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[aprssig] Linking digipeaters

John Gorkos jgorkos at gmail.com
Mon Mar 7 16:31:56 UTC 2011


I'm going to have to go with Kai on this one:  I think the days of adding 
functionality to modems via ROM needs to die, quickly and quietly.  There's 
two peices of functionality you're calling for:  a couple of modems to convert 
audio back and forth to digial signals, and a real CPU to do the routing.
A KPC3+ from HRO costs $199 today.  It will give me a one band digipeater that 
I need to physically burn new ROM into to get additional functionality.  If I 
want to add a second radio, I'm out at least $199 for a second TNC, plus 
whatever is going to do the logic between the two bands.

All of my digis from now on will be Linux embedded computers like this (for 
$125, or $150 with a nice case and wall-wart)
http://www.mini-box.com/Alix-3D-Board-2-LAN-1-MINI-PCI-1_2?sc=8&category=1361

Running either cheap KISS digis like this for $50
http://www.tnc-x.com/

or built on one of these:
http://sites.google.com/site/ki4mcw/Home/arduino-tnc for about $25

The Alix board has 2x serial ports and 2x USB ports.  I put a 4GB flash card 
($15 at Fry's) with a full install of Debian 6 onboard, and run APRX or 
aprsdigi with aprsd.  My initial cost (TNC, embedded computer, case, cables, 
etc) is about $200, but the incremental cost drops significantly ($25 per TNC 
for the Arduino/KISS TNC).  Also, I can hook it up to Ethernet or put a 3G USB 
dongle in and remotely administer it, or use it as an IGate.  I can change 
beacons easily, and I can even set it up to do remote, on-air configuration if 
there's no hardline available.  If a new paradigm comes along, I'm not going 
to be driving up and down mountains with new ROM chips; I just replace a 
software package on the digi.

My goal in North Georgia is to push an Internet connection as close to the 
digipeater as possible.  When you can buy a 10-mile range, 5.8Gz microwave 
link that runs at 100Mb/s for $160 COMPLETE:
http://www.doubleradius.com/Ubiquiti-NanoBridge-M5-5-GHz-22-dBi-Hi-
performance-MIMO-Bridging-Device?sc=2&category=39749
There's no reason not to put intelligent digis with Internet connections 
everywhere we can.  We've got EMA agencies lined up to give us a rooftop mount 
and an ethernet run to get the internet to the top of the mountain, especially 
when we can use that same internet connection for D-Star, or EchoLink, or a 
weather station, etc.

The fact of the matter is we can do a LOT better than we're doing now, for 
less money and with more functionality.  I'm tired of giving my money to old-
school ham-radio companies like Kantronics that haven't released an original 
idea in 20 years, who are satisfied with the status-quo, and who are 
overcharging by more than $100 for archaic designs.  I'd love to see someone 
flood the market with cheap AtMega or PIC-based KISS-only TNCs with a USB 
connection.

Just my thoughts.


On Monday, March 07, 2011 09:56:02 la3qma at aprs.la wrote:
> Quoting "Wes Johnston, AI4PX" <wes at ai4px.com>:
> > It sure would be nice if we had a multiport KISS controller that would
> > take KISS frames from multiple TNCs, perform the digipeating functions
> > and spit the modified KISS frames back out the same or different ports.
> > 
> > I think digined would do this, but it runs on a DOS pc.  I'm thinking
> > more along the lines of something running on a small processor such that
> > the TT4 and T2s are based on.  Most of these simple KISS devices don't
> > use flow control, so the device would have ot be able to buffer a couple
> > of packets from each port at a time.  It'd probably require a real
> > hardware UART.
> > 
> > Any ideas?
> 
> Maybe you can use APRX ??
> 
> http://wiki.ham.fi/Aprx.en
> 
> 
> This software can use multiple radios and you can divide them by
> "interfaces" so each of them have different rule sets.
> You can do cross band etc.
> 
> Kai Günter
> LA3QMA
> 
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