PPM MarkIV project progress report

[Willy Bayot]

Hi,

This is the sound of the proton precession from our PPM.
It is an exponentially-decaying signal of frequency of 2050Hz corresponding to the earth magnetic field in my region.

Willy

[Willy Bayot]

Hi all,

We have now exhausted all our stock of MarkIV boards, we have sold them all.
Thus, we prepare a new MarkIVB series with upgraded specs to be available before the end of this year. Depending on our costs of production which could be higher, we'll probably have to slightly revise our price structure. Thus, I'll publish a precise pricing when the new units will be available but the pricing already published is a good approximation of what it will be.

The new units will have programmable tuning (no more DIP Switch) and the option of a Windows-based control program (connected to the PPM through an USB link) to set the system parameters and review previously captured survey grid files without removing/inserting the SD Card. Actually, these two upgrades together will completely avoid opening the cover of the NEMA box.
This link will be available both for the basic LCD version and the GUI version.

The same control program will also be used for real-time control of the PPM during underwater surveys based on GPS fixes. It will plot the PPM data and the GPS fixes on the PC Screen. This configuration does not require any other operator interface (can run on a blind box) but it is also available on the normal LCD or GUI versions.
I have attached a screen dump of the program in operation in relation to a PPM MarkIVB equipped with the GPS Option.

Willy

[Willy Bayot]

MarkIVB production is out.

Hi all,

We have received from production the new batch of boards designed for the MarkIVB systems.
All these boards have been tested one at a time in Canada and will come in Belgium within a week.
The updated price structure document is available there: http://users.skynet.be/fa352591/Mark...012_prices.pdf

Willy

[carthage]

Pictures

Hi Willy; happy New Year to you and to all the Geotech form participants.

Willy is it possible to add pictures to see the new PPM?

[Willy Bayot]

Hi Willy; happy New Year to you and to all the Geotech form participants.

Willy is it possible to add pictures to see the new PPM?

Hi,

All the upgrades applied from the MarkIV to the MarkIVB series are internal to the control box.
There are upgraded boards to support the programmable tuning and the still improved SNR and there are the corresponding upgrades of the software application.
Thus, the look of the control box in the two main configuration options (LCD or GUI options) is the same as for the MarkIV systems.
The home page of our web site has been updated with the new price list and package descriptions:
http://users.skynet.be/fa352591/index.htm

Willy

[Willy Bayot]

Hi Willy; happy New Year to you and to all the Geotech form participants.

Willy is it possible to add pictures to see the new PPM?

This is few PIX of two markIVB systems built for underwater surveys. The first one has an LCD+keypad to be able to make underground as well as underwater surveys and the second one is a 'blind' configuration. Both have a USB connection to an operator interface on a PC.
You can see the two boxes closed, one box opened and two pix with the details of each board.
Inside the box with its transparent cover, you can see the GPS module at the upper left of the picture.

The last picture is a screen dump of the PC program while reviewing one GPS-based grid file.

Willy

[syed ayub basha]

Sir I want to buy.

Sir Now i want to buy your product. first i have some thing to talk about the product.
1) what is the max. depth it will detect the item as per object size. you have any table to explain this question.
2) if under ground any other metal means non ferrous. it will detect or not. because my magnetic locator showing non ferrous items also. i don't know how it is showing?
3) in sub surface any cavity is presence. can this meter detect that cavity?
4) I am from India. how can you send this full equipment with assemble, with out battery.
5)please send your price and other details to my ID

[email protected]

[Beausmobil]

Used equipment?

Hi Willy, your project sounds like it's on point. I am looking for underwater equipment and as always don't have a ton of money. What do you have for sale ( tow fish )...
Thanks Beau

[KonstantinT]

Hi,

This is the sound of the proton precession from our PPM.
It is an exponentially-decaying signal of frequency of 2050Hz corresponding to the earth magnetic field in my region.

