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APPARATUS AND METHOD FOR NETWORK LEVEL SYNCHRONIZATION IN MULTIPLE LOW EARTH ORBIT (LEO) SATELLITE COMMUNICATIONS SYSTEMS

  • US 20150270890A1
  • Filed: 03/19/2015
  • Published: 09/24/2015
  • Est. Priority Date: 03/19/2014
  • Status: Active Grant
First Claim
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1. A method for synchronization in a satellite communications system comprising one or more satellites, wherein transmissions to each of at least a one of the satellites occur via a respective communications link with the satellite, the method comprising:

  • determining a system timing reference based on a global positioning system (GPS) timing reference and determining a system frequency reference;

    periodically determining a timing delay factor and a frequency Doppler factor for each of the satellite(s) to which the transmissions occur based on respective satellite ephemeris data reflecting velocity and direction vector motion of the satellite;

    dynamically adjusting the system timing reference based on the timing delay factor, and dynamically adjusting the system frequency reference based on the frequency Doppler factor, for each of the satellite(s) to which the transmissions occur; and

    synchronizing timing and frequency of the transmissions to each of the satellites based on the respective adjusted system timing reference and the respective adjusted system frequency reference.

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