|1. What is GPR?|
The OKO-2 GPR is a portable lightweight low-prices system designed for non-destructive environmental monitoring. The OKO-2 GPR includes control unit or control processing unit and antennas. All antennas are interchangeable and meet the needs of a broad range of applications.
OKO-2 is device designed for a geotechnical, geoecological, hydrological, hydrogeological, archeological applications such as:
|4. What about the price?|
Please send your request to firstname.lastname@example.org
|5. What about the training?|
| Three-days Training course (Moscow, Russia) is provided to Customers who purchase the GPR The training program includes: |
The training is provided by specialists of Geotech Ltd. having significant practical experience in application of GPRs for addressing a wide range of tasks beginning from surveying to complex geological and engineering explorations.
|6. Do you lease OKO GPRs?|
We do not lease GPR. Operations can be done by our specialists.
|7. Is it easy/difficult to learn how to interpret GPR positioning data?|
As any skill interpretation of GPR positioning data can be divided into several levels: basic, advanced and professional. GPR Positioning Basics course provides fundamentals of interpretation. This knowledge is sufficient for independent operation but is just basic knowledge and corresponds to beginner’s level. For improvement of your skills practical experience is of primary necessity. It is desirable to work independently at the sites where almost everything is known. Participation in GPR-positioning workshops and conferences regularly held in Russia and abroad will significantly push your skills upward. People with basic geological or geophysical education for sure have absolute advantage over people without special education. However, it is not a reason to lose heart and refuse purchase of a GPR.
|8. How is antenna unit selected for addressing a specific task?|
Antenna unit first of all depends on the task that you plan to address as well as a depth of exploration. Scanning depth and resolution data of different antenna units can be found in the Antenna Unit section. But we strongly recommend you to consult with sales specialist before purchasing a GPR as to take into account all possible aspects.
|9. What is the accuracy of depth testing and sizing of objects?|
Depth testing accuracy to 99% depends on the accuracy of evaluation of dielectric permeability of layers. Error per unit in the value of dielectric permeability of layers can produce error of up to 10% of depth. Sizing of object is possible only if dimensions of objects exceed wave length. Accuracy of sizing of object in lateral plane directly depends on accuracy of surveying of traces of chart. Reliability of evaluation of vertical size of object as well as reliability of depth testing depends on the accuracy of evaluation of dielectric permeability. However, if the target object is metal it is not possible to determine its vertical dimensions due to 100% reflection of a signal from the upper surface of such object which results in failure of the electromagnetic wave to scan the environment below this surface. Such objects form screens for GPR observation. When dimensions of objects are less or comparable to a wave length the object is recognized as a point – diffraction of an electromagnetic wave occurs. In this case it is impossible to size the object.
|10. Which software products can be used for processing and interpretation of GPR data?|
GPR OKO-2 basic package includes Professional version of GeoScan32 software designed for recording, processing and interrupting GPR data. GPR exploration data obtained by GPR OKO-2 can be saved in international data format SEG-Y and subsequently processed with any software product designed for interpretation of seismic or GPR data that supports this format, for example, RadExplorer or RadExProPlus.
|11. What feedthrough signal time shift shall be set in GeoScan32 scan window prior to scanning?|
During manufacturing of antenna unit an optimum feedthrough signal time shift is programmed in the memory of antenna unit, so when you enter the scanning window of GeoScan32 software and press the Connect button, software defines an antenna unit and the feedthrough signal time shift for connection of antenna is set automatically. Shift of feedthrough signal is set at a level of 10-20% from the beginning of time scale of the connected antenna.
|12. What scanning step shall be set in parameters of GeoScan32 software scan window?|
Optimum step between samples for each antenna unit is specified in Table 2.4.1. of the of GPR OKO-2. The value of this parameter can be increased but when it exceeds the recommended values more than two times, objects can be missed between two samples.
|13. What stack value shall be set in parameter of GeoScan32 software scan window?|
| Stack determines the value of repeated reception of each trace and its subsequent summing-up. Increase of this parameter allows detection of weaker signals, deepens the actual scanning depth and improves quality of image but at the same the recommended antenna unit scroll speed goes down during the profile recording.|
|14. What is the purpose of Threshold Value parameter and what is the function of its value?|
Threshold value parameter is used for automatic localization of a feedthrough signal position. GeoScan32 determines place of a feedthrough signal for binding zero point of the depth scale.
|15. How airborne noises received during GPR scanning can be distinguished from signals reflected from real boundaries in section?|
Inclination procedure from the Options menu can be used if profile has at least one hyperbola branch for identification of airborne noise. Position the cursor on the top part of the inclined line, press and hold the left button of the mouse and move the cursor to the lower part of the inclined line. Speed of electromagnetic wave in this environment will be displayed in the left bottom corner of the screen. If speed exceeds 30 cm/ns then airborne noise is recorded in profile.
|16. Why does the value of feedthrough signal shift set in the scan window of GeoScan32 software differ from the shift value displayed in “Profile Properties” window?|
To obtain the shift value was set in the scan window of GeoScan32 software it is necessary to divide feedthrough signal shift value displayed in the “Profile Properties” window by 256. The obtained integer number will correspond to the Rough direct signal shift value in the scan window and remainder of the division further divided by 8 (for single point antennas) or by 64 (for multiple point antennas) will be equal to the Smooth feedthrough signal shift value. “S” letter is added to multiple point antennas – e.g., AB-90S.
|17. Does GPR OKO-2 feature godograph capability?|
Godograph scanning mode of GPR OKO-2 is provided by GeoScan32 software. Design of the AB-90, -250 and -150 antenna units allows disconnection of transmitter from receiver and scanning in the godograph mode with distance reference to the receiver movement.
|18. What is the procedure for setting zero point of depth scale when processing scanning files?|
The following shall be done for setting zero point of the depth scale:
There is a second method for setting zero of the depth scale. Set the horizontal line of the Trace Window to maximum of the second half-period (Fig. 2) of feedthrough signal and press the pp button in the right top part of the Trace Window. Depth scale zero point will be also set to proper position. Remember when using the second method for setting depth scale zero: