some UWB GPR TX stage ideas

[Tepco]

Why this part of forum is so empty? For development of UWB GPR obviously some form of transmitter is needed. Generating nanosecond, or sub-nanosecond pulses whit high peak power and high voltage is not beyond reach of DIY hobby constructor. Actually, not more complex, expensive or part specific than Surf PI. (Maybe equipment can be to verify performances, but this can be handled somehow).

Here i put a small compilation of some (maybe) useful papers, dealing whit avalanche transistor pulser circuits, maybe interesting to someone.Good luck.

http://www.4shared.com/file/GI_aKbmq/UWBTX.html

(~3.5MB .zip)

[Mechanic]

Many thanks! I have been looking into gpr recently so I am trying to absorb as much information as possible.

Although I am not sure that it will suit my purpose(determining depth to bedrock)as the australian goldfields have a lot of clay layers, and after the rain we have had in recent times it will all be wet. I have seen a few articles that say that gpr don't like wet clay....

[Tepco]

No, GPR don't like anything wet really. This is just compilation of papers to give some idea, not part of any particular project etc. I built similar pulsers before, but for other purposes, never had time to play whit GPR (but now i have). My idea is to build some sort of "learning platform" and get some experience first. Point of this post is replacement of expensive and impossible to find SRD stuff whit 3¢ worth ubiquitous devices like 2N5551.

[Altra]

Did you guys see this thread? It looked interesting until they took it commercial. There are some photos of their circuit boards on the web page.

http://www.geotech1.com/forums/showthread.php?t=16559


Web page
http://www.pulsediscriminator.net/

Regards
Mark

[Mechanic]

Yep saw the thread, sent Anto an email about a week ago, no reply as yet
It was an interesting thread.
There would be a fair bit involved in making a gpr, especially on the software side of things.

[Altra]

Here's an easy to build UWB circuit. It won't penetrate the ground, but its a start. Maybe beef up the output? Even if it can't be worked into the bases for a GPR, I want to experiment with it. Lots of uses ie, motion sensors, distant measurements, communications etc. There is an engineer at the Lawrence Livermore labs named Thomas McEwan who has done a lot of work on UWB. If you search the patent database, he has about twenty patents with lots of schematics and theory.

Mark

[chand9091]

Nice post ...........

[Davor]

I have some experience with chirp sonar, and my strong belief is that chirp radar is the right way to proceed because of a direct conversion that results with (binaural) audio that does not require any computation at all, and best of all, resonant properties of antennas are almost completely irrelevant.