Setting up a Raspberry Pi based APRS RX IGate with an RTL-SDR

Recently amateur radio hobbyist WB20SZ wrote in to us to let us know about his work with creating an easy to build receive only APRS internet gateway (IGate) with a Raspberry Pi and RTL-SDR dongle. The process involves using WB20SZ’s “Dire Wolf” software which is a free Linux based APRS encoder/decoder. He writes that it can be used to observe APRS traffic, as a digipeater, APRStt gateway or Internet Gateway (IGate). Setting up the APRS IGate is a simple matter of piping the received APRS audio from rtl_fm into the direwolf software. Instructions for installing direwolf can be found here.

APRS stands for Automatic Packet Reporting System and is a packet radio protocol used by radio amateurs to broadcast real time data such as messages, announcements, weather station reports and sometimes the location of vehicles. If an APRS station has a GPS attached to it, the broadcasts will also contain the GPS coordinates. Internet Gateways or IGates are repeaters that are used to receive messages from a local radio and pass them on via the internet to a transmit capable IGate repeater anywhere in the world. To run an IGate you should be a radio amateur with a callsign. A global aggregation of APRS broadcasts received by IGates can be seen at

Various APRS messages seen on
Various APRS messages seen on
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Did you ever resolve this? I have the same issue

Jim O'Hern AD4XX

I have a NooElec R820T2 dongle connected to my Pi3B. I followed the Direwolf installation instructions as closely as I could, but I am having a heck of a time with the audio.
Here is the error message I get:

Dire Wolf version 1.5
Includes optional support for: cm108-ptt
Reading config file /home/pi/direwolf.conf
Audio device for both receive and transmit: plughw:1,0 (channel 0)
ALSA lib pcm_hw.c:1822:(_snd_pcm_hw_open) Invalid value for card
Could not open audio device plughw:1,0 for input
No such file or directory
Pointless to continue without audio device.


I’m up and running. Not as clear as some Raspberry apps. Some steps could be clearer for sure. But if you’ve done other things with the Pi, you might be able to fill in the gaps. A few things I got lucky on. Any advice on setting the gain value? I use the default of 43, but I really think this needs to be tweaked. I like how they use SDR# to get the PPM setting. Is there a way to get the best gain setting that way? SDR# seems to use an index rather than the actual SDR gain setting.


I’m new to the RasPi and want to build this igate for our APRS digi. Having problems finding links that work from the “docs”. Does anyone have a list of steps to follow to make this work for a noob like myself?

EB5TC working perfect in RPi B+ and RT820L.
Only autostart problem solved with chmod command 🙂


It’s worth noting that the below tuning software that works with Direwolf and rtl. It automatically adjusts the receiver by taking a look for known NOAA stations. It stores the ppm adjustment and starts Direwolf with the correct freq. I was able to receive aprs from a station about 30 km away over the SDR, and an outdoor ham antenna. Not too shabby for a $15 RTL.


Only problem following these, they are incomplete, downloads missing from websites. I have followed several different install guides, all have failed.


I had no trouble. Had an iGate running in under 20 minutes.