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[aprssig] APRS radios

Joel Maslak jmaslak-aprs at antelope.net
Sat May 24 23:26:58 UTC 2008

On May 24, 2008, at 4:53 PM, Bob Bruninga wrote:
> APRS is really quite simple.  There are only 4 types of packets,  
> position, status, message and queries.  All one has to do is  
> capture them and display them.  And provide a simple user interface...

That's a slight bit of an understatement.

I asked about bulletins yesterday.  Yep, that's a message packet,  
sure, well...maybe just almost, it doesn't have a sequence number.   
To fully implement the "message" types of packets, you have to do a  
bunch of special bulletin processing.  Then you have to think about  
third party packets...

Position packets have at least three major variations that I can  
think of off the top of my head - raw GPS strings (and two different  
strings might be sent), compressed, and MIC-E.  Then there are  
objects, which is a type of position packet, but...

The thing that makes the APRS spec very difficult to fully implement  
is that things were just randomly added on.  As a result, people  
implement the parts they need to get their immediate need met and  
prioritize the other parts as lower priority - because everything in  
APRS seems to be a "special case".  And as we all know, no software  
program every is "finished".  (well, except APRSDOS!)

> Interesting to hear you complain.  Teenagers have no problem text  
> messaging using their phone pads and in fact, seem quite happy with  
> it.  We have had local/global text messaging and email built into a  
> ham radio APRS HT since 1998 (the D7).

I'm no teenager - I don't have the motor control or the  
eyesight!  :)  But I do use a smartphone with keyboard - a much  
better design for heavy messaging.  The touch tone pad is great for  
"mostly telephone calls with some messaging, or a bored teenager".   
The keyboard is a better two-way text communication tool.

> In the mean time, I have sure had 10 years an a lot of fun with it...

Yes, me too.
> Its amazing the kind of communicaitons we can acomplish if we just  
> do it...

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