[TangerineSDR] Mag update?

David G. McGaw david.g.mcgaw at dartmouth.edu
Mon Aug 3 22:50:25 EDT 2020


I did a quick and rough test of the magnetometer change vs temperature.  
Here is my raw data.  I was measuring the Z-axis which here in NH is 
about 50 uT while changing the temperature, as measured by the T 
sensor.  I heated the unit up above 85C and then put it under a 
cardboard cover to slow down the cooling and equilibrate the 
temperature.  Here is my raw data:

T        Z-axis

2750.9 uT

3050.85

3550.77

4050.7

4550.7

5050.5

5550.4

6050.1

6549.9

7049.6

7549.2

8548.6


Noise was about .10 uT peak-peak.


David N1HAC



On 8/3/20 12:15 PM, Dr. Nathaniel A. Frissell Ph.D. via TangerineSDR wrote:
>
> This all sounds very good. I’m eager to see the results.
>
> 73 de Nathaniel W2NAF
>
> *From:* TangerineSDR <tangerinesdr-bounces at lists.tapr.org> *On Behalf 
> Of *Julius Madey via TangerineSDR
> *Sent:* Monday, August 3, 2020 11:57 AM
> *To:* Kim, Hyomin <hmkim at njit.edu>; TAPR TangerineSDR Modular Software 
> Defined Radio <tangerinesdr at lists.tapr.org>
> *Cc:* Julius Madey <hillfox at fairpoint.net>
> *Subject:* Re: [TangerineSDR] TangerineSDR Digest, Vol 16, Issue 
> 32_RM3100temperature effects
>
> Great ! Out of direct sunlight and close to ground level would be best.
>
> On 8/3/2020 11:28 AM, Kim, Hyomin wrote:
>
>     This time, I will try to place the sensor as close as possible to
>     the science magnetometer at Jenny Jump and insulate it to minimize
>     the temperature effect if any.
>
>     Gil (the site manager) and I will not be available until next week
>     but will try to address this issue as soon as possible.
>
>     Hyomin
>
>
>     NJIT logo
>     <https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.njit.edu%2F&data=02%7C01%7CDavid.G.McGaw%40dartmouth.edu%7C3b6a91608e414c3e359408d837c88c7e%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C637320681789745357&sdata=ucpyw%2FCCoLnq8YpSxPDMvU6K9r7Kgz7CaZbXeNqFNk0%3D&reserved=0>
>
>     	
>
>     *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/
>     <https://nam12.safelinks.protection.outlook.com/?url=https:%2F%2Fweb.njit.edu%2F~hmkim%2F&data=02%7C01%7CDavid.G.McGaw%40dartmouth.edu%7C3b6a91608e414c3e359408d837c88c7e%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C637320681789745357&sdata=BHNGmalVicIaozYaLs8qrpyLbAZVxSgPteuU4DFCMP4%3D&reserved=0>
>     104 Tiernan Hall, 161 Warren Street, Newark, NJ 07102
>
>     On Sun, Aug 2, 2020 at 1:49 PM Julius Madey via TangerineSDR
>     <tangerinesdr at lists.tapr.org <mailto:tangerinesdr at lists.tapr.org>>
>     wrote:
>
>         That is the claim.  So either that's not the case, or perhaps
>         it holds for levels in excess of a few hundred nT or something
>         else is causing the variations that were observed at Jenny
>         Jump and in my various tests.  It is probably not B fields
>         very local to the adapter board, which sees currents in the
>         10mA range.  Just did some tests with 100mA into a twisted
>         pair of #31 magnet wire held near different parts of the
>         RM3100 board.
>
>         If the twisted pair was 0.5cm or more away from anything on
>         the board, no effect observed.  If it lay directly on one of
>         the sensing inductors, effect was ~ 50nT.
>
>         Another thought on temperature stability .... place the mag in
>         an in-ground vault.  Back in the 60's when we needed xtal
>         oscillator stability on the cheap and better than the usual
>         xtal oven of the day, we put the oscillator assembly about 3
>         feet underground.  Very stable short term and excellent long
>         term.  It would certainly work for 24 hour observation periods.
>
>         Jules Madey-K2KGJ
>
>         On 7/31/2020 1:38 PM, tangerinesdr-request at lists.tapr.org
>         <mailto:tangerinesdr-request at lists.tapr.org> wrote:
>
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>             Today's Topics:
>
