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This ground penetrating radar (GPR) has been designed specially for treasure hunting. The GPR can find subsurface
heterogeneities, such a cavities, tunnels and other objects. All GPR are excellent to survey in rocks and sands, good in rather dry
soils without clay, and useless in soil with clay and wet soils .The obtained information immediately appears on the laptop display.
The GPR can find good, subsurface cavities larges than 1metre x 1m x 1m, with an almost flat ceiling. Smaller objects will be found
with difficulty and not so deeply. The laptop can be any , with Windows XP or Vista, and USB port , 1.4GHz or more.
The GPR can to be carried by a single operator. In the sounding process, the operator is getting real-time information as a
radiolocation profile (radargram) on a display (on a notebook). The GPR draw the radargram for 60 seconds (in this time operator
can see the received part of the radargram) , after that operator can record it on a hard disc with any name for further use, or/and
start new. The GPR can scanning with the time window(time that gpr receive after transmit pulse) 50nS, 100nS or 200nS.
Wen the operator carry the GPR, antennas must be from 5 to 20 centimetres over the ground surface. Distance between antennas
can be from 0.5 to 1.5 metre.
The antenna system is dipole, unshielded, air coupled.
Antennas:
75MHz - length-1,5m, depth-6m, resolution-1.5m Current consumed - 0.3A from 12V battery
100MHz - length-1m, depth-5m, resolution-1m Weight - kg 4 with battery
150MHz - length-0,75m, depth-4m, resolution-0.8m More suitable is antenna 100MHz
250MHz - length-0,5m, depth-2m, resolution-0.5m
350MHz - length-0,3m, depth-1.5m, resolution-0.3m
Depth - detection depth - Distance between ceiling of a cave in rock(limestone) and ground surface . If a ceiling is flat and
cave=4x(Antenna resolution) . Depth is dependent on the parameters of the rock or soil.
Manufacturers advertise for similar antennas 150Mhz depth from 7m to 10m, but with a small letters write 'Depth of investigation is
understood to be detection depth of a flat boundary with reflectance equal to 1'. But reflectance equal to 1, have only metal flatness
4m X 4m, or a lake bottom. A cave in limestone or dry Soil, have reflectance equal to 0.4 and then 10m x 0.4=4m, but it is true if the
cave is big and have a flat ceiling.
The examples below are real and everyone can test it.
Examples:
1. Photo and result of a little cave: width 1.5m, length 2m, height 0.8m, the ceiling is 1m deep from the surface.
2.Photo, result and plan of the cave: width 1.5m, height 1.8m, the ceiling is from 1.2m to 4m deep from the surface.
position a - the ceiling is 2m deep from the surface
position b - the ceiling is 2.2m deep from the surface
position c - the ceiling is 3m deep from the surface
position d - the ceiling is 4m deep from the surface
Position d - width 3m, height 2m, the ceiling
is 4m deep from the surface.
GPR - EXPERIMENTAL TEST RESULT
Cave ( width 0.4meters, length 0.8m, height 0.25m ) in a rather dry soil without clay on the depth 0.5m , covered with a plastic
flatness 0.9m x 0.5m x 5mm - non conductor , (tested that GPR can not detect the flatness in air, can not detect difference
between air and flatness)
antenna - 300 MHz
time window - 50 nS
1. Photo
2. Plan of cave
3. Radargram
3. GPR cross section of the ground structure and photos:
terrain - before digging
terrain - after digging
terrain- after digging, with light brown layer, from 1 to 2 meters deep
Download software (Windows demo version) http://gpr.hit.bg/GPRdemo.sfx.exe
To see more videos and photos click on:
https://www.youtube.com/profile?user=valchevgpr#g/u
http://s237.photobucket.com/albums/ff305/valchevgpr/Ground%20penetrating%20radar%20GPR/
With the GPR you will be able to detect cavities in rock or sands with dimensions width Xm, length Xm, height Xm at a depths
2*Xm. As an example if a cave have width 2m, length 2m, height 2m and flat or oval ceiling, the GPR will can detect the cavities
on depth 4m in rock.
The GPR can detect cavities in rather dry soil without clay with dimensions width Xm, length Xm, height Xm on depth Xm. As an
example if the cave have width 2m, length 2m, height 2m and flat or oval ceiling, GPR will be able to detect the cave on depth
2m in soil.
m=metrŠµ
If the ceiling is not flat or oval, or is acute, the depth is smaller.
When the soil is wet, the depth is smaller. In practice it is very difficult or impossible to predict how deep GPR can see in soil
because it is depend from soils characteristics. More about factors influencing the penetration depth of GPR you can read from:
http://soils.usda.gov/survey/geography/maps/GPR/methodology.html
GPR Pitfalls - http://mysite.du.edu/~lconyers/SERDP/gpr_pitfalls2.htm
Guide to Interpreting Radar Profiles - http://nesoil.com/gpr/profiles.htm
Since 04-20-2009 the depth is increased 20% for big objects and 50% for small objects.
Since 01-06-2010 the software is upgraded , added the gray scale mode, time window 25nS and speed control .
On the next pictures can to seen the result from detecting a metal plate 60x15mm in concrete depth 15cm with High frequency
GPR - antenna 1.6 GHz .
Coloured mode Gray scale mode
| The same test with windows based software Positions A C D |
| High frequency GPR and antenna 1.6 GHz http://hfgpr.hit.bg |
More information will be added later
Since 01-06-2010 the GPR is upgraded , added the buttons for start and stop survey .
See video https://www.youtube.com/profile?user=valchevgpr#p/u/1/Sk4iv9t7A24
.
NEW
400MHz shielded resistively loaded bowtie antenna
https://sites.google.com/site/vgeoradar/home/400mhz-shielded-antenna
In the "WORLD ATLAS OF GROUND CONDUCTIVITIES"
http://hamwaves.com/antennas/gnd-sigma/vlf_mf_ground_conductivity_atlas.pdf
you can to see if your region is suitable for GPR survey, if a GPR will have good depth.
If ground conductivity is less than 1mS/m the conditions are perfect.
If ground conductivity is less than 5mS/m the conditions are good.
If ground conductivity is more than 10mS/m , GPR will be useless in this region , you can to use a GPR only on rocks
in this region.
A copy of my GEORADAR equipment is provided to the
Geoteam at the Faculty of Physics and Engineering
Technologies of Plovdiv University 'Paisiy Hilendarski'. Find
details here http://geo.physics.uni-plovdiv.bg/pvgpr.htm
| New Multi electrode resistivity meter https://sites.google.com/site/resmeter/ |