Journal notes, SWCTRL board Ver. 0.8.8
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
(be sure to hit refresh to pick up our latest changes and entries)
Project Documentation (very early stages)
Journal Notes:
Monday, November 15, 2010
Overnight: PDF, TXT, 7 day Wing Kp Index PDF, slight activity in the geomagnetic field, but less than predicted.
late evening: more of the same patterns of recent days, still at sub-storm levels though PDF. The Wing Kp model is predicting higher levels of activity PDF, but so far, although the geomagnetic field is more active than past weeks, the activity seems to be falling short of even K4 levels. It will be interesting to see what happens overnight.
The newest SWCTRL blank prototype PCBs should be in tomorrow. I hope to build one and put it in service. Once the NBLNA and SWCTRL boards are in near final form for the first kit offering, I will work on a first disribution version of the software.
Tuesday, November 16, 2010
Overnight: PDF, TXT, another roughly triangular shaped pulse before 10 pm last evening, otherwise the geomagnetic field is relatively quiet here in upstate, NY.
Built the newest version of the SWCTRL board (Ver. 0.8.8) PDF this afternoon JPG1, JPG2. Changed over to the new board at 7:12 pm. I set the resonating capacitor to our operating value of about 125 nF and it came right on with no problems. All seems well (the small break in the data just after 7 pm is where the changeover occured): PDF. The relay is plugged into gold plated MillMax jacks (not visible in this picture).
While removing the last prototype, I did notice that one of the wires to the amplifier (the NBLNA board) was just sitting below the captive part of the binding post terminal. It must have been making good contact anyway since all has been fine. That is, however, one minor disadvantage of these captive terminals, is that it is possible to snug up the screw, only to realize that the wire is below the captive rectangular area.
Wednesday, November 17, 2010
Overnight: PDF, TXT. There were a few relatively slow undulations on the magnetogram somewhat similar to the past two or three days, otherwise the geomagnetic field was quiet.
The FDM magnetometer ran well with the new SWCTRL board (Ver. 0.8.8) PDF overnight with no problems JPG. The assembled board dropped right in and the system came on fine, which seems a good indication for success by kit builders. The kit is still some months off as we return now to software development and explore the issue of distributing a LabView installable application (where the experimenter is not required to own a LabView development package). The amplitude distribution this afternoon looks good PDF.
Thursday, November 18, 2010
The THAT Corp. very kindly provided samples of the 1510. Bench testing went very well with a slight improvement in both the NBLNA gain and noise floor (1.66 nV / rt-Hz compared with 1.79 rt-Hz). I believe the 1510 to be a high quality part. Unfortuntely, there is something about our front end design and/or the temporary imbalance at the input when the powered coil is powered that the 1510 does not like. While input and output waveforms with a 10 uV input sine wave look fine on the bench, installed in the FDM magnetometer, the FID waveform is very distorted. I do not know if it is our biasing scheme, an undesired resonance with our input common mode filter and/or other input bias and filter components, or the imbalance during the polarization cycle. Another mystery to look into later. I want to emphasize that this problem should not be taken as a negative comment on the 1510 part. For reasons unknown, in our current design, the 1510 is not a part-for-part replacement with the ADI SSM 2019.
Friday, November 19, 2010
Overnight: PDF, TXT. The geomagnetic field was very quiet overnight.
Saturday, November 20, 2010
Overnight: PDF, TXT. I finally got around to some line (mains) synchronization experiments.
Sunday, November 21, 2010
Overnight: PDF, TXT. The geomagnetic field was very quiet overnight, the down turn at the right of the magnetogram is the beginning of a normal diurnal cycle. These overnight measurements were made in the standard experiment configuration using the National Instruments USB 6008 control and digitization module. Afternoon: sample log spectra PDF, spectra PDF.
Project Documentation (very early stages)
QUESTIONS/COMMENTS/notice of typos, etc. send email to joegeller at gellerlabs dot com
COPYRIGHT © 2009, 2010 JOSEPH M. GELLER, All rights reserved.