[aprssig] APRS-IS Duplicate Packets

[Heikki Hannikainen]

On Mon, 3 May 2010, Robert Bruninga wrote:

> Tapio Sokura wrote:
>> a duplicate I consider the sender callsign-ssid, target
>> callsign and the body of the packet.... Also all white space
>> immediately preceding the cr or lf is dropped from the
>> duplicate
>> checksum calculation.
>
> Can't do that.  Yaesu VX-8R radios end with a space character to
> distinguish the type of radio.  The last 2 bytes of a Mic-E
> packet contain the MFR and TYPE codes.  For the VX-8R it is a
> space.

So, after trimming the whitespace off the VX-8R's type code, it's MFR+TYPE 
pair is 1 byte long, while everyone else's codes are 2 bytes long, so I'd 
guess it's still possible to figure out the VX-8R? Besides, we're only 
talking about not considering the whitespace while checking for duplicates 
- not actually trimming spaces from a packet which is in transit.

Who came up with a space as a significant character in the end of a 
packet, anyway? Technically, that's a very, very unfortunate selection, 
and a very recent one, too. These kinds of things should probably be 
discussed somewhere in the open so that such mistakes could be avoided. If 
manufacturers or new models cannot be discussed, at least the selection of 
new IDs and protocol features can be.

   - Hessu