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

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Talbot, Nicholas C.
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): Mull, Fred H.
• Application Number:
  US09/151,372
• Time in Patent Office: 831 Days
• Field of Search: 342/357.17, 342/357.06, 342/357.08, 342/357.09, 342/118, 342/450, 342/357.03, 342/127, 342/458, 33/292, 356/3
• US Class Current: 342/357.27
• CPC Class Codes: G01C 1/02 Theodolites
• 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 19/235 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 including a satellite navigation receiver and a reference oscillator with a reference frequency output that can be related to precision time standards obtained from orbiting navigation-satellite transmissions. Such time standards are output by the satellite navigation receiver and are highly precise. An electronic distance meter (EDM) is included and has an EDM-transmitter for launching an out-bound signal to a distant target, and an EDM-receiver for receiving a reflected signal from the distant target. A phase measurement device is connected to the reference oscillator, and also to both the EDM-transmitter and EDM-receiver. It provides for a measurement of the difference in the number of cycles of the reference frequency between the out-bound signal and the reflected signal. A post-processor is connected, such as by radio link or floppy disk, to receive the measurement of the difference in the number of cycles of the reference frequency and the precision time standards obtained from orbiting navigation-satellite transmissions. Post-processing is then able to relate the corresponding measurements and time standards such that a distance-to-target measurement can ultimately be computed. Therefore routine calibration of the EDM is unnecessary. The measurement of the difference in the number of cycles of the reference frequency is time-tagged and stored for later retrieval to construct a time-ordered log. The precision time standards obtained from the orbiting navigation-satellite transmissions are similarly time-tagged and stored. Thus a series of distance-to-target measurement can be computed according to the order they were originally collected in the field by the EDM, as might be necessary in a legal inquiry.

Claims

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.

2. The surveying instrument of claim 1, further comprising:

a post-processor connected to receive said measurement of said count of said number of cycles of said reference frequency output, and connected to receive said reference 1.00 Hz signal, and able to relate corresponding measurements and time standards such that a distance-to-target measurement can ultimately be computed.

3. The surveying instrument of claim 1, wherein:

said measurement of said count of said number of cycles of said reference frequency output is time-tagged and stored for later retrieval to construct a time-ordered log, and said precision time standards obtained from orbiting navigation-satellite transmissions are similarly time-tagged and stored for later retrieval to further construct said time-ordered log, wherein a series of distance-to-target measurement can be computed according to the order they were originally collected in the field by the EDM.

4. The surveying instrument of claim 1, further comprising:

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 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, 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.

5. The surveying instrument of claim 4, 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.

6. A surveying instrument, comprising:

a broadcast time-standard radio receiver for receiving WwV-like broadcast time-standard transmissions;

a reference oscillator with a reference frequency output that is related to a precision-time standard decoded from a broadcast time-standard transmission demodulated by the radio receiver;

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

a phase measurement device connected to the reference oscillator and to both said EDM-transmitter and EDM-receiver and providing for a measurement of the difference in the number of cycles of said reference frequency between said out-bound signal and said reflected signal.