[OZAPRS] APRS with Foundation license

[Kevin Dawson]

G'day.

Ray Wells wrote:

> The ax25 specification set the six character limit for the callsign, 
> plus the SSID which is in the range 0 - 15. The v2.0 specification we 
> still use today emerged in 1984. I can't remember what limits, if any, 
> existed in the father of packet, the Vancouver Protocol or the original 
> V1.0 ax25 specification that displaced Vancouver. I do remember the hot 
> debate about which was best, Vancouver or ax25 - this was circa 1983.

Religious wars over packet?  Never :-)

The early Vancouver versions used a single octet for an address 
(assigned by a coordinator), so was somewhat unable to cope with the 
onslaught of interest that packet created.  Version 3 extended the 
address capabilities, but by then AX.25 had become popular so V3 never 
got much of a foot in the door.

> I have to confess I do not know what would happen with a seven character 
> callsign but given that the last character ends up where the SSID is 
> expected, one could expect packet corruption.

The SSID is only 4 bits in its relevant octet (hence 0 to 15).  Other 
bits are used for control functions, so you would probably see more than 
just packet corruption if you just blindly put the last callsign 
character in there.

The dash in a packet callsign is just a notational nicety ("syntactic 
sugar", as one Uni lecturer put it).  It's not transmitted.

Kevin