GELLER Labs "Backyard Science"
Thoughts on a proton precession magnetometer design - a Proton Magnetometer Project
The goal of this project is a low cost high performance proton magnetometer (a digital magnetometer) kit for schools and amateur scientists to be able to accurately measure and monitor changes in the Earth's total magnetic F field.
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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 are actively working to obtain copyright re-print rights. (Scientific American told us that they do not hold the copyright re-reprint rights for the column. Please contact us at the email address below if you are or know of the person or entity who is the present owner of these rights.) The full article can be still found in many public libraries or private collections. Also, the February, 1968 Scientific American issue occassionally shows up on eBay.
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 low cost / relatively easy to build / high performance proton precession magnetometer suitable for home and school magnetic observatories. Probably (too early to know for certain) we will offer a box of parts including one or more printed circuit boards, most or all active and passive components, and/or the code and plans to build a stand and pick up coils (the sensor assembly). At present, we are leaning towards the National Instruments USB 6008 DAQ module for digital control and data acquisition (no decision yet). If we use a commercial DAQ module, users will buy the module directly from the manufacturer. National Instruments offers an academic discount. Users will probably also provide a PC or laptop, requirements to be determined.
September 3 to September 26, 2009, Journal notes, initial experiments in the back yard.
September 28 to November 24, 2009, Journal notes, setting up the test stand.
November 25, 2009, Journal notes, fluid testing.
December 1 to December 15, 2009, Journal notes, Digitizers.
January 1 to January 4, 2010, Journal notes, The Dead Zone.
January 5 to January 31, 2010, Journal notes, Harmonic Inversion and FDM.
February 1 to February 4, 2010, Journal notes, I/Q FDM and the FOM filter.
February 6 to February 16, 2010, Journal notes, Thinking about what comes next.
Wednesday, February 24, 2010
Overnight run: PDF, TXT, USGS PDF. Working on other projects, still considering where to go next.
Monday, March 8, 2010
A few days run showing the local diurnal variation (disturbed by vehicles coming and going): PDF, TXT; 24 hours PDF, 12 hours PDF, USGS PDF. We seem to get a really nice ramp from about 12 pm to 3 pm local time. For amateur labs with less instrumentation, these relatively linear ramps might prove useful for testing signal processing techniques such as frequency estimators. Still considering where to go next, tackling a few other projects and waiting for more snow melt.
Tuesday, March 9, 2010
Added a waveform graph of the envelope of the precession signal (before apodization): PDF.
QUESTIONS/COMMENTS/notice of typos, etc. send email to joegeller @ gellerlabs dot com
COPYRIGHT © 2009 JOSEPH M. GELLER, All rights reserved.