pulseEKKO PRO 5 5-Data Collection Mode Data Collection Mode After timezero has been properly set up (Section 4: P65), data collection can begin. Ensure that the transmitter and receiver are fully powered and initialized by checking that the Power LED on the top of the unit has stopped flashing. Select Run pulseEKKO to initiate data collection. Collect mode will collect data or replay previously collected data.
5-Data Collection Mode pulseEKKO PRO Figure 5-2: Selecting Collect Line Data will display this screen. The user can select the line number to be collected. The default line number is the lowest line number available. As lines are collected, their associated number will appear in black on this screen. Use the A and B buttons to move to any number on the list. When ready to collect data press 1 - Run. If you select the number of an existing line, you will have the option to Overwrite or View the data file.
pulseEKKO PRO 5-Data Collection Mode Error Messages: Messages will be displayed if any system connection is incorrect or if there is a problem with the system (Section 7: P95). Collect Screen: A sample of a screen data plot while in COLLECT mode is shown in Figure 5-4. Figure 5-4: Data collection screen with traces plotted in grey scale. The horizontal distance of data plotted on the screen depends on the pixel width of the traces (Section 3.5.
5-Data Collection Mode pulseEKKO PRO Trace Type: Depending on the user’s choice for Trace Plotting Type (Section 3.5.1: P56) the data will be plotted as either grey scale (Figure 5-4) or wiggle traces (Figure 5-5). In general, wiggle traces are commonly used for deep geological sounding where horizontal and vertical distances are similar.
pulseEKKO PRO 5-Data Collection Mode A fiducial marker is activated by pressing the Fiducial button or the A button on the keypad during data acquisition (see Figure 5-4). The position and name of the object encountered at each marker can be recorded in a field notebook. The fiducial marker is written to the trace header of the next trace to be collected. Fiducial markers are numbered sequentially (F1, F2 etc.).
5-Data Collection Mode pulseEKKO PRO Figure 5-7: A time axis (left) and depth axis (right) can be plotted on the left of the data image by pausing the data collection and pressing Scale once for a time axis and twice for a depth axis. The user should be aware that if an accurate depth axis is desired, the proper radar wave propagation velocity (see Section 3.2.6 Radar Velocity on page 39) must be used to generate the correct depth.
pulseEKKO PRO 5-Data Collection Mode 5.5.4 Calib - Velocity Calibration GPR systems can be used to scan into many different materials including soil, rock, concrete, snow, ice and wood. The radio wave emitted by a GPR system will travel at different velocities depending on the material being scanned. As discussed earlier (Section 3.2.2.1: P35), depth estimates are only accurate if the system has been properly calibrated to determine the velocity of the material being scanned.
5-Data Collection Mode pulseEKKO PRO Pressing the Up, Down, Left, and Right buttons once makes a very small change in the position of the hyperbola. These buttons must sometimes be pressed many times to move the hyperbola to the correct position. The Repeat button speeds up the movement of the hyperbola. Select the direction (Left, Right, Up or Down) and press Repeat. The hyperbola will then start moving in that direction.
pulseEKKO PRO 5.5.4.2 5-Data Collection Mode Identifying Air Reflections Some hyperbolic reflections can also be caused by objects not in the subsurface such as fences, overhead wires and, in some conditions, even large trees. An important part of data interpretation is learning to recognize these unwanted “air” events and differentiate them from the desired subsurface events. Good field notes are indispensable for helping identify unwanted events on the data.
5-Data Collection Mode 5.5.4.3 pulseEKKO PRO Target of Known Depth If there are no suitable hyperbolas visible in the data to perform the Hyperbola Matching described above, it may be the situation that there is a target of known depth in the area being scanned. If this is the case, use the bottom tip of the hyperbola matching triangle and move it until it lies on top of the GPR response to the known target.
pulseEKKO PRO 5.6 5-Data Collection Mode Collect Grid Data As the name implies, Collect Grid Data is selected when the user is ready to collect data in an organized grid. 5.6.1 Select Line Direction The first screen will ask which line direction is being collected, X Lines or Y Lines. Refer to Section 3.4.6 GPR Grid Type on page 51 for definitions of X lines and Y lines. Figure 5-12: When collecting grid data, the direction of the lines (X or Y) needs to be determined. 5.6.
