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Radar tank gauge

  • US 4,847,623 A
  • Filed: 01/20/1988
  • Issued: 07/11/1989
  • Est. Priority Date: 02/19/1986
  • Status: Expired due to Fees
First Claim
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1. In a radar tank gauge having a focused antenna mounted in close proximity to the surface of the tank contents, for generating a continuous wave swept frequency radio frequency signal transmitted to said surface, including simultaneous measurement of a signal reflected from said surface, and generating a difference signal representative of the distance between the antenna and tank level, the improvement comprising:

  • means generating an antenna radiated signal of predetermined frequency and duration;

    means receiving a reflected signal from said surface;

    means deriving a signal representative of the difference between said transmitted and reflected signal said difference signal including the entire frequency range of said reflected signal;

    means measuring frequency and amplitude of said difference signal said measurement in time phase synchronization with said transmitted signal;

    means storing groups of said measured difference signals, said groups having a predetermined time duration and representative of the entire frequency range of said measured difference signal;

    means transforming said difference signal groups from the time to frequency domain, thereby generating a power spectral density representation of each said synchronously measured difference signal group;

    means determining the frequency centroid of said transformed signal whereby a carrier frequency closely representative of the true difference frequency is identified.

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