FlightAware is a company that specializes in distributed ADS-B aggregation, in order to produce real time maps and information about what aircraft are in the air. In 2021 FlightAware was acquired by Collins Aerospace, which is a subsidiary of Raytheon Technologies, a large US aerospace and defense contractor.
Most of the data that FlightAware obtains comes from volunteers all around the world running an RTL-SDR dongles on their Raspberry Pi based image. The dongles receive the ADS-B 1090 MHz broadcasts from aircraft which contain information about the aircraft including GPS location.
Back in 2016 they released the FlightAware ProStick, which is an ADS-B optimized RTL-SDR with onboard 1090 MHz LNA. Later in 2017 they released the Prostick Plus which improved performance in high interference areas due to the addition of a 1090 MHz SAW filter.
Their post goes into more detail about their products, and note that they are currently designing a new Prostick Plus with filter placed before the LNA instead of after. They also discuss how they are looking into higher end 12-bit ADCs for their receiver hardware, and at creating a dual channel receiver for the 978 MHz UAT band as well. They then go on to discuss the software architecture behind the ADS-B decoder they use.
Thank you to a contributor for submitting an article about Airframes.io, which is an ACARS/VDL2/HFDL/Satellite ACARS aggregation site. The article below it attributed to Kevin Elliott and was edited by Frank Vance. They would also like to attribute the large group or volunteers at Airframes.io.
One of the most popular hobbyist uses of SDR is receiving and decoding vehicle information data such as ADS-B for aircraft or AIS for marine traffic. Some hobbyists have been banding together to exchange their mutual data streams to provide coverage over wide geographic areas.
One of the largest and most successful such projects in the aviation realm is ADS-B Exchange (https://www.adsbexchange.com/), where over 8,000 volunteer feeders provide ADS-B data to a global aviation map in real time.
But modern air carriers have much more data to and from their aircraft than just the position information from ADS-B. In the 1970s, ACARS was created to carry that traffic. Today, ACARS is seen on its own frequencies on VHF, embedded in AVLC on the VDL2 VHF frequencies, on HF (shortwave) frequencies using the HFDL network of stations worldwide, and on satellite on both the Inmarsat (ACARS over AERO, or AoA) and the Iridium (called ACARS over Iridium, or AoI) systems.
Airframes.io (https://app.airframes.io/) is a project that has been under development for a while to aggregate ACARS data in the same way ADS-B Exchange is aggregating ADS-B data. Under the capable leadership of Kevin Elliott (https://github.com/kevinelliott), software development has progressed to the point that new feeders are actively being sought to improve the global coverage and provide a broader base of data to improve the decoding.
With a wide variety of data sources, this is a collaboration project that is open to all levels of SDR hobbyists. A simple RTL-SDR.COM unit attached to a Raspberry Pi with a smaller antenna works well with the VHF coverage. Depending on one's interest level, an HFDL feeder may require multiple SDRs with much broader frequency range, capable of reception in the sub-30 MHz bands. The L-band based Iridium AoI uses a small antenna as well, but requires a wide bandwidth SDR. Finally, reception of the C-band Inmarsat (AoA) traffic may involve a moving dish antenna of at least 6 foot diameter to obtain usable signals.
What kind of data is seen in ACARS? One can observe weather conditions aloft, messages to/from the carrier operations staff, information about the origin and destination of the flight, and technical data on the aircraft operation (not all of which can be decoded at this time.) Additionally, the HFDL and satellite feeds offer location information out of sight of the traditional ADS-B coverage, such as over the oceans and polar regions.
Additional information about setting up a receiver/feeder for HFDL, Inmarsat L-band, Inmarsat C-band, and Iridium L-band is available on The Bald Geek's GitHub page: https://thebaldgeek.github.io/Consider joining with the dozens of volunteers already feeding and contributing software updates to the Airframe.io project.
Thank you to Don for submitting news about the release of his new software titled "Skies-ADSB". Skies-ADSB is a browser based app that provides a 3D view of the air traffic around your area. The software can be served on a local networked Raspberry Pi, with ADS-B data being provided by an RTL-SDR connected to the Pi.
skies-adsb is a virtual plane spotting progressive web app (PWA) / virtual aquarium (with aircraft instead of fish) / interactive real-time simulation.
