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Subsurface Views

EKKO_Project is the new PC-based software for GPRdata management, plotting, processing, interpretationand reporting. In future all Noggin, pulseEKKOPRO, Conquest and SPIDAR GPR systems will exploit thepower of EKKO_Project.

EKKO_Project features project (.gpz) files that contain all theGPR data, associated files and attached files. An entire GPRsurvey, along with all the processed and interpreted data, iscontained in just one file, making it easy to store and sharedata with others.

Sensors & Software Inc.

GPR Technology Vol 8, No. 32, October 2012

Gansu Dunes - GPR research in China

EKKO_Project has a simple, intuitive interface with many powerful features.

- Complete GPR Data AnalysisEKKO_Project

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From our customers' files

The Interpretation Module The Base package

The Processing Module

The Cold and Arid Regions Research Institute inLanzhou in Northwest China carries out extensiveGPR surveys for numerous applications. Their inter-ests include glaciers and monitoring the currentstate of ice thickness. Another area of particularimportance is the extensive dune region in GansuProvince.

One of the dunes appears in Figure 1 and shows asmall oasis in an otherwise undulating field of largeand endless dunes. The area is spectacular from ascenic point of view.

The major concern with the underlying geology is the depthof the groundwater in the area. These dunes movewith time and themaintenance ofoasis areas andmonitoring thechanges with timeare critical.

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In this issue

Gansu Dunes . . . . . . . . . . . . . 1, 2

EKKO_Project . . . . . . . . . . . 1, 3

See us at . . . . . . . . . . . . . . . . 4

Ask-the-Expert . . . . . . . . . . . . 4

s u b s u r f a c e i m a g i n g s o l u t i o n s

Subsurface Views Page 2October 2012Sensors & Software Inc.

EKKO_Project (continued from page 1)Project Explorer - is a window similar to Windows Explorer formanaging the GPR data. It lists all the GPR data (Linesets and Grids)in the project. New Linesets can be easily added or created and GPRlines copied or cut from one lineset and pasted into another.

GPR Line Acquisition tab - displays all the survey parameters and otherdata acquisition details of the GPR line including Antenna Frequency,Start Position, End Position, Step Size, Time Window and Stacks.

LineView - GPR lines are quickly displayed using the LineView mod-ule. LineView emulates EKKO_View, software developed andadvanced over many years, for cross-sectional viewing of GPR linedata. Features include color and/or wiggle trace displays, multiple colorpalettes, axes control, simple gains, zooming, contrast and sensitivityadjustment and velocity calibration tools. Every GPR line in the proj-ect is available in LineView; specific lines can be displayed, or the entiresurvey can be plotted and viewed at once.

GPS & Topography files - are automatically integrated with theassociated GPR lines. When plotted with LineView, the GPS posi-tion of every trace is displayed and an elevation axis can replace thedefault depth axis.

Interpretation Module - the optional Interpretation Module operateswithin LineView, allowing the user to add interpretations directly on theGPR lines. Interpretation options are points, polylines, boxes and anno-tations. Interpretation reports list local and globally-positioned interpre-tation files that are easily imported into GIS and AutoCAD software or2D or 3D surface visualization software.

Attached Files - the files associated with a project can be added to anEKKO_Project .gpz file and attached to a Lineset, Grid or a specificGPR line. The possibilities are endless but some examples include:

ww photos of the survey site,ww videos of the site or data collectionww audio files describing the site or data collectionww field notes document

EKKO_Project launches the associated software, such as Word, MediaPlayer and Photo Editor, to open the attached file.

Processing Module - is an optional add-on for EKKO_Project.It provides GPR line editing such as cropping data and repositioningtraces, time gains, time filtering (lowpass, highpass and bandpass), spatialfiltering, migration and instantaneous attributes. Favourite processingstreams can be saved as recipes to be applied to data in other projectfiles.

ww

ww

ww

ww

Some Sensors & Software GPR systems already generate project (.gpz) filesin the hardware that can be copied to a PC and opened in EKKO_Project.Users with older hardware can still take advantage of the benefits ofEKKO_Project for data management and analysis. Any collection of GPRlines, either a Lineset or a Grid, is easily imported into EKKO_Project andsaved as a .gpz file.

EKKO_Project is now shipping with all Noggin and pulseEKKO PRO GPRsystems. It is also available as an upgrade to current users of EKKO_View,EKKO_View Deluxe and EKKO_Interp. Contact us for the details. nn

ww

ww

ww

The Base packageAncillary data canbe attached to individual GPR data files, linesetsor grids.

Attached file suchas photos, videos, or notes

t = Topographyi = Interpretationsg = GPSp = Processing

The Interpretation ModuleThe Interpretation ModuleUsers can interactively add localized targets, Users can interactively add localized targets, layers, labels and identifiers on the GPR lines.layers, labels and identifiers on the GPR lines.

Many processes are availableincluding migration, time and spatialfiltering and attribute creation.

Frequently-usedprocessing recipes canbe built, stored andre-used.

