For a while I am using now a Raspberry PI running as APRS iGate based on the APRX software. I have APRX configured as APRS receive-only iGate: APRS packets received by a VHF radio are send over the Internet to the APRS server farm. I use the MicroModem with KISS protocol as TNC. One could also configure APRX to run as RX/TX iGate or as APRS Repeater.
The Raspberry PI boots from a SD card that holds the operating system. Installing the operating system on the SD card is described on several websites. The easy way is to buy a SD card with a pre-installed Wheezzy/Raspbian OS. I have done all configurations over the network from my Windows notebook. So I did not use a keyboard and screen attached to the Raspberry PI. The Raspberry PI and Notebook are attached to my Internet Router that is providing a TCP/IP address to both of them via the DHCP protocol. In my case the Raspberry got the IP 10.10.10.29. I could see the assigned IP addresses on the DHCP information screen provided by my Internet router.
Now it is possible to connect from the laptop over TCP/IP. I always use the ping command for verifying the TCP/IP connectivity:
If this works then we can access the Raspberry PI via SSH. I am using MobaXTerm as SSH client on laptop but other clients like PUTTY also work fine. For the first logon use Raspberry's default credentials ( User: pi, Password: raspberry ). When we are logged in, we are ready for the next step.
For the initial setup the latest version of the raspi-config package shall be used. I had also some problems with the wolfram-engine. So it might be a good idea to remove the wolfram engine since we will not use it for the IGate and update the software afterwards:
- sudo apt-get remove wolfram-engine
- sudo apt-get update
- sudo apt-get upgrade
These steps take a while. When finished we can perform the basic configuration by running the command with the following selections:
SSH needs to stay enabled. We reboot the Raspberry PI and login again using our SSH client.
- Expand file system to use the complete SD card
- Set a new password.
- Set the correct time zone in internationalization options
- Disable SPI, I2C and Serial console in advanced options
The APRX software package can be downloaded from here. We need a Debian package for the Raspberry PI, so we take the latest aprx*.armhf.deb file and install it using the Debian package manager:
- sudo wget http://ham.zmailer.org/oh2mqk/aprx/aprx_2.08.580-1_armhf.deb
- sudo dpkg -i aprx_2.08.580-1_armhf.deb
Now we have installed all required software including the operating system. The only thing left to do is the iGate configuration.
The APRX software is configured by the file /etc/aprx.conf. The configuration is well described in the APRX documentation. Here is my configuration file as example for a RX-only iGate, the actual passcode has been replaced by stars:
We can use Nano for editiing the APRX configuration file:
myloc lat 4719.76N lon 00816.32E
serial-device /dev/ttyAMA0 9600 8n1 KISS
beacon symbol "I&" $myloc comment "Rx-only iGate in Buettikon AG"
The TNC is connected to the Tx and Rx pins on the GPIO connector. I am using the MicroAPRS TNC, so I have to set the communication parameters to 9600 Baud, 8 data bits, 1 stop bit, no parity and the KISS protocol. It is important to remember that the Raspberry PI uses 3.3 Volt logic - higher voltages on the Tx and Rx pin can fry the CPU. So one might need some voltage level shifter.