Aircraft are tracked via unfiltered ADS-B transponder data in real-time and rendered in 3D.
The Ham FM Radio app allows the user to quickly tune and listen in to the 144-148, 150-174 and 420-450 MHz ham radio communications via presets. For the second ADS-B app, James notes that it's an early release for feedback. It allows the user to receive ADS-B data and plot it on a radar like display.
Thank you to Wayne Campbell for submitting news about the release of the latest 0.5.0 iteration of his RTL-SDR compatible 'rsadsb' software package that plots ADS-B aircraft positions on a terminal based display. Wayne has also created a blog post describing how to set up a Raspberry Pi based portable ADS-B setup with his software.
The package consists of two separate programs 'dump1090_rs' and 'radar' (aka adsb_deku). The dump1090_rs program is a rust implementation of the dump1090 ADS-B decoder and 'radar' is the terminal based map. A quickstart guide for setting up both programs is also available.
The software can run on a Raspberry Pi and works well displayed on a portable touchscreen. It appears that the terminal display is very responsive with zoom controls for the radar display, a coverage map, and a tidy list of all detected aircraft.
If you're interested in terminal based displays, we've posted about a similar terminal based ADS-B plotter called 'coole-radar' in the past, as well as a terminal based spectrum analyzer display called retrogram.
In December of last year we posted about a video demonstrating the many features that the SDRAngel software comes standard with. Recently they've added a new feature which are 3D maps that can be used to visualize signal data.
In the latest video demonstration they show these 3D maps projecting NOAA weather satellite images onto a 3D globe and at the same time tracking the NOAA satellites over the globe as it produces imagery. They also show the software visualizing a 3D model of aircraft on the globe, using live ADS-B data to show aircraft maneuvers when taking off, cruising and landing. With multiple SDRs they also show how the visualization can be combined with air traffic voice. Finally they also show marine vessels being visualized via live AIS data. There appear to be a wide range of vessel 3D models implemented.
A common example of a data aggregator that makes use of RTL-SDRs is most of the flight tracking websites, such as FlightAware and FlightRadar24. Contributors to the service will usually set up RTL-SDR + Raspberry Pi based receivers that feed ADS-B aircraft data received from the local area to these websites. Data from contributors from all over the world are then combined onto a single map, allowing for a global live picture of aircraft traffic.
Some other examples on the list that use RTL-SDRs include Amateur Radio APRS tracking, marine traffic, police/EMS audio feeds, train traffic, weather audio feeds, satellite ground station feeds and general web based remote SDR access. Added to the list are also aggregators based on other devices for applications like lightning detection and seismic activity reporting.
SDRAngel is a general purpose software defined radio program that is compatible with most SDRs including the RTL-SDR. We've posted about it several times before on the blog, however we did not realize how much progress has occurred with developing various built in plugins and decoders for it.
Thanks to Jon for writing in and sharing with us a demonstration video that the SDRAngel team have released on their YouTube channel. From the video we can see that SDRAngel now comes stock with a whole host of built in decoders and apps for various radio applications making it close to an all-in-one SDR platform. The built in applications include:
ADS-B Decoder: Decodes aircraft ADS-B data and plots aircraft positions on a map
NOAA APT Decoder: Decodes NOAA weather satellite images (in black and white only)
DVB-S: Decodes and plays Digital TV DVB-S and DVB-S2 video
AIS: Decodes marine AIS data and plots vessel positions on a map
VOR: Decodes VOR aircraft navigational beacons, and plots bearing lines on a map, allowing you to determine your receivers position.
DAB+: Decodes and plays DAB digital audio signals
Radio Astronomy Hydrogen Line: With an appropriate radio telescope connected to the SDR, integrates and displays the Hydrogen Line FFT with various settings, and a map of the galaxy showing where your dish is pointing. Can also control a dish rotator.
Radio Astronomy Solar Observations: Similar to the Hydrogen line app, allows you to make solar measurements.
Broadcast FM: Decoding and playback. Includes RDS decoding.
Noise Figure Measurements: Together with a noise source you can measure the noise figure of a SDR.