GPR - project

[tesororockhound]

Seeker, I respect where you are coming from, but I think the whole point of this thread is to get the TH community together to build a working GPR. For example, I know a little about EE but my strong point is in Computer Science. I am willing to spend the time, which is a resource, putting together a computer GPR interface. Hopefully, if we get enough people together others can chip in or suggest corrections either to your GPR design or to the software.

By vaguely suggesting that others, who may not be experienced in EE, read through the thread and try to assemble the GPR, I think is counter productive. It would almost be like getting all the parts to a car and telling a non mechanically inclined person to assemble it with very limited instructions and knowledge.

Someone mentioned that they were knowledgable about antenna's, RF. If we all chip in and lay our cards on the table we can improve, and hone the design over time. At least that is my suggestion.

Otherwise, this noble project will fall to the wayside as others may not be knowledgable enough to assemble it, or inclined to pursue it if it seems the burden falls on a few people to accomplish the project.

[Unregistered]

Seeker,
I read a lot of articles about UWB GPR . But I have same problems . I can not build RF part .
And I decided that your project is more suitable for me for start. I can make transmitter and i have idea how to make antenna. The main difficulty is mixer. I have not any idea how to make PCB for SHF mixer. Can you explain in detail how to make it ?

[seagsm]

Seeker,
I read a lot of articles about UWB GPR . But I have same problems . I can not build RF part .
And I decided that your project is more suitable for me for start. I can make transmitter and i have idea how to make antenna. The main difficulty is mixer. I have not any idea how to make PCB for SHF mixer. Can you explain in detail how to make it ?

[Seeker]

Seeker,
I read a lot of articles about UWB GPR . But I have same problems . I can not build RF part .
And I decided that your project is more suitable for me for start. I can make transmitter and i have idea how to make antenna. The main difficulty is mixer. I have not any idea how to make PCB for SHF mixer. Can you explain in detail how to make it ?

Hi, UBW GPR is hard to do. You will need in some parts and instruments, which not be find easy.
So, to make mixer you mast find a splitter for satellite converter , to split signal between two receivers. It is from 900MHz to 2,1GHz, but still work up to 3GHz. Second thing is one old sat. converter for 5GHz or 10GHz band.
Inside you can find GaAs FET transistors.At last you need ferrite balun for output transformer.In fact you do not need PCB, you can solder elements on splitter board in box.Two F-connectors you can use for incomming signals,third for output signal, power supply mast get in through a duct capacitor.Incomming transformer is the same what is in splitter.Be very careful when solder FET's, they are sensitive on gate.The FET's mast be closely to the incomming transformer.

[seagsm]

Thanks Seeker . Now I understandhow to buildit. I will try.

[Unregistered]

GPR prototype

thank Seeker for all the info.
The RF part seems easy: 2.4GHz transmitter, power ampli,
diversion module , antenna.
RX: opposite polarisation antenna, mixer (from antenna and diversion module).
Now can we have some more info about "low frequency"
circuit? ( sensitivity, band-pass, etc)
PS I need to "see" only 20-30 cm inside a wall.
Any idea appreciated.
Thank to all
Paolo

[Unregistered]

High resolution -low range GPR

. Is your electronics sistem also adaptable for higher frequencies (higher resolution, lower range)? For uses like probing walls, etc..

Hi Leto,
are you working on something to see inside walls?
Paolo

[schatzsucher]

can i use an emp-source for transmitter?

[Seeker]

thank Seeker for all the info.
The RF part seems easy: 2.4GHz transmitter, power ampli,
diversion module , antenna.
RX: opposite polarisation antenna, mixer (from antenna and diversion module).
Now can we have some more info about "low frequency"
circuit? ( sensitivity, band-pass, etc)
PS I need to "see" only 20-30 cm inside a wall.
Any idea appreciated.
Thank to all
Paolo

Hi, for 20-30cm inside wall you can use 10GHz band for good resolution, the diagram is same as 2,4GHz. You can use modified sat. converter at 10GHz as TX .Output power is about 40-50mW , but it is enough to penetrate through concrete or stone up to 50 cm and return to RX module.
DARPA had some developments to detect people behind wall at 10GHz.
So, the "low-frequency" is function of deviation of TX by modulated frequency and form of signal. You can make experimen to define deviation and "low-frquency" in your case.

[Seeker]

can i use an emp-source for transmitter?

Hi, what is emp-source?

[Unregistered]

Hi, for 20-30cm inside wall you can use 10GHz band for good resolution, the diagram is same as 2,4GHz. You can use modified sat. converter at 10GHz as TX .Output power is about 40-50mW , but it is enough to penetrate through concrete or stone up to 50 cm and return to RX module.
DARPA had some developments to detect people behind wall at 10GHz.
So, the "low-frequency" is function of deviation of TX by modulated frequency and form of signal. You can make experimen to define deviation and "low-frquency" in your case.

Thank you Seeker.
I will try to use a "gunnplexer" from a motion control ( 10GHz ). There is a small problem : Tx and RX are complanar .

[schatzsucher]

Sorry, I can not read German.

thank´s at google
http://translate.google.com/translat...language_tools

or other translater-engien

[seagsm]

UWB radar

A practical hands-on description on how to build a prototype of an ultra wideband (UWB) radar
http://www.uniroma2.it/fismed/faculty/Stadero/papers/osee.pdf

[aft_72005]

Hi seagsm

Thanks for this link, seem as good practical
Idea in the matter.
Best regards .

[seagsm]

Ultrawideband Ridged Pyramidal Horn Antenna

Abstract:
We report the numerical analysis and experimental
characterization of an ultrawideband (UWB) antenna designed
for radiating short microwave pulses. The antenna consists of a
pyramidal horn, a ridge, and a curved launching plane ..........
http://www.engr.wisc.edu/ece/faculty/hagness_susan/li_IEEEAWPL_03.pdf

I think , we can use it for GPR...