Patent ID: 6774839
Filing Date: 2004-08-10
Classification: G01C,G01S

Abstract:
A method of operating an electronic distance meter (EDM) subsystem of a total station, comprising the steps of:substantially continuously receiving from at least one orbiting GPS satellite radio signals with timing information controlled by an atomic clock on board said satellite; constantly providing a global positioning system (GPS) receiver with a navigation computer for maintaining tracking of said radio signals and for deriving precise timing information from said radio signals; persistently providing a local reference oscillator with a timing signal based on said derived precise time information; permanently providing the EDM subsystem with a signal from said oscillator wherein said EDM subsystem sends an outbound laser signal to a distant target and receives an inbound signal reflected by said target; measuring a difference between said out-bound signal and said resulting in-bound signal reflected from said distant surveyor target to determine the line-of-sight distance to said target; wherein, the step of measuring provides a signal time-of-flight measurement with an accuracy derived from said precise timing information in said timing signal and from which a similarly accurate distance-to-target is computed.