## Difference Of Length surveys in res2dinv

Geophysical applications on environmental investigation, mineral prospecting, engineering, archaeology, forensics, hydrology...
MohsenTM
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### Difference Of Length surveys in res2dinv

hi every one.
I have a problem in res2dinve for invertion data and output image.
in res2dinv when i inverting data, length is higher then length of my surveys on earth.!!!
for example i have 32 meter length and in inverted file length is 48 meter.
how can i solve this problem.

file Data:

Archaeolab
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### Re: Difference Of Length surveys in res2dinv

Hi,

In data line 12 of your file you have:
24.00000, 2.00000, 13.000000 24.00000

The data points in RES2DINV .dat file for the dipole-dipole array have the following format:
1 - The position of the first electrode of current quadrupole, if in row 5 is set ‘0’ or the mid-point
2 - ‘a’ spacing for AB and MN =2.00
3 - 'n' factor =13.00
4 - RHO =24.00

This quadrupole has a size ‘a’+’na’+’a’, 2+2x13+2=30m. The last ‘N’ electrode is located on 24+30=54m
from first position of this survey and this data point is located on 24+30/2 = 39m, according to the this data.

The Electre Pro software from IRIS Instrument is useful for making of electrode sequences.

http://www.iris-instruments.com/elrec-pro.html
MohsenTM
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### Re: Difference Of Length surveys in res2dinv

hi again
i read RES2DINV manual several times but i I do not understand well or I can't write true data format.please help me white a example:
IF I HAVE 20 Probe and 'a' spacing is 2 meter .How do I write the data file correct?
thanks
Archaeolab
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### Re: Difference Of Length surveys in res2dinv

Enter these values in Electre Pro and you will get very correct electrode sequence.

I see another problem.
The Rho values in your file is to coarse.
The five zeros after the decimal point do not make them more precise.
The Rho in dipole-dipole electrode arrays are calculated with very big values of geometric factor "K".
Which means that the measured voltage is too small, and for this is needed a precise resistivity meter.
If you use EPE earth resistivity logger or similar earth resistivity meter, they are not suitable for any RES2DINV measurements.
Archaeolab
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### Re: Difference Of Length surveys in res2dinv

I got this result after research over powerline and gas pipeline with my resistivity meter.
The equipment is eight channels 24b sigma/delta ADC resistivity meter, two remote electrodes and two moving frames with nine electrodes.

pole-pole array,
0.5m electrode spacing,
8 levels,
34m length of survey.
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MohsenTM
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### Re: Difference Of Length surveys in res2dinv

If you use EPE earth resistivity logger or similar earth resistivity meter, they are not suitable for any RES2DINV measurements.
yes i use an EPE earth resistivity logger of john Becker https://www.mediafire.com/file/6qemujmq ... r.rar/file
I use it for archeology and research on ancient hills and ground.this device is very simple...But Standard and Company device is very Expensive.Is the performance of Company devices very different from this device?(of course yes!!!)
My diple dipole propping sequence is similar to this sitehttp://x2ipi.ru/news/sorting-of-measurements.that is true? other array is here.Other

arrays are also there.
I very tried to currectly learn and idetify underground features up to a depth of at 5 meter whit this device.but i did not get currect accurate and good result.inject current and voltage in ground how much in standard devises or your 24b sigma/delta ADC resistivity meter? if current or voltage is low i can up these.
In fact, I am an electronics and control engineer and not a geologist.Apparently a lot of experience is needed.But I use your tips.
Last edited by MohsenTM on Thu Dec 23, 2021 8:52 am, edited 1 time in total.
MohsenTM
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### Re: Difference Of Length surveys in res2dinv

Archaeolab wrote: Wed Dec 22, 2021 9:24 am I got this result after research over powerline and gas pipeline with my resistivity meter.
The equipment is eight channels 24b sigma/delta ADC resistivity meter, two remote electrodes and two moving frames with nine electrodes.

pole-pole array,
0.5m electrode spacing,
8 levels,
34m length of survey.
how much gas pipe diameter? Is this the gas pipe on the right? line survey cross gas pipeline? The material of the gas pipe is metal and the area around the pipe is covered with insulating material.؟ true?
Archaeolab
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### Re: Difference Of Length surveys in res2dinv

I'm not a geophysicist either.
I am interested in archeology and earth resistivity tomography.
Many years ago I also made EPE logger, but a few days later I threw it away.
For 100-200m length resistivity sуrvey is needed +/-30-100V transmitted voltage, depending on the type of soil. EPE logger provides +/-5V. It is resistance, not resistivity meter. For RES2DINV files is needed to calculate "K" geometric factor for each point.
I know treasure hunters who have paid \$7,000 for EPE based resistance meter.
I made this RM after many years of trial and error.

