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Autonomous satellite navigation system

  • US 6,608,589 B1
  • Filed: 04/21/1999
  • Issued: 08/19/2003
  • Est. Priority Date: 04/21/1999
  • Status: Expired due to Term
First Claim
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1. A satellite navigation system, comprising:

  • a radio frequency receiver incorporating a plurality of channels for concurrently processing code containing signals received from a plurality of global positioning system satellites, wherein said radio frequency receiver comprises;

    a plurality of antennas;

    a plurality of preamplifiers, driven by each one of said plurality of antennas; and

    a separate downconverter for each one of said preamplifiers for processing the amplified signals produced thereby, wherein each of said downconverters comprises;

    a phase locked loop frequency synthesizer;

    a reference oscillator for driving said phase locked loop frequency synthesizer;

    a mixing means for combining an output of said phase locked loop frequency synthesizer with an output of said preamplifier;

    an intermediate frequency band pass filter for processing the output of said mixing means; and

    a quantizer for producing a pair of complementary signals from an output of said intermediate frequency band pass filter;

    a microprocessor for executing software which manipulates data processed by said plurality of channels according to an extended Kalman filter to autonomously generate estimates of position, velocity, time and earth-sun vector data;

    position-based event notifications and predictions; and

    orbit determinations; and

    an application specific integrated circuit for tracking said code containing GPS signals, wherein said application specific integrated circuit comprises;

    a latch circuit for sampling said pair of complementary signals from two of said downconverters and producing therefrom a pair of complementary quadrature signal samples and a pair of complementary non-quadrature signal samples;

    a plurality of tracker channels, wherein said tracker channels each comprises;

    a plurality of accumulators;

    a separate latch register for outputting the contents of each of said accumulators for outputting the contents thereof;

    a coarse acquisition code generator; and

    a differential mixer for combining said signal samples with a code created by said course acquisition code generator to lock the phase and frequency of said code carried by said signal samples with said code created by said course acquisition code generator; and

    a data router for distributing each of said complimentary signal sample pairs to a different one of said tracker channels;

    wherein the application specific integrated circuit produces tracking data for each of said global positioning system satellites from said amplified signals processed by said downconverters;

    wherein the radio frequency receiver, the microprocessor, and the application specific integrated circuit are onboard the satellite.

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