DISCRIMINATING SIGNAL PROCESSING

[Tinkerer]

Here is the RX and analog signal processing of the discriminating IB-PI.
It has been tested on the breadboard and gives good sensitivity and discrimination.
There are many things that can still be improved. I would love to hear constructive comments and suggestions.

Remember, this is an "OPEN SOURCE PROJECT". Anybody is free to copy, build, improve or distribute it. Its final quality will depend on the input from intelligent people from all over the world.

I am working now on the PCB layout.

Then comes the field testing.

Tinkerer

[Alexismex]

Hello tinkerer,
Please can you upload a better resolution of the schematic for experiment and contribute at the project
Thank you very much
Alexis.

[Helikeon]

Here is the RX and analog signal processing of the discriminating IB-PI.
Tinkerer

Hello Tinkerer,

I wish to construct this myself to see how it performs, but the schematic diagram is of low resolution (only 53KB) and I am unable to read the component values etc. when printed.

Is it possible for you to post another image please?

One which will fill a full A4 page when printed will be good, although I am able to convert the image to monochrome myself, if necessary.

Thank you.

[Tinkerer]

Discriminating PI

Hello tinkerer,
Please can you upload a better resolution of the schematic for experiment and contribute at the project
Thank you very much
Alexis.

Hi Alexismex

attached are the EAGLE files in ZIP. I hope it works.

Tinkerer

[Tinkerer]

TINKERERS_V1_SIGNAL PROCESSING PCB

Here is the TINKERERS_V1 signal processing board.

Tinkerer

[Tinkerer]

TINKERER_V1 DISCRIMINATING PI PCB

Here are the EAGLE files of the TINKERERS_V1 SIGNAL PROCESSING BOARD.

Tinkerer

[PICON]

Hi Tinkerer,

How is your IB-PI project going, is it at the testing stage yet? I haven't seen any posts for some time. Your project is an interesting design with the electronic adjustable coil balance.

Would the coil balance control need to be adjusted alot as you move across different ground? If so can it be made fully automatic by sampling the TX pulse height in the RX coil and get the micro to control the coil balance circuit to keep it at the correct balance.

I would like to see this project as a fully working detector. If you need any help with code writing, design, or just to bounce any ideas off me I am willing to help.

Best Regards
PICON

[Tinkerer]

Hi Tinkerer,

How is your IB-PI project going, is it at the testing stage yet? I haven't seen any posts for some time. Your project is an interesting design with the electronic adjustable coil balance.

Would the coil balance control need to be adjusted alot as you move across different ground? If so can it be made fully automatic by sampling the TX pulse height in the RX coil and get the micro to control the coil balance circuit to keep it at the correct balance.

I would like to see this project as a fully working detector. If you need any help with code writing, design, or just to bounce any ideas off me I am willing to help.

Best Regards
PICON

PICON,

thanks for the interest.

The TINKERERS_V1 has a manually adjustable Ground Balance and an automatic Ground Balance that works in tracking mode and automatically switches over to pinpoint mode with the presence of a target.

Very aggressive ground can overload the input. In this case, the balance of the coil can be adjusted to remove the overload and bring the balance back to within the limits.

Indeed I could use some help. The TINKERERS_V1 uses a lot of new ideas that would be best implemented in digital form. However, since I know next to nothing about programming, I could not explain the works to a programmer.
Therefore I implemented the design in analog form, where I can test everything and then better explain the various functions.

Basically, the TINKERER_V1 works fine. It is quite sensitive, has good depth and good FE discrimination.
There are many potentiometers, too many, the idea is to implement most of these functions digitally.
Just these days I made a major breakthrough with FE discrimination. As you probably know, there are some ferrous targets that are difficult to differentiate. Thin rusty steel sheet, bottle tops fall into this category.
I have now managed to obtain good discrimination on these targets also.

The TINKERERS_V1 is an "OPEN SOURCE" design. Free for anyone to copy, improve and build.

I would much appreciate your help.

Tinkerer

[mickstv]

Hi Tinkerer, I've been looking at building the signal processing section to use on my frontend, anyway I have a couple of questions because I'm not sure about the timing setup.

With the 3rd sample is it sampling the total receive period between TX pulses ?

With the ground balance sample and hold, does it have the same duration as the 3rd sample ?



