Journal notes, Fast relay operation
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 (very early stages)
Journal Notes:
Wednesday, October 13, 2010
Overnight: PDF, TXT. Ordered prototype boards for the latest versions of both the SWCNTRL and NBLNA boards today (see project documentation).
Thursday, October 14, 2010
Overnight: PDF, TXT. Quiet overnight. Sample spectra PDF, log spectra PDF.
Friday, October 15, 2010
Saturday, October 16, 2010
Sunday, October 17, 2010 (G1 minor magnetic storm (but, only about a 30 nT swing here in upstate NY))
Overnight: PDF, TXT, more detailed view (5 nT/div) of the main F field excursion PDF. Using a 2 day magnetogram PDF, compare Saturday after 12 am to last night's activity. Costello 7 day (called it a K4) PDF, NOAA Space Weather Now (called it a G1 magnetic storm (K5)) PDF, NRCan OTT PDF, USGS PDF.
10/17 late evening into 10/18 early morning: here is the day's magnetogram including the 2 am 10/17 disturbance PDF. Let's see what happens overnight.
Monday, October 18, 2010
Overnight: PDF, TXT. Compare the magnetogram 12 am to 8 am period using a two day plot PDF, between the 10/17 disturbance and the relatively quiet period last night. The spikes this morning are the normal Monday morning school buses and garbage trucks, the down turn just before 10 am is part of the normal diurnal cycle in the geomagnetic field.
Tuesday, October 19, 2010
Overnight: PDF, TXT, slightly active as compared to past quiet overnight periods.
NOAA announced that the Costello model PDF that we have discussed many times since our project begain is being replaced by the Wing Kp model PDF.
Wednesday, October 20 , 2010
Overnight: PDF, TXT, the geomagnetic field was very quiet overnight. 7 day NOAA Wing Kp model PDF.
Thursday, October 21, 2010
Overnight: PDF, TXT, very quiet.
Friday, October 22, 2010
Overnight: PDF, TXT, very quiet. New prototype blank PCBs are in. I hope to build one of them today.
It turns out that the entire system with the hybrid FET-Relay board can make measurements on the order of several seconds. For some applications, it may be practical to relax or to turn off the FOM filter for measurements on the order of seconds (to limit or eliminate auto-retry cycling). A gradiometer for field use (using a laptop or possibly a netbook computer) might be practical (however fast cycling or field use is not an immediate goal). Mechanical stress might limit the hours on the relay, however, we have recently acquired a relatively large stock of the newly selected small signal relay, so change out at some interval of tens of hours for rapid cycling could be as easy as changing out batteries. In observatory use (presently a 2 minute measurement rate, with some additional auto-retry cycling at 8 seconds), the relay (with zero-current switching) is expected to last for thousands of hours.
Running now (evening) on the new SWCTRL zero-current hybrid FET-Relay switching board! JPG The new board corrected a previous grounding error and reversed the relay sense back so that the relay is closed (energized) only during the polarization event (we had accidentally reversed the normally open and normally closed contacts last round).
Project Documentation (very early stages)
QUESTIONS/COMMENTS/notice of typos, etc. send email to joegeller at gellerlabs dot com
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