[TangerineSDR] Magnetometer current state

Kim, Hyomin hmkim at njit.edu
Wed Oct 23 13:18:52 EDT 2019

First, we need to know what output value unit is. Is it nT (nano
Tesla, which space physicists prefer)? or Gauss? No matter what, we
need to make sure if the total magnetic field from the magnetometer in
your location is close to what's expected there. Here, the total
magnetic field can be obtained by sqrt(X^2+Y^2+Z^2) as the output has
three components. The total field can be compared with a model. The
model can be found on the web at:

This is quite straightforward to use and very much self-explanatory.
That is, you specify the geographic coordinates of your location to
see what total field should be. For example, here in Newark, the total
field is approx. 51700 nT (= 51.7 uT = 0.517 Gauss). If you don't see
a number you'd expect from your reading, there has to be some kind of
a conversion (bit number to magnetic field?), which I am not familiar
with as this is what's defined in the sensor module.

Hope this helps.

On Wed, Oct 23, 2019 at 12:55 PM David Witten <wittend at wwrinc.com> wrote:
> Hyomin,
> Thanks for the response!
> This list seems the best place for me to post my progress and concerns, as I am not sure that I have the direct email address for all who might be interested.
>> The second item that you listed is actually what my students struggled
>> with. This is one of the important processes to make sure we get meaningful data.
> I need your input in particular on the meaning of the readings.
> I am just extracting 8 bit quantities from the sensor, shifting and concatenating them into 16 bit values, masking off a few bits, and multiplying by a seemingly arbitrary constant.  The conversion is from some code I found for another micro environment, and came with no documentation or comments.
> I now have the 'PNI Commboard', and I hope soon to test the values it returns against my own.  I had hoped to avoid buying this thing, but I couldn't see another way.
> But that is just the raw values, I have no sense at all what they represent.
> For now I am concentrating on making a small board that takes some of the uncertainties out of using the demo boards and provides robust connections for the various projects.
> I am particularly interested in the needs of the other projects that may use this setup.  I would really appreciate input from the non-PSWS projects.
> Dave Witten, KD0EAG
>> From: "Kim, Hyomin" <hmkim at njit.edu>
>> To: TAPR TangerineSDR Modular Software Defined Radio <tangerinesdr at lists.tapr.org>
>> Cc:
>> Bcc:
>> Date: Tue, 22 Oct 2019 09:09:28 -0400
>> Subject: Re: [TangerineSDR] Magnetometer current state
>> Dear Dave
>> Sorry that I missed this email yesterday. Thank you very much for the
>> great work!
>> The second item that you listed is actually what my students struggled
>> with. This is one of the important processes to make sure we get
>> meaningful data. As Nathaniel mentioned, we could install it at Jenny
>> Jump so the data from your magnetometer can be compared with data from
>> our existing magnetometer.
>> Very much looking forward to hearing from you about your further progress!
>> Regards,
>> Hyomin

Hyomin Kim, PhD
Assistant Professor
Center for Solar-Terrestrial Research
New Jersey Institute of Technology
Tiernan Hall, Room 101
161 Warren Street, Newark, NJ. 07102
Tel. 973-596-5704

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