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Monopulse angle determination

  • US 8,269,665 B1
  • Filed: 01/29/2010
  • Issued: 09/18/2012
  • Est. Priority Date: 01/29/2010
  • Status: Active Grant
First Claim
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1. A radar system, comprising:

  • a beam direction controller;

    a transmitter for transmitting subpulses at nominal frequencies F with modulation which is capable of resulting in an actual average frequency different from frequencies F;

    a monopulse receiver for receiving signals from a target, and for generating rho (ρ

    ) signals, each of which rho signals is a real component of one of eight complex monopulse ratios, four of which represent a Δ

    α

    angle and the other four of which represent a Δ

    β

    angle;

    a polynomial processor coupled to said receiver, for producing uncorrected cosine differences of angular offsets of a target from a commanded beam pointing direction or angle cosines
    cos(α

    0

    α

    )−

    cos α

    0
    cos(β

    0

    β

    )−

    cos β

    0;

    a multiplicative correction processor for multiplying said uncorrected cosine differences by a factor including (a) a frequency at which a polynomial is determined and (b) an actual average frequency of a particular subpulse, to thereby generate multiplied cosine differences for each subpulse;

    a summing correction processor coupled to said multiplicative correction processor for adding to said multiplied cosine differences a correction term for compensating for apparent movement of the target arising in a particular direction from beam movement at each subpulse, to thereby generate a plurality of multiplicatively and additively compensated angles or angle cosine difference signals; and

    an averaging arrangement coupled to said summing correction processor for averaging said angles or angle cosine difference signals over all subpulses of a pulse to thereby produce averaged angular difference signals representative of a location of the target,whereinρ

    =a real component of one of eight complex monopulse ratios;

    Δ

    α

    =difference of half-antenna outputs corresponding to an α

    direction;

    Δ

    β

    =difference of half-antenna outputs corresponding to a β

    direction;

    α

    0=direction angle measured from a positive X axis to a beam direction line;

    β

    0=direction anile measured from a positive Z axis to the beam direction line;

    δ

    α

    =departure angle from beam direction angle α

    0; and

    δ

    β

    =departure angle from beam direction angle β

    0.

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