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Time-tagging electronic distance measurement instrument measurements to serve as legal evidence of calibration

  • US 6,163,294 A
  • Filed: 09/10/1998
  • Issued: 12/19/2000
  • Est. Priority Date: 09/10/1998
  • Status: Expired due to Term
First Claim
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1. A surveying instrument, comprising:

  • a satellite navigation receiver for providing a precise and stable reference 1.00 Hz signal derived from an atomic clock;

    a phase comparator connected to receive said reference 1.00 Hz signal and a reference-oscillator-sample output, and for providing an error-signal output;

    an integrating filter connected to receive said error-signal output, and for driving a static phase error to zero for synchronization with a reference-oscillator-control output;

    a reference oscillator with a reference frequency output that can be related to said atomic clock via said reference 1.00 Hz signal, the phase comparator, the integrating filter, and said reference-oscillator-control output;

    an electronic distance meter (EDM) having an EDM-transmitter for launching an out-bound signal to a distant target and an EDM-receiver for receiving a reflected signal from said distant target; and

    an EDM-phase measurement device connected to the reference oscillator and to both said EDM-transmitter and EDM-receiver and providing for a measurement of a count of a number of cycles of said reference frequency output that are generated between a launch of said out-bound signal and a receipt of said reflected signal;

    wherein, said count of a number of cycles of said reference frequency output is proportional to a target-range distance to said distant target.

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