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Frequency counting apparatus and method

  • US 4,786,861 A
  • Filed: 09/01/1987
  • Issued: 11/22/1988
  • Est. Priority Date: 09/01/1987
  • Status: Expired due to Term
First Claim
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1. A device for determining the phase of a periodic reference signal at a predetermined time, the device comprising:

  • charge storage means;

    current source means;

    first switch means connected between the current source means and a reference potential;

    second switch means connected between the current source means and the charge storage means; and

    control means connected to receive the reference signal and a signal representing the predetermined time, the control means including means for sensing a periodic characteristic of the reference signal, means for causing the current source means to be disconnected from the reference potential at the predetermined time, means for causing the current source means to be disconnected from the charge storage means upon the occurrence of said characteristic after the predetermined time, and means for measuring the voltage on the charge storage means after the occurrence of said characteristic and for producing therefrom a phase signal an representing the phase of the reference signal at the predetermined time.

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