The soil was wet and I chose 20ma tx current
The gas pipeline is placed in a concrete construction about 4m. wide, and there are other communications in it.
I didn't know about the power line, I was told it was a power line for military use.
Last edited by Archaeolab on Fri Dec 24, 2021 2:19 pm, edited 1 time in total.
Archaeolab
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### Re: Difference Of Length surveys in res2dinv

Good results can be obtained with Earth Resistivity Meter by Robert Beck, but for each measurement you have to calculate R and Rho.
Avoid dipole-dipole electrode array, it is very good, but it is for very good RM devices.

https://www.geotech1.com/cgi-bin/pages/ ... /index.dat

EPE logger is suitable for Snuffler or TerraSurveyor software.
Archaeolab
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### Re: Difference Of Length surveys in res2dinv

My electrode arrays.
Attachments
Last edited by Archaeolab on Fri Dec 31, 2021 7:02 am, edited 2 times in total.
MohsenTM
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### Re: Difference Of Length surveys in res2dinv

Many years ago I also made EPE logger, but a few days later I threw it away.
you made EPE of (john becker)?
Why? because for low voltage at output transmitter of the EPE(john becker)? or something else?
Good results can be obtained with Earth Resistivity Meter by Robert Beck, but for each measurement you have to calculate R and Rho.
Avoid dipole-dipole electrode array, it is very good, but it is for very good RM devices.
what are characteristics of a good RM?
you are currently use Robert earth resistivity?
What are your experiences with resistance changes to the volume and size of metals in your excavations in Archeology?
MohsenTM
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### Re: Difference Of Length surveys in res2dinv

Archaeolab wrote: Thu Dec 23, 2021 6:00 pm My electrode arrays.
Array.jpg
how much distance between A- B and M8-N probes?
I plan to set up a survey area to test various conditions for possible anomalies such as masonry or brick empty jars and jars filled with metals, tunnels and chambers.
In my opinion, one hardship is better than a thousand times speculation and confusion.
Archaeolab
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### Re: Difference Of Length surveys in res2dinv

In my opinion, one hardship is good when it is overcome.
In this matter there are many hardships, if one is not overcome, then - many speculation and confusion could occur.

John Becker's project in EPE magazine opens the Pandora's box for many amateur archaeologists.

I am not a geophysicist or archaeologist and I think in a simple way.

A good way to see underground is to measure its resistance or resistivity.
To obtain a true image from the measurement it is necessary to create a correct .XYZ file with values of R as accurate as possible /for resistance/.
Resistance, Ohm’s Law. R=V/I.
For this it is necessary to measure exactly V and I.
Concerning the EPE logger.
If the required current is 10mA at 10V Tx the maximum resistance of the soil between A and B must be maximum 1000 ohms. /1000 ohms=10V/0.01A/
If the resistance is greater than 1000 ohms, what is the current through the soil? Тhis project does not indicate this.
The current source of the EPE logger is not precise enough.
The measured voltage is presented as xxxH, yyyL, and these values are not stable.
R=543H-507L/may be 10mA. This equation is too complicated for me, some people have been solving it for eighteen years.

A much more accurate image is obtained with resistivity measurements.
They are recorded in the .DAT file for RES2DINV software.
Resistivity, Rho = K*R. K - geometric factor, which must be calculated for each quadrupole.
This should be easier for engineers, but it is a very big problem if it is not solved.
A lot has been written on the net /RES2DINV manual, M.H.Loke coursenotes/

There are forums where you can find John Becker’s project fans and lovers to discuss it.

Robert Beck's, project.
Тhe receiver is built with an amplifier synchronous rectifier, and filter stages. A voltmeter is connected to it, which measures the received voltage in V / mV.
Тhe transmitter is powered by + - 18 V and has a relatively good current source as well as a current indicator.
I do not use it.

A good RM should have characteristics that allow it to measure accurately V and I of the survey area . Practical solution of Ohm's law.

