Tagged: airband

Frugal Radio: Monitoring General Aviation VHF Communications

Rob from Frugal Radio has recently uploaded the next part his airband monitoring series. This episode covers the topic of monitoring General Aviation communications, which consists of communications with non-military and non-airline aircraft.

In the video Rob discusses what you might hear on general aviation channels, including things like parachuters, news helicopters, air ambulances, police aircraft, aerial surveyors, ultralights, aerobatics, flight training, private and corporate, and sightseeing. He then discusses the various frequencies in use in Canada, North America and the UK.

Monitoring General Aviation Communications in VHF Air Band

Tech Minds: Using BaseStation Software with any ADSB Hardware + XRange2 Demonstration

BaseStation is an old ADS-B visualization program that was originally made to be used with BaseStation SBS receivers which were commonly used for ADS-B reception before the discovery of the RTL-SDR. Many old time ADS-B enthusiasts may already be set up with this software and would like to continue using it, however may have a dead SBS unit, or simply want to use a more modern receiver.

In his latest video Tech Minds demonstrates how you can use the ModeSMixer software to translate ADS-B data coming from an RTL-SDR compatible program like dump1090 into the BaseStation data format.

How To Use BaseStation With ANY ADSB Hardware - Software ModeSMixer

Tech Minds has also released an earlier video demonstrating the AirNav RadarBox XRange2. This appears to be essentially an ADS-B optimized RTL-SDR and Raspberry Pi in a plastic box, with custom SD Card set up and ready to go. At a price of US$299 it is quite an expensive premium to pay, but it may be of use to aviation enthusiasts who have poor technical computer skills that still want to set up a home aircraft tracking station.

Airnav Radarbox XRANGE 2 - Enhanced ADSB Standalone Receiver

Frugal Radio: Monitoring VHF Airband Aviation Frequencies at the Airport

Rob from Frugal Radio has recently uploaded the next video in his airband monitoring series. In this video Rob explains various airband communications that can be received from the airport, and explains about needing to be in the line of sight of an airport in order to receive them.

He goes on to explain signals and airport radio communications channels such as ATIS, Clearance Delivery, Tower, Arrivals (Approach), Departures, Radar and Terminal communications. The video provides various examples of these communications being received with an SDRplay software defined radio.

Monitoring VHF Airband Aviation Frequencies at the Airport

Frugal Radio: Monitoring Aviation Communications Part One

Rob from Frugal Radio has recently started a new YouTube series all about monitoring aviation communications. In his first video Rob gives an overview on what can be aviation signals can monitored and recommends a few hardware scanners as well as software defined radios for monitoring.

This is an introductory video to my new series aimed about monitoring aviation communications. Throughout the series we will talk about:

  • Civil Airband (aka VHF airband)
  • Military Airband (aka UHF airband)
  • HF Aeronautical communications
  • Decoding aircraft data on HF and VHF
  • Decoding CPDLC transmissions and much more!
  • Good frequency scanners to use, like the Uniden BC125AT and BCT-15X
  • Recommended Software Defined Radios (SDR)

Monitoring Aviation Communications - Part 1

AirNav 20% Off ADS-B Hardware Black Friday/Cyber Monday

AirNav is the company behind RadarBox24.com, a flight data aggregation service similar to sites like FlightAware.com and FlightRadar24.com. RTL-SDR hardware is typically used to receive ADS-B, and like other providers AirNav have their own custom ADS-B optimized RTL-SDR unit. In addition they sell RTL-SDR's optimized for UAT 978 MHz and the VHF Airband. They also have a range of ADS-B/UAT/VHF airband outdoor antennas as well as filters.

Currently their products are discounted by 20% for Black Friday/Cyber Monday sales. The discount is available on Amazon, as well as directly from their store with coupon GET20.

The Spectrum Monitor: The ABCs of ADS-B and Airband Reception using Software Defined Radio

Thank you to Mario Filippi (N2HUN, WQWL238) for submitting news about his latest article that has been published in the March 2020 edition of The Spectrum Monitor magazine. The article is titled "The ABCs of ADS-B and Airband Reception using Software Defined Radio", with the description reading:

Ever wonder about all the planes you see in the sky overhead where you live? What flight is that; where is it going; how high and how fast is it? All of these planes transmit on one frequency: 1090 MHz and you can monitor them all as Mario shows us. He tells us what receiver to use, which antenna (hint: you can build a better ADS-B antenna than you can buy), which software to use and how to assemble your own desktop virtual radar screen.

The article isn't free to access as it's published in the Spectrum Monitor magazine, however the magazine only costs $3 and contains a number of other airband related articles too.

The Spectrum Monitor: 2020 Aviation Edition
The Spectrum Monitor: 2020 Aviation Edition

Using a KerberosSDR to Monitor Air Traffic Control Voice, ADS-B, ACARS & VDL2 Simultaneously on a Raspberry Pi 3B+

The KerberosSDR is our 4-channel phase coherent capable RTL-SDR unit that we previously crowdfunded back in 2018.  With a 4-channel phase coherent RTL-SDR interesting applications like radio direction finding, passive radar and beam forming become possible. KerberosSDR is currently available from the Othernet store and Hacker Warehouse for US$149.95.

