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Method and apparatus for tracking the position and velocity of airborne instrumentation

  • US 5,347,285 A
  • Filed: 06/15/1992
  • Issued: 09/13/1994
  • Est. Priority Date: 06/15/1992
  • Status: Expired due to Term
First Claim
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1. The method for tracking the position of at least one moving object from a processing station wherein a receiver in each of said moving objects intercepts wideband spread spectrum signals transmitted from a plurality of satellites passing above the horizon, the method comprising the steps of:

  • (a) compressing said wideband signals received from each said satellite into a narrow band by a ratio of at least 100;

    1 without knowledge of the code sequence of said wideband signals;

    (b) removing frequency bias with a reference oscillator having a frequency offset value whereby to produce a narrow baseband;

    (c) forming said narrow baseband so as to be comprised of sine wave superpositions;

    (d) transmitting said baseband to said processing station and producing a digital representation of said sine wave superpositions at said processing station;

    (e) processing said digital representations to produce spectral lines composed of amplitude, frequency and phase values;

    (f) generating a synthetic spectrum including a frequency offset value corresponding to the frequency offset value of said reference oscillator based on approximate location and velocity of said satellites and the moving object and producing digital synthetic spectrum values representative of said spectrum;

    (g) comparing said spectral lines with said digital synthetic spectrum values to determine the identity of each said satellite corresponding to each said spectral line; and

    (h) estimating the reference oscillator frequency offset value in determining the location and velocity of each said moving object.

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