How to improve my Surf PI 1.2 for a mission like this: Underwater search for iron/steel solely

[Loola]

U1 (555) is the TX oscillator. You could change R1 (100k) to 180k, and R2 (3k3) to 22k. This will give you a TX pulse width of 332us and a transmit rate of 329pps. Alternatively, replace R1 and R2 with trimmers, and adjust the values to get exactly what you want. However, the Surf-PI also uses the TX oscillator to generate the audio tone, which is 623Hz, so the audio tone will be much lower if you change these components.

I don't know the maximum sample delay setting on the Surf-PI, but this is adjusted by P2 (100k). You may have to change the values of P2 and/or C9 to achieve 100us.

Otherwise, have a look at Minipulse Plus Rev-E, which already has on-board trimmers to allow independent adjustment of the PX pulse width and transmit rate. There is a separate VCO audio oscillator, which means that the audio tone will be unaffected.

Qiaozhi
This was valuable info for this project. Many thanks.

[Loola]

mine coil 1mx1m was esp-ly projected for seach in winter time and in summer time on boat drilling (you know this small resine fishers pumping boats).
write if you need more winter pics.

Kt315

Thank you for the book tip! I will look it up.

Aha, was you walking on ice and searching on the bottom?
If so, what was the maximal depth of water that you were able to get signals?
I live in the northern part of Sweden and we have frozen lakes and rivers at winter.
So it would be a good option on searching at bottoms. Interesting certainly. If my assumptions are right there is.

[Qiaozhi]

As for pulse delay and TX width, I will try those numbers. But at this moment my lack of knowledge on how to adjust TX width on the Surf PI 1.2 keeps me from trying that.

U1 (555) is the TX oscillator. You could change R1 (100k) to 180k, and R2 (3k3) to 22k. This will give you a TX pulse width of 332us and a transmit rate of 329pps. Alternatively, replace R1 and R2 with trimmers, and adjust the values to get exactly what you want. However, the Surf-PI also uses the TX oscillator to generate the audio tone, which is 623Hz, so the audio tone will be much lower if you change these components.

I don't know the maximum sample delay setting on the Surf-PI, but this is adjusted by P2 (100k). You may have to change the values of P2 and/or C9 to achieve 100us.

Otherwise, have a look at Minipulse Plus Rev-E, which already has on-board trimmers to allow independent adjustment of the PX pulse width and transmit rate. There is a separate VCO audio oscillator, which means that the audio tone will be unaffected.

[kt315]

[kt315]

ok. still pics from winter amigo!

[Loola]

bom bom bom. ITMD? did your read HH article?

'tuned' is if you CAN control the width operatively by a pot on your housing panel. ie not fixed.

Read the ITMD? No!
Can that be managed with the Surf PI 1.2?
If so, where and what to connect to the PCB?

[Loola]

I used to make a diver held detector called Aquatec. The pulse delay was set at 100uS and TX width 350uS. Many of these detectors were sold to the offshore industry to locate tools dropped from drilling platforms; capped off wellheads that were buried under sand waves in the North Sea; lost anchors and anchor chains; iron cannons and cannon balls; lost outboard motors etc etc. It would of course detect large non-ferrous items but nothing small. Also, longer delays make the detector less responsive to the surrounding sea water.
For pure ferrous only detection a diver held magnetometer is best.

Eric.

Ferric Toes
This is for sure useful information. To hear it from someone who actually have worked with this. Happy, happy, happy, thank you very much.
As for pulse delay and TX width, I will try those numbers. But at this moment my lack of knowledge on how to adjust TX width on the Surf PI 1.2 keeps me from trying that.
About magnetometers, I have done some fruitless experiments with that. I to, think that this would be the preferred technique to use.
Do you know of any DIY project in this matter? Preferably a soldering kit.

[kt315]

mine coil 1mx1m was esp-ly projected for seach in winter time and in summer time on boat drilling (you know this small resine fishers pumping boats).
write if you need more winter pics.

[Ferric Toes]

I used to make a diver held detector called Aquatec. The pulse delay was set at 100uS and TX width 350uS. Many of these detectors were sold to the offshore industry to locate tools dropped from drilling platforms; capped off wellheads that were buried under sand waves in the North Sea; lost anchors and anchor chains; iron cannons and cannon balls; lost outboard motors etc etc. It would of course detect large non-ferrous items but nothing small. Also, longer delays make the detector less responsive to the surrounding sea water.
For pure ferrous only detection a diver held magnetometer is best.

Eric.

[kt315]

bom bom bom. ITMD? did your read HH article?

'tuned' is if you CAN control the width operatively by a pot on your housing panel. ie not fixed.

[Loola]

Kt315

How do I adjust pulse width and specially an increase off it, on the Surf PI 1.2?
And what do you mean with ”tuned”?

Thanks for your info

[kt315]

I will do adjustment to sample delay
---
you may take a data from deepers. delta pulse has first sample delay width from 40 to 160us.
pulse width from 120 to 500us tuned.

[Loola]

Qiaozhi

Okay, I will do adjustment to sample delay to see what changes it makes.
I do not have the opportunity to do it now, but in the near future I will.

Thank you.

[Loola]

green

Nice graph. Interesting for sure. A little over my head though. But I guess that your kind of knowledge is what is needed here. Thank you.

[Loola]

kt315
Nice! Now you got me thinking .................. But no, I will start with a handheld detector.