[TangerineSDR] Fwd: another 24hour RM3100 run and comparison with Fredericksburg

Fri Oct 30 16:35:49 EDT 2020

Hi Hyomin and Jules,

We are soon going to be able to send out the new prototype magnetometers that will interface with the PSWS radio systems. Scotty has them in his possession now, and we will work them up for shipping soon.

73 de Nathaniel W2NAF

From: Kim, Hyomin <hmkim at njit.edu>
Sent: Friday, October 30, 2020 12:53 PM
To: Julius Madey <hillfox at fairpoint.net>
Cc: Dr. Nathaniel A. Frissell Ph.D. <nathaniel.frissell at scranton.edu>; TAPR TangerineSDR Modular Software Defined Radio <tangerinesdr at lists.tapr.org>; John Gibbons <jcg66 at case.edu>; David Witten <wittend at wwrinc.com>
Subject: Re: [TangerineSDR] Fwd: another 24hour RM3100 run and comparison with Fredericksburg

Sounds good, Jules.
It doesn't matter where more than two magnetometers are installed. I simply wanted to see multiple magnetometers running in the same environment so we confirm that magnetometers put out reliable data once installed at many locations.
I'd like to hear from Dave Witten about our action plan.

Hyomin

[NJIT logo]<https://www.njit.edu/>
Hyomin Kim
Assistant Professor
Physics
Center for Solar-Terrestrial Research
Institute for Space Weather Sciences
hmkim at njit.edu<mailto:hmkim at njit.edu> • (973) 596-5704
https://web.njit.edu/~hmkim/
104 Tiernan Hall, 161 Warren Street, Newark, NJ 07102

On Thu, Oct 29, 2020 at 1:50 PM Julius Madey <hillfox at fairpoint.net<mailto:hillfox at fairpoint.net>> wrote:
Hyomin,
Since our last, I've had to devote time to several other matters and haven't progressed much toward your unit.  However, that appears to be a good thing since I was planning to send you the single mag unit I've been using here repackaged for burial up to 30 inches and with cable connections that match your present setup. Along with that, I was building a two magnetometer unit to do comparisons in my location.

So, I'll reverse course and finish the two mag unit for you.  The magnetometer adapter boards will be the same as you're using now the only change being the second magnetometer and the termperature sensor will have different addresses on the i2c bus .... you access both mags on the same cable.  Dave Witten will have to do some program changes to capture both units but the setup will provide the best arrangement for comparison of two magnetometers ...... both in the same local temperature and magnetic environment.

Jules

On 10/29/2020 1:15 PM, Kim, Hyomin wrote:
Hi Jules,
Could you please briefly give us an update on how things go?
I'd like to have at least two sensors so signals can be compared back to back.

[NJIT logo]<https://www.njit.edu/>
Hyomin Kim
Assistant Professor
Physics
Center for Solar-Terrestrial Research
Institute for Space Weather Sciences
hmkim at njit.edu<mailto:hmkim at njit.edu> • (973) 596-5704
https://web.njit.edu/~hmkim/
104 Tiernan Hall, 161 Warren Street, Newark, NJ 07102

On Tue, Oct 13, 2020 at 11:33 PM Kim, Hyomin <hmkim at njit.edu<mailto:hmkim at njit.edu>> wrote:
Sounds good. Looking forward to it!
We also have to coordinate with Gil or Chris (another NJIT engineer) who will escort us there.

Hyomin

[NJIT logo]<https://www.njit.edu/>
Hyomin Kim
Assistant Professor
Physics
Center for Solar-Terrestrial Research
Institute for Space Weather Sciences
hmkim at njit.edu<mailto:hmkim at njit.edu> • (973) 596-5704
https://web.njit.edu/~hmkim/
104 Tiernan Hall, 161 Warren Street, Newark, NJ 07102

On Tue, Oct 13, 2020 at 8:40 PM Julius Madey <hillfox at fairpoint.net<mailto:hillfox at fairpoint.net>> wrote:
I think that would work.   Have to finish some assembly here and then come up with a schedule.
Jules
On 10/13/2020 5:13 PM, Dr. Nathaniel A. Frissell Ph.D. wrote:
Hi Hyomin and Jules,

If I’m available, I’d like to join you as well. I’d really enjoy getting to meet Jules in person.

