[TangerineSDR] cal results

David Witten wittend at wwrinc.com
Sat Apr 25 23:59:29 EDT 2020

Julius (and anyone else),

Please realize that you are running far ahead of what this code was
intended to do.  It was meant to illustrate the general technique used to
interact with the device.  It was never intended to give meaningful
results.  I had thought that I conveyed that it is only intended to show
that these boards work in a physical sense.

At the least, I know that all the vectors in this code require a correction
for gain.  This is not my current development repository,

I sent Frankie Bonte and her father a much more expensive PNI demonstration
board. It was my hope that they would use it to explore the relationship
between the values from this code and  the values that PNI's own code
produces.  They seem to have chosen to go in some other direction that I do
not understand.  I never received any feedback so I had to purchase another
Demo board and I have not gotten around to using it because I have no
usable Windows machines.

Again, do not expect the code in this github repo to give meaningful
results.  These results have ALWAYS looked wrong to me.

I have another private repo that I have been working on for months, and I
will only make it available when it seems ready to me.

Davei Witten, KD0EAG

On Sat, Apr 25, 2020 at 10:18 PM Julius Madey <hillfox at fairpoint.net> wrote:

> Dave,
> Made several runs with X,Y and Z sensors interchanges in different
> orientations.
> Y and Z  have equal sensitivities
> X sensitivity is significantly higher
> Using the NOAA model values for my Lat, Long and Altitude, multiplying X
> by 0.056 and Y and Z values by 13 gives results quite close to the
> predicted model values with the resulting LSDs equal to 1nT.  Close enough
> to get a much better idea of noise level.
> Looking at the Helmholtz pair test data again, the multiplication values
> are twice those quoted above......a factor of 2 difference between the two
> methods.  Given that the NOAA model values are probably very close to what
> the measured values should be, and since (ambient + test field) - (a,bient
> - test field) = 2 x test field, the calculated value for the Helmholz field
> is probably off by a factor of two .... back to my notes on the coil field
> ....
> I don't see anything in the setup instructions for the 3100 registers to
> suggest such a difference and I haven't dug into the code yet.
> I don't want to post anything on the repository until the calibration
> results check out.
> Regards and stay well ...
> Jules   K2KGJ
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