How I spent my summer vacation.

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How I spent my summer vacation.

• By Matthew Ludwig

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GEM-2 and Geomagnetic Surveying at a Coalition
Period Archeological Site

• Looking for hidden treasures in the GEM-2 and
  GM data sets collected at the LANL Archaeological
  Site LA-135290
• SAGE 2002
• Matthew Ludwig
• Santa Fe, NM

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• Presentation Outline
• GEM-2
• The Raw Data
• The Data Processing
• The Interpretation
• GM
• The Raw Data
• The Data Processing
• The Interpretation
• Comparisons Conclusions

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The GEM-2
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• Presentation Outline
• GEM-2
• The Raw Data
• The Data Processing
• The Interpretation
• GM
• The Raw Data
• The Data Processing
• The Interpretation
• Comparisons Conclusions

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Step 1 Unprocessed GEM DataLow Frequency Real
Component
GEM-2 Data Processing
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• Presentation Outline
• GEM-2
• The Raw Data
• The Data Processing
• The Interpretation
• GM
• The Raw Data
• The Data Processing
• The Interpretation
• Comparisons Conclusions

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Step 2 Linear Trend Removal
GEM-2 Data Processing
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Step 3 5 Pass Smoothing
GEM-2 Data Processing
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Step 4 Expanding the Scale
GEM-2 Data Processing
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• Presentation Outline
• GEM-2
• The Raw Data
• The Data Processing
• The Interpretation
• GM
• The Raw Data
• The Data Processing
• The Interpretation
• Comparisons Conclusions

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Low Frequency 1000Hz
GEM-2 Interpretation
In-Phase
Quadrature
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Middle Frequency-5000Hz
GEM-2 Interpretation
In-Phase
Quadrature
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High Frequency-15000Hz
GEM-2 Interpretation
In-Phase
Quadrature
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• Presentation Outline
• GEM-2
• The Raw Data
• The Data Processing
• The Interpretation
• GM
• The Raw Data
• The Data Processing
• The Interpretation
• Comparisons Conclusions

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Geomagnetics
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• Presentation Outline
• GEM-2
• The Raw Data
• The Data Processing
• The Interpretation
• GM
• The Raw Data
• The Data Processing
• The Interpretation
• Comparisons Conclusions

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Survey 1 6/28/02 N-S
8
15
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Survey 2 6/30/02 W-E
40
STAKE
2
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W-E vs. N-S
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• Presentation Outline
• GEM-2
• The Raw Data
• The Data Processing
• The Interpretation
• GM
• The Raw Data
• The Data Processing
• The Interpretation
• Comparisons Conclusions

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Step 0 Raw Data (SD)
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Step 0 Raw Data (SD)
Ymxb
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Step 1 Removal of Trend (SD)
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Step 2 FFT to Frequency Domain Log Plot (FD)
LOW-
High-
Nyquist Frequency
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Step 3 Log plot of the Results of Bandpass
Filter in Frequency Domain
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Finally Bandpass filtered data
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Comparing Filtered Results
Line 8-1
Line 40-2
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• Presentation Outline
• GEM-2
• The Basics
• The Data Processing
• The Interpretation
• GM
• The Basics
• The Data Processing
• The Interpretation
• Comparisons Conclusions

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GEM-2 (LF) vs Magnetics (NS)
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MN
STAKE
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Conclusions

• Both data sets turned out to appear more
  meaningful after filtering
• Low Frequency GEM-2 and Magnetics Plots show
  obvious similarities
• Surface structure correlations are more apparent
  in the GM data
• It will be interesting to see the results of the
  excavation study