EDMCAL: Processing EDM calibrations in NSW
The Surveyor General of New South Wales is a verifying authority under the National Measurement Act 1960 and responsible for ensuring that surveyors use verified measuring equipment. According to the Surveying and Spatial Information Regulation 2012, surveyors are required to verify their Electronic Distance Measurement (EDM) equipment in relation to an Australian standard of measurement of length at least once a year. For this purpose, Land and Property Information (LPI) provides and maintains several EDM baselines across the state. LPI is currently in the process of improving this infrastructure by upgrading existing baselines and building new baselines for the calibration of EDM instruments. This paper presents the current status of EDM baseline infrastructure in NSW and outlines the data processing performed by LPI in regards to EDM calibrations. The EDMCAL software currently employed by LPI is described and compared to a spreadsheet calculation generated by the University of New South Wales. Finally, LPI’s new online EDM baseline booking system is introduced. This online system should now be used by surveyors to book access to all EDM baselines in NSW in order to allow efficient and effective use of existing and future baseline infrastructure.
Electronic Distance Measurement: An Introduction
1 History.- 2 Physical Laws and Units Related to EDM.- 2.1 Definitions.- 2.2 Frequency Spectrum.- 2.3 Velocity of Light in a Vacuum.- 2.4 Units and Their Definitions.- 2.4.1 Second of Time.- 2.4.2 Metre.- 2.4.3 Kelvin.- 2.4.4 Other Units in EDM.- 3 Principles and Applications of EDM.- 3.1 Pulse Method.- 3.1.1 Principle of the Pulse Method.- 3.1.2 Applications of the Pulse Method.- 3.2 Phase Difference Method.- 3.2.1 Phase Difference Between Transmitted and Received Signal.- 3.2.2 Phase Difference Between Two Received Signals.- 3.3 Doppler Methods.- 3.4 Interferometry.- 3.4.1 Principle of a Michelson Interferometer.- 3.4.2 Principle of Operation of the HP 5526 A Laser Measurement System.- 3.4.3 Vaisala Interference Comparator.- 4 Basic Working Principles of Electronic Distance Meters.- 4.1 Electro-Optical Instruments.- 4.1.1 Principle and Components.- 4.1.2 Methods of Modulation and Demodulation of Light and NIR Waves.- 4.1.3 Methods of Phase Measurement.- 4.2 Microwave Instruments.- 4.2.1 Introduction.- 4.2.2 Working Principle and Components.- 4.2.3 Effects of Reflections in Microwave EDM (Multipath).- 5 Propagation of Electromagnetic Waves Through the Atmosphere.- 5.1 Atmospheric Transmittance.- 5.2 Range of EDM Instruments.- 5.3 Phase Refractive Index.- 5.4 Group Refractive Index of Light and NIR Waves for Standard Conditions.- 5.4.1 First Example.- 5.4.2 Second Example.- 5.4.3 Third Example.- 5.4.4 Error Analysis.- 5.5 Group Refractive Index of Light and NIR Waves at Ambient Conditions.- 5.5.1 Error Analysis.- 5.5.2 Omission of Humidity.- 5.6 Refractive Index of Microwaves.- 5.6.1 Error Propagation.- 5.7 Coefficient of Refraction.- 5.8 Measurement of Atmospheric Parameters.- 5.8.1 Measurement of Atmospheric Pressure.- 5.8.2 Measurement of Atmospheric Temperature.- 5.8.3 Measurement of Atmospheric Humidity.- 5.8.4 Computation of Partial Water Vapour Pressure from Psychrometer Measurements.- 5.8.5 Computation of Partial Water Vapour Pressure from Relative Humidity.- 5.9 Determination of the Refractive Index.- 5.9.1 Normal Procedures.- 5.9.2 Limitations of Normal Procedures.- 5.9.3 Special Procedures.- 6 Velocity Corrections to Measured Distances.- 6.1 Reference Refractive Index.- 6.2 First Velocity Correction.