Although the KerberosSDR was mostly created to help unlock projects requiring phase coherency, we've had interest from multiple users asking for information on how to use the KerberosSDR as a tool for monitoring multiple separate signals at once.

Doing this is actually very simple. If you ignore the extra circuitry to make the KerberosSDR phase coherent, the KerberosSDR is at it's core just 4 separate RTL-SDR dongles connected to a quality USB hub. So if you're not using our coherent demo software, then plugging a KerberosSDR into a PC or single board PC will result in four RTL-SDR dongles that can be accessed individually.

The tutorial below could also be done with four individual RTL-SDR dongles, but you would also want to have a reliable powered USB hub.

Example Aviation Radio Monitor

Below we show an example tutorial of how the KerberosSDR could be used as a 4-channel aviation monitor for monitoring air traffic control, ADS-B, ACARS and VDL2 simultaneously on a single Raspberry Pi 3B+. The video below shows a demo.

KerberosSDR Monitoring Air Traffic Control Voice, ADS-B, ACARS & VDL2 on a Raspberry Pi 3 B+

The first step is to simply burn the latest Raspbian Buster to an SD Card, and set up your WiFi wpa_supplicant file as you would on any standard Raspbian install. Also add a blank file called "SSH" or "SSH.txt" to the boot directly to enable an SSH connection. Alternatively you could set this up with a monitor. We used Raspbian Buster Lite, as we are not intending to use the desktop GUI.

Next use PuTTY or your preferred terminal software to connect to your Raspberry Pi via SSH. You may need to use your routers config software/page to find the IP address of the Raspberry Pi. The default SSH port is 22.

Finally, update the repos on your install before continuing with the software installation process.

sudo apt update
sudo apt install librtlsdr-dev rtl-sdr

KerberosSDR Hardware Setup

Here we connected a single quarterwave ground plane antenna tuned to the airband frequencies to three input ports on the KerberosSDR via a cheap RF TV splitter. The fourth antenna input was to a RadarBox ADS-B antenna.

The KerberosSDR and Raspberry Pi are powered via two official Raspberry Pi 5V plug packs, and the KerberosSDR is connected to the Pi via a single short high quality USB cable.

Setup Topology
Setup Topology

Installing RTL-Airband

RTLSDR-Airband is an efficient command line based scanner program for the RTL-SDR. It works by rapidly scanning over a set of frequencies and looking for active signals, and playing the active AM or FM transmission. When an active signal is found it can be configured to stream the audio to an Icecast server, record to a file, or to play directly to your speakers. Alternatively you can also configure it to stream multiple channels simultaneously. If set up to stream to an Icecast server you can listen to the scanned audio from any device on your network with an internet browser.

Here we will use RTL-Airband to scan the air traffic control voice bands which are used by air traffic controllers and pilots to communicate by voice with one another. The transmissions are in AM and are found between 118–136.975 MHz.

First install the pre-requisites, and then install RTL-Airband.

sudo apt-get install -y build-essential libmp3lame-dev libshout3-dev libconfig++-dev libraspberrypi-dev librtlsdr-dev

wget -O RTLSDR-Airband-3.0.1.tar.gz https://github.com/szpajder/RTLSDR-Airband/archive/v3.0.1.tar.gz
tar xvfz RTLSDR-Airband-3.0.1.tar.gz
cd RTLSDR-Airband-3.0.1
make PLATFORM=rpiv2
sudo make install

Next install an Icecast server onto your Raspberry Pi. This will allow us to connect to the Pi via a web browser to listen in to the audio.

sudo apt-get install icecast2 -y

The install steps will ask you to input admin passwords of your choice, make sure you remember or write these down.

Now edit the rtl_airband.conf file with:

sudo nano /usr/local/etc/rtl_airband.conf

Paste in the configuration below making sure to set the actual frequencies used by air traffic control and airlines in your particular area by adding or removing frequencies from the "freqs" line.

Also be sure to set the "index" to whatever antenna input you have used (0 - 3) on your KerberosSDR for your VHF air band antenna. You may want to experiment with the gain value, but for now you can leave it as default.

If you are using another template for the config file, ensure that the "correction" value is set to 0 as the KerberosSDR uses a TCXO and requires no PPM correction.

Finally, don't forget to also set the Icecast server password that you set up in the previous step, making sure to leave the username as "source".

type = "rtlsdr";
index = 2;
gain = 32;
correction = 0;
mode = "scan";
freqs = ( 118.1, 118.7, 119.5 );
labels = ( "Tower A", "Tower B", "Tower Control");
outputs: (
type = "icecast";
server = "";
port = 8000;
mountpoint = "stream.mp3";
name = "Airband Voice";
genre = "ATC";
description = "My local airport - aggregated feed";
username = "source";
password = "kerberos";
send_scan_freq_tags = false;

Next set up the Icecast server if required using the instructions here. If the default port and number of source is fine for you, you can leave everything as default.

