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 magnetometer) 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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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 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.
Project Documentation, Links and References (very early stages)
Journal Notes:
Tuesday, March 1, 2011 - G1 Geomagnetic Storm!
Overnight: PDF, TXT NOAA Costello Index PDF Moved to one minute 'fast cycle' 10:22 am PDF , a detailed view PDF . NRCan Ottawa PDF, USGS PDF. 11:05 am Another relatively fast down-turn PDF, 1:00 pm PDF., overview of the relatively minor storm so far (back to 100 nT span) PDF. 3:15 pm PDF. 3:31 pm PDF, probably some hours to go, NOAA Costello Index PDF. 6:03 pm PDF . 8 pm, another well formed positive impulse PDF, Costello PDF. The auroral oval has expanded, however not quite the US lower 48 NOAA SWN PDF. Here is an overview of the event so far PDF. 10:42 pm PDF.
Wednesday, March 2, 2011
Overnight: PDF, TXT . Overview of the minor G1 geomagnetic storm PDF, more detailed view, PDF, 7 day NOAA Costello index PDF, NOAA K index PDF. Evening, 6:28 pm, the geomagnetic field is somewhat unsettled this early evening PDF.
Thursday, March 3, 2011
Friday, March 4, 2011
Overnight: PDF, TXT. 10:30 am local, 1455 data points since about 11 am 3/2. free induction decay (FID) (the precession signal) FDM Amplitude PDF (highly temperature dependent, probably because of the NMR tau1 temperature dependence), FDM figure of merit (FOM) PDF, statistical 'mode' (most common value) 2e-7, average 1e-6. Sample Spectra PDF, Log Spectra PDF, Spectra PDF2, Log Spectra PDF2. For new readers, our working fluid remains 4 Oz (125 mL) Prestone Windshield DeIcer in a Nalgene sample bottle in only the powered coil of our counter-wound coil sensor pair. Please see our Articles and Project Docs pages for more information.
Our current project status is: For the moment (situations can always change), project kits are delayed for financial reasons to early 2012. We have a working hardware and software design (Version 1!). Many of the parts for the kits are already in stock and on hand in full quantity, and some parts remain to be ordered in large quantity. NBLNA and SWCTRL PCBs are now out of stock from prototype builds and Beta kits in the field (one built and operational, several in progress!), and the documentation needs some updating to reflect changes of recent months. The hybrid Relay-FET zero current switching design has proven to be very robust. For those concerned about the small signal gold contact telecom relay, we have just under ten thousand of them in stock. I do not anticipate any problems supplying spares as needed (each kit comes with five or ten TBD).
All of the Beta kits are now out, However, If an amateur scientist or university group would like to build a FDM PPM magnetic observatory kit before 2012, for $300 ($US) per kit, plus actual shipping cost, we could order more prototype PCBs (about a two week delivery time from PCB order to us receiving the boards) and put together up to five more kits. Kits include only all parts for the NBLNA and SWCTRL modules including the cast aluminum Hammond boxes.
Kits do not include power supplies, a Windows 7 computer (does not need to be dedicated, in fact, our FDM PPM is running on this PC as I edit here), a National Instruments NI USB-6008 module (NI offers academic discounts), PVC parts for the coils, wire for the coils, cable to the sensor stand, wood parts or the plastic container for the sensor stand.
Please note, the current project is for a fixed base geomagnetic observatory (Total Earth's Magnetic Field "F" scalar). We do not at this time support a portable instrument version. Also, we do not at this time offer assembled FDM PPM instruments.
Kits do include via email (only with a kit purchase) our compiled LabView executable supervisory program (still in development, works fine, but not a completed project), and the compiled FDM Win7 executable called by the LabView program (builders do not need to own a copy of a LabView development package).
This is a somewhat advanced kit, not suitable for new kit builders or those without electronics experience. For those without sufficient electronic construction experience who are interested in building and/or operating an amateur geomagnetic observatory, it might be practical to team up with a local engineering student, professor, retired engineer or experienced electronics technician. The FDM module is a "black box" software module which converts an acquired precession waveform to an estimated frequency. There is no need for advanced mathematics knowledge.
The FDM proton precession magnetometer kit documentation is all here at our website on the Articles and Docs pages. Kits will not include any documentation. We will provide any reasonable email tech support as requested at no additional cost. Modules can be returned to us for preliminary testing and/or tuning as needed. There will be an additional charge of $25 / module for testing with possible additional repair charges over that (only if repair or re-work is needed) and a charge for actual return shipping (probably something similar to the old Heathkit return and repair model).
Our FDM PPM magnetic observatory kit is not RoHS compliant, however, our understanding is that EU hobbyists are permitted to purchase up to one RoHS non-compliant kit for their own personal use as an exception under the RoHS laws. PLEASE Note, however, that under US law, we must declare the actual purchase price on US customs forms. We are not able to check "gift" or to list a cost other than the actual purchase price.
Project Documentation, Links and References (very early stages)
QUESTIONS/COMMENTS/notice of typos, etc. send email to joegeller @ gellerlabs dot com
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