My RM provides current between 0.25 and 100mA by a current source which is controlled from 12bit DAC and Tx current is measured through shunt resistors with 24bit ADC. Tx voltage is between +-12 and +-200V.
The distance between A-B and M8-N probes should be more than 5 times the length of the survey if a multi-electrode configuration is used, but both frames have a small depth of measurement and I chose a length of about 120m.
I will make a new measurement with 60 electrodes 0.5 m electrode spacing and dipole-dipole configuration to get more depth. My RM allows control of active electrodes with 5 Rx channels multiplexer.
Last edited by Archaeolab on Mon Dec 27, 2021 4:24 pm, edited 2 times in total.
Archaeolab
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### Re: Difference Of Length surveys in res2dinv

I did a 0.5m pole-dipole and a pole-pole survey over 0.25-0.3m waste pipes.
The surface was in poor condition, roots, leaves, waste.
The pole-pole model has a small absolute error 3.4%, but the tubes are not visible.
In my opinion, for detailed surveys in archeology it is good to use DD and Schlumberger arrays and short distances between the electrodes.
MohsenTM
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### Re: Difference Of Length surveys in res2dinv

In my opinion, one hardship is good when it is overcome.
It is easy after any difficulty.
In this matter there are many hardships, if one is not overcome, then - many speculation and confusion could occur.
I am at this stage.....
The measured voltage is presented as xxxH, yyyL, and these values are not stable.
for this problem I read again the EPE project of john becker, in the part of "Data sampling" he says :
"About once a second, the pulse train stops while the 32 sample values are averaged, and the l.c.d. display updated. The
pulse train then recommences for another second. This gives the soil time to respond to the re-application of the a.c. waveform, and for the effects of any d.c. currents to be over-ridden." this is not a problem of designing. he intentionally create this.
this Method similar of IP?(similar). EPE meterial of Data is potential(Volt), we need convert Digital Sample to Voltage. number of side # if 1023 mean voltage in P1and P2 is 5V. if 250 near 1.25v -if 500 2.5v or anything.all these if amplitude is equal=1.
therefor in EPE john we have a voltmeter and current source.for watch current use a mA meter at outut current C1.so R=V/I -ohm
For K (geometric Factor):

Tell me if I'm wrong.
in software Electre pro in section "configuration" -Timing, what is that ? Does this determine the sampling time?
Circuits john and robBrt can be combined.
your RM is Pro. how much did you pay for it ?
how does the switching system work?
i can question ? where are you from?
MohsenTM
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### Re: Difference Of Length surveys in res2dinv

what is the reaction of resistivity for cavities and large volume Metals ..؟
in your survey image red area is high resistivity and blue area very low resistivity ??/
blue is metals volume or water and red is ??...you better know.
in firs my survey i Detect a tunnel from near 1 meter of surface.i generate many image by Difference of sitting in res2denve all this image show my tunnel in center.

.............

.............

.............
Archaeolab
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### Re: Difference Of Length surveys in res2dinv

The EPE logger stores the values of the ADC conversion from the input voltage to the PIC uC, not the voltage or resistance.
These values can be useful in a very small range because the microcontroller does not have information about the selected gain or current values.
Also, the AD converter is low resolution with no reference voltage.
At low measured voltages, the error will be very large. It will be accurate at voltage levels of about 0.05-0.1 to 5 V. This means that throughout the study the measured voltage must be in this range, outside it the data will be wrong.
For multi-electrode arrays, especially Dipole-Dipole, voltages will be measured in a wide range, from a few mV to a few V.
With the EPE logger, only large objects or anomalies can be detected.
One resistance can be measured with 0.5% as well as with 50% accuracy.

ElectrePro is designed for IRIS devices, but will be useful after configuring an array, in the 'View Sheet' you will see all the data needed to create a valid RES2DIN .DAT file, including the geometric factor 'k', which should multiply the measured resistance to obtain Rho.
I didn't see you do this in your DAT file.
You will get better results in the EXCEL table with hand-entered data and the help of Robert Beck’s RM. You can do this yourself or assign it to a microcontroller.

Regarding the possibilities of the Electrical resistivity method, there are many comparative tables for the possibilities of the geophysical methods. It is suitable for walls and cavities, but not for small objects and metals.
Even the most advanced electronics cannot overcome the limitations of geophysical methods.
Don't have high expectations from the EPE logger, you won't get good results.
I salute everyone to whom the projects of John Becker and Robert Beck have helped to do something better.
I know people deceived of a lot of money who have bought a similar RM being promised unrealistic opportunities.

