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
6-Surveying Techniques pulseEKKO PRO
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4) Place the DVL and control module between the antennas but off to the side.
5) On the DVL, under Survey Parameters, set the Survey Type to CMP/WARR (Section 3.4.5:
P51).
6) Under Survey Parameters, set the Start Position value to the starting antenna separation
(Section 3.4.1: P50).
7) Set the Step Size (Section 3.2.5: P38) to double the amount that each antenna will move.
Typically, the step size will be similar to the step size recommended for the frequency of the
antenna being used but, if necessary, round the number down to a number that is easily
divisible by two. For example, the normal step size for 100 MHz antennas is 0.25m but moving
each antenna 0.125m for a CMP is difficult, so in this case, it is better to set the step size to
0.2m and move each antenna 0.1m for the collection of each trace. The point is that CMP
collection is fast, so make small steps.
8) There are several options to trigger the collection of each trace (Section 3.3.1.1: P43). If a third
person is available for data acquisition, set the system in CANBUS trigger mode and have one
person on each antenna and the third person at the DVL pressing the electrical trigger at each
collection point. With two people and a fibre optic trigger, put the system in Fibre Optic trigger
mode and have the person with the transmitting antenna control the data acquisition. The third
option with two people (or even one person) is to set the system in Free Run mode (Section
3.3.1.3: P43) so data collection occurs based on time and put a 2-5 second (or longer) delay
between traces (Section 3.3.3: P44) to allow the operators to move the antennas to the new
locations.
9) CMP data collection should continue until the amplitude of the reflections is very weak or down
to the noise level in the data, Figure 6-11 is a good example.
Figure 6-11: CMP survey data (left) can be processed to produce an average velocity section (right) that shows high amplitudes
(bulls-eyes) indicating the average velocity to each reflector.