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

Julius Madey hillfox at fairpoint.net
Mon Sep 21 16:17:36 EDT 2020

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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>             <mailto:TangerineSDR at lists.tapr.org>
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>         -- 
>         ----
>         Phil Erickson
>         phil.erickson at gmail.com <mailto:phil.erickson at gmail.com>
> -- 
> ----
> Phil Erickson
> phil.erickson at gmail.com <mailto:phil.erickson at gmail.com>

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