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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Project Documentation, Links and References (very early stages)
Journal Notes:
Monday, May 30, 2011
Overnight: PDF, TXT. Changed the battery out on the temporary sensor temperature indicator (fluid temperature is calculated from the NMR Tau 2 measurement).
Tuesday, May 31, 2011
Wednesday, June 1, 2011
Thursday, June 2, 2011
Friday, June 3, 2011
Overnight: PDF, TXT, return to quiet Wing Kp PDF.
Saturday, June 4, 2011 - G2 Magnetic Storm!
Late Afternoon: After 4 pm local, there were two fast excursions of the geomagnetic field, the second at about 6 pm local (UTC -4) PDF. (This magnetogram might include vehicle offsets). Evening: This G2 geomagnetic storm (NOAA SWN PDF) had an unusually fast onset with no smaller waveforms preceding it. Some of the field excursions, such as the negative going excursion at about 9 pm local have been very fast PDF. Wing Kp PDF. The magnitude of the swings in the total field (F scalar) has not been that great (<100 nT), however there have been some very fast edges (dB/dt) this evening PDF. Past G2 events have caused changes of the total field on the order of 200 nT.
Sunday, June 5, 2011
Overnight: PDF, TXT. NRCan Ottawa, Canada (about 200 miles North of our location in upstate, NY, US) PDF. Overview of yesterday's sudden onset G2 geomagnetic storm PDF.
Monday, June 6, 2011
Overnight: PDF, TXT. NOAA K indices showing the June 4/5 G2 magnetic storm PDF.
Tuesday, June 7, 2011
Our local magnetogram (upstate NY, US, UTC -4) shows some significant geomagnetic activity this afternoon PDF, NOAA SWN PDF, global K4 - NOAA K index PDF, Wing Kp Indices PDF. late evening PDF, PDF, Wing Kp PDF.
Wednesday, June 8, 2011
Thursday, June 9, 2011
Overnight: PDF, TXT. Early evening, there was an interesting (albeit minor) pulsed waveform this afternoon PDF. 10:30 pm (local, UTC -4) PDF.
Friday, June 10, 2011
Overnight: PDF, TXT. The polarization time controller, which servos the polarization time to maintain a substantially constant free induction decay (FID) signal amplitude continues to run flawlessly PDF. We are holding about a 0.85 V precession signal peak envelope voltage using a range of polarization times from about .8 to 1.6 seconds for the range of recent outdoor temperature variation. The temporary temerature sensor which was in the sensor coil box maxes out at 100 F, so with summer temperatures it was moved down to the outside of the sensor stand rain cover to monitor ambient air temperature (rough at best from the heating in the cover to some partial exposure to sunlight). Recall that the working NMR fluid temperature is calculated directly from the cycle to cycle measurement of Tau 2. The occasional periods of elevated Tau 2 measurements are believed related to some kind of EMI/RFI signals and are not understood. Fortunately the PEV servo operates indepedently of the Tau 2 measurement. The working NMR fluid sample continues to be a 125 mL (4 Oz) Nalgene bottle of Prestone De-Icer windshield washer fluid (rated to -30 c).
Saturday, June 11, 2011
The current settings of a FID (precession) signal amplitude (peak envelope) desired voltage of 0.85 V (servo'd by the PEV servo as a variable polarization time for PEV amplitude) are providing high quality measurements as judged by figure of merit values (FOM) now commonly in the e-7 and e-8 range PDF. The FDM amplitude is the amplitude of the fundamental frequency (the Larmor frequency) as distinguished from the peak envelope voltage of the precession signal which includes many frequency components (within the bandwidth of the analog narrow band low noise amplifier (NBLNA)). The PEV servo operates on a moving average of the single cycle filtered envelope maximum value (not the FDM amplitude), so the amplitude servo operates independently of the FDM calculation.
We have been running for some time now -without- the snubber capacitor discussed in months past. With the now stable 0.85 V FID / 1 V scale on the USB 6008 operating configuration, the snubber capacitor issue needs to be re-visited. The switch control module (SWCTRL) snubber capacitor might not be needed and/or do more harm than good, an open question to be looked at further.
Sunday, June 12, 2011
Project Documentation, Links and References (very early stages)
Want to build your own FDM Proton Precession Magnetometer?
QUESTIONS/COMMENTS/notice of typos, etc. send email to joegeller @ gellerlabs dot com
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