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[aprssig] Ambiguity due to GPS

Scott Miller scott at opentrac.org
Sat Jan 7 23:52:28 UTC 2006


> Take a look for your self on the APRS-IS and come to your own 
> conclusions.

Ok.  According to aprsworld, there are 5 distinct OpenTracker users with 7-7
paths, versus 12 for the TinyTrak3 and around 100 for the generic 'APRS'
tocall.  Including weather and telemetry, the average packet size is 46
bytes for the OT, 40 bytes for the TT3, and 62 bytes for generic APRS.

> 144.39 is used exclusively for APRS compliant packets.  Other 
> protocols
> should use another frequency.

Doesn't always happen that way.  If you run an Igate with a TNC in KISS mode
and install SAMBA with the default configuration, you'll get NBNS name
broadcasts over IP on the air.  Ignoring the PID is just as silly as
ignoring the FCS checksum.  It's there for a reason.

> Not true around Chicago.  Take a look at the samples I provided in a
> previous post.  

I've shipped roughly 50 OpenTrackers to the Chicago area in the last couple
of months.  If you're seeing a disproportionate number of misconfigured
trackers, it's because there's been a pretty large influx recently.  Again,
it's all about education.

I don't mind adding more warnings to my next software release, but I expect
that'll never satisfy everyone.  There are too many different ideas on
what's appropriate and what's not.  And I WILL provide a less obvious option
to enable an expert mode - no need to torture knowledgeable users with
constant warnings when they know what they're doing.

> Not quite.  The added TXD overhead is reduced on the original 
> transmission,
> and perhaps on the first digipeat.  After that, there is no advantage.

I disagree.  Any reasonable digipeater will buffer and retransmit the
packets together.

> >But it doesn't even come close to doubling channel usage - 
> >it's more like a
> >20% increase.
> 
> Still should not be condoned or permitted.

Should not be PERMITTED?  Ok, that's where I draw the line.  We obviously
have very different ideas about how this hobby is supposed to work.  There's
no point in continuing this argument.  I already include good information in
my manual, but I'll add more.  I already provide reasonable defaults in my
configurations, but I'll add some extra warnings.  But you DO NOT get to
tell people what they can and can't do with their equipment unless you're
the FCC.

Scott
N1VG







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