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Method and system for restarting a reference clock of a mobile station after a sleep period with a zero mean time error

  • US 6,725,067 B1
  • Filed: 03/24/2000
  • Issued: 04/20/2004
  • Est. Priority Date: 03/24/2000
  • Status: Expired due to Fees
First Claim
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1. A method for restarting a high frequency reference clock of a mobile station after a sleep period with a zero mean time error, wherein during most of the sleep period the high frequency, reference clock is deactivated and a low frequency low power sleep clock is utilized instead, the method comprising:

  • calibrating the sleep clock with respect to the reference clock during a specified calibration period including counting a first number of reference clock cycles from the beginning of the specified calibration period until the first rising edge of a first sleep clock cycle, waiting for a predetermined number of sleep clock cycles to occur, and counting a second number of reference clock cycles from the rising edge of a last sleep clock cycle until the end of the calibration period;

    adding the first number of reference clock cycles to the second number of reference clock cycles to calculate an actual number of reference clock cycles;

    calculating an expected number of reference clock cycles for the specific calibration period;

    determining a calibration error between the reference clock and the sleep clock by subtracting the expected number of reference clock cycles from the actual number of reference clock cycles;

    determining a wake-up time error based upon the calibration error; and

    utilizing the wake-up time error to compensate for the error of the sleep clock such that the reference clock restarts at the end of the sleep period with a zero mean time error.

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