predetermined position with respect to the receiving antennas for transmitting the simulated target echo signal toward the receiving antennas;

    (c) range gating means coupled to the signal processing means for distinguishing between components of the first summation signal representing a target in the selected surveillance range interval and the simulated target at the predetermined range;

    (d) phase comparison means coupled to the range gating means and to the signal processing means for producing a first phase signal representing the phase difference between the first summation signal components representing the target in the selected surveillance range and corresponding components of the second summation signal, and for producing a second phase signal representing the phase difference between the first summation signal components representing the simulated target and corresponding components of the second summation signal, said latter phase difference representing a phase error of the system;

    (e) bearing detecting means coupled to the phase comparison means for producing from the first phase signal a target bearing signal representing the bearing of the target in the selected surveillance range; and

    (f) phase correction means coupled to the phase comparison means and responsive to the second phase signal to correct for the system phase error, thereby substantially eliminating the affect of said error from the target bearing signal.

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