Willy

Hi,

I looked your's file in an audio editor. I have a few questions for you.

1.This file was created by copying the same pieces of the signal. Is this true?
2.The signal is passed through a narrow-band bandpass filter. Real precession signals look a bit wrong.
3.Could you show the original file? I want to estimate the ratio of signal to noise without the use of narrow-band filter. My preliminary estimate is about 30 dB.
4.What is the relative and absolute accuracy? What is the value of the gradient resistance you got?

As far as I've heard you use the Jim Koehler's algorithm.
I researched this algorithm. I got about 1,3 nT accuracy on test signals with a signal-noise ratio 40 dB and the sampling time 0.5 seconds. His algorithm is much inferior to other algorithms. Maybe you have changed it somehow?

The published source code of this algorithm has a mistake. I can publish a corrected version to all who wish to explore it.

BR
Konstantin.

[ApBerg]

Hi,

I looked your's file in an audio editor. I have a few questions for you.

1.This file was created by copying the same pieces of the signal. Is this true?
2.The signal is passed through a narrow-band bandpass filter. Real precession signals look a bit wrong.
3.Could you show the original file? I want to estimate the ratio of signal to noise without the use of narrow-band filter. My preliminary estimate is about 30 dB.
4.What is the relative and absolute accuracy? What is the value of the gradient resistance you got?

As far as I've heard you use the Jim Koehler's algorithm.
I researched this algorithm. I got about 1,3 nT accuracy on test signals with a signal-noise ratio 40 dB and the sampling time 0.5 seconds. His algorithm is much inferior to other algorithms. Maybe you have changed it somehow?

The published source code of this algorithm has a mistake. I can publish a corrected version to all who wish to explore it.

BR
Konstantin.

Hello Konstantin.

Like to see the info you have....

Best regards.

Ap

[KonstantinT]

Hello Konstantin.

Like to see the info you have....

Best regards.

Ap

In the file main.c change 210 -211 lines from

if (diff > 5.0) for (k = i; k < CYCLE_COUNT; k++) arctangents[j][k] -= TWO_PI;
if (diff < - 5.0) for (k = i; k < CYCLE_COUNT; k++) arctangents[j][k] += TWO_PI;

to

if (diff > PI) for (k = i; k < CYCLE_COUNT; k++) arctangents[j][k] -= TWO_PI;
if (diff < - PI) for (k = i; k < CYCLE_COUNT; k++) arctangents[j][k] += TWO_PI;

It is best to explore this algorithm in Matlab. The resulting accuracy is much lower Cramer-Rao Lower Bound.

[ApBerg]

In the file main.c change 210 -211 lines from

if (diff > 5.0) for (k = i; k < CYCLE_COUNT; k++) arctangents[j][k] -= TWO_PI;
if (diff < - 5.0) for (k = i; k < CYCLE_COUNT; k++) arctangents[j][k] += TWO_PI;

to

if (diff > PI) for (k = i; k < CYCLE_COUNT; k++) arctangents[j][k] -= TWO_PI;
if (diff < - PI) for (k = i; k < CYCLE_COUNT; k++) arctangents[j][k] += TWO_PI;

It is best to explore this algorithm in Matlab. The resulting accuracy is much lower Cramer-Rao Lower Bound.

Hello Konstantin.

Is it the main.c file that is with the Koehler project in CircuitCeller May 2007 ?
Have you made that project ?
Last month I bought the CC backup CD from 2007 and have read about that project..
Nice info.. as al the info from Jim Koehler is, also the info (and project) from Willy Bayot is great.

But with all that info I cannot yet get a proton mag running...to bay a mag from Willy ( I sure like that ) is for me not an option... no budget (wife kills me ....yes she told me..)

I sure would like a diy project that is on a lower budget...with a Microchip that knows what to do..

Best regards

Ap

[KonstantinT]

Hello Konstantin.

