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Offline Bill CarsonTopic starter
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« on: April 03, 2009, 09:20:09 am »
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Jim Koehler has developed a nice PPM which may interest readers of this forum.  He also has a good discussion of the theory of a PPM at his site here:

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http://members.shaw.ca/jark/PPM.html


And, you can find most of the construction details of his PPM on this site:

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http://www.jandspromotions.com/philips2005/Winners/AR1746.htm


He has also published an article on this PPM in the May 2007 issue of Circuit Cellar.

I have not built his PPM, so can't be much assistance with it.



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Offline Christian
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« Reply #1 on: April 07, 2009, 06:31:46 pm »
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Hello Bill,

I have purchased two Mark II Proton Magnetometer Kits from Jim & Willy. They look to be very well made and I look forward to finishing them.

Regards,

Christian

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Offline Bill CarsonTopic starter
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« Reply #2 on: April 08, 2009, 06:03:30 am »
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Interesting, I was not aware that there was a kit.  Do you have a link to it or did you just contact Jim directly?  I have always wanted to build his design, but can never seem to find the time.

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Offline Bill CarsonTopic starter
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« Reply #3 on: April 10, 2009, 02:29:11 pm »
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OK - I found it, you are talking about the magnetometer project by Willy Bayot who apparently collaborated with Jim. I had seen this but forgot. Willy's page is here:

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http://perso.infonie.be/j.g.delannoy/BAT/PPMGuidelines.htm


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Offline willy bayot
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« Reply #4 on: April 30, 2009, 12:16:21 pm »
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HI,

That link is quite old.
You would better use this one:

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http://www.ppm-markii.net/index.htm


 Hello Willy


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« Last Edit: April 30, 2009, 12:18:13 pm by Christian »
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Offline Bill CarsonTopic starter
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« Reply #5 on: April 30, 2009, 02:18:55 pm »
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Hello

Thanks for the link.  I am very impressed with your project and look forward to reading more from the documents you have up there.

I am curious whether your PPM uses the phase slip method of calculation that Jim Koehler described in his May 2007 article in Circuit Cellar?  I must admit I don't entirely understand the math of the method.  I am wondering how sensitive it is to noise since it relies on amplitudes to solve for instantaneous phase.  Are you aware of any articles that discuss the phase slip method in any more detail?

B.C.

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Offline willy bayot
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« Reply #6 on: April 30, 2009, 03:34:29 pm »
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Bill,

This is indeed using the algorithm we both have designed and tested.
It is quite insensitive to noise. It does not rely on amplitudes but on phases. Variations of amplitude do not influence the frequency calculation results. However, we also measure the amplitude and the standard deviations in order to add quality factors to our readings.
We have thoroughly tested it under various levels of noise and it is much more noise-resilient than any zero-crossing/counting/timing algorithm.
However, we do not wish to discuss about this algorithm in more details. YOu just need to know that it works very well under bad noise conditions even if the Low noise pre-amplifier circuits we have designed and the double coil sensor  reduce this noise as much as possible.

Willy

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