[aprssig] SSID on to-call?

Stephen H. Smith wa8lmf2 at aol.com
Fri Feb 4 18:13:16 EST 2011

On 2/4/2011 2:27 PM, Lynn W. Deffenbaugh (Mr) wrote:
> The SSID field in the Destination Address (i.e. in the 7th address byte) is
> encoded as follows:
> APRS Digipeater Paths in Destination Address SSID
> SSID Path SSID Path
> -0 Use VIA path -8 North path
> -1 WIDE1-1 -9 South path
> -2 WIDE2-2 -10 East path
> -3 WIDE3-3 -11 West path
> -4 WIDE4-4 -12 North path + WIDE
> -5 WIDE5-5 -13 South path + WIDE
> -6 WIDE6-6 -14 East path + WIDE
> -7 WIDE7-7 -15 West path + WIDE
> Now, if there's any digipeaters out there that actually have multiple 
> antennas with directionality is one question and whether the software driving 
> said multi-directional digis is actually sensitive to these -SSIDs is yet 
> another question...

It wasn't intended to select antennas.  The orginal idea was that digipeaters 
would maintain tables of nearby digis and their location relative to 
themselves.  (Presumably based on the other digi(s) own coordinates in 
beacons.  The digi would then make a decision on whether or not to digipeat 
based on the direction the incoming packet came from, if this kind of 
to-address was present.

The scheme was supposed to make possible linear paths involving fewer digis , 
rather than the omni-directional flooding over an ever-widening circular area 
you get with WIDE, WIDEn-N, etc.   The scheme (which is also supported by Mic-E 
to shorten the entire path to a single 4-bit nybble) never really got off the 
ground, due to the limited intelligence of the ubiquitous KCP3-based digis.

I'm not certain but I think the directional path scheme is now officially 



Stephen H. Smith    wa8lmf (at) aol.com
EchoLink Node:      WA8LMF  or 14400    [Think bottom of the 2M band]
Skype:        WA8LMF
Home Page:          http://wa8lmf.net

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