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[aprssig] Balloon DFing on APRS (test lines)

Bob Bruninga bruninga at usna.edu
Fri Mar 2 19:14:49 UTC 2012


Subject: Re: [aprssig] Balloon DFing on APRS (test lines)

> I ONLY look for BRG/NRQ after a CSE/SPD Data Extension.

Yes.  This was for mobile DFing, so assume it is always there.  But do not
require there to be anything specific in that /000/000 field.  APRSdos puts
in OBJECT in that location if it is an object.  So look for NRQ in its fixed
location whether or not it has valid CSE/SPD data or not.

> Q is a quality which governs the degree width of the wedge...

Actually, The "quality" was simply intended to be on a subjective 1-to-9
scale.  There is no way to define it much more precise than that.  The only
reason we need an actual value is if you want to display a wedge.  But
wedges are not at all well defined either.  RF does not have edges.  SO we
usually define an antenna pattern by its 3 dB line, but this does not mean
there are no signals beyond it.

OK, lets go with 9 is one degree and back off from that as y ou suggest.
But we must make it very clear to users that this stuff is all subjective...

People have a better chance at remembering 1, 2, 4, 8, 16, 32, 64...

But again, they really have no such data in most cases.  What they have is a
gut feel as to how well their bearing line is.  On a scale of 1 to 9.  You
can use your power=s of two to define the width of the wedges (that is what
it was intended for) but we need to not let then people start taking these
overlapping wedges and then trying to make *computational* assessments.
Garbage in  garbage oiut.

The value of the wedges is again, to display the sender's opinion as to his
quality.

Anyway, Glad to hear of your implementation!

Bob, Wb4APR





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