- 6.2.1 Derivation of First Velocity Correction for the Infrared Distance Meter Kern DM501.- 6.2.2 Derivation of First Velocity Correction for the Infrared Distance Meter Pentax PM-81.- 6.2.3 Derivation of First Velocity Correction for the Pulse Distance Meter Distomat Wild DI3000.- 6.2.4 Derivation of First Velocity Correction for the Microwave Distance Meter Siemens-Albis SIAL MD60.- 6.2.5 Derivation of First Velocity Correction for the Microwave Distance Meter Tellurometer CA1000.- 6.3 Real-Time Application of First Velocity Correction by EDM Instrument.- 6.4 Second Velocity Correction.- 6.5 Refined Method of Reduction of Measured Distance to Wave Path Chord.- 7 Geometrical Corrections.- 7.1 Reduction to the Spheroid Using Station Heights.- 7.1.1 First Method: Step-by-Step Solution.- 7.1.2 Second Method: Closed Solution.- 7.1.3 Analysis of Errors.- 7.2 Reduction to the Spheroid, Using Measured Zenith Angles.- 7.2.1 Introduction.- 7.2.2 Reduction to the Spheroid: Closed Solution.- 7.2.3 Reduction to the Spheroid: Step-by-Step Solution.- 7.2.4 Analysis of Errors.- 8 Miscellaneous Corrections, Computations and Numerical Examples.- 8.1 Correction of Measured Distance to Zenith Angle Ray Path.- 8.1.1 Correction for Unequal Heights of Theodolite, EDM Instrument, Target and Reflector.- 8.1.2 Correction for Theodolite-Mounted EDM Instruments.- 8.1.3 Correction for Telescope-Mounted EDM Instruments.- 8.2 Eye-to-Object Corrections for Zenith Angles and Distances.- 8.2.1 Eye-to-Object Correction for Zenith Angles.- 8.2.2 Eye-to-Object Correction for Distances.- 8.2.3 Numerical Example.- 8.3 Height Difference from Measured Zenith Angle(s) and Slope Distance.- 8.3.1 Single Zenith Angle Measurement.- 8.3.2 Reciprocal Zenith Angle Measurements.- 8.4 Determination of the Coefficient of Refraction from Reciprocal Zenith Angle Measurements.- 8.4.1 Derivation of the Equation for the Coefficient of Refraction.- 8.4.2 Error Analysis.- 8.5 Reduction to Centre of Distances.- 8.5.1 Angles and Distances Measured at Satellite Station.- 8.5.2 Angles Measured at Centre Station, Distances at Satellite Station.- 8.6 Numerical Examples.- 8.6.1 Reduction of a Long Distance.- 8.6.2 Reduction of a Short Distance.- 9 Electro-Optical Distance Meters.- 9.1 Classification of Electro-Optical Distance Meters.- 9.1.1 Classification According to Range.- 9.1.2 Classification According to Accuracy.- 9.1.3 Classification According to the Degree of Integration with Theodolites.- 9.1.4 Special Features of Modern Short Range Distance Meters.- 9.2 Design of Some Electro-Optical Distance Meters.- 9.2.1 Kern DM500.- 9.2.2 Topcon ET-1.- 9.2.3 Distomat Wild DI3000.- 9.2.4 Kern Mekometer ME5000.- 10 Reflectors.- 10.1 Introduction.- 10.2 Glass Prism Reflectors.- 10.2.1 Accuracy of Reflectors.- 10.2.2 Shape and Size of Reflectors.- 10.2.3 Phase and Group Refractive Index in Glass.- 10.2.4 Reflector Constant.- 10.2.5 Effects of Errors of Reflector Alignment.- 10.2.6 Temperature Effects.- 10.2.7 Care of Reflectors.- 11 Batteries and Other Power Sources.- 11.1 Review of Power Sources.- 11.2 Batteries Used in EDM.- 11.2.1 Primary Batteries.- 11.2.2 Secondary Batteries.- 11.3 Sealed Nickel-Cadmium Batteries.- 11.3.1 Construction and Principle.- 11.3.2 Discharge Characteristics.- 11.3.3 Charge Characteristics.- 11.3.4 Capacity and Life of Battery.- 12 Errors of Electro-Optical Distance Meters.- 12.1 Additive Constant.- 12.2 Short Periodic Errors.- 12.2.1 Electrical or Optical Crosstalk Errors.- 12.2.2 Analogue Phase Measurement Errors.- 12.2.3 Multipath Errors.- 12.2.4 Experimental Results.- 12.2.5 Reduction of Short Periodic Errors.