Sonar for treasure hunting.

[Geo]

Hi.

Before some days a person show me a device (handmade) who he said that it is a sonar. It has the ability to detect all metals in the ground(no discrimination) at some meters depth (he told me for 20m depth but i don't believe him) and about 20 meters long....
The strange is that it don't detect any object at air. I tried to measure at what frequency it transmmited but no results. I used to measure the frequency a small coil loop connected to the oscilloscope, a transduser and a microphone.
Has anyone any idea how to measure the frequency of it???
PCB is fixed with glue so i can't do anything else.

Regards

[Krzysztof]

Hi Geo.
Expect to digital broadcasting (something like Ground-Penetrating Radar.)
Give a small coil measurement, digital oscilloscope good quality and memory. I think that a minimum of 100 Ms/s or better.
There are 2 ways:
1. Transmission 50MHz<f<500MHz for a 1 millisecond and pause tens of milliseconds.
2. Short one-shot (as in PI), and break a few dozen milliseconds.
In both methods, the device waits for a response. I do not have to be LCD.
The ordinary oscilloscope did not even go near, so hard to scientists today (reverse inginiering).
Give some details and photo ...
How do wonder transmits waves towards the earth?
Size of coil will provide a range of frequencies. How many coils 1 or 2?
Best regards.
Chris.

[Qiaozhi]

Hi.

Before some days a person show me a device (handmade) who he said that it is a sonar.

If it's sonar, then you might be able to "hear" it using a bat detector.
http://pw1.netcom.com/~t-rex/BatDetector.html

[Rov]

Maybe Long wave reception only.as per ground an sea.Low HZ.an the specialised recievers required.

[Geo]

Hi.
I will try to draw it. Next time who i will see it i will take some photos.
There are two sensors (no coils), one inside a plastic window and the other outside of the box conected through a cable.

Regards

[Geo]

Sonar is closed to this shema...

[Geo]

If it's sonar, then you might be able to "hear" it using a bat detector.
http://pw1.netcom.com/~t-rex/BatDetector.html

Hi Qiaozhi.
I tried with a transduser connected to the oscilloscope but no input signal. I have the scope at 2mv/div. Maybe the signal to be lower. If yes then i must make the Batdetector.
Regards

[Geo]

Hi Geo.
Expect to digital broadcasting (something like Ground-Penetrating Radar.)
Give a small coil measurement, digital oscilloscope good quality and memory. I think that a minimum of 100 Ms/s or better.
There are 2 ways:
1. Transmission 50MHz<f<500MHz for a 1 millisecond and pause tens of milliseconds.
2. Short one-shot (as in PI), and break a few dozen milliseconds.
In both methods, the device waits for a response. I do not have to be LCD.
The ordinary oscilloscope did not even go near, so hard to scientists today (reverse inginiering).
Give some details and photo ...
How do wonder transmits waves towards the earth?
Size of coil will provide a range of frequencies. How many coils 1 or 2?
Best regards.
Chris.

Hi Chris.
I believe that it uses transdusers as sensors, so the frequency is low...

Regards

[Geo]

Maybe Long wave reception only.as per ground an sea.Low HZ.an the specialised recievers required.

Hi Rov.
Can you explain more????

Regards

[Krzysztof]

Hi Geo.
Again, two possibilities
1. If the transducer looks like an electret microphone, you do BAT detector.
2. If sealed, lightweight, it can be gradiometer. Then you are looking for 50-100kHz by inductive coupling (near the coil).
Best regards.
Chris.

[ApBerg]

Hi Qiaozhi.
I tried with a transduser connected to the oscilloscope but no input signal. I have the scope at 2mv/div. Maybe the signal to be lower. If yes then i must make the Batdetector.
Regards

Hello Geo,

If it is a Bat detector..... take some key's rattle with them, in that sound are a lot harmonics, this make's a bat detector go nuts...

Best regards

Ap

ps. if someone wants to make a bat detector let me know...some years ago I found one circuit that works nice ..I think...

[Geo]

Hi Geo.
Again, two possibilities
1. If the transducer looks like an electret microphone, you do BAT detector.
2. If sealed, lightweight, it can be gradiometer. Then you are looking for 50-100kHz by inductive coupling (near the coil).
Best regards.
Chris.

Hi Chris.
The problem is that i tried both methods.... with a coil near to sensors and with a transduser ( and a microphone) near to both sensors but without results..

Regards

[Geo]

Hello Geo,

If it is a Bat detector..... take some key's rattle with them, in that sound are a lot harmonics, this make's a bat detector go nuts...

Best regards

Ap

ps. if someone wants to make a bat detector let me know...some years ago I found one circuit that works nice ..I think...

Hi Aq.
If you will find the schematic of the bat detector you can attach it here so to see it.

Btw....
Who is your opinion in order to we draw a metal detector supported in acoustics frequencies??

Regards

[ApBerg]

Hi Aq.
If you will find the schematic of the bat detector you can attach it here so to see it.

Btw....
Who is your opinion in order to we draw a metal detector supported in acoustics frequencies??

Regards

Hello Geo,

Found the schematic from the batdetector...

I never have seen an acoustics detector that can see so deep in the ground....I think a heavy power is needed for the energy that is needed to go so deep ??

Best regards.
Ap

[Krzysztof]

Hi Geo.
A bit different translator today.
1. Notice, that the method of USG ( the transducer) it loses on crossing through two zones about large difference of thickness signal very a lot of.
Reflection on border of zones the wave.
Sonar in water has only one zone!
In medicine on USG gel patient be greased - one zone!
2. was this if would gradiometr type MI (magnetoinductive), (eg. FMG3) this also hard from far to measure from internal core the inductive field of small coil, 50kHz, working with current 1mA .
Write what weight of one sensor ( very light / light / heavy)?
What weight of gun - this depends from the power supply.
The battery of type 6F22 - 9V will not permit on work with large current! Battery 12V (0,5 kg and heavier) GPR suggests.
The Sensor in figure of coil from the ferite core length 5cm and the VLF more suggests the method.
You have choice now - what were Your feelings?
Best regards.
Chris.