The ProcessingModule

Subsurface Views Page 3October 2012Sensors & Software Inc.

s u b s u r f a c e i m a g i n g s o l u t i o n s

Gansu Dunes(continued from page 1)

The research institute has carried out anumber of GPR surveys to investigatethe base of the dune area. ApulseEKKO PRO GPR with antennafrequencies of 50, 25 and 12.5 MHz ismost commonly used for theseinvestigations.

Figure 1 shows a survey crew movingthe 12.5 MHz antennas over the crestof a dune. A large official team ofresearchers and observers participatedin this inaugural test of the GPRinvestigation method. The key aspectof the photo is the wide-open view ofthe oasis.

Data from a 50 MHz GPR survey lineare shown in Figure 2. These dataclearly indicate that the GPR seesthrough the dune to the underlying base formation: a water-saturated silt-mud deposit.Except for the compensation fortopography and a minor adjustment inthe amplitude time gain function todisplay the data in the most effectivemanner, the GPR line shows raw data.

Use of GPR in this interesting andvital area of China is ongoing. Thespectacular nature of the geography isone of true beauty. Understandingthis area in more depth is of greatvalue to the Chinese community. nn

Figure 1: Survey team carrying 12.5 MHz antennas along the crest of the dune in north western China.

Figure 2: Example 50 MHz GPR profile over a dune. Data have been compensated for topographic variations.

Can GPR be used to image the bottom of a cave?

The short answer is yes but in reality it is very difficult and thebottom of a cave is seldom imaged effectively. To imagethe bottom of a cave, GPR signals must travel from thetransmitting antenna on the surface through the soil and rock to thetop of the cave.

Ask-the-Expert The signal needs to travel through the air or water filling the caveand reflect from the bottom. It then needs to travel the reversedirection back to the surface to be detected by the receivingantenna (Figure 1a). Every step of the way, the signal is beingscattered and attenuated, leaving very little, if any, to detect.Assuming that the attenuation does not completely absorb thesignal, the biggest factor for detecting the bottom of the cave is theshape. Flat or round surfaces reflect the most signal back to thesurface; this why we can routinely see the bottom of flat ice(Figure 2) or the bottom of a round, non-metallic pipe (Figure 3).

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Subsurface Views Page 4October 2012Sensors & Software Inc.

See us at ...AGUSan Francisco, CADecember 3 - 7, 2012http://fallmeeting.agu.org/2012/

Arctic Technology ConferenceHouston, TXDecember 3 - 5, 2012http://www.arctictechnologyconference.org/

Technical Papers & Notes1.

2.

Creating an Isosurface Image with Voxler 2 Using 3D Data from ConquestView 3or EKKO_Mapper 4 - Sensors & Software Inc. Technical Note; 2010By: Sensors & Software Technical Staff ref 444

Creating 3D Animations with Voxler 2 - Sensors & Software Inc. Technical Note; 2010By: Sensors & Software Technical Staff ref 445

Imaging Concrete with GPR workshops - November 15, 2012 - New

York, NY Upcoming GPR workshops

s u b s u r f a c e i m a g i n g s o l u t i o n s

www.sensoft.ca sales@sensoft.ca Tel: 905-624-8909 Fax: 905-624-9365

The bottom of caves, however, canhave very complex shapes thatscatter the GPR signals in alldirections, significantly reducingthe amount of signal reflectedback to the surface (Figure 1b).

Other factors are the velocity ofthe GPR signals within the caveand the height of the cave. GPRsignals travel in air at the speed oflight (0.3 meters or about 1 footper nanosecond) about 2-3 timesfaster than rock and about 9 timesfaster than water. This means thatif the cave is only a few feet high,the reflection from the bottomof the cave comes just a fewnanoseconds after the reflectionfrom the top of the cave. Thispotentially interferes with thebottom reflection and makesit difficult to interpret withconfidence (Figure 4). As theheight of the cave increases, or ifthe cave is full of slow-velocitywater, the signal takes longerto travel through the cave. Thereflection from the bottom of thecave will then separate from thereflection from the top, makinginterpretation easier. nn

Ask-the-Expert

Figure 1: The bottom of a smooth-bottomed cave is detectable but most caves have a complex shape thatscatters away the GPR signal before it can reach the surface.

Bottom of ice

Figure 2: The bottom of ice is usually a smoothboundary and gives a very clear and strong reflectionas indicated here.

Figure 3: The top and bottom of non-metallic pipesare analogous to a cave but regular in shape. In thisdata example, the top and bottom of a water filledpipe are detected.

Figure 4: The GPR reflected signal fromthe bottom of an air-filled cave is difficultto see in this example because thereflections and scattered response fromthe top of the cave interfere with andmask the bottom reflections. The twoevents are close together in timebecause the travel-time in the highvelocity air is so short.

Bottom of pipe

Top of pipe

Top of cave Top of cave

Bottom of cave?? Bottom of cave??

Figure 1a Figure 1b

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