>                 1. Re: Mag update? (David G. McGaw)
>
>                 2. Re: Mag update? (David G. McGaw)
>
>             ----------------------------------------------------------------------
>
>             Message: 1
>
>             Date: Fri, 31 Jul 2020 13:36:38 -0400
>
>             From: "David G. McGaw"<david.g.mcgaw at dartmouth.edu>  <mailto:david.g.mcgaw at dartmouth.edu>
>
>             To:tangerinesdr at lists.tapr.org  <mailto:tangerinesdr at lists.tapr.org>
>
>             Subject: Re: [TangerineSDR] Mag update?
>
>             Message-ID:<3718db2a-97b4-eba5-8f0a-e94ead711cd7 at dartmouth.edu>  <mailto:3718db2a-97b4-eba5-8f0a-e94ead711cd7 at dartmouth.edu>
>
>             Content-Type: text/plain; charset="utf-8"; Format="flowed"
>
>             Interesting, this, as it says on the RM3100 webpage "Measurements are
>
>             stable over temperature and inherently free of offset drift" and a
>
>             temperature coefficient is not even mentioned in the specs.
>
>             David N1HAC
>
>             On 7/31/20 11:18 AM, Julius Madey via TangerineSDR wrote:
>
>                 Good morning all.? Betty Zhang at PNI is responding to the request and
>
>                 has asked for more information which I have supplied, including some
>
>                 of the JJ test comparisons, how I ran the calibration runs I did, data
>
>                 reduction, etc.
>
>                 I would suggest one further item for consideration in getting to a
>
>                 useable solution.? If RM3100 temperature turns out to be a concern,
>
>                 place the sensor in a small foam insulated box with a proportionally
>
>                 controlled heater which maintains the temperature at something just
>
>                 above what would be considered the highest environmental temperature
>
>                 around the sensor.? That should be relatively simple to do without
>
>                 introducing an interfering magnetic field local to the sensor.? Some
>
>                 power would be required but with careful design, I would think well
>
>                 within 1 watt.
>
>                 Another possibility would be using peltier effect heat pumps to do the
>
>                 same thing, although the technology would probably result is stronger
>
>                 local B fields from the peltier device and require more power.? The
>
>                 insulated foam box and proportional heater is also probably the
>
>                 cheapest approach considering the need to keep overall costs for the
>
>                 expected users low.
>
>                 Regards,
>
>                 Jules
>
>                 On 7/31/2020 10:26 AM, David Witten wrote:
>
>                     Hyomin,
>
>                     I'm not certain what the next step should be.? Julius is hoping for
>
>                     further response from PNI on this subject.
>
>                     If temperature compensation does account for the differences in
>
>                     observed response I would think that the important thing to? do may
>
>                     be to find a way to calibrate out the discrepancy.? Then we can look
>
>                     at insulation to further minimize the effect.
>
>                     Calibration will hopefully give us more meaningful values to begin?with.
>
>                     Insulation will dampen the effect of those behaviors over short
>
>                     timespans.
>
>                     Fortunately, neither requires changes?in the basic circuit, just
>
>                     adjustments to the data collection and device packaging.
>
>                     Dave
>
>                     On Fri, Jul 31, 2020 at 9:10 AM Kim, Hyomin <hmkim at njit.edu  <mailto:hmkim at njit.edu>  
>
>                     <mailto:hmkim at njit.edu>  <mailto:hmkim at njit.edu>> wrote:
>
>                          Hi Dave
>
>                          Sorry that I've been out of the loop for a while as I was
>
