Back in early 2016 we posted about a journalist who used an RTL-SDR to gather ADS-B data about the type of aircraft used at the world economic forum in Davos. The idea was to help highlight the vast wealth and power of the attendees by showing off their heavy use of private aircraft.

Now more recently Laurent Bastien Corbeil has published a similar article in Motherboard (a Vice News tech magazine) explaining how he tracked police and military planes at this years G7 summit which was held in Canada in early June. Laurent used an RTL-SDR Blog V3 with the small dipole antenna attached to a window to gather ADS-B data from all the aircraft activity during the summit.

ADS-B is a radio system used on modern aircraft which broadcasts the aircraft's current GPS location and other data such as aircraft identifiers. It is now used extensively by air traffic controllers as it is significantly more reliable than traditional radar. With a simple RTL-SDR it is possible for anyone to track and plot ADS-B data on a map, and this is how tracking sites like flightradar24.com and flightaware.com work.

From his collected data he was able to spot several interesting aircraft such as Canadian Air Force Chinooks, C130 Hercules', RCMP Pilatus', a military Bombardier