[aprssig] X-digi install report

Jason Winningham jdw at eng.uah.edu
Sat Oct 15 16:22:19 CDT 2005

I got my X-digi kit last week.  Assembly took about 15 minutes. I  
didn't get a chance to install and test until today.

Assembly was very straightforward. There are few parts and the  
instructions are clear.

Installation into the tnc-x is easy, but there are 2 ways to install  
it since the connector isn't keyed.  I oriented the module the same  
way the X-track module went in, which turns out to be backwards for  
the x-digi.  Neither the x-digi nor the tnc-x seemed to be harmed by  
this mistake.  Note that the instructions clearly state how to  
correctly install the module (if you read them).

Configuration is fairly straightforward.  One thing that didn't work  
the way I expected was the UIFLOOD limit and UITRACE limit values - I  
had to set them one higher than I expected.  For example, I want to  
support WIDE3-3 (and less).  I had to set the UITRACE limit to 4 to  
accomplish this.  My settings are:

C.     Set Digipeater Callsign.         :KG4WSV-7

F.     Set UIFlood Callsign.            :AL
L.     Set UIFlood Limit.               :8
T.     Set UITrace Callsign.            :WIDE
M.     Set UITrace Limit.               :4

This allows AL7-7 and WIDE3-3.  A PATH of WIDE4-4 or higher results  
in this:

transmitted from D7: KG4WSV-1>STSS8R,WIDE4-4:'s\bl >/>
digipeated by X-digi: KG4WSV-1>STSS8R,KG4WSV-7*:'s\bl >/>

so a WIDE4-4 path gets one hop.

The TNC-X serial port is at least partially active during operation.   
It appears that any digipeated packets are also transmitted out the  
serial port (in KISS mode, of course).  I was not successful in  
transmitting packets from my favorite APRS application (xastir) using  
the TNC-X while the X-digi was installed.  Note none of this is  
mentioned in the documentation.  It is apparently assumed that you  
will use the TNC-X for a digi or a TNC, but not both at the same time.

I'm pleased with the ease of building, installing, and configuring  
the X-digi.  I would like to be able to use the TNC-X to at least  
receive all packets that are heard via the serial port and, even  
better, be able to share the TNC with another application and  
transmit packets from the application. I would also like to see a  
schematic provided.

I think the X-digi is an exciting development.  It would be  
relatively simple to interface the x-digi (either the module or just  
its PIC processor) to any KISS-mode TNC and extend the TNCs  
capabilities.  Hams now have a software platform for implementing  
network algorithms that are much more advanced than existing  
capabilities without resorting to use of a PC or shoehorning code  
onto a PROM for an obsolete hardware platform.  This means that  
advances made can actually be implemented in the field in  
circumstances where a PC would not be considered.


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