5-Data Collection Mode 5.7 pulseEKKO PRO View Previously Collected Lines After GPR data files have been collected, it is possible to view them on the DVL screen by using the Collect Line Data or Collect Grid Data option and selecting an existing file. When asked to Overwrite or View the file, select the View option. Figure 5-14: To view a previously collected data line on the DVL screen, select Collect Data and select an existing line number.
pulseEKKO PRO 5-Data Collection Mode Figure 5-16: Viewing an existing data line. The data image scrolls onto the screen just like during real data collection. The scroll speed can be increased and decreased using the A and B buttons. The line can be plotted with a different gain or use the Gain+ and Gain- buttons to increase and decrease the current gain value. ReStart will plot the line again.
6-Surveying Techniques 6 6.1 pulseEKKO PRO Surveying Techniques Low Frequency Reflection (Profiling) Mode 6.1.1 Two Person Operation The most common method of data acquisition in rough terrain will be with two people in a configuration shown below (Figure 6-1). The person carrying the DVL and Control module has a belt battery fastened around their waist to power these units. The optional DVL carrier shown is not a necessity for the DVL operator.
pulseEKKO PRO 6-Surveying Techniques 6.1.2 One Person Operation One person operation is performed in the configuration shown below (Figure 6-2) with the optional DVL carrier (Section 2.5.3: P23) and the fibre optic beeper/trigger (Section 2.5.2: P20). Figure 6-2: One person operation setup. The operator moves the antennas to each data location point and collects the trace using the fibre optic beeper trigger. The data are visible in real time on the DVL screen.
6-Surveying Techniques pulseEKKO PRO 6.1.3 Strain Relief for Fibre Optic Cables Figure 6-3: Fibre optic cables can be broken or damaged if care is not taken. The most common breakage point is right at the connectors when the cables are snagged or pulled hard. Protect the fibre optic cables by making a strain relief. Take an extra loop of cable and tape it to the handle. That way, if the cable gets pulled, the strain is taken up by the tape and not the cable. 6.1.
pulseEKKO PRO 6-Surveying Techniques 6.1.5 Antenna Movement If practical, antennas should not move while data are being collected, as indicated by the duration of the beeping tone. Keeping the antennas static assures the highest quality stacked data. When the beep stops, the antennas can be moved to their next position in preparation for the next trace. Obviously, holding antennas stationary is impractical if a continuously moving platform is used for data acquisition (Figure 6-5). 6.
6-Surveying Techniques 6.3 pulseEKKO PRO Antenna Orientation Both the high and low frequency, bistatic antennas of the pulseEKKO PRO system have the flexibility to allow different orientations with respect to one another. Figure 6-6: Definitions of antenna orientations available with bistatic antennas. Perpendicular-Broadside (PR-BD) is most commonly used for reflection surveys. The most common antenna orientation is the parallel-broadside configuration.
pulseEKKO PRO 6.4 6-Surveying Techniques Triggers If the Trigger Method is set to CANBUS, Fibre-Optic or DVL Key (B), the following data collection sequence is followed: a) Set the antennas at the correct separation and centred on the starting position for the survey line. The antennas should be oriented perpendicularly to the survey line direction as shown in Figure 6-7. b) The data collection screen on the DVL should display “Press Trigger”.
6-Surveying Techniques 6.6 pulseEKKO PRO Odometer Data Acquisition Data acquisition can be controlled by an odometer triggering the radar system to collect data at specified step sizes (Section 3.3.1.2: P43). There are several odometers available for the pulseEKKO PRO system including the Big Wheel Odometer (See Figure 2-23 on page 17), SmartCart odometer (Figure 6-8) and the vehicle odometer (contact Sensors & Software for more details).
pulseEKKO PRO 6-Surveying Techniques If maintaining speed is important, the other option is to reduce the time window (Section 3.2.2: P35) or number of stacks (Section 3.2.7: P40) to allow the traces to be collected faster. Data trace acquisition speed can also be increased by increasing the temporal sampling interval but it is important to make sure that the temporal sampling interval does not exceed twice the recommended value or the data will be aliased and may become uninterpretable (Section 3.2.
