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

Tue Sep 15 11:45:27 EDT 2020

If it is picking up a 10 nT level secular change, that is fabulous for a
reasonable cost sensor!  Maybe Jules has a ground induced current nearby?
Anyhow, temperature sensitivity at a more precise level is I'm sure all
part of the calibration needs, so we'll find out later...

Phil

On Tue, Sep 15, 2020 at 11:40 AM Kim, Hyomin <hmkim at njit.edu> wrote:

> Ah, yes I agree - the secular change seems to be a little off. I paid more
> attention to the small scale variations which look to be similar. This is a
> mystery to me. Maybe our sensor is not so precisely calibrated, say, to
> ambient temperature or something? Or we found another magnetic anomaly near
> where Jules lives!!
>
>
> [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 15, 2020 at 11:34 AM Phil Erickson <phil.erickson at gmail.com>
> wrote:
>
>> Hi Hyomin,
>>
>>  You have a more expert eye than I do, so I read your statements as
>> "uncalibrated axes", which of course is entirely correct for this RM3100
>> data.  I just don't know how to separate the geophysical (latitudinal
>> difference) from the instrumental (positional axes are not exactly the
>> same).  I was reacting mostly to the 24 hour secular change in each
>> component.  Is it reasonable to assume that is much less sensitive for
>> horizontal vs vertical components?
>>
>> 73
>> Phil
>>
>> On Tue, Sep 15, 2020 at 11:27 AM Kim, Hyomin <hmkim at njit.edu> wrote:
>>
>>> Hi Phil,
>>> At a first glance I thought the Z traces matched well as the relative
>>> values appear to be similar in that axis. If I am not wrong, Bz is oriented
>>> toward the center of the earth for the USGS mags. I believe the USGS mag is
>>> quite precisely oriented whereas our mag is not. Thus any slight offset in
>>> orientation can be seen noticeably as Bz has the biggest values? Also, the
>>> latitudinal difference between his place and Fredericksburg could be
>>> another factor?
>>>
>>> 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 15, 2020 at 10:39 AM Phil Erickson via TangerineSDR <
>>> tangerinesdr at lists.tapr.org> 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
>>>>
>>>
>>
>> --
>> ----
>> Phil Erickson
>> phil.erickson at gmail.com
>>
>

-- 
----
Phil Erickson
phil.erickson at gmail.com
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