[aprssig] Advice requested please

Lynn W. Deffenbaugh (Mr) ldeffenb at homeside.to
Thu May 9 06:38:05 CDT 2013


My opinion is that there's enough packet corruption caused by 
mis-configurations and I wouldn't release something that makes it even 
more prevalent, especially in the callsign portion of the packet because 
we'll end up with "ghost" stations popping up.

If you keep banging on the issue, I'm sure you can bring it to some sort 
of resolution.  If you even just use KISS, you'd get the nice <C0> 
wrapping characters that assist, but don't guarantee, that everything in 
between came through.  At least then, a dropped leading <C0> will end up 
causing the entire packet to be dropped.  And KISS is self-synchronizing 
because adjacent <C0> characters are just ignored.

There's other means of wrapping the packets that are more robust, but 
the advantage of KISS is that most APRS client applications already 
support it.

Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32

On 5/5/2013 5:17 AM, Chris Moulding wrote:
> Recently I've been developing a Bluetooth version of the APRS TNC Digi 
> Tracker. I've also written an Android app which receives the APRS 
> traffic received by the Digi Tracker sent over the Bluetooth link. The 
> app can also igate the traffic to the APRS-IS over wi-fi or 3G.
>
> This works really well using an Android phone as a head up display 
> while driving and also allows easy deployment of a receive only APRS 
> igate for emergency comms.
>
> There is however a problem. When the distance between the Digi Tracker 
> and Android phone gets too high the Bluetooth link starts losing the 
> first few characters from some packets before the Bluetooth link 
> fails. This could allow incorrect packets to be sent to the APRS-IS 
> usually with errors in the station callsign.
>
> If the phone and Digi Tracker are close together say inside a car the 
> Bluetooth link is 100% and the traffic is perfect.
>
> I'd like to seek the advice of the members of the group. Do I release 
> this with a warning to keep the phone and Digi Tracker close together 
> or should I forget about releasing it as it may compromise the quality 
> of the APRS network?
>
> Regards,
>
> Chris, G4HYG
>
>



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