[aprssig] APRS and Unicode

Robert Bruninga bruninga at usna.edu
Fri Jan 6 12:41:50 EST 2017

> - Callsigns are limited to 6 ASCII (not unicode) alphanumeric characters
> in the AX.25 spec, and by extension, KISS protocol:


Is this also correct for third-party messaging/APRSIS?  Are lower-case
characters permissible?

No, if you are talking about APRS "messaging", the TOCALL is a 9 byte fixed
length field that can conatin alphanumeric in all 9 spots and mixed case.
(I think that some radios did not full understand this and will not handle a
mixed case outgoing message..  Obviously it has to be UPPERCASE and match
the radio's call when it receives a message and when it ACKS the message,
But some of these radios will not allow you to send a "message" or bulletin
to a mixed case of 9 character address. This restriction was not intended in
the APRS design.

Notice, this mixed case and 9 byte field ALSO applies to OBJECT and ITEM
NAMES that are the same 9 byte field.

- In any other text, UTF-8 encoding should be used, and non-ASCII characters
are permissible.
- In the case of Unicode text, the length limitations in the APRS docs
should be interpreted as characters rather than bytes (e.g. the message
length specifically says ’67 characters’, not ’67 bytes’).

AGREE, it is the displayed characters that were the limit.


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