GPH 492/692

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GPH 492/692 GPS/Survey Team Results Spring 2010 (to support gravity survey) Jay Goldfarb Courtney Murphy Garry Richardson Jason Henderson

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GPH 492/692. GPS/Survey Team Results Spring 2010 (to support gravity survey). Jay Goldfarb Courtney Murphy Garry Richardson Jason Henderson. Summary of Methods. Trigonometric leveling (total station) for upper Hidden Valley gravity points (with one GPS elevation) - PowerPoint PPT Presentation

Transcript of GPH 492/692

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GPH 492/692GPS/Survey Team Results

Spring 2010(to support gravity survey)

Jay GoldfarbCourtney MurphyGarry RichardsonJason Henderson

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SUMMARY OF METHODS Trigonometric leveling (total station) for upper

Hidden Valley gravity points (with one GPS elevation)

Mapping-grade GPS (Trimble ProXH) on remainder of Hidden Valley, Prater Way, and City of Sparks gravity reference points

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Maps produced using .kml files imported into Google Earth

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SURVEY RESULTS Estimated horizontal accuracies are

between 10 cm – 10 m (upper Hidden Valley points), due to different grades of GPS used for location.

Estimated vertical accuracy ranges from 10 cm to 75 cm, depending primarily on time of day of GPS data collection. (poor GDOP in afternoon)

(all estimates at 68% confidence level)

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EFFECT OF HORIZONTAL POSITION ERROR ON GRAVITY ESTIMATION

Effect of 30 m error in latitude on normal gravity calculation:

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EFFECT OF ELEVATION ERROR ON GRAVITY CALCULATION

2/67.2

)04192.03083.0(

cmg

mhmGaldghdg

-> a 20 cm elevation error results in 0.04 mGal error

-> a 75 cm elevation error results in 0.15 mGal error