[aprssig] APRS radios
hessu at hes.iki.fi
Sun May 25 04:33:30 CDT 2008
On Sat, 24 May 2008, 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...
Its really quite complicated. There are so many different types of
packets, and so many different types of packets for the same purpose (a
position packet), with a large amount of options and extensions and
special cases. Like the one here, a message suddenly isn't a message, but
a bulletin, because the destination callsign has a special prefix. It
could be so much simpler and still have all the same features. I know, it
seems too late to fix it... but it really cannot honestly be called
I know it's a massive task to implement APRS on a big computer, using a
scripting language which is very good for implementing string parsers.
It's even more work in C. It must be really, really hard to implement all
of it properly in a tiny embedded device with very little memory.
Luckily embedded CPUs are getting more powerful and have more memory to
spare than before, so the manufacturing cost of adding APRS in a radio
comes mostly from writing the code and adding a GPS chip. If the protocol
spec would be smaller, it'd be cheaper to do it.
Don't get me wrong, I think APRS is pretty damn cool. I spent most of my
spare time last year implementing an user interface for it, and had a lot
of fun in the process. Just don't call it simple. :)
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