[aprssig] Identifying TX Igates

Heikki Hannikainen hessu at hes.iki.fi
Mon Sep 19 11:25:43 CDT 2011

On Mon, 19 Sep 2011, Bob Bruninga wrote:

> RX-only IGates kill the functionality of the APRS-IS as a universal system!

But their operators should not feel any guilt. They might have very good 
technical or regulatory reasons not to TX. Please try not to make them 
feel bad - we should actually be thankful to the RX-only igate operators, 

If they kill any functionality, that's the software's fault, not the 
operators. Additional igates should only make the whole system better, 
whether they are RX or TX igates, if things work right. Ok, TX igates 
could make it even better. But RX is good, too. :)

> Compounding this problem is that we have no way of knowing if people are
> using the right symbol for their IGate.  Are they using "I" because it is
> really  a TX Igate, or just because it seems logical?

Users are generally not very good at configuring obscure settings like 
this correctly (and it's very hard to even reach everyone involved to 
educate them). I believe that the software (igate, aprs-is, aprs.fi...) 
should figure out in some other way whether the transmitter actually 
works, than by looking at the symbol.

> APRS-IS local service.  These guys will take the trouble to indicate a TX
> Igate.  When we see one of those, we have proof-positive that the IGate
> includes a two-way TX capability.

And then the TX might stop working (break) and the symbol would stay the 
same. It would be good if the system could automatically figure out where 
the working transmitters are. For example, the neighbouring RX igate does 
hear the RF transmissions from the TX igate, which can then serve as the 
positive proof.

> I& - is an IGate, but is ambiguous with respect to transmitting
> R& - means it is definitely an RX only IGate
> T& - Means it is definitely a TX IGate with one hop path only
> 2& - means it is a TX igate clobbering two hops in all directions
> 3& - means it is a TX SPAM GENERATOR , (or a legitimate special case)
> Etc..
> Should we do this???

If the symbols should indicate things like this at some point with good 
reliability, then the igate software (aprx, aprsisce, etc) should probably 
automatically set the symbol according to it's settings. If TX igate is 
enabled with 1 hop path, the software should automatically set it's symbol 
to T& (and not let the user change it back). But I'm not sure what would 
be the value of this? There would be legitimate reasons to use other 
symbols, like weather stations and digipeaters with igate functionality.

   - Hessu

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