Is it the main.c file that is with the Koehler project in CircuitCeller May 2007 ?
Have you made that project ?
Last month I bought the CC backup CD from 2007 and have read about that project..
Nice info.. as al the info from Jim Koehler is, also the info (and project) from Willy Bayot is great.

But with all that info I cannot yet get a proton mag running...to bay a mag from Willy ( I sure like that ) is for me not an option... no budget (wife kills me ....yes she told me..)

I sure would like a diy project that is on a lower budget...with a Microchip that knows what to do..

Best regards

Ap

In an attachment to my previous post are the source of the Jim Koehler's project from Philips contest. I'm not made this project. We produce our proton magnetometers. Also, we have launched the production of our overhauser sensors. The price range for our devices - from $ 2200 to $ 8000.

We had high hopes for Jim Koehler's algorithm, because we wanted to get the accuracy of 0,1 nT with proton sensors. But unfortunately, it does not get the required accuracy with the standard signal-to-noise ratio of 30-40 dB . So we had to develop their own algorithms for computing the precession frequency.

BR
Konstantin

[signman]

Questions about corrections

In an attachment to my previous post are the source of the Jim Koehler's project from Philips contest. I'm not made this project. We produce our proton magnetometers. Also, we have launched the production of our overhauser sensors. The price range for our devices - from $ 2200 to $ 8000.

We had high hopes for Jim Koehler's algorithm, because we wanted to get the accuracy of 0,1 nT with proton sensors. But unfortunately, it does not get the required accuracy with the standard signal-to-noise ratio of 30-40 dB . So we had to develop their own algorithms for computing the precession frequency.

BR
Konstantin

What do the corrections you make in the code do? Is it more accurate? Did the code not work without those changes?

With the SNR of 40db the code was not accurate enough? IF you feed a strong signal into the code, does it perform better? Is the problem of the ability of the algorithm to not be able to generate accurate results? Or is the code not immune enough to the noise of the proton signal to produce a better accuracy?

Looking at the video of the bayot mag, it seems to be more accurate than you are claiming it is...using a .5 second sample time.

I've built a pretty nice proton mag. Not as many bells and whistles as Willy's but performs as well. I'd be interested in building an Overhauser mag. Do you sell sensors? a schematic? a kit?
Thanks,
SM

[Willy Bayot]

These corrections are indeed useful but that does not change the accuracy of the algorithm.
This code segment is just required when the reference sampling frequency is too far from the frequency to be measured, thus, in the case of very large field gradients. In those exceptional cases, the slope has to be corrected because of quadrant overlapping. The original code is still working well even if the threshold of PI is more precise to detect those overlaps than the approximate value of 5.
This algorithm is the best we could design to accurately measure a noisy signal with spikes as it usually is in the real world. It uses all the possible data redundancy available in the signal over a period of 250msec, i.e. around 1000 periods and uses the average of 1000 individual measurements to calculate the final precession frequency.
It also calculates the quality factor of the measurement (standard deviation between the 1000 measurements) and produces it together with the net nT value.
Note that the published algorithm was using a sample period of 500msec and a polarization time of 5sec. We are now doing a net reading rate of one reading per second
Our system resists to a hot 220V 50Hz cable running at 50cm from the sensor.
The sensitivity of our whole system is proven to be sub-0.1nT in real survey practice.
The algorithm does not live by itself in the PPM. The performance of the whole system also depends very much upon its sensor technology, its circuit switching and analog stages.

However, we are always ready to learn and acquire more experience in order to improve our PPM systems.
Since we have made the effort to publish our algorithm as originally implemented in code (even if it has been much improved since then), we would be very glad to get in return more than just the sentence 'His algorithm is much inferior to other algorithms'.
If Konstantin knows a better algorithm, we would be listening to his suggestions and possibly, read and study the real code of a better algorithm.
We also are interested in the practical building of an Overhauser system. Any info available?

Thanks,

Willy