Journal notes, NBLNA Testing
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:
Monday, November 8, 2010
Tuesday, November 9, 2010
Overnight: PDF, TXT, quiet, waiting for the new SWCTRL boards Ver. 0.8.8; thinking about experiments in synchronous line triggering (measurement delays from a line trigger, just more curiosity at this point, synchrnous line triggering is not needed for the experiment).
Wednesday, November 10, 2010
Overnight: PDF, TXT, quiet (small step change after 8:00 pm is a distant parked vehicle departing). Sample spectra PDF, log spectra PDF. The spectra and log spectra are noted periodically in the journal for several reasons. The spectra gives an indication of instrument performance, thus presumably for some types of failures, there would be a change a shape. Also, during infrequent periods where there appear to be a number of auto-retry cycles each measurement, the spectrum might show an offending EMI/RFI signal (although out FDM signal to noise ratio is just about as effective). Finally, for the upcoming line synchronization experiments, I wanted to have a few records of power line spurs over several days and times. However, as discussed earlier, it is unlikely that our present single pulse, single polarizing coil system can do NMR spectroscopy, that is display any meaningful families of spectra representing a particular sample being used (still Presestone -30 C De-Icer windshield wiper fluid). The FDM mathematics is certainly powerfuly enough (It was developed for NMR spectroscopy), however our present hardware system does not support such studies.
Thursday, November 11, 2010
Overnight: PDF, TXT, some small amount of activity (sub-storm levels, possibly global K4 this morning) PDF (the larger amplitude of the last measurement shown on the late morning pdf (amplitude graph in the upper right) is just a normal statistical variation of the FID (free induction signal) amplitude, and of no particluar significance, and not related in any way to the increased activity).
evening: finally after days of quiet, there is a little geomagnetic activity (albeit at sub-storm levels) PDF, TXT, NOAA Space Weather PDF, USGS PDF, NRCan OTT PDF. By 9 pm est (0200 UTC), the field seems to have returned to quiet PDF, maybe not (9:23 pm) PDF (10:46 pm) PDF.
Friday, November 12, 2010
Overnight: PDF, TXT, NOAA WingKp 7 day Index PDF, the geomagnetic field was active overnight compared to past days and weeks, but still at sub-storm levels. There was an interesting pattern of three negative going triangular shaped waves a few hours apart.
On Building NBLNA boards: We are beginning to collect some notes on building and testing the NBLNA board in preparation for kit sales (still some months off). I recommend soldering in the #18 folded copper test points loops first (not shown). Next, one approach is to solder in the Kemet mil. spec. CKO6 bypass capacitors and 8 pin MillMax DIP sockets. (We use a plastic cap to hold the socket flush while soldering two diagonal pins to tack it in place before soldering the remaining pins.) This picture also shows proper placement of the ferrite beads on the power supply input diodes. We actually bend the D1 D2 leads first, then slide the ferrite beads on. JPG The R1 and R2 parts are actually input chokes, one complete turn of excess leads (long) from the 100 pF ceramic filter capacitors. JPG Next, wind the input common choke, 5 or 6 turns on a ferrite core (wire size to follow). Strip the leads so the core sits flush or just above the board. You can use #24 magnet wire in which case you can do 6 or 7 turns, but then it is more difficult to idenetify the leads. This is mostly a high frequency RF choke, 5 to 8 turns is fine, the number is not critical and the cutoff frequency is decades above the signal of interest. The coils (leads 1 and 2) show on the silk screen as a short line. Also, note the chokes now installed at the R1 and R2 postions. JPG Also, note the ferrite beads on the power supply reverse protection diodes D1 and D2.
Saturday, November 13, 2010
Sunday, November 14, 2010
While building and testing another Ver. 0.9.2 NBLNA board, I wrote a partial first draft of our Part IV article, Building and Testing the NBLNA. See our articles page. This is an early work in progress, however comments are always welcomed. The NBLNA article discusses an alternative effective noise bandwidth measurement technique using just a few resistors and an AC voltmeter. I should probably submit a short a article on this method for Electronics Design or EDN design ideas. It is a very simple and reliable way to measure the effective noise bandwidth of an amplifier using the Johnson (Nyquist) noise equation.
Geomagnetic activity could be starting PDF, Wing Kp PDF, stay tuned! Just another negative triangular shaped pulse PDF. It will be interesting to see if there is a series of them as we saw on Friday, 11/12/10 PDF. Interesting, another series of triangular pulses PDF. These patterns are probably well known, well understood phenomena in geomagnetism.
Project Documentation (very early stages)
QUESTIONS/COMMENTS/notice of typos, etc. send email to joegeller at gellerlabs dot com
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