- 12.3 Scale Errors.- 12.3.1 Oscillator Errors.- 12.3.2 Diode Errors.- 12.4 Non-Linear Distance-Dependent Errors.- 12.5 Summary and Mathematical Model of Errors.- 13 Calibration of Electro-Optical Distance Meters.- 13.1 Introduction.- 13.1.1 Reasons for Calibration.- 13.1.2 Concept of Calibration.- 13.2 Calibration on EDM Baselines.- 13.2.1 Geometric Design of EDM Baselines.- 13.2.2 Physical Design.- 13.2.3 Measurements on EDM Baselines.- 13.2.4 Analysis of Baseline Measurements.- 13.2.5 Determination of Baseline Lengths.- 13.3 Calibration on Cyclic Error Testlines.- 13.3.1 Design of and Measurements on Cyclic Error Testlines.- 13.3.2 Semi-Graphic Determination of Short Periodic Errors.- 13.3.3 Analytical Determination of Short Periodic Errors.- 13.4 Calibration of Modulation Frequency.- 13.4.1 Frequency Measuring Techniques.- 13.4.2 Calibration of Ageing and Warm-Up Effects.- 13.4.3 Frequency Versus Temperature Characteristic.- 13.5 Accuracy Specifications of EDM Instruments.- Appendices.- A. First Velocity Correction for Precise Electro-Optical Distance Measurement.- B. Tables of Saturation Water Vapour Pressures.- C. Parameters of the ICAO Standard Atmosphere.- D. Data of a Selection of Electro-Optical Distance Meters as Required for the Derivation of the First Velocity Correction and for Calibration Purposes.- E. Technical Data of a Selection of Short Range Distance Meters.- F. Technical Data of a Selection of Pulse Distance Meters.- G. Technical Data of a Selection of Long Range Distance Meters.- H. Critical Dimensions of a Selection of Reflectors.- References.
Radiotracking large wilderness mammals: integration of GPS and Argos technology
We tested 30 prototype global positioning system (GPS) radiocollars on brown bears (Ursus arctos) over a 3-year period on the Kenai Peninsula, Alaska. Collars were of 2 design types: GPS units with an Argos (Argos Data collection and Location System) satellite uplink (n = 19) and GPS units where the data were stored on board (n = 10) for retrieval at a later date. All units also contained a conventional VHF (very high frequency) transmitter and weighed 1.7 kg. GPS-Argos units obtained 10-82% of expected GPS fixes, and fix rate declined significantly (P < 0.05) with time after deployment. Argos uplink success (proportion of successful transmissions of stored data) was linearly related to GPS fix rate (r = 0.91, P < 0.001). Storeon-board units obtained significantly more successful fixes when compared with the GPS-Argos units (t = -4.009, P < 0.001). Fix success rate for deployed store-on-board collars ranged from 13-96%; because of the increased number of attempted fixes per day, these collars obtained fixes on 97% of days deployed. Accuracy of the GPS units was less than predicted by the NAVSTAR GPS technology using the course acquisition code. Reduced accuracy was likely a result of the proportion of 2-dimensional versus 3-dimensional fixes obtained, although we could not determine this statistic from recorded data. Increased overstory closure was the only variable measured that partially explained the reduced likelihood of a successful fix. Stem density, stem diameter, and overstory height measured within 3 m of the collar did not affect fix success. GPS fix success rates for collars attached to bears varied more and were lower than fix rates for stationary collars placed in various vegetation types, suggesting that the bear, terrain, and movement all influence both fix and uplink success rate. Application of this new technology to grizzly and brown bear research and comparisons to studies with moose (Alces alces) are discussed.