[aprssig] Now this is an interesting use for APRS

scott at opentrac.org scott at opentrac.org
Wed Apr 12 20:10:45 CDT 2006

> Apparently it uses some type of encoding system in order to allow you
> exclusive access to control your system via APRS so that others can
> not get in.  While this makes sense from an operational standpoint, it
> sounds like encrypted or "coded" transmissions to me...  Another
> blatant rule violation.

The authentication scheme I saw described was just a time-dependent code - a
chosen seed value is incremented by a fixed amount ever so many minutes, and
rolls over at another specified number.  Seems like an incredibly easy
scheme to crack given even a few samples, but the point is that as long as
it's only for authentication, it's not against the rules.  Go read Part 97 -
the prohibition is against obscuring the MEANING of any message.  An ARES
group using a code word to report something (discovery of a dead body, for
example) is a violation.  Using a pass phrase to access your TNC isn't.
(Incidentally, I've seen the ARES/sensitive information thing come up before
- I think it was addressed by tapping out a message in CW with the DTMF pad,
which your average reporter with a scanner can't follow.)
> It's not a product targetted to the Amateur Radio community, but
> rather a product for general public use with an Amateur Radio
> "feature".  The first question I had asked was "why"?  Just use your

Is the feature being marketed to the general public?  I only glanced over it
the other day, but I didn't get that impression.  I definitely intend to do
some 'home automation' style things with my new tracker - it'll already
switch a 20-amp load in response to an APRS message.  Though really I'm
aiming more for amateur SCADA type applications than true home automation.


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