GPR - project

[Davor]

With a chirp radar you may drop components 2 and 3, but don't tell anyone

[Bigstarman]

No, no, no!
Believe me, it's still very early.
For many years I taught GIS operators and create programs. If the @$$ to give the coolest PC with the most clever software, nothing good will come of it.

[jant1962]

GPR home
GPR technology requires a deep understanding of the engineering principles involved, and you should be able to design equipment that meets your purposes. The cost and quality are difficult obstacles to overcome to make a home GPR. Radiation is a dangerous element in this appliance.


home design
You can remove a magnetron oscillator and a microwave generator and place it in a waveguide with the size that provides the required wavelength, as well as width and depth. Fed with a car alternator or other generator type antenna can be used as receiver and transmitter. The receiver must connect to the GPR software on a computer or a tablet by a analog to digital converter.

[moodz]

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.
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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

... GPR ... a very interesting subject .. but how to investigate on the cheap ???

only need say from 300 Mhz to 1.5 Ghz anything else wont penetrate the ground or lack resolution.

.. ha ha ... ebay has everything you need.

RX is the hardest bit ... but wait ... theres one for less than $10 and does 24 Mhz to 1.8 Ghz



How cheap is that ?

and the software is open source and free !!! ( needs a little bit of coding on your part )



This is a wide band radio with I Q sampling ( so you can detect phase ) and you can run lots of them off the same computer through USB bus.

The TX is simple compared ...

GPR EMISSION CHARACTERISTICS


The FAA tested a GPR with six interchangeable antennas that are centered on frequencies 300, 400, 500, 900, 1000, and 1500 MHz.

The GPR tested produces a signal with a specified pulse rate of 85 kHz peak and a specified 64 kHz average pulse rate. A transmitter is contained within the housing of each antenna. The largest antenna (300 MHz model) has the following emission characteristics (as provided by the GPR operator’s manual):

Radiated peak power: 1.0 watt
Radiated average power: 0.20 watts
Approximate radiated average power per MHz: 0.65 Microwatt/MHz
Approximate center frequency: 300 MHz
Approximate pulse duration: 3 nanoseconds
Approximate bandwidth +/- 50%. (i.e. +/- 50% x 300 MHz = +/-150 MHz. Total 10 dB bandwidth of 300 MHz.)





There ... I have done the heavy lifting for you .. only needs polishing.

Come on you gurus .. what can you do ?


moodz

[Orbit]

-- switch for gpr or magnetometer ,transmitter receiver 2.5ghz software = https://www.youtube.com/watch?v=31RM...U&spfreload=10 ..https://www.youtube.com/watch?v=aKP6...U&spfreload=10