User's Manual
Table Of Contents
- 5 Data Collection Mode
- 6 Surveying Techniques
- 6.1 Low Frequency Reflection (Profiling) Mode
- 6.2 High Frequency Reflection (Profiling) Mode
- 6.3 Antenna Orientation
- 6.4 Triggers
- 6.5 Free Run
- 6.6 Odometer Data Acquisition
- 6.7 Signal Polarity
- 6.8 Spatially Aliasing the Data
- 6.9 Creating a Test Line for Data Quality
- 6.10 Adding GPS for Positioning
- 6.11 Common Mid-Point (CMP) Survey
- 6.12 Transillumination Surveys
- 7 Troubleshooting
- 8 File Management
- 9 Care and Maintenance
- 10 Helpful Hints
- Appendix A: Data File Formats
- Appendix B: GPR Signal Processing Artifacts
- Appendix C: Excerpts from the HP Fiber Optic Handbook
- Appendix D: Health & Safety Certification
- Appendix E: FCC Regulations
- Appendix F: Instrument Interference
- Appendix G: Safety Around Explosive Devices
pulseEKKO PRO Appendix B: GPR Signal Processing Artifacts
B-1
Appendix B: GPR Signal Processing Artifacts
Wow
All GPR data has a low frequency component to it. The magnitude of the low frequency component and
how it manifests itself in the data depends on the ground conditions around the antennas and the distance
between the antennas. In general, the low frequency component of the radar signal does not propagate
but diffuses into the ground. In other words the lower end of the spectrum sees an inductive (eddy current)
type response as opposed to a propagating (displacement current) type response.
The result is that the large transmit pulse emitted by the radar can be followed by a slowly decaying
transient. This shown as a sketch in Figure B-1 (a) and in real data in Figure B-2. Various terms have been
applied to this decaying transient. In some instances it is referred to as wow; sometimes it is referred to as
system saturation recovery. These terms are historical in nature because the response was often
caused by system response characteristics rather than being a ground induced response.
Figure B-1: Effect of inductive WOW on GPR data.