73 de Nathaniel

From: Kim, Hyomin <hmkim at njit.edu><mailto:hmkim at njit.edu>
Sent: Tuesday, October 13, 2020 5:02 PM
To: Julius Madey <hillfox at fairpoint.net><mailto:hillfox at fairpoint.net>
Cc: TAPR TangerineSDR Modular Software Defined Radio <tangerinesdr at lists.tapr.org><mailto:tangerinesdr at lists.tapr.org>; John Gibbons <jcg66 at case.edu><mailto:jcg66 at case.edu>; David Witten <wittend at wwrinc.com><mailto:wittend at wwrinc.com>; Dr. Nathaniel A. Frissell Ph.D. <nathaniel.frissell at scranton.edu><mailto:nathaniel.frissell at scranton.edu>
Subject: Re: [TangerineSDR] Fwd: another 24hour RM3100 run and comparison with Fredericksburg

Hi Jules - Thanks for your tip. Would you be willing to come down here to install it together? It would be fun!

All - It appears that the magnetometer I have is behaving well. However, it would be better if I have about >2 sets so I can check whether all the sensors are consistently behaving (which is extremely important for such a largely spaced network configuration). Do we have a timeline for more testing sets? If not, I will visit Jenny Jump to install the sensor again with a better temperature management scheme as Jules suggested.

Sorry for my slow response. I am quite swamped by my teaching workload this semester (somewhat unexpected...).

Cheers,
Hyomin

[NJIT                                                            logo]<https://www.njit.edu/>
Hyomin Kim
Assistant Professor
Physics
Center for Solar-Terrestrial Research
Institute for Space Weather Sciences
hmkim at njit.edu<mailto:hmkim at njit.edu> • (973) 596-5704
https://web.njit.edu/~hmkim/
104 Tiernan Hall, 161 Warren Street, Newark, NJ 07102

On Mon, Oct 5, 2020 at 6:07 PM Julius Madey <hillfox at fairpoint.net<mailto:hillfox at fairpoint.net>> wrote:
Hyomin,
During your run, the temperature of the 3100 was probably reasonably constant so your result is consistent with basic 3100 specs.  Keeping the temperature constant over 24 hours should give you a close alignment with future JJ station measurements.   Good news.
I can house your rm3100 in the same way I did mine or, I think I have enough extra parts now from Dave to make one up and send it down .... possibly drive it down since you're about 150 road miles from here, which I can do in three hours.
Jules
On 10/5/2020 5:31 PM, Kim, Hyomin wrote:
Hi Dave, Jules and Nathaniel,
Sorry that it took me so long to work on the data that was retrieved from Jenny Jump. The two sensors (Bartington and our mag) were placed inside a solenoid which was then placed inside a mu-metal case. Long story short, there is NO reason to believe that our magnetometer behaves in a different way compared to the other. They trace the artificially generated fields well. The only thing that needs to be addressed later is that the given field was so big that the output signals were saturated - the fields inside the solenoids should have been decreased to avoid saturation. My oversight that I had to leave the site in a rush. However, both sensors traced the fields in the same way. I hope I will have more time to stay at Jenny Jump next time to monitor the signals more carefully as the NJIT system has now been fixed.

Please share this during the Tangerine meeting tonight as I will not be able to attend it this time due to the conflict with my lecture which is expected to be longer than last week...

Hyomin

[NJIT                                                            logo]<https://www.njit.edu/>
Hyomin Kim
Assistant Professor
Physics
Center for Solar-Terrestrial Research
Institute for Space Weather Sciences
hmkim at njit.edu<mailto:hmkim at njit.edu> • (973) 596-5704
https://web.njit.edu/~hmkim/
104 Tiernan Hall, 161 Warren Street, Newark, NJ 07102

On Tue, Sep 22, 2020 at 9:45 PM Julius Madey via TangerineSDR <tangerinesdr at lists.tapr.org<mailto:tangerinesdr at lists.tapr.org>> wrote:
Dear John,
Yes, temperature information was posted a while back.  PNI initially claimed that there was no temperature effect due to the essentially self compensating scheme used for field measurement. After I measured as much as a 7-10nT per degree C tempco in some controlled oven experiments and sharing that data with PNI, PNI eventually replied that engineering had measured a maximum of +/- 2nT per degree C for the inductors alone but had not characterized the complete sensor.

The data I have taken so far is not complete but indicates that the tempco (1) may not be equal on all axes, including differences in sign and (2) may not be assumed to be equal for any two units and (3) may not be linear with temperature, making algorithmic correction of the recorded data difficult.

Hence, my attempts to achieve temperature stabilization to better than 1 degree C over 24 hours for the recordings I've been doing (sensor in a housing that can be easily buried sub surface).

Have also done some experiments with an insulated chamber containing a thermal mass, equivalent to a low pass filter, to achieve stabilization.

Another approach is a temperature controlled oven set to a few degrees above expected maximum local ambient temp but that requires power, which complicates long cable runs.

At just 19-20 inches below grade in my shaded woodlot, 24 hour temperature stability has been within 0.7C.  Another 12-16 inches for the next install should bring that to a diurnal variation of perhaps 0.1C in this location.

