looking for home-made G.P.R.

[Dirk]

sampler

Hi

My english is not good too. So I attach two files.
I think you use a samling strategy like (b) not like (a).
In case (a) you would need a ADC with giga samples
per second (Gsps) in case (b) only kilo samples (ksps).
(c) i think schows the function of of the Sampler, so
In your block diagram the graph shows not the true
behavior at the output of the sampler. The signal is
not spreaded analog (continuously in time and value)
from 60ns to 55ms.

Best regards

[Valchev]

It is stroboscopic metod. Example is with 10 pulses to be simple, realy it is many many more. It is no my idea, it is а classical metod. And output pulses form is ideal. Conversion time of PIC is < 0.020mS, Out puls is 55ms.

[Dirk]

Sample

Hi

That is what I think that it is.

Best regards

[Unregistered]

petar valchev,

your email address seems not working...do you have any other contact address?

gen

[Valchev]

Hi,
[email protected]
[email protected]
( [email protected] )

[Unregistered]

thanks....
your two email worked...i sent u...email....

gen

[Unregistered]

petar valchev,

to my recollection, i was the one who started this topic...looking for home-made gpr....because the gprs, the commercial gprs are too expensive.....very glad that u made one......

Peace!

gen

[Valchev]

Test

GPR - EXPERIMENTAL TEST RESULT
Cave ( width 0.4meters, length 0.8m, height 0.25m ) in a dry soil 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. Plan of cave
2. Photo
3. Radargram

[Valchev]

Link

Link

Detection of Buried Agricultural Drainage Pipe
Using Conventional Geophysical Methods

B. J. Allred, N. R. Fausey, L. Peters, Jr., C. Chen, J. J. Daniels, H. Youn

........ As an overall goal, this investigation focused on extensive testing of four conventional geophysical methods, geomagnetic surveying, electromagnetic induction, resistivity, and ground penetrating radar, to determine which was most efficient and effective in detecting buried agricultural drainage pipe...........

http://www.geology.ohio-state.edu/~j...cs_Paper_1.pdf

.......... Ground penetrating radar (GPR) was the only geophysical method of the four tested during this phase of research that had success in detecting buried drainage pipe.............

[Valchev]

GPR depth according to EuroGPR trade association:
http://www.eurogpr.org/factsheet.htm#

click on
No1 Introduction to GPR

[schatzsucher]

do you have to exchange interest more gradiometer for gpr?

[Valchev]

Excuse Me, I have no interest.
I do not offer or sale schematics.

[romtech]

The best article on building a GPR unit:
http://www.ece.jhu.edu/~pps/ECE777/A...RS/p520580.pdf

This really details some of the problems.
I don't see how I could build one cheaply.

Comments please.

[Valchev]

Home made cheap Ground penetrating radar

Good pdf.
The pulse generator from p520580.pdf is suitable only for a UWB radar(in air).
If you wish GPR to work on not completely flat ground surface, must to use pulse generator from hundreds volts to kilo-volt.
If I do not make mistake Figure 14 is not the right schematic to use a RF mixer as a sampler.
You can make good cheap Ground penetrating radar with cheap elements, without DSP and MC100EP196, but you will have more difficultys to design and adjust.
To design a GPR most expensive is the time. If you have not the big team of professional engineers you will need years.

[romtech]

Design Pulse circuits

The hardest part for me would be generating the precise sampling pulses.
Any jitter in the pulses would destroy the signal.
For the time scales involved, I would need sampling pulses under 1 ns, maybe a few hundred ps in width. I wouldn't know how to start doing this.

I guess you could switch hundreds of volts with special mosfets. Kilovolts might require capacitive discharge into special pulse transformers and pulse forming circuits. This would be another job that I would need to hire and Electrical Engineer to get done.

I've seen GPR units that are just under $10,000.
Spending $10,000 to $20,000 might be the cheap way to go.

Thank You for your input.