>                          completely caught up with something else. May I ask you what the
>
>                          current status is?
>
>                          I can visit Jenny Jump if there is something that I can do. At
>
>                          this moment, I cannot think of anything that can be fixed from my
>
>                          end.
>
>                          If the temperature compensation is the issue, I could install
>
>                          insulations around the sensor.
>
>                          Hyomin
>
>                          NJIT logo
>
>                          <https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.njit.edu%2F&data=02%7C01%7CDavid.G.McGaw%40dartmouth.edu%7C2e59f624469544810c1c08d8356521e1%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C637318055785489421&sdata=TmqWJw6VYdRSrTgS2xSIifG4OTUj6z5lcBLqd2UedyY%3D&reserved=0>  <https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.njit.edu%2F&data=02%7C01%7CDavid.G.McGaw%40dartmouth.edu%7C3b6a91608e414c3e359408d837c88c7e%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C637320681789755315&sdata=NPkBosTmBhBS2wYv0poh6V16oCwYx%2F1o5Znw4QtGFLA%3D&reserved=0>
>
>                            *Hyomin Kim*
>
>                          Assistant Professor
>
>                          Physics
>
>                          Center for Solar-Terrestrial Research
>
>                          Institute for Space Weather Sciences
>
>                          hmkim at njit.edu  <mailto:hmkim at njit.edu>  <mailto:hmkim at njit.edu>  <mailto:hmkim at njit.edu>?? (973)?596-5704
>
>                          https://web.njit.edu/~hmkim/  <https://nam12.safelinks.protection.outlook.com/?url=https:%2F%2Fweb.njit.edu%2F~hmkim%2F&data=02%7C01%7CDavid.G.McGaw%40dartmouth.edu%7C3b6a91608e414c3e359408d837c88c7e%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C637320681789765273&sdata=2VoO3Q96MjJxabOXnnX2z6K3Py7eG4UB0hJXFSlrl7Y%3D&reserved=0>
>
>                          <https://nam12.safelinks.protection.outlook.com/?url=https:%2F%2Fweb.njit.edu%2F~hmkim%2F&data=02%7C01%7CDavid.G.McGaw%40dartmouth.edu%7C2e59f624469544810c1c08d8356521e1%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C637318055785499423&sdata=Nz%2B0y9A0svN6RegTKpvfpWgJ%2FCb1N1vKkFr71fqtDFg%3D&reserved=0>  <https://nam12.safelinks.protection.outlook.com/?url=https:%2F%2Fweb.njit.edu%2F~hmkim%2F&data=02%7C01%7CDavid.G.McGaw%40dartmouth.edu%7C3b6a91608e414c3e359408d837c88c7e%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C637320681789765273&sdata=2VoO3Q96MjJxabOXnnX2z6K3Py7eG4UB0hJXFSlrl7Y%3D&reserved=0>
>
>                          104 Tiernan Hall, 161 Warren Street, Newark, NJ 07102
>
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>             ------------------------------
>
>             Message: 2
>
>             Date: Fri, 31 Jul 2020 13:37:51 -0400
>
>             From: "David G. McGaw"<david.g.mcgaw at dartmouth.edu>  <mailto:david.g.mcgaw at dartmouth.edu>
>
>             To:tangerinesdr at lists.tapr.org  <mailto:tangerinesdr at lists.tapr.org>
>
>             Subject: Re: [TangerineSDR] Mag update?
>
>             Message-ID:<f86f2596-ef2b-25c7-5b12-3f83c4429cb3 at dartmouth.edu>  <mailto:f86f2596-ef2b-25c7-5b12-3f83c4429cb3 at dartmouth.edu>
>
>             Content-Type: text/plain; charset="utf-8"; Format="flowed"
>
>             Interesting, this, as it says on the RM3100 webpage "Measurements are
>
>             stable over temperature and inherently free of offset drift" and a
>
>             temperature coefficient is not even mentioned in the specs.
>
>             David N1HAC
>
>             On 7/31/20 11:44 AM, Julius Madey via TangerineSDR wrote:
>
>                 One more thought.? I've asked PNI for information both on temperature
>
>                 and supply voltage sensitivity, the only two variables I could think
>
>                 of besides the need to minimize local B fields due to currents in
>
>                 circuit board traces, nearby wiring, etc.