Jules K2KGJ

On 9/22/2020 7:52 PM, John Gibbons wrote:
All,

I have not kept up on this thread due to other commitments, but I don't see any mention of the temperature data and plotting correlated to the data acquisition of the 3 axis magnetometer (or more likely I missed it).

I believe that the RM3100 uses ferrite core inductors for the 3 axis magnetic pickups and ferrites definitely have a tempco (voice of experience...). Even a 1 Deg C may have an impact on the mu of the ferrite at the 1nT measurement levels.

You've probably already done this (if so please point me to it) but has this been looked at / tested for / quantified?

John N8OBJ

John C. Gibbons
Director - Sears Undergraduate Design Laboratory
Dept. of Electrical Engineering and Computer Science
Case Western Reserve University
10900 Euclid Ave, Glennan 314
Cleveland, Ohio  44106-7071
Phone (216) 368-2816<tel:216-368-2816> FAX (216) 368-6888<tel:216-368-6888>
E-mail: jcg66 at case.edu<mailto:jcg66 at case.edu>

On Mon, Sep 21, 2020 at 4:18 PM Julius Madey via TangerineSDR <tangerinesdr at lists.tapr.org<mailto:tangerinesdr at lists.tapr.org>> wrote:
Forgot to mention that one thing to keep in mind is the difference in raw data processing between the absolute value sliding 1minute average plots I do with a spreadsheet with the more complex algorithm delta B plots from Intermagnet.  I'm not sure how the 10nT anomaly would appear if the same Intermagnet processing algorithm was used.
Hyomin ?????
On 9/15/2020 10:38 AM, Phil Erickson wrote:
Hi Dave,

  The X and Y traces return after 24 hours to nearly the same relative value in both the reference and RM3100 traces.  The Z trace does not.  Ionospheric currents flowing in the E region should not affect Z exclusive of X and Y under most any geometry I can think of, so I wondered whether the uncalibrated RM3100 was likely causing this.  (I have never professionally calibrated a magnetometer, so Hyomin might need to comment here.). In other words, I always assume there is some measurement systematic until it has been completely ruled out before assigning it to geophysical variation.

73
Phil W1PJE

On Tue, Sep 15, 2020 at 10:34 AM David Witten <wittend at wwrinc.com<mailto:wittend at wwrinc.com>> wrote:
@Phil,

Correlation is great, and surely some further calibration issues may remain.  But these sensors are NOT colocated - (200-300+ mi apart?) .  Wouldn't it be suspicious if they did correlate perfectly?  If they did, shouldn't  we ask if we do really need an extensive array of these sensors?  Presumably there will always be some local variation at this scale?  (don't know, just asking)

Dave Witten, KD0EAG

On Tue, Sep 15, 2020 at 7:21 AM Phil Erickson <phil.erickson at gmail.com<mailto:phil.erickson at gmail.com>> wrote:
Hi all,

  There appears to be a 10 nT drift in the Z component for the RM3100 that is not in the Fredericksburg traces.  Is that slow systematic bias expected?  Maybe things are not calbrated over that time frame quite yet?

73
Phil W1PJE

On Mon, Sep 14, 2020 at 10:49 PM David Witten via TangerineSDR <tangerinesdr at lists.tapr.org<mailto:tangerinesdr at lists.tapr.org>> wrote:
I don't believe that my previous post carried the file K2KGJ provided.
---------- Forwarded message ---------
From: Julius Madey <hillfox at fairpoint.net<mailto:hillfox at fairpoint.net>>
Date: Mon, Sep 14, 2020 at 4:26 PM
Subject: another 24hour RM3100 run and comparison with Fredericksburg
To: Kim, Hyomin <hmkim at njit.edu<mailto:hmkim at njit.edu>>, David Witten <wittend at wwrinc.com<mailto:wittend at wwrinc.com>>, Dr. Nathaniel A. Frissell Ph.D. <nathaniel.frissell at scranton.edu<mailto:nathaniel.frissell at scranton.edu>>, Dave Larsen <kv0s.dave at gmail.com<mailto:kv0s.dave at gmail.com>>

All,
I was hoping to record a relatively short term event but missed one about 10 days ago.  However, there was a good run on the 12th with an ~30nT excursion on the Y axis lasting about an hour.  In the attached pdf, the three axes of the RM3100 again track the Fredericksburg magnetometer station data quite closely.  The RM3100 plotted data points are simple running 60second averages and not the more complex filtering algorithm used by Intermagnet stations for their 1 minute data points.

The vertical axes scales on all plots are as close as I could match them by eye in cutting and pasting.

I believe the value to the right on the Intermagnet plot is the mean for the 24 hour period.  I did not try to compute a 24 hour mean.

One of the products for the future for general interest would be a running plot like those available on Intermagnet.org.  I guess we can dream a bit.

Jules - K2KGJ
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