EDMCAL: Processing EDM Calibrations in NSW Volker Janssen & Tony Watson Survey Infrastructure and Geodesy

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Outline • Current EDM baseline infrastructure in NSW. • EDMCAL software. • UNSW spreadsheet. • Comparison of EDMCAL & UNSW spreadsheet. • Online EDM baseline booking system. • Conclusion.

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Current EDM Baseline Infrastructure

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EDMCAL • Determines dist, AC & SF. • Originally written at UNSW in 1978 & modified at LPI. • Current version created in Dec 2013.

P1 HI P2 HT SD Press Temp

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EDMCAL Processing • Input file checked for #pillars & #obs. • Obs’d SDs (d1) reduced to HDs at height of lowest pillar:

• 2nd veloc corrn ignored (insignificant over such dist).

• Wave path arc to chord (d1d2) reduction also insignificant.

approx. AC input by user

1st veloc: ambient atm conditions

slope wave path chord HD at mean elev

HD at mean elev chord dist at lowest pillar elev

chord dist at lowest pillar elev (d3) arc (d4)

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EDMCAL Processing • STD of obs computed. • Formation & soln of normal matrix. • Output of calibration results

& data snooping. • LS adjustment based on

reduced distances to solve for dist from pillar 1 and AC.

• 1D similarity trafo using calibrated dist as coords to solve for SF.

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EDMCAL Processing • Output summary:

AC SF

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UNSW Spreadsheet

• Developed by B. Harvey in 2006. • Determines AC & SF via LS for

4-8 pillar baselines. • Cyclic error example included.

Note: • Requires rel. humidity as input. • Requires met data to be corrected before input.

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Datasets • 25 LPI baseline verification datasets:

Wollongong: 600 m Kingscliff: 721 m Wagga: 535 m Eglinton: 849 m Dubbo: 765 m Lethbridge Park: 984 m

Instrument: Leica TCA2003 (2000-10) ... 1.0 mm + 1 ppm Leica TS30 (2011+) ... 0.6 mm + 1 ppm

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Comparison: AC ~0.3 mm ~0.3 mm <0.8 mm 0.1 mm

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Comparison: SF ~0.5 ppm ~0.5 ppm ~1.5 ppm ~0.5 ppm

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Comparison: Distances • Diff in distances from pillar 1 in mm (AC & SF applied):

High level of agreement. Differences negligible for most

EDM calibrations in practice.

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Online Baseline Booking System

• Automatic booking confirmation email. • User to carry printout while on site. • Efficient use of baselines. • More informed decision making at LPI.

http://lpi.nsw.gov.au/edmbooking

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Conclusion • LPI continues to improve EDM baseline infrastructure. • EDMCAL & UNSW spreadsheet provide comparable

EDM calibration results (AC & SF). • Important to use latest verification data as ‘known’ inter-

pillar distances to obtain reliable calibration results. • Standard EDM calibration in prism mode does

not calibrate reflectorless EDM laser. • Beware of dist extrapolation.

• EDM baseline booking system please use it!

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