6-Surveying Techniques 6.9 pulseEKKO PRO Creating a Test Line for Data Quality One of the best ways of detecting problems with the GPR system is, shortly after receiving the system and getting comfortable with its operation, to collect a line of data at a convenient, easily accessible location. The line does not have to be too long but 100 - 200 traces is a good guide. This data line should be saved electronically and perhaps plotted out on paper and dated.
pulseEKKO PRO 6-Surveying Techniques 6.11 Common Mid-Point (CMP) Survey A Common Mid Point (CMP) survey is performed to measure GPR velocity in the survey area. A CMP survey is best done in an area with flat lying reflectors and relies on changing the antenna separation to increase the signal path length from the mid point reflector (Figure 6-10). The resulting data can then be processed using a semblance analysis routine to extract average velocities to the reflectors (Figure 6-11).
6-Surveying Techniques pulseEKKO PRO 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.
pulseEKKO PRO 6-Surveying Techniques 6.12 Transillumination Surveys For a transillumination survey the transmitter and receiving antennas are placed at opposite sides of a structure to study the transmission properties of the dividing material. Depending on the structure shape, it is desirable to obtain as many different raypaths through the structure as possible. This is achieved by varying the transmitter and receiver geometry around the structure.
6-Surveying Techniques pulseEKKO PRO Figure 6-13: Cross hole transillumination surveys with the pulseEKKO PRO system require the use of 50, 100 or 200 MHz borehole antennas available from Sensors & Software. 6.12.2 Walls, Pillars and Monument Surveys Another type of transillumination survey uses the surface antennas to send signals through a structure like a wall, pillar or monument. Figure 6-14: Transillumination survey setup.
pulseEKKO PRO 7 7-Troubleshooting Troubleshooting The pulseEKKO PRO system is designed to minimize user problems; however, all electronic devices are subject to possible failure. The following are troubleshooting hints if your system fails to operate. If the radar is not running properly, an error message will be displayed indicating the possible cause of the problem (Figure 7-1).
7-Troubleshooting pulseEKKO PRO Figure 7-2: Make sure fibre optic strain relief colour matches the receptacle door colour (grey to grey and black to black). Reset the System by Powering Down: If the connections are OK but the error persists, try powering down the system completely. This power down will include turning off the DVL and Control module as well as the transmitter and receiver and fibre optic beeper/trigger (if present). Then power everything back on and see if the system runs. 7.
pulseEKKO PRO 7-Troubleshooting Check the battery voltage with a voltmeter. Try to do this while the battery is still attached to the DVL and control module to get a true measure of the voltage while under load (it may be necessary to open the battery case or belt battery case and connect the voltmeter to the positive and negative battery terminals).
7-Troubleshooting pulseEKKO PRO The receiver and transmitter contain a voltage monitoring circuit that will cause the Power LED on top of the units to slowly flash when the battery voltage is getting low. When this occurs, batteries should be replaced as soon as possible. If the batteries are not replaced and the voltage continues to drop, the unit will eventually turn off. If the voltage of the discharged batteries is measured some time after they have been changed it will be higher than 10.
pulseEKKO PRO 7-Troubleshooting All battery compartments should be checked periodically for proper operation. Take a known good pair of batteries and install into the battery compartments. Ensure the power light activates with no intermittent operation. If the power light will not activate look in the battery compartment and check the battery contact for signs of excessive stress. Also check the condition of the 2A fuse wiring.
