[aprssig] Injecting Traffic Incident Objects

Frank Knobbe k4fhk at knobbe.us
Mon Sep 19 18:15:56 CDT 2016

On Sat, 2016-09-17 at 20:01 -0400, K5ROE Mike wrote:
> The state of Virginia publishes an RSS feed of traffic incidents that 
> include enough information to be useful as APRS objects.  I have written 
> a rudimentary parser to inject these into APRS.
> Before I continue into the project, it seems wise to probe the list 
> members with some questions:
> 1) the propriety , would this somehow be against the 'vision' of APRS?

I think providing services to mobile stations via RF is inline with the
vision of APRS.

> 2) has this been tried before and deemed to be a bad idea?

Yes, I've been operating such a system for the last 3 years. (See my
offline reply).

> 3) Would it better to inject APRSIS or RF?  If RF should I consider a 
> longer path than WIDE2?

That depends on how you architect your solution. The main purpose is to
provide mobile users with traffic info, so RF is given. It will be gated
to APRS-IS by Igates. However, you can also spin this around by have
your system inject it into APRS-IS, and have an Igate or two pick it up
from there and bring it to RF. For my State of Tennessee, for example,
I'm bringing traffic objects to RF in Middle TN only. However, if other
areas would like to receive coverage, they can "tap the feed" from
APRS-IS and bring it onto RF for their area (and their area only).
There's another ham that brings these on RF in the West TN area. Care
has to be taken with the proper filters to provide coverage for the
intended area. Since TN is rather long, it made no sense to bring
objects to RF with 5-7 hops to cover the whole State. That's unnecessary
and unacceptable congestion. So instead, I service MidTN with two hops,
and the other fella West TN. No coverage in East TN yet, but could be
facilitated by an Igate operator with the appropriate filters.

Anyway, since in this scenario there are multiple Igate covering their
own areas via RF, the actual feed is injected into APRS-IS for sourcing
from there. Knoxville mobiles are not interested in traffic accidents in
Memphis. So plan your coverage area wisely.


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