EPE resistivity logger

[rael]

Hi Ivica,

The "magic" 137.5 Hz /2.75x50Hz/ is most popular frequency used in Lock-In Amplifier based RM systems.
This frequency provides very good rejection of 50Hz.
The RM85 resistance meter use the following operating frequencies:
17.5, 20, 22.5, 35, 40, 72.5, 80, 85, 90, 122.5, 137, 140, 142.5 Hz.
Frequence = k x 50Hz.
k = 0.35, 0.4, 0.45, 0.7, 0.8, 1.45, 1.6, 1.7, 1.8, 2.45, 2.75, 2.8, 2.85

Frequencies provides rejection of 60Hz.
21, 24, 27, 42, 48, 87, 96, 102, 108, 147, 165, 168, 171Hz.

RM85 Resistance Meter by Geoscan Research
http://www.geoscan-research.co.uk/RM...Data_Sheet.pdf

[ivconic]

Hi Ivica,

The "magic" 137.5 Hz /2.75x50Hz/ is most popular frequency used in Lock-In Amplifier based RM systems.
This frequency provides very good rejection of 50Hz.
The RM85 resistance meter use the following operating frequencies:
17.5, 20, 22.5, 35, 40, 72.5, 80, 85, 90, 122.5, 137, 140, 142.5 Hz.
Frequence = k x 50Hz.
k = 0.35, 0.4, 0.45, 0.7, 0.8, 1.45, 1.6, 1.7, 1.8, 2.45, 2.75, 2.8, 2.85

Frequencies provides rejection of 60Hz.
21, 24, 27, 42, 48, 87, 96, 102, 108, 147, 165, 168, 171Hz.

RM85 Resistance Meter by Geoscan Research
http://www.geoscan-research.co.uk/RM...Data_Sheet.pdf

Thanks for the info!
I'll see what Atmega will be able to produce from those using same timer and same prescaler.
I think codding will be easier part than drawing noiseless pcb.

[rael]

I have no experience with Atmega. This is the part from my program for timer control of PIC18 uC.


#include <18F46K20.h>
//???????..
#define XTAL_FREQ 44236800 // OSC freq in Hz //4x11.0592 MHz
//???????..
#INT_TIMER0
void timer0_interrupt()
{
set_timer0(timer_freq);//
output_toggle(PIN_B2) ; //TX FREQUENCY
}
//???????..
setup_timer_0(T0_INTERNAL|T0_DIV_; // 16 bit timer
//???????..

switch (TX_FREQUENCY)
{
case (1):
timer_freq=26038;//17.5Hz
break;
case (2):
timer_freq=30975;//20Hz
break;
case (3):
timer_freq=34815;//22.5Hz
break;
case (4):
timer_freq=45787;//35Hz
break;
case (5):
timer_freq=48255;//40Hz
break;
case (6):
timer_freq=56001;//72.5Hz
break;
case (7):
timer_freq=56895;//80Hz
break;
case (:
timer_freq=57403;//85Hz
break;
case (9):
timer_freq=57855;//90Hz
break;
case (10):
timer_freq=59893;//122.5Hz
break;
case (11):
timer_freq=60508;//137.5Hz
break;
case (12):
timer_freq=60598;//140Hz
break;
case (13):
timer_freq=60685;//142.5Hz
break;
}
}

[Prospekteur]

Ive worked in the past with a RM85,
We had not the advanced model. I had seen now that the advanced model has a wider range of currents (up to 10mA), wider range of operating frequencies (17.5 to 142.5 Hz in 13 steps plus user defined frequency. It would be fantastic if that will be possible in the next version. But I will also go with the 137Hz, because I had good results with the old Beckers model.

@Ivonic: Will it be a homemade project for interested people or will you sell it as a ready built unit? Pcb's or kits where we have something to work on our own would be great. For me the most fun is to build at least a part of a unit at my own;-). No problem if you want to protect your work (because its also possible to encrypt arduino codes) and sell your work as a ready built complete unit;-). But Im searching more for a project, where I can built and programming a bit at my own, so I will definitely following this thread here to see where it goes;-) Wish you much success and good nerves for your project!

[ivconic]

Ive worked in the past with a RM85,
We had not the advanced model. I had seen now that the advanced model has a wider range of currents (up to 10mA), wider range of operating frequencies (17.5 to 142.5 Hz in 13 steps plus user defined frequency. It would be fantastic if that will be possible in the next version. But I will also go with the 137Hz, because I had good results with the old Beckers model.

@Ivonic: Will it be a homemade project for interested people or will you sell it as a ready built unit? Pcb's or kits where we have something to work on our own would be great. For me the most fun is to build at least a part of a unit at my own;-). No problem if you want to protect your work (because its also possible to encrypt arduino codes) and sell your work as a ready built complete unit;-). But Im searching more for a project, where I can built and programming a bit at my own, so I will definitely following this thread here to see where it goes;-) Wish you much success and good nerves for your project!

