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

Tue Oct 13 17:02:02 EDT 2020

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

[image: 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 • (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> 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
>
>
>
> [image: 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 • (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> 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 <216-368-2816> FAX (216) 368-6888 <216-368-6888>
>> E-mail: jcg66 at case.edu
>>
>>
>>
>> On Mon, Sep 21, 2020 at 4:18 PM Julius Madey via TangerineSDR <
>> 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>
>>> 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>
>>>> 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> wrote:
>>>>>
>>>>>> I don't believe that my previous post carried the file K2KGJ provided.
>>>>>>
>>>>>> ---------- Forwarded message ---------
>>>>>> From: Julius Madey <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>, David Witten <wittend at wwrinc.com>,
>>>>>> Dr. Nathaniel A. Frissell Ph.D. <nathaniel.frissell at scranton.edu>,
>>>>>> Dave Larsen <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
>>>>>> --
>>>>>> TangerineSDR mailing list
>>>>>> TangerineSDR at lists.tapr.org
>>>>>> http://lists.tapr.org/mailman/listinfo/tangerinesdr_lists.tapr.org
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> ----
>>>>> Phil Erickson
>>>>> phil.erickson at gmail.com
>>>>>
>>>>
>>>
>>> --
>>> ----
>>> Phil Erickson
>>> phil.erickson at gmail.com
>>>
>>>
>>> --
>>> TangerineSDR mailing list
>>> TangerineSDR at lists.tapr.org
>>> http://lists.tapr.org/mailman/listinfo/tangerinesdr_lists.tapr.org
>>>
>>
>> --
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>>
>
>
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