KB9IQX ACARS Receiver

A backyard site running TLeconte acarsdec ACARS decoder on a Raspberry Pi Zero.

The goal was to piggyback an ACARS radio and decoder onto a Pi Zero that is forwarding ADS-B packets from another ADS-B receiver to open-source ADS-B sites Opensky Network and ADSB Exchange. Since the Zero has a free USB port, the theory is that it should have the processing power to handle one SDR.

Equipments:

• Raspberry Pi Zero W
• 850 milliamp power
• SD card, 16Gb or smaller will suffice
• cheap, generic RTL-SDR dongle Adafruit #1497
• 1/4 wave monopole antenna, preferably cut to Airband length
• if needed, additional needed cable putting antenna in a good receive location

Setup:

TL;DR: Script that does all the following is here.

Detailed instructions follow.

1. Install Osmocom rtl-sdr

Excellent instructions at satsignal.eu. Distilled down here:

            sudo apt-get update
            sudo apt-get upgrade
            sudo printf 'blacklist dvb_usb_rtl28xxu\nblacklist rtl2832\nblacklist rtl2830' > /etc/modprobe.d/nortl.conf
            sudo apt-get install git-core
            sudo apt-get install git
            sudo apt-get install cmake
            sudo apt-get install libusb-1.0-0-dev  
            sudo apt-get install build-essential 
            git clone git://git.osmocom.org/rtl-sdr.git
            cd rtl-sdr
            mkdir build
            cd build
            cmake ../ -DINSTALL_UDEV_RULES=ON
            make
            sudo make install
            sudo ldconfig
            cd ~
            sudo cp ./rtl-sdr/rtl-sdr.rules /etc/udev/rules.d/
            git clone git://github.com/MalcolmRobb/dump1090.git
            cd dump1090
            make
            sudo reboot
        

2. Install libacars

               cd /usr/local/src
               git clone https://github.com/szpajder/libacars.git
               sudo apt-get install zlib1g-dev libxml2-dev
               cd libacars/
               mkdir build
               cd build
               cmake ../
               make
               sudo make install
               sudo ldconfig
           

3. Install acarsdec
   

               git clone https://github.com/TLeconte/acarsdec
               cd acarsdec
               mkdir build
               cd build
               cmake .. -Drtl=ON
               make
               sudo make install
           

Operation

The following is simple command line output. It will keep the command and window open for as long as your session does not time out. I've had this running for weeks at a time

That's it! You should periodically see cryptic looking messages pop up on your screen. More usage instructions, including different ouput formats, can be found on the github page.

Options! Options! Additional operational options.

But the above less useful for unattended operation, or for logging purposes, or daemon-like usage. To "set it and forget it" put the command somewhere in your startup scripts -- either run it as a service/daemon via init/systemd... or just throw it into rc.local or crontab. (Examples courtesy of [satsignal.eu]:

 
   where options:

      -g == gain in tenths... so 480 is a gain of 48 (sdr limit is umm 49 I believe)
      -r == device index, if you have multiple devices, 
            which is unnecessary on Pi Zero but is good practice. 
            0 is first SDR device and so on
      -l == file to log output, if you would prefer that instead of screen
            this is useful for unattended operation. you can set up your site to
            check this file from a web browser, por ejemplo
      -j == send copy of output in JSON format to host and port
      -n == send copy of output in PlanePlotter format to host and port
      -N == send copy of output in acarsdec format to host and port

      111.222.333.444 == IP address of server to forward messages to

       >/dev/null == sends the initial startup messages to the aether, essentially quiet output
       2>&1       == sends error messages to same place as output, essentially quiet output 

   

To send json to a remote server and port:

To send planeplotter format to a remote server and port:

To keep logs by date and to put initial status message to a generic log file:

ACARS Frequencies

Here are the ACARS frequencies to tune. My notes for USA frequencies follow. Originally taken from the acarsd site

Operating Notes:

CPU Loads, typical