[aprssig] "station which heard ... directly on the radio"

Pete Loveall AE5PL Lists hamlists at ametx.com
Tue May 21 08:38:42 CDT 2013


What software is improperly appending -0 as a SSID in a TNC2 format?  Both the TNC2 and AEA formats do not permit -0 as a SSID because no SSID is the representation of a SSID of zero and -0 fails many duplicate checking algorithms working with the TNC2 format.  In fact, many APRS-IS server software will drop that packet because of the -0 SSID representation.

While showing all callsign-SSIDs with an asterisk that have the digipeated bit set won't generally break anything, it is also not compliant with the TNC2 and AEA formats.  Again, this is an improper recreation of the packet by the software reporting the packet.  The only callsign-SSID to be shown with an asterisk is the last -digipeater- (callsign-SSID in path) with the C bit set.  In other words, do not show the source call with an asterisk, do not show an asterisk on any callsign-SSIDs preceding the last callsign-SSID with the C bit set, and do not show an asterisk on any callsign-SSID without the C bit set (even if you think it should have been set).  It is not up to your software to assume that some other software didn't do it correctly.  That may have been done on purpose by the originator to use an unrecognized callsign-SSID for part of the path.

Hope this helps.

73,

Pete Loveall AE5PL
pete at ae5pl dot net



> -----Original Message-----
> From: Kristoff Bonne
> Sent: Monday, May 20, 2013 5:16 PM

> However, it's not realy clear how exactly this should be corrected.
> 
> I noticed that when you just set the asterisk everywhere where that bit is
> set, you get paths like this:
> ... to U0QRQ5-0 via ON0WTO-2*,WIDE1-0*,ON0OST-0* (just copied this off
> the air 5 minutes ago).
> 
> Is this correct? When I look in the archive of "raw" messages on aprs.fi, I do
> not see such an paths overthere! The asterisk in only on the last message or
> the one before that?
> 
> 
> 
> On what addresses in the path does there need to be a asterisk?
> All addresses with the C-bit set? Only the last? Only the last, or the one
> before that if the last address in the path is a "WIDE"?
> But what if that WIDE-address at the end of the path does not have a '*'
> itself?


More information about the aprssig mailing list