Patent ID: 6163294
Filing Date: 2000-12-19
Classification: G01C,G01S

Abstract:
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; andan 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.