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[aprssig] APRS Message character sets ?

Stephen H. Smith wa8lmf2 at aol.com
Thu Jul 10 01:41:35 UTC 2008


Matti Aarnio wrote:
> I am asking the  aprssig  to form a consensus of what shall be the canonic
> message character-set and encoding beyond US-ASCII ?
>
>
> he APRS specification 1.0.1 defines that used character set is ASCII in
> many places where it defines charactersets at all.
>
> This is quite understandable in view of TNC2 interfaced systems with
> 7E1 type communication channel -- which is unable to pass thru any extended
> characters.
>
>   


1)    TNC2-type systems are normally initialized to 8-N-1 (not the 
default 7-E-1) for APRS with the  TNC commands

AWLEN 8
8BIT ON

(or equivalent for other TNCs) so that they WILL be transparent to 8-bit 
characters.  This is required so that any arbitrary character values 
created by Mic-E encoding will pass.    In fact I have modified the TNC2 
firmware Ver 1.1.9 to DEFAULT to 8-N-1 bit transparent mode so no init 
is even required.


2)    Since the APRS network infrastructure is heavily based on legacy 
1980s-1990s packet hardware that doesn't support 16-bit/character 
encoding (i.e. UniCode), I wouldn't hold my breath for 16-bit support 
any time soon.   Not to mention that the most widely used APRS 
application (UI-View) is now frozen in time and unchangeable.    




--

Stephen H. Smith    wa8lmf (at) aol.com
EchoLink Node:      14400    [Think bottom of the 2M band]
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