Several years ago i lost all the good enthusiasm and good will to share.
I swore than that i will never ever give anything for free.
Especially not something in which i involved decent work.
So, if i ever manage to finish it, the way i want and described above; it will not be free.
Than again, i am not all in money; so price will probably be friendly and affordable.
So yes, it will probably be on sale, preferably as kit, with affordable price.
But than; i already gave schematic for free, didn't i?
It is Becker's schematic with some adaptations. Gain and output resistance will be switched through the menu system options with use of buttons.
I'll try (not promising that i will 100% achieve) to add more frequencies, but main 137Hz will stay for sure.
Also there is switching between two control ("sevice") signals and the third, the main, which will be seriously sampled and processed.
I did it like that because of lack of pins at Atmega. So in interrupt i will sample the main signal and take as many as possible samples of it, while in a spare tics i will take occasional samples of
two control ("service") signals and probably display them somewhere on LCD. Maybe also store them in the same pack of data for a column\row.
I don't know if that is relevant and important. Will see.
In case you don't need those two pre-samples; you can omit U1.
(I just noticed two "U1" which is mistake. My mistake. There are two CD4052 and are not the same "U". Should be enumerated. I will correct that.)
Also on schematic there are leds that are about to be used in developing stage.
Later on not planned on device. But can be also used to save space on LCD, or on device version without LCD.
I also gave truth tables for all three switching circuits.
So, it is still Beckers resmeter in essence. But adapted for Atmega32P and with compromises that came along.
So if you are enough skilled in programming; you can use my schematic and write your own code.
Only important thing is main sampling, sampling the main signal coming from U3d. And must be put in critically timed function.
Everything else is not critical and can be done easier.
Of course, i have few more ideas on this too. But it is too early to talk on them now.

[ivconic]

Providing higher currents will not be the problem too.

[Prospekteur]

Ok....I see youre fully into it;-). Cant wait to see first signs of live of youre unit. No matter how you will build and sell it, i will purchase one from you. Thanks a lot that you invest so much afford in an advanced version of Beckers great design

[ivconic]

Robert Beck did also a good job here:

[yudo]

Hello ivconic, greetings from Turkey, I bought a new device epe. I have no information about the device. This is the first time I will be using this kind of device. But I don't know how to use it, are there any documents I should download? At the same time, are there resistance equivalent values, ie frequency figures? (such as water, space, gold) do you have frequency values for numbers that are also equivalent to meaning? Thanks already for your help . Best regards

[ivconic]

Hello ivconic, greetings from Turkey, I bought a new device epe. I have no information about the device. This is the first time I will be using this kind of device. But I don't know how to use it, are there any documents I should download? At the same time, are there resistance equivalent values, ie frequency figures? (such as water, space, gold) do you have frequency values for numbers that are also equivalent to meaning? Thanks already for your help . Best regards

page 7, post #158

[ivconic]

...

[Prospekteur]

Hello ivconic, greetings from Turkey, I bought a new device epe. I have no information about the device. This is the first time I will be using this kind of device. But I don't know how to use it, are there any documents I should download? At the same time, are there resistance equivalent values, ie frequency figures? (such as water, space, gold) do you have frequency values for numbers that are also equivalent to meaning? Thanks already for your help . Best regards

You are not really able to use the values which Ivconic has posted. The posted ones are Ohm/metre. The Epe Res does not show Ohm/metre, it doesnt also show Ohm. It only showing a relative value, which is for example in soil a lower value as in granite. You have to learn a lot about soil properties, no matter what unit you use. Also you never will find gold with a resmeter like this. Read some books about this thematic and you will understand whats possible with such a unit and how to use it.

[ivconic]

You are not really able to use the values which Ivconic has posted. The posted ones are Ohm/metre. The Epe Res does not show Ohm/metre, it doesnt also show Ohm. It only showing a relative value, which is for example in soil a lower value as in granite. You have to learn a lot about soil properties, no matter what unit you use. Also you never will find gold with a resmeter like this. Read some books about this thematic and you will understand whats possible with such a unit and how to use it.

I am too exhausted to constantly repeat those facts.
Thanks for posting them!
Ever since i made and announced my magnetometer project, complete device and kits; i was constantly flooded by similar questions, rarely on forum, but literally on daily basis here in real life, via phones, emails and messengers.
It is very exhausting to try to explain to people these facts. Especially to layman who only dreams how to immediately strike fortune and solve all their life problems.
It is real torture.
Sometimes i pull back all my advertisements for week or two; to take a short rest from such bunch of yoyos.
Also i added another (non public) sim card number to my phone, and known public one is switched off in those resting periods.
If i summing all what i benefited and lost from magnetometer project, built devices and kits; it is 10% : 90% in favor of lost. In all possible aspects.
I only generated horrible quantity of problems, affecting my everyday normal private life.
Everybody... literally EVERYBODY has something to ask. NOBODY (except 1/10 of percent of all cases) is ready to buy and pay.
World turned to a free stuff constantly annoying beggars and people who will gladly waste your time on endless empty talking.

[Prospekteur]

@Ivconic: Oh man......that sreally exhausting. Thats a lot energy and time you lost for other people that are too lazy to invest patience and solve some problems at their own. Its a shame that people think you are commited to help them around the clock because you know a lot about it I understand it, Im also often turning my telephone off over the weekend, for me this is big freedom;-). For me personally It would be absolutely boring if I had not to solve riddles at my own. I read books years before I ever worked with geophysical units, because I wanted to learn everything about it before I really are able to buy such a complex expensive unit. For me its some sort of challenge to find answers at my own. Also it is with metal detectors. Ive read books like "inside the metal detector" and honestly I didnt understand every layout which is in this book, but I learned a lot. Also I had to say that without the help of some people in this great forum I would stuck in some problems till this day;-). But as you said there are a lot people nowadays who think things have to work like a dream immediately without any knowledge because they invested money for it. Sometimes its better not to have too much money because misery makes people a lot more inventive;-).

[ivconic]

I am member for 14 years on this forum.
I learned much by reading from what other people are writing.
The key is in effort, reading, understanding.
Sometimes even to ask question. But with sense.
For example; it is strange to see question "how to make coil for TGSL" on last page at that topic!?
Telling us what? That one who dare to ask such question; spits on everything what's been done in hundreds of pages before, on that topic.