Self-calibrating electronic distance measurement instrument

• US 6,670,913 B1
• Filed: 09/29/1998
• Issued: 12/30/2003
• Est. Priority Date: 07/24/1998
• Status: Expired due to Term

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: McCusker, Michael V., Talbot, Nicholas C.
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US09/163,286
• Time in Patent Office: 1,918 Days
• Field of Search: 342/127, 342/134, 342/174, 342/357.17, 342/357.14, 342/357.12, 342/357.06
• US Class Current: 342/357.31
• CPC Class Codes: G01C 15/002 Active optical surveying means optical plumbing G01C15/105
• CPC Class Codes: G01S 17/86 Combinations of lidar systems with systems other than lidar, radar or sonar, e.g. with direction finders
• CPC Class Codes: G01S 19/14 specially adapted for specific applications
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• CPC Class Codes: G01S 19/37 Hardware or software details of the signal processing chain
• CPC Class Codes: G01S 7/4021 of receivers
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating

Abstract

A combined satellite positioning and electro-optical total station system includes a reference oscillator that provides local oscillator signals for a satellite navigation receiver and a precision frequency source for use by an electronic distance meter. When the satellite navigation receiver is locked onto and tracking orbiting navigation satellites, the highly precise cesium-rubidium clocks in the navigation satellite system can be used as standards to control the reference oscillator in the combined satellite positioning and electro-optical total station system. Baseline measurements made by the electronic distance meter are therefore not subject to mis-calibrations and drift as long as the satellite navigation receiver is locked onto and tracking the orbiting navigation satellites.

Claims

1. A surveying instrument comprising:

a satellite navigation receiver with a pulse-per-second output derived from an atomic time standard used in a related orbiting navigation satellite;

a reference oscillator controlled by said pulse-per-second output and providing a reference frequency with a timing accuracy directly related to a timing accuracy of said atomic time standard;

an electronic distance meter 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;

a theodolite with a telescope connected to an angle measurement instrument mechanism that together can automatically locate said distant target and determine an elevation and an azimuth to said distant target;

a phase measurement device connected to the reference oscillator, said EDM transmitter and said EDM receiver, and providing for a time measurement of the difference between said out-bound signal and said reflected signal using said reference frequency; and

a navigation computer disposed within the satellite navigation receiver and connected to receive a target-position seed value related to said distant target; and

a servo actuator connected to mechanically manipulate the theodolite in azimuth and elevation;

wherein, a distance-to-target measurement is computed with an accuracy dependent on said timing accuracy of said atomic time standard;

wherein, the navigation computer is connected to the servo actuator and provides a signal that will preposition the theodolite; and

wherein, the phase measurement device automatically provides a target range measurement to a user at said distance target; and

the theodolite automatically provides a vector angle measurement to said user to said distant target.

2. A surveying instrument comprising:

a satellite navigation receiver with a pulse-per-second output derived from an atomic time standard used in a related orbiting navigation satellite;

a reference oscillator controlled by said pulse-per-second output and providing a reference frequency with a timing accuracy directly related to a timing accuracy of said atomic time standard;

an electronic distance meter 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;

a phase measurement device connected to the reference oscillator, said EDM transmitter and said EDM receiver, and providing for a time measurement of the difference between said out-bound signal and said reflected signal using said reference frequency; and

wherein, a distance-to-target measurement is computed with an accuracy dependent on said timing accuracy of said atomic time standard; and

wherein the satellite navigation receiver is remotely located and communicates via a radio link to the reference oscillator to be adjusted and maintained by a plurality of navigation satellite transmissions received by the satellite navigation receiver.