Cellphone stabilization of EDM instruments

• US 20050124287A1
• Filed: 12/09/2003
• Published: 06/09/2005
• Est. Priority Date: 12/09/2003
• Status: Abandoned Application

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Janky, James M.
• Application Number:
  US10/732,124
• Publication Number:
  US 20050124287A1
• Time in Patent Office: Days
• US Class Current: 455/2.10
• CPC Class Codes: G01C 15/002 Active optical surveying means optical plumbing G01C15/105
• CPC Class Codes: G01S 13/36 with phase comparison between the received signal and the contemporaneously transmitted signal
• CPC Class Codes: G01S 17/36 with phase comparison between the received signal and the contemporaneously transmitted signal
• CPC Class Codes: G01S 7/4004 of parts of a radar system
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating

Abstract

An electro-optical total station system includes an EDM reference oscillator trained and disciplined by reference frequency standard information derived from local cellular telephone base station transmission carriers.

Claims

1. A surveying instrument, comprising:

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;

a phase measurement device connected to the reference oscillator and to both said EDM transmitter and EDM receiver and providing for a time measurement of the difference between said out-bound signal and said reflected signal from which a distance-to-target measurement can be computed;

a reference oscillator that provides a timing basis for the phase measurement device and that can be trained by an external precision frequency standard; and

a cellphone connected to receive cellular telephone base station transmissions and to extract there from frequency stabilization information for use by the reference oscillator.

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

a theodolite with a telescope connected to the EDM and an angle measurement instrument mechanism that together can determine an elevation and an azimuth to said distant target.

3. The surveying instrument of claim 1, wherein:

the cellphone is a receiver only and is not necessarily a commercial subscriber to any service provided by said cellular telephone base station.

4. The surveying instrument of claim 1, wherein said cellphone and cellular base station operate according to the GSM industry standard.

5. A method of automatically calibrating an electronic distance meter, comprising the steps of:

deriving precise time information from externally generated cellular telephone base station radio transmissions;

correcting a local reference clock for an EDM with a signal obtained in the step of deriving; and

measuring a time phase difference between an out-bound signal and an in-bound signal reflected by a distant surveyor target using a reference time-base obtained from said local reference clock.

6. The method of claim 5, wherein:

the step of deriving includes the use of a cellphone receiver.

7. The method of claim 6, wherein:

the step of measuring said time phase difference includes observations of a plurality of phase differences observed by said electronic distance meter at a plurality of out-bound and in-bound signal frequencies.

8. The method of claim 6, further comprising the steps of:

automatically providing a target range measurement to a user at said distance target by said electronic distance meter; and

automatically providing a vector angle measurement to said user to said distant target obtained by a theodolite.

9. A surveying instrument, comprising:

a satellite navigation receiver;

a cellular telephone base station having its transmissions frequency referenced from signals obtained from the satellite navigation receiver;

a cellular telephone receiver able to provide frequency reference information based on signal transmissions it receives from the cellular telephone base station;

a reference oscillator with a frequency offset that is controlled by information provided from the cellular telephone receiver;

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; 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 time between said out-bound signal and said reflected signal from which a distance-to-target measurement can be computed.

10. A surveying instrument, comprising:

a satellite navigation receiver;

a cellular telephone base station having its transmissions frequency referenced from signals obtained from the satellite navigation receiver;

a cellular telephone receiver able to provide frequency reference information based on signal transmissions it receives from the cellular telephone base station;

a reference oscillator with a frequency offset that is controlled by information provided from the cellular telephone receiver, and wherein a determination of said frequency offset is used later in software to correct for frequency errors;

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; and

a phase measurement device connected to the reference oscillator and providing for a distance-to-target measurement computed from said determination of said frequency offset in software to correct for errors;

wherein, a calibration signal provided to the phase measurement device enables an automatic and continuous calibration in software of distance-to-target measurements.