7-Troubleshooting pulseEKKO PRO Figure 7-6: After connecting the fibre optic cable as shown in Figure 7-5, select System Setup - Acquisition Control - Fibre Optic Testing. Figure 7-7: The fibre optic test routine will continuously test the cable. During the tests, gently move the cable around, especially near the connectors, to see if a failure occurs. If so, repair or replace the fibre optic cable.
pulseEKKO PRO 7.3 7-Troubleshooting Control Module Related Errors Control Module related errors are generated whenever the DVL fails to communicate with the control module for any reason. The most common causes of these errors are the following: a) Control Module-to-DVL connection is loose or faulty. b) The Control Module is damaged. The following checks should be carried out. a) With the system completely hooked up turn the DVL and control module OFF then back ON again and retry the system.
7-Troubleshooting pulseEKKO PRO 4) With the system running, find the fibre optic cable from the transmitter and disconnect it at the control module and look for a red light coming from the top hole in the control module. Plug this cable back in and unplug the Input (black) cable at the transmitter. Check for a red light coming from the cable. If the signal is still not found, contact Sensors & Software Inc. (Section 7.10: P103). 7.
pulseEKKO PRO 7-Troubleshooting This is an indication that the fibre optic cables are damaged. Check all cables (Section 7.2: P99) and replace or repair. There are also short fibre optic cables located inside the transmitter and receiver that may be causing the problem (see item K in Figure 9-1). Before attempting to clean or replace these cables, contact Sensors & Software (see below). 7.
8-File Management 8 pulseEKKO PRO File Management From the main menu (See Figure 2-36 on page 27), pressing the 2 button selects File Management. GPR data directories and files collected on a DVL can be transferred to an external computer or deleted from the DVL. File Management Options 1 and 2 (Transfer Directory and Transfer File) require that the DVL be connected to a PC to allow for data transfer.
pulseEKKO PRO 8.1 8-File Management Connecting the DVL to a PC To transfer all the data files in one directory from the DVL to an external computer, the computer must be connected to the DVL using the special parallel PXFER cable that is supplied with the system (Figure 8-1). Note that this is a special cable and standard 25 pin to 25 pin or Laplink cables will not work. As well, the computer must have the utility program called WinPXFER running on it (Section 8.2 on page 106).
8-File Management 8.2 pulseEKKO PRO Installing and Running the WinPXFER Software on a PC The system will come with a CD containing the WinPXFER software installation. This will be the WinPXFER folder on the CD. Run the SETUP.EXE program to install WinPXFER. If necessary, refer to the software installation document that came with the system. This same document in electronic format is in the root folder of the CD.
pulseEKKO PRO 8-File Management Figure 8-3: Data Directory Transfer screen. The triple arrows (>>>) on the left indicates which directory is currently selected. Use the A and B buttons to move the arrows up or down to different directories. To transfer the directory to the PC, press the 2 (Send) button. It is also possible to use the 1 button to Tag several directories so they can all be sent at once. 8.4 Transfer File Once the parallel XFER cable is connected (Section 8.
8-File Management pulseEKKO PRO The data will be transferred from the DVL to the computer and saved in the current folder listed by the WinPXFER software. The progress of the data transfer will be displayed on the DVL screen and the external computer. When the data transfer is complete, exit from the WinPXFER program. Press any button on the DVL to return to the main menu. 8.5 Delete Directory To delete the data in a directory on the DVL, from the File Management menu, press Delete Directory.
pulseEKKO PRO 8.6 8-File Management Delete File To delete an individual data file from the DVL to a PC, select Delete File from the main File Management menu. On the next screen (Figure 8-6), use the A and B button to select one of the 20 available directories, then use the 1 button (Next Line) to move through the data lines in the directory. When the name of the data line to transfer appears, press 2 (Transfer Line) to send it to the PC. Figure 8-6: Line Delete screen.
