×

Satellite receiver system having doppler frequency shift tracking

  • US 5,432,521 A
  • Filed: 01/14/1994
  • Issued: 07/11/1995
  • Est. Priority Date: 01/14/1994
  • Status: Expired due to Term
First Claim
Patent Images

1. A satellite receiver system that provides acquisition and frequency tracking of a Doppler-shifted radio signal received from an orbiting satellite, said satellite receiver system comprising:

  • a Costas phase-lock loop that receives the radio signal and provides an error signal at an error signal output for controlling a conversion frequency generated by a voltage controlled oscillator;

    said voltage controlled oscillator coupled to said Costas phase-lock loop, wherein said voltage controlled oscillator generates the conversion frequency for down-converting the radio signal in said Costas phase-lock loop, and wherein said voltage controlled oscillator comprises a programmable frequency synthesizer that can be programmed to generate a plurality of frequencies selectable in steps; and

    .a Doppler frequency acquisition and tracking element coupled to said voltage controlled oscillator, wherein said Doppler frequency acquisition and tracking element adjusts the conversion frequency to compensate for a Doppler frequency shift occurring in the radio signal due to orbital motion of said orbiting satellite, and wherein said Doppler frequency acquisition and tracking element comprises;

    a coarse adjustment element coupled to said programmable frequency synthesizer for selecting a suitable one of the plurality of frequencies to provide a coarse adjustment of the conversion frequency to compensate for the Doppler frequency shift; and

    a fine adjustment element coupled to said error signal output for generating a fine adjustment signal at an adjusted error signal output for providing a fine adjustment of the conversion frequency to compensate for the Doppler frequency shift.

View all claims
  • 4 Assignments
Timeline View
Assignment View
    ×
    ×