Humanitarian Demining with Ultra Wide Band Ground Penetrating Radar
1. Background Removal in Array-Based UWB Radars for Landmine Detection Delft University of Technology, The Netherlands Public University of Navarre, Spain Álvaro Muñoz Mayordomo Dr. Miguel Ángel Gómez Laso Dr. Alexander G. Yarovoy
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22. SCOPE OF THIS THESIS : Clutter Removal INTRODUCTION GPR Clutter Removal LITERATURE SURVEY ALGORITHM IMPLEMENTATION ALGORITHM TESTING ONLINE APPROACH OFFLINE APPROACH PERFORMANCE STUDY SCENARIO A SCENARIO B SCENARIO C SCENARIO D Signal-Background Ratio Comput. Requirements Signal-Background Ratio Comput. Requirements EVALUATION AFTER MIGRATION SCENARIO E Energy-Background Ratio SCENARIO C SCENARIO D
64. METHODS COMPARISON INTRODUCTION GPR Clutter Removal ANALYSIS COMPARISON Off line Sliding window n Sliding window m A k (t), k = 1 ,…, n A k (t), k = 1 ,…, m Moving Weighted On line/Off line Sliding window m A k (t), k = 1 ,…, m Moving Median On line/Off line Sliding window m A k (t), k =1,…, m Moving Average On line Prediction range p A n-p (t), A n+p (t) Two-Sided Linear Prediction On line Weighting factor α A n (t), b n-1 (t) Exponential Averaging On line None A n (t), A n-1 (t) FIR Filtering Recommended Application Algorithm Parameters A-scans involved in Background Model Algorithm features Algorithm/Technique
65. METHODS COMPARISON INTRODUCTION GPR Clutter Removal ANALYSIS COMPARISON On line Sliding window m Number of components p A k (t), k <= p Principal Components Off line Averaging radius R A xy (t), x 2 + y 2 <= R 2 Cylindrical Moving Average Off line Time delay τ Amplitude scale α Sliding window m A Ref (t) Shifted and Scaled Time Domain On-line/Off-line Time delay τ Amplitude scale α Sliding window m A Ref (t) Shifted and Scaled Frequency Domain Off line Time delay τ Amplitude scale α A Ref (t) Shifted and Scaled Arbitrary Recommended Application Algorithm Parameters A-scans involved in Background Model Algorithm features Algorithm/Technique
66. Background Removal in Array-Based UWB Radars for Landmine Detection INFLUENCE OF TECHNIQUES ON LANDMINE DETECTION INTRODUCTION GPR Clutter Removal ANALYSIS COMPARISON INFLUENCE
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75. Background Removal in Array-Based UWB Radars for Landmine Detection CONCLUSIONS AND FUTURE WORK INTRODUCTION GPR Clutter Removal ANALYSIS COMPARISON INFLUENCE CONCLUSIONS
Current humanitarian demining rate is low and expensive. Therefore a global effort must be done worlwide to fight this issue. The overall political and legal framework is covered by the Ottawa Treaty from December 1997
GPR can work either in time domain or frequency domain
Response signal sn(t), ground reflection bn(t) and random noise e . It is usually expressed in Volts in the time domain
At the present time, no one standing-alone sensor or demining technique has shown total reliability in all sorts of environments and conditions. This leads to the idea of combination of several types of sensors to improve single performance.
Landmines signatures must be extracted from raw data.
Data Focusing, Imaging or Migration
equally distributed weights assures acceptable performance in all sorts of scenarios. Such an approach is followed
Best results are shown. A study of parameters have been done for each algorithm
ALPHA=0.3
being N the number of A-scans involved in one single background calculation
The targets are isolated scatterers, or the distance among them is large; Constant roughness or smoothly varying background along the track under survey.
The targets are isolated scatterers, or the distance among them is large; Constant roughness or smoothly varying background along the track under survey.
The weight Wn ( ti ) applied to the ith data sample of the nth A-scan is computed as the ratio of the total instantaneous amplitude within the averaging window over the instantaneous amplitude associated with the data sample An(ti).
Main objective in this technique is tracking of the surface profile by subtracting a modified version of a preselected A-scan.
Main objective in this technique is tracking of the surface profile by subtracting a modified version of a preselected A-scan.
The signal in the local area minimizing the up most equation for component An(ωk) is the Reference Background for such a frequency component.
The signal in the local area minimizing the up most equation for component An(ωk) is the Reference Background for such a frequency component.
Operations are done in the original time-domain; Signals involved in calculations are not Complex (as in frequency domain) but Real; Optimization of parameters αn,i and ζn,i has to be done only once for each A-scan under process (instead of K as before).
It is a two-dimensional approach to a Moving Average subtraction. Averaging is made within a circular local area centered in the A-scan under process. Spatial window is that of a cylinder whose basis is surrounding the A-scan to be processed and thus corresponds to the geometry of cylindrical landmines.
In the particular situation when a GPR array is used, averaging window becomes an ellipse due to different resolution in along-scan ( dx ) and cross-scan ( dy ) directions. α and β define the ellipse. In the latter case, different time delays of back-scattered waves reaching each receive antenna have to be taken into account and thus compensated.
In the particular situation when a GPR array is used, averaging window becomes an ellipse due to different resolution in along-scan ( dx ) and cross-scan ( dy ) directions. α and β define the ellipse. In the latter case, different time delays of back-scattered waves reaching each receive antenna have to be taken into account and thus compensated.
Those 3 may be suitable to be included in the processing chain of the self developed IRCTR GPR system
Those 3 may be suitable to be included in the processing chain of the self developed IRCTR GPR system
Those 3 may be suitable to be included in the processing chain of the self developed IRCTR GPR system
Those 3 may be suitable to be included in the processing chain of the self developed IRCTR GPR system
At the present time, no one standing-alone sensor or demining technique has shown total reliability in all sorts of environments and conditions. This leads to the idea of combination of several types of sensors to improve single performance.
At the present time, no one standing-alone sensor or demining technique has shown total reliability in all sorts of environments and conditions. This leads to the idea of combination of several types of sensors to improve single performance.
At the present time, no one standing-alone sensor or demining technique has shown total reliability in all sorts of environments and conditions. This leads to the idea of combination of several types of sensors to improve single performance.
At the present time, no one standing-alone sensor or demining technique has shown total reliability in all sorts of environments and conditions. This leads to the idea of combination of several types of sensors to improve single performance.
At the present time, no one standing-alone sensor or demining technique has shown total reliability in all sorts of environments and conditions. This leads to the idea of combination of several types of sensors to improve single performance.
At the present time, no one standing-alone sensor or demining technique has shown total reliability in all sorts of environments and conditions. This leads to the idea of combination of several types of sensors to improve single performance.
At the present time, no one standing-alone sensor or demining technique has shown total reliability in all sorts of environments and conditions. This leads to the idea of combination of several types of sensors to improve single performance.
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