Raspberry Pis and APRS
Posted on January 17, 2013 in Projects
I’ve now had two Raspberry Pis for a few days. Three more are on their way. The great question is always what to do with the little computers. They’re not the fastest things I have on hand, but their convenience and price is what makes them interesting.
So far, I’ve decided on two tasks for the devices. The one is now colocated in my data centre space and is running my APRS Tier2 service for the Edmonton area APRS network. The Pi does a good job at running aprsc and the APRS Hog daemon.
At home, I run a digipeater and APRS iGate. I’ve decided to turn the second Pi into this digipeater and iGate, instead of the much more power hungry Core i7 that currently deals with it (my workstation). I use javAPRSSrvr on the workstation, but it is a little bulky to run on the resource limited Pi. The new installation is using aprx instead. This lightweight daemon takes very little memory and CPU to perform a similar task. It really only needs to listen on RF for incoming packets and send them back up to my tier 2 server running on the other Pi.
During a recent ham flea market, I picked up a rather old PK-232 packet modem which presently runs a packet BBS that never, ever gets used. Since it handles all of the transmitter interfacing and the packet TNC functions, it’s an easy addition onto the Pi. The Pi does have an actual serial port UART, but to keep life simple, I’m just using a USB serial adapter that has worked well on the workstation. (The current node is using a Kenwood TS-2000’s built-in TNC for the APRS packets.)
I’ll followup on this post when I complete the project of the iGate at the house. Since another Arduino project is a homebrew AX.25 modem using PWM modulators and “software” decoding of packet data, I later plan to glue the two together into a Raspberry Pi with an Arduino packet modem instead of using the PK-232 (which is relatively power hungry). You can find more details about my AX.25 Arduino project on its own project page.