8-File Management 8.7 pulseEKKO PRO View Disk Space The View Disk Space option allows the user to see how much disk space has been used and how much remains. The remaining amount is expressed in kilobytes, as a percentage of the total disk space as well as how many traces and how much distance this amount of space represents, based on the current settings for time window, sampling interval and step size. Figure 8-7: View Disk Space screen.
pulseEKKO PRO 9 9.1 9-Care and Maintenance Care and Maintenance General To operate the pulseEKKO PRO equipment in a geophysical field environment, the user should exercise the normal care afforded other field instrumentation. Items that require specific maintenance procedures are listed below together with detailed descriptions of the procedures. All the equipment is ‘shower proof’ but will not tolerate total immersion.
9-Care and Maintenance pulseEKKO PRO Figure 9-2: Location of spare parts shown in Figure 9-1. 9.3 Radar Unit If operated in dusty conditions the control module, transmitter and receiver fibre optic sockets may become dusty inside. In such conditions open the unit up on a regular basis and blow out or vacuum all the dust. 9.
pulseEKKO PRO 9-Care and Maintenance Always push in and remove the cable by holding the strain relief jacket or the plastic end connector. Pulling on the cable will loosen the crimp and damage the cable. After connecting the fibre optic cables to the antenna electronic boxes, loosely loop the cable and tape off some slack onto the handles (Figure 6-3). Most breaks occur right at the cable ends when they are accidentally pulled.
9-Care and Maintenance pulseEKKO PRO The following procedure describes how to repair the fibre optics cables that link the pulseEKKO PRO unit to the transmitter and receiver units. The procedure and materials used are described in the HewlettPackard Opto-Electronic Data Book excerpts of which are provided in Appendix C: Excerpts from the HP Fiber Optic Handbook.
pulseEKKO PRO 9-Care and Maintenance Step 2 Slide the two strain relief jackets over the fibres remembering that the blue fibre optic connector will correspond with the black strain relief jacket and the grey fibre optic connector with the grey strain relief jacket. Step 3 Place the crimp ring and the connector over the end of the cable; the fibre should protrude about 0.12 inch (3 mm) through the end of the connector.
9-Care and Maintenance pulseEKKO PRO Step 6 Place the flush connector and the polishing fixture on the dull side of the 3 micron pink lapping film and continue polishing the fibre and the connector for approximately 25 strokes. The fibre end should be flat, smooth and clean. The cable is now ready for use.
pulseEKKO PRO 10-Helpful Hints 10 Helpful Hints 10.1 Batteries Replace batteries before they go dead. Nothing is more annoying than losing data in the middle of a traverse. Carry plenty of spares. 10.2 Measuring Position When performing a profile where the accuracy need only be accurate to the nearest metre, set the step size equal to some fraction of your antenna spacing. On the rope used to hold the antennas at a fixed spacing, mark the step size.
10-Helpful Hints pulseEKKO PRO 118
pulseEKKO PRO Appendix A: Appendix A: Data File Formats Data File Formats pulseEKKO Data File Format HEADER (.HD) FILE: The header file, identified by the file extension .HD, is an ASCII file. An example is shown below. 1234 Data Collected with pulseEKKO PRO 2005-01-12 NUMBER OF TRACES = 136 NUMBER OF PTS/TRC = 409 TIMEZERO AT POINT = 96 TOTAL TIME WINDOW = 327 STARTING POSITION = 9.500000 FINAL POSITION = 77.000000 STEP SIZE USED = 0.500000 POSITION UNITS = metres NOMINAL FREQUENCY = 100.
Appendix A: Data File Formats 22 23 24 25 26 - 32 pulseEKKO PRO Zero flag: 0 = data okay, 1=zero data (not used) Time of day data collected in seconds past midnight. Comment flag: 1 = comment attached. Comment The data section consists of an array of two-byte integers, one value for every data point.
pulseEKKO PRO Appendix B: Appendix B: GPR Signal Processing Artifacts 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.
