[aprssig] BEACON - APRS or Not?

[Steve Dimse]

Not everything on an APRS network must be valid APRS data. This is  
especially common with BEACON packets, which is the default in some  
TNCs for beaconing. You may have noted that the APRS packet types are  
identified by the first character of the payload, for example > means  
a status packet follows. You may have noticed that only special  
characters are used to defined the packets types. This minimizes the  
chance of a non-APRS beacon packet (which most likely starts with a  
letter or number) being confused for an APRS packet.

The destination address is used to exclude packets for ALT Net  
operation, but just because a packet has a destination that is a valid  
APRS destination the packet does not need to contain valid APRS  
formatted data. Your parser must gracefully ignore those things it  
cannot understand...

Steve K4HG

On Aug 9, 2009, at 7:21 PM, Shawn Stoddard wrote:

> I have been working now and then on an APRS parser. During my  
> testing I have had the opportunity to review in great detail some of  
> the packets being transmitted in my vicinity. Two of the local  
> digipeaters periodically transmit a packet to a destination address  
> of BEACON. Per the APRS 1.01 specification this is one of the APRS  
> destination addresses. Due to that I assumed the contents of the  
> packet should be a valid APRS packet of some type, a status packet  
> perhaps. Am I thinking down the correct path?
>
>
>
> _______________________________________________
> aprssig mailing list
> aprssig at tapr.org
> https://www.tapr.org/cgi-bin/mailman/listinfo/aprssig
>