I have no experience with field research.
I applied an example of a study with good contact of the electrodes with the ground, with an absolute error of 1.22%, and another example of two measurements in the same place with poor contact of the electrodes with the ground. In the Pole-Pole measurement, despite the short distances between the electrodes of 0.5 m and an absolute error of 3.4%, no waste pipes are visible, only waste and wet earth.

I did not buy this resistance meter, this is my project, not a Pro.
There are two ways to work. With two movable frames which are connected by a relay multiplexer to 8 Rx channels, with which Dipole-Dipole and Schlumberger modes with a depth of 1m are selected,
Pole-Dipole with a depth of 2m and Pole-Pole with a depth of 4m.
With the second mode of operation, up to 255 electrodes can be controlled via RS232, which are connected to AB or 1 to 5 Rx channels. I have made 72 active electrodes.
I intend to do research for the next archeological season and test it to collate 2d files into one 3d file.
Archaeolab
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### Re: Difference Of Length surveys in res2dinv

For each measurement, a .DAT and .LOG file is created and saved to the SD CARD.
They look like this:

LINE_17. LOG

Injection # 15, Quadripoles # 113 - 120
Itx=19.970mA, MN1=105.012, MN2=61.349, MN3=44.956, MN4=35.540, MN5=29.067, MN6=24.881, MN7=21.823, MN8=19.213mV
QTx=0.1186, Q1=0.0143, Q2=0.0143, Q3=0.0171, Q4=0.0209, Q5=0.0782, Q6=0.0982, Q7=0.0791, Q8=0.0391%
Vrx/Irx=MN1= 5.25, MN2= 3.07, MN3= 2.25, MN4= 1.77, MN5= 1.45, MN6= 1.24, MN7= 1.09, MN8= 0.96Ohm
AppRes=MN1=16.51, MN2=19.30, MN3=21.21, MN4=22.36, MN5=22.86, MN6=23.48, MN7=24.03, MN8=24.18Ohm/m

LINE_17.DAT

Pole-Pole Line
0.50
2
488
0
0
..............................
7.50 0.50 16.519
7.50 1.00 19.302
7.50 1.50 21.216
7.50 2.00 22.363
7.50 2.50 22.863
7.50 3.00 23.484
7.50 3.50 24.031
7.50 4.00 24.180
Archaeolab
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### Re: Difference Of Length surveys in res2dinv

Archaeolab wrote: Thu Dec 23, 2021 6:00 pm My electrode arrays.
I changed the picture, on the previous picture the geometric factor for the Pole-Pole array was wrong.
Archaeolab
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### Re: Difference Of Length surveys in res2dinv

DIPOLE-DIPOLE Electrode Array
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MohsenTM
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### Re: Difference Of Length surveys in res2dinv

hi again.
Itx=19.970mA
---------> is current injection...?
QTx=0.1186, Q1=0.0143, Q2=0.0143, Q3=0.0171, Q4=0.0209, Q5=0.0782, Q6=0.0982, Q7=0.0791, Q8=0.0391%
-------> what is that?
Vrx/Irx=MN1= 5.25, MN2= 3.07, MN3= 2.25, MN4= 1.77, MN5= 1.45, MN6= 1.24, MN7= 1.09, MN8= 0.96Ohm
---------->ration of voltage and current Recived from earth?
and
AppRes=MN1=16.51, MN2=19.30, MN3=21.21, MN4=22.36, MN5=22.86, MN6=23.48, MN7=24.03, MN8=24.18Ohm/m
----->apparent resistivity how calculated from these?
i know earth resistivity raw is: p=k.dv/di in this k is geometric factor.
Archaeolab
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### Re: Difference Of Length surveys in res2dinv

The first data row contains information for injected current in the ground and
measured voltage from the eight channels simultaneously.
In the second row, Q is the quality factor that shows the difference between
the smallest and the largest measured value, which is averaged.
In this case five stacks with two measurements each.
This is a DC resistivity meter.
On the third line Vrx / Irx = is wrong, it must be Vrx / Itx =.
This is the calculated resistance, which multiplied by 'k' gives
the AppRes /Rho/ in the fourth row, the third column in the .DAT file.
MohsenTM
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