[aprssig] Linking digipeaters

Phil N6TCT phil_aprssig at lapsley.org
Mon Mar 7 14:43:48 EST 2011

Totally agree, John.

As a low-power alternative to the (very nice) Linux embedded PC you
mentioned below, you might also consider the BeagleBoard: a 3" x 3" 1
GHz embedded ARM processor that runs Linux, has ethernet, onboard stereo
audio (line in and out), and consumes less than 1.5 watts.  It costs
$150.  Running asterisk app_rpt it makes a great repeater controller and
VOIP link, and running something like aprs4r or aprx it could make a
great intelligent digi.  Details at http://beagleboard.org/

BTW, the Black Rock Amateur Radio Association has done something very
similar to what you describe below: a solar-powered repeater on a
mountaintop with a 5 GHz wifi shot back (14 miles or so) to civilization
for VOIP and whatnot.

Phil, N6TCT

John Gorkos wrote:
> 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.

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