edmcal: processing edm calibrations in nswlocate’14, canberra, 7– 9 april 2014 14 conclusion •...
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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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