>
>                 I did not find data on the temperature stability of the 3.3 volt
>
>                 regulator Dave's JJ board? is using but the regulator I used with the
>
>                 original adapter board Dave sent me has about 5 millivolts of change
>
>                 out of 3.3 volts between 25 and 50 C and Dave's is probably similar.?
>
>                 That doesn't seem like enough change to produce the observed
>
>                 variations but that information was given to PNI as well.
>
>                 On 7/31/2020 10:26 AM, David Witten wrote:
>
>                     Hyomin,
>
>                     I'm not certain what the next step should be.? Julius is hoping for
>
>                     further response from PNI on this subject.
>
>                     If temperature compensation does account for the differences in
>
>                     observed response I would think that the important thing to? do may
>
>                     be to find a way to calibrate out the discrepancy.? Then we can look
>
>                     at insulation to further minimize the effect.
>
>                     Calibration will hopefully give us more meaningful values to begin?with.
>
>                     Insulation will dampen the effect of those behaviors over short
>
>                     timespans.
>
>                     Fortunately, neither requires changes?in the basic circuit, just
>
>                     adjustments to the data collection and device packaging.
>
>                     Dave
>
>                     On Fri, Jul 31, 2020 at 9:10 AM Kim, Hyomin <hmkim at njit.edu  <mailto:hmkim at njit.edu>  
>
>                     <mailto:hmkim at njit.edu>  <mailto:hmkim at njit.edu>> wrote:
>
>                          Hi Dave
>
>                          Sorry that I've been out of the loop for a while as I was
>
>                          completely caught up with something else. May I ask you what the
>
>                          current status is?
>
>                          I can visit Jenny Jump if there is something that I can do. At
>
>                          this moment, I cannot think of anything that can be fixed from my
>
>                          end.
>
>                          If the temperature compensation is the issue, I could install
>
>                          insulations around the sensor.
>
>                          Hyomin
>
>                          NJIT logo
>
>                          <https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.njit.edu%2F&data=02%7C01%7CDavid.G.McGaw%40dartmouth.edu%7C4a7b93ba3ecd455d4e0f08d83568b144%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C637318071068004568&sdata=O09d%2FBt6N3Iq%2FUVQ5KdQz6V0Km3YIN%2BucnCkc1JQC8E%3D&reserved=0>  <https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.njit.edu%2F&data=02%7C01%7CDavid.G.McGaw%40dartmouth.edu%7C3b6a91608e414c3e359408d837c88c7e%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C637320681789775223&sdata=H6uOa%2F1m4ad5ZqG5fZC48ZI38v3K86nBZoVrEiBnLZc%3D&reserved=0>
>
>                            *Hyomin Kim*
>
>                          Assistant Professor
>
>                          Physics
>
>                          Center for Solar-Terrestrial Research
>
>                          Institute for Space Weather Sciences
>
>                          hmkim at njit.edu  <mailto:hmkim at njit.edu>  <mailto:hmkim at njit.edu>  <mailto:hmkim at njit.edu>?? (973)?596-5704
>
>                          https://web.njit.edu/~hmkim/  <https://nam12.safelinks.protection.outlook.com/?url=https:%2F%2Fweb.njit.edu%2F~hmkim%2F&data=02%7C01%7CDavid.G.McGaw%40dartmouth.edu%7C3b6a91608e414c3e359408d837c88c7e%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C637320681789775223&sdata=WRwBs7Qy86UEiCfSplyHYSvED0NXNLmAzebDp9b2RwM%3D&reserved=0>
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>                          104 Tiernan Hall, 161 Warren Street, Newark, NJ 07102
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