Build a Geomagnetic Observatory ! GELLER Labs "Backyard Science"
Thoughts on a proton precession magnetometer design - a Proton Magnetometer Project. Build an Earth's field magnetometer.
The FDM MAGNETOMETER1 project is a low cost high performance proton magnetometer (a digital magnet
ometer) kit under development for universities and amateur scientists to be able to accurately measure and monitor changes in the Earth's total magnetic F field and to observe geomagnetic storms. Magnetic storms can cause large excursions in the field and are of concern to interests ranging from electrical power grids, radio communications, and satellite operations, to aurora watchers and amateur radio operators.
1 Filter Diagonalization Method "FDM" (harmonic inversion), see Jan 21 and Jan 23 entries, based on: Vladimir A. Mandelshtam, Howard S. Taylor, Harmonic inversion of time signals and its applications, Journal of Chemical Physics (1997), Volume 107, Issue 17, 1997, Pages 6756-6769
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NOAA Space Weather Prediction Center, Top News of the Day! Space Weather Canada current space weather and regional forecasts.
I created a new Proton Magnetometer Group at Yahoo groups for those interested in discussing proton magnetometers with an emphasis on Earth's field measurements. I will try to keep it as open as possible without getting attacked by spam. I will also try first with no review of posts, let's see what happens. Please keep it friendly and professional. Use of real names is preferred, possibly required in the future.
September, 2009
Well, it seems every couple to few years I start thinking about the famous C. L. Stong Scientific American Magazine, "The Amateur Scientist" column on Nicholas Wadsworth's proton magnetometer (more to follow on the Wadsworth article). Every time I go back and re-read the project, I marvel over how competent the description is and what a challenging design it must have been back then. Here is a low resolution snap-shot view of page 1 solely for purposes of identification. (We have not been able to obtain copyright re-print rights. Scientific American told us that they do not hold the copyright re-reprint rights for the column, and the presumed present owner of these rights, the last editor of the column, has not answered our several email inquiries.) The full article can still be found for free, or perhaps for the cost of copies, in many public libraries or private collections. Also, the February, 1968 Scientific American issue occassionally shows up on eBay.
I mention the Wadsworth/Stong article since so many of us over the years have attempted to build a single bottle absolute proton precession magnetometer (including non-gradiometer, noise cancelling double bottle versions) over the years based on, or at least inspired by Wadsworth's original project from that Amateur Scientist column. As discussed in our Part II article, while brilliant in its "simplicity" of design and inspiration, in hindsight, as gradiometers go, the Wadsworth instrument was actually pretty crude as to resolution (on the order of 20 nT). That said, the Wadsworth article, now from so many years past, was for sure the source of inspiration for our current project. Also, I hasten to add that by simplicity, I am referring to Wadsworth's overall technology. Anyone who has tried to assemble a gradiometer according to Wadsworth's plans will tell you, it was anything but simple to build a working unit!
NOAA's Space Weather Prediction Center posts a webpage on Solar Cycle Progression. During this lull in solar activity before the solar cycle maximum, GELLER (Geller Labs) is working towards a low-cost proton magnetometer kit. The goal of our project is a relatively low cost / relatively easy to build / high performance proton precession magnetometer suitable for home and school magnetic observatories. We plan to offer a box of parts including one or more printed circuit boards, most or all active and passive components, executable program code (currently Windows only, possibly a LINUX version in the future), and plans to build a stand and pick up coils (the sensor assembly). We are using National Instruments USB 6008 DAQ module for digital control and data acquisition. Kit builders will buy the USB 6008 DAQ module directly from the National Instruments (NI offers an academic discount for most colleges and university groups). Users will provide a PC or laptop, which does not need to be dedicated to the magnetometer application.
NOAA Space Weather Prediction Center, Top News of the Day! Space Weather Canada current space weather and regional forcasts .
Project Documentation, Links and References
Journal Notes:
Monday, November 7, 2011
Instrument Health: Polarization Controller PDF, FDM FOM and amplitude PDF.
Case Study: NBLNA Testing and calibration - (revised 11/8) This case study is just an example and does not replace the PART V NBLNA article which includes more details on testing the NBLNA board.
Tuesday, November 8, 2011
Wednesday, November 9, 2011
Thursday, November 10, 2011
Instrument health: polarization controller PDF, FDM FOM and amplitude PDF. There does appear to be a very slight improvement in instrument performance with the faster polarization coil current discharge achieved with the IRFI1310N as compared with the original IRLIZ24N. I suppose, barring any other negative aspects of the 1310 we should change over to the IRFI1310N as our specified and supplied part. Present systems need not upgrade with any urgency as the improvement in average FDM FOM is very minor.
Friday, November 11, 2011
Overnight: PDF.
Saturday, November 12, 2011
Instrument Health - polarization controller PDF, FDM FOM amplitude PDF, sample spectra PDF, log spectra PDF. These PDFs are generated in post processing with Excel (from the TXT file) and with a second version of fdm for generating spectra (the working version of FDM called by teh LabView program only returns the fundamental frequency and related paramaters such as, FDM amplitude, figure of merit (FOM), and narrow band signal to noise ratio (NBS/N).
Sunday, November 13, 2011
Overnight: PDF, TXT, the geomagnetic field was very quiet overnight.
Want to build your own FDM Proton Precession Magnetometer?
Project Documentation, Links and References
QUESTIONS/COMMENTS/notice of typos, etc. send email to joegeller @ gellerlabs dot com
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