Prsentation PowerPoint

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Some remarks about drift and jumps of relative
gravimeters Michel SARRAILH, BGI
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(a) The profile method (double occupation)
1 2 3 4 5 1 2
3 4
(b) The step method (triple occupation)

• 2 3
• 2 3 4
• 3 4 5

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(a) Drift 0.1/0.5 time unit jump 0.2
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(b) Drift 0.1/0.5 time unit jump 0.2
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USB data acquisition card (8 bits 0-256)
memories
Altera microprocessor
batteries
rheostats
Cable from the voltmeter output
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USB data acquisition card (8 bits 0-256)
Time (seconds)
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Voltmeter output Effects of clamping
unclamping
Clamp/unclamp
Clamp
Unclamp
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Voltmeter output /- 0.2 rotation
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Gravity preprocessing software

• Existing packages
• Gravap T.Schüler (IfEN)
• CG3tool IRD (Gabalda Bonvallot)
• Gravtool

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A freeware project
- Java (multiplatform) - Graphic interfaces

• Preprocessing
• Earth tides station parameters
• converted from Wparex (Wenzel)
• Earth tides corrections (GR31 505 waves, no
  ocean loading)
• Mean value determination
• Drift correction (linear or parabolic
  hypothesis)
• Jump detection

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Network adjustement

• Least square adjustment
• Free or constrained adjustment
• Cholesky, SVD, Tikhonov
• Outlier detection

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GravPrep
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GravPrep
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GravPrep
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(No Transcript)
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Drift correction
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Network adjustment
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Network adjustment
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Network adjustment
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Validation package
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Validation package
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Interpret 2.5 bodies