GPR - project

[ali_cmi]

I read the whole thread but being a Bachelors student, I got about 20 % of them. If you have any idea about it then please share.

Here's what I posted in several forums in search for answers. It explains what I require.

Thanks for replying.

"Hello,
I am a final year student of BEE Telecom. I chose my Final Year Project to design a Transmitter and Receiver for GPR. GPR has already been developed in my institute. It uses VNA (Vector Network Analyzer) as its source.

Some features of that project are:
-> Double-Ridged Horn Antenna
-> Synthetic Aperture Radar (SAR) with UWB source (VNA) in Mono-synthetic mode
-> Only s11 (first parameter of s-parameters) was measured by VNA
-> 2.4 GHz center frequency with 1 GHz Bandwidth---a pulse with 1 ns duration transmitted by a Stepped-freqeuncy transmitter
-> Tx and Rx are in VNA
-> Only Return Loss measurements are observed
-> Data from VNA is processed in Matlab to create a rough image of observed reflections

I hope the data above is enough for you to get the idea. I have just started working in the project

Since VNA is a multipurpose device and the already-implemented project used it to find S11 only, I chose this project to introduce portability in GPR. (VNA available in my institute is bulky)

In short, my goal is to develop a Tx and Rx which function as the VNA does; thus introducing portability.

The problem is that I have no idea where to begin. I need a head start. I need to develop complete understanding of how the Stepped-Frequency Transmitter (used in already-developed project) and compatible receiver works and I have to develop the whole system without changing other features like antenna, codes etc.

Please guide me and point me in the right direction.

Regards. "

[Overtheedge]

Well, read all the posts and I just don't see it happening. Among the reasons there is lack of knowledge and experience with UHF/microwave construction and design.

Might I suggest you find a ham operator active on the microwave bands. Most of us build or modify our equipment.

No matter what approach you use, you are stuck with physics. Low freq gets ground penetration, but no resolution. High freq just the opposite.

Forget inexpensive Gunn devices as they are real low power and don't hold up well to high power pulsed work. Impatt diodes are probably a better choice as they use higher voltages ergo less amperage per watt. The X-band Impatt module I have on the rack uses about 100VDC compared to the 7-8VDC my Gunnplexers use.

Nothing wrong with direct conversion aka homodyne receivers.

You might consider the guts from a recording fish-finder as the display device. With a few changes, the pulse timing circuit could be used for triggering the transmitter.
-----------------------
Look, I have no doubt you folks know metal detectors. That is why I read your posts; to learn from you. My electronics background is military RF communications repair and amateur radio.

So you might wanna use your MD knowledge and make a UHF/microwave metal detector using the same concepts as a mix of PI and RF. You'll need to learn some stuff about how RF acts at UHF/microwave frequencies: ie. even the PCB traces are frequency determining devices either as a tuned circuit or chokes. Often when you don't want them to be.

The Radio Society of Great Britain has some great books available on microwave design and construction. There are several amateur radio vhf-microwave societies in the US that publish annual proceedings with lots of neat stuff.

Oh, and don't forget that the US military (and probably NATO and the old Soviet Union) has/had UHF metal detectors. The schematics are available. The ones I'm familiar with, AN/PRS-7, (first hitch in army was field radio repair, second was combat engineer aka sapper) detected voids that were indicative of the old soviet non-metallic box mines.

My only experience with radar was the old AN/PPS-5 ground surveillance radar. It was doppler only and a real dog. Used a pencil triode for RF. A simple gunnplexer could do the same job better and cheaper.

If you are interested in the AN/PRS-7, the tech manual was on the web; TM 5-6665-293-13.

I'm NOT the MD expert. You guys are compared to me. But I am pretty good at RF from DC to 24GHz. But most of my test equipment poops out at 12.4GHZ.

Oh well. Consider this post an opinion and worth exactly what you paid for it.
eric

[zixelll]

Hello friends who completed the circuit with its software has the gpr Thank you so much for sending me [email protected]

[gadgetmaker]

Why don't you guys just bu an EASYRAD unit for 2700EURO; it looks like a good unit for the money.......

[Auftragssucher]

EASYRAD GPR V2

Why don't you guys just bu an EASYRAD unit for 2700EURO; it looks like a good unit for the money.......

It IS an good device! I tested it several times and it makes a good Job! And it is absolutely affordable! Look here: www.easyrad.de (German Website!) and here the last test-results: http://easyrad.de/pages/produktdaten/testberichte.php

[gadgetmaker]

Auftragssucher, I am working with Krasimir and Anton on a shielded 400 MHz antenna system and cart. I am using a modified self grounding bowtie antenna that has 6-7 db of gain and the enclosure uses both lossy foam and ferrite tile absorbers. Please let me know the best way to contact you directly. I am located in Arizona. Karl

[NIKOLLS]

Dear colleagues! There Is a continuation at this remarkable on the simplicity and originality of project P.Stephens (http://letitbit.net/download/48235.4...ens.pdf.html)? It would be desirable to learn about the program of reception and decoding of the data received from system, executed on PSoC CY8C27443. With deep respect NIKOLLS.

[Predrag]

Could be useful...

http://www.gichd.org/fileadmin/GICHD...shi_thesis.pdf

[Davor]

Hvala

[niku211x]

Could be useful...

.......the sampler of the videoplus georadar...............
http://www.google.ro/url?sa=t&rct=j&...82001339,d.d2s

[Clif de Chim]

Hi, everybody!
I have a little question ... What are, in your opinion, the characteristics of a good GPR? And why? The fact is that I find myself in need of buying one for a project, but I have some doubts, as you have experiences in this area I think you can help me.
Thank you!
I look ...

[Davor]

First and foremost - a high contrast display for direct sunlight conditions. Of course it must actually work, but that's not what you had on mind.
Stay away from gadgets you need to tweak on the go, as those are just distracting. Also make sure you are comfortable with the mode of transferring measured data for later use - if any.

[Clif de Chim]

Thanks, Mr Davor!
But do you have any one that you could propose me? It's about a mining project, so something that can give me a good idea of the subsurface, I mean helping me save time by leading me to the right place where the products are located, when it will be matter of drilling.

[Davor]

I'm not sure GPR is optimal technology for mining. If it goes deeper than 10m and if it involves similar materials, you'll hardly find anything with GPR.

[Bigstarman]

Modern GPR is a complex of three components - radar, computer & specialized software and a competent & experienced operator.
From this complex it is impossible to drop any components.