Appendix B: GPR Signal Processing Artifacts pulseEKKO PRO Figure B-2: Display of a single data trace (left) and data section (right) with the low frequency WOW component present. Compare these plots to the figure below where the WOW has been removed with the DEWOW high pass filter. Turn the DEWOW filter off to see this low frequency component of the data when plotting the data with Windows-based software.
pulseEKKO PRO Appendix B: GPR Signal Processing Artifacts Dewow Artifacts 1) Pulse Precursor The result of high pass filtering can induce two types of artifacts into the plotted data sections. The first is a pre-cursor to the onset of a pulse (Figure B-1 (b) and Figure B-3, left). When the original data are high pass filtered the wavelet is stretched in time with additional oscillations occurring before and after the original pulse.
Appendix B: GPR Signal Processing Artifacts pulseEKKO PRO Other Types of Filters For dealing with the inductive wow response, high pass filtering is necessary. If an alternative high pass filter is available or the user wishes to try a different type of high pass filtering, the raw data contains all of the information and experimentation can be carried out using the raw data. A DC removal can also be used to remove a DC level from all the traces in the input data set.
pulseEKKO PRO Appendix C: Appendix C: - Excerpts from the HP Fiber Optic Handbook Excerpts from the HP Fiber Optic Handbook C-1
Appendix C: - Excerpts from the HP Fiber Optic Handbook C-2 pulseEKKO PRO
pulseEKKO PRO Appendix D: Health & Safety Certification Appendix D: Health & Safety Certification Radio frequency electromagnetic fields may pose a health hazard when the fields are intense. Normal fields have been studied extensively over the past 30 years with no conclusive epidemiology relating electromagnetic fields to health problems. Detailed discussions on the subject are contained in the references and the web sites listed below.
Appendix D: Health & Safety Certification pulseEKKO PRO References 1. Questions and answers about biological effects and potential hazards of radio-frequency electromagnetic field USA Federal Communications Commission, Office of Engineering & Technology OET Bulletin 56 (Contains many references and web sites) 2. Evaluation Compliance with FCC Guidelines for Human Exposure to Radio Frequency Electromagnetic Fields.
pulseEKKO PRO Appendix E: Appendix E: FCC Regulations FCC Regulations This device complies with Part 15 of the USA Federal Communications Commission (FCC) Rules. Operation in the USA is subject to the following two conditions: (1) this device may not cause harmful interference and (2) this device must accept any interference received, including interference that may cause undesired operation.
Appendix E: FCC Regulations pulseEKKO PRO and construction does not actually result from the inspection; the intended purpose of the operation of the UWB device is to determine if construction is required. We also believe that the GPRs and wall imaging systems may be operated for one of the purposes described in the regulations but need not be operated directly by one of the described parties.
pulseEKKO PRO Appendix E: FCC Regulations FCC GROUND PENETRATING RADAR COORDINATION NOTICE NAME: ADDRESS: CONTACT INFORMATION [CONTACT NAME AND PHONE NUMBER]: AREA OF OPERATION [COUNTIES, STATES OR LARGER AREAS]: FCC ID: [E.G. QJQ-PE-PRO-TLF-A)] EQUIPMENT NOMENCLATURE: [ E.G. PULSEEKKO PRO TLF-A] Send the information to: Frequency Coordination Branch., OET Federal Communications Commission 445 12th Street, SW Washington, D.C.
Appendix E: FCC Regulations pulseEKKO PRO E-4
pulseEKKO PRO Appendix F: Appendix F: Instrument Interference Instrument Interference Immunity regulations place the onus on instrument/apparatus/device manufacturers to assure that extraneous interference will not unduly cause an instrument/apparatus/device to stop functioning or to function in a faulty manner. Based on independent testing house measurements, Sensors & Software Inc. systems comply with such regulations in Canada, USA, European Community and most other jurisdictions.
Appendix F: Instrument Interference pulseEKKO PRO F-2
pulseEKKO PRO Appendix G: Safety Around Explosive Devices Appendix G: Safety Around Explosive Devices Concerns are expressed from time to time on the hazard of GPR products being used near blasting caps and unexploded ordnance (UXO). Experience with blasting caps indicates that the power of Sensors & Software Inc.’s GPR products are not sufficient to trigger blasting caps.
Appendix G: Safety Around Explosive Devices pulseEKKO PRO G-2