Thanks
Mick

[Tinkerer]

Hi Tinkerer, I've been looking at building the signal processing section to use on my frontend, anyway I have a couple of questions because I'm not sure about the timing setup.

With the 3rd sample is it sampling the total receive period between TX pulses ?

With the ground balance sample and hold, does it have the same duration as the 3rd sample ?



Thanks
Mick

Hi Mick,

it has been some time since I worked on this project, so I need to revisit and try to remember how everything functions and what the purpose of each section is.

What do you use for the timing?

How is your TX?

What kind of coil do you use?

The Tinkerers is for IB coils. Ideally the samples should be easy to move around, earlier or later, to enhance certain features or attenuate other features.

For example, if you are searching for specific targets, you want to enhance the response of such kind of targets.
Now, if your site is littered with lots of rusty fragments of sardine cans or bottle tops, you want to enhance the discrimination of these targets so that you waste less time on digging.

All the best

Tinkerer

[mickstv]

I've actually been messing with one of moodz earlier versions of the diff coil frontend. So it's a diff coil with a That1510 amp supply is 9 volts for the TX and +/- 5 volts for the amp etc.

The timing is based on 555 timer for TX then the samples are produced with 74hc221's. I've got three sample outputs setup so far.

Once finished I'll be testing in the golden triangle, if I can get it finished before Christmas Holidays.




Mick

[Tinkerer]

I've actually been messing with one of moodz earlier versions of the diff coil frontend. So it's a diff coil with a That1510 amp supply is 9 volts for the TX and +/- 5 volts for the amp etc.

The timing is based on 555 timer for TX then the samples are produced with 74hc221's. I've got three sample outputs setup so far.

Once finished I'll be testing in the golden triangle, if I can get it finished before Christmas Holidays.




Mick

Is your UNIPI working? if it is, it would be better to use that for the timing.

You can start with the following sample sequence and see how it works out. It depends a lot on the coil configuration.

The sample gold, is about 5us after TX switch ON, about 10us sample time.

The sample FE is also about 10us duration, just before TX switch ON.

The sample ALL, is about 15us after switch OFF, the same 10us duration.

The sample GB is taken about 15us after switch OFF, 20us duration. This sample samples the sum of the other 3 samples.

On the sample FE there is a pot, to scale the sample. You can put pots on all 3 samples to give more possibility to enhance or attenuate the signal of any of the samples.

Tinkerer

[mickstv]

Is your UNIPI working? if it is, it would be better to use that for the timing.

You can start with the following sample sequence and see how it works out. It depends a lot on the coil configuration.

The sample gold, is about 5us after TX switch ON, about 10us sample time.

The sample FE is also about 10us duration, just before TX switch ON.

The sample ALL, is about 15us after switch OFF, the same 10us duration.

The sample GB is taken about 15us after switch OFF, 20us duration. This sample samples the sum of the other 3 samples.

On the sample FE there is a pot, to scale the sample. You can put pots on all 3 samples to give more possibility to enhance or attenuate the signal of any of the samples.

Tinkerer

Hi Tinkerer, the UNIPI is working but only has two sample points so I decided to use the 74HC221's for the first version. Once I've got it working I'll move back over to a micro.

Thanks for the timing info. I'll let you know how I get on.



Mick

[Tinkerer]

Hi Tinkerer, the UNIPI is working but only has two sample points so I decided to use the 74HC221's for the first version. Once I've got it working I'll move back over to a micro.

Thanks for the timing info. I'll let you know how I get on.



Mick

If you show me an oscilloscope picture with the complete cycle RX signal wave form, I can help you adjust the sample timing for best discrimination results.

Do you have a functioning hex file for the UNIPI? The ones I downloaded from the forum, do not work for me. I am still trying to use the dsPICF4012. Once I have this one running OK I want to try the dsPIC4011 that has the 4 sampling pulses.

Tinkerer

[mickstv]

The one currently loaded is at the link below, remember to do the 10mhz crystal mod to make it run. The crystal goes across pin 9 and 10 and two 22pf capacitors from each pin to ground. Also you have to remove the satlock circuit and pullup resistor from pin 10.

http://www.geotech1.com/forums/showp...7&postcount=67


Here are the output pictures the first one is 100us per div and the bottom is 50us per div to give you a better look at the output of the THAT1510, the rails as mentioned before are 9 volts for the TX and +/- 5 volts to run the amp etc. It also has a separate +5 volt reg for the logic circuits.




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