Now to start RTL-Airband run:

sudo rtl_airband -f

To listen to the scanned audio, browse to http://RASPI_IP_ADDRESS:8000/stream.mp3 on any device connected to the same network

Installing dump1090

Leave the RTL-Airband PuTTy window open, and open a new instance of PuTTy and once again connect to the Raspberry Pi in a new session. We will install the FlightAware branch of dump1090, as this is the most up to date version. dump1090 allows you to track aircraft that are transmitted ADS-B.

sudo apt-get install build-essential debhelper librtlsdr-dev pkg-config dh-systemd libncurses5-dev libbladerf-dev
git clone https://github.com/flightaware/dump1090
cd dump1090
dpkg-buildpackage -b

Now we can run dump1090 with the following line. Make sure to set the "--device 3" flag to the antenna input that you have connected your ADS-B antenna to. In our case we connected it to the last SMA input which is input 3.

./dump1090 --device 3 --interactive --net

Now to view the data on a map, you can install Virtual Radar Server on any Windows PC on the same network. Once installed, add an "AVR or Beast Raw Feed" receiver, with the IP address of your Raspberry Pi and Port 30002.

Installing ACARSDeco2

Again, leave both PuTTy windows open, and open a new PuTTy SSH terminal and connect again. Here we'll install ACARSDeco2 which is a multiband ACARS decoder. ACARS is an acronym for Aircraft Communications Addressing and Reporting System which is a digital communications system that aircraft use to send and receive short messages to and from ground stations. Most messages are unreadable telemetry data intended for computers, but often you will see messages about weather, wind, dangerous cargo warnings, fuel loading information and more.

ACARSDeco2 is not an open source program, so you'll need to first download the compressed file from http://xdeco.org/?page_id=30 on a PC. Make sure to get the Raspberry Pi 2/3 version of ACARSdeco2 for Stretch.

Now use a program like WinSCP to transfer the .tgz file to the Raspberry Pi. In WinSCP select SCP as the file transfer protocol, log in with "pi/raspberry" and drag the file over to the Pi's home folder.

Then back on the Raspberry Pi, simply move the file into it's own folder, and extract the files.

mkdir acarsdeco2
mv acarsdeco2_rpi2-3_debian9_20181201.tgz acarsdeco2
cd acarsdeco2
tar -xvzf acarsdeco.tgz

Now you can run the program with the following command. Make sure to specify the ACARS frequencies used in your area if they are different. Also here we used antenna input 1 for the ACARS antenna and specified that with "--device-index 1". If you are running Virtual Radar Server on your Windows PC as explained in the dump1090 install, you can enter the Windows VRS server IP address, so that location data will be sent back to the ACARSdeco2 server.

./acarsdeco2 --device-index 1 --freq 131550000 --freq 131450000 --gain 34 --http-port 8081 --vrs-url

Now on your Windows PC, open a browser and open PI_IP_ADDR:8081 to view the incoming ACARS messages.

Installing dumpvdl2

Again, leave both PuTTy windows open, and open a new PuTTy SSH terminal and connect again. Here we will install dumpvdl2 which is a VDL2 decoder. VDL2 is a replacement for the aging ACARS system which is being phased out in some areas. In some areas VDL2 is now more common than ACARS, and in some areas it's the opposite.

First install pre-requisites.

sudo apt-get install build-essential cmake git libglib2.0-dev pkg-config librtlsdr-dev

Dumpvdl2 requires libacars to work, so install libacars first:

git clone https://github.com/szpajder/libacars 
cd libacars
mkdir build 
cd build 
cmake ../ 
sudo make install 
sudo ldconfig

Finally, install dumpvdl2

git clone https://github.com/szpajder/dumpvdl2.git
cd dumpvdl2
mkdir build
cd build
cmake ../
sudo make install

Now to run dumpvdl2:

dumpvdl2 --rtlsdr 2 --gain 35

dumpvdl2 has no webserver so it can only be viewed from the terminal window.

Alternative Tools

Stations in the USA could replace one program with dump978, which decodes UAT positional data from smaller aircraft. If you live near a glider range, a FLARM decoder could also be used. You could also run an AIS receiver if you live near a water way.

Further Steps

If setting this up as a permanent station, you might want to go ahead and create a startup script that runs these programs on boot. Then you won't need to open up PuTTy terminals to start all the programs. The easiest way to do this is to use the @reboot code in crontab to run your script. Be sure to use sudo crontab -e for running RTL-Airband as this requires root.

An Overview of Aircraft Communication Modes from HF to UHF

Over on YouTube icholakov has uploaded an informative video that gives an overview of the main communication modes that aircraft use from HF to UHF. In the video he also gives examples of those modes being received and decoded with an SDR.

The modes that he explains and demonstrates are VHF voice, VHF ATIS automated weather, ACARS short data messages, HF voice, HF automatic weather, HF data selective calling (SELCAL), HF data link (HFDL) and UHF ADS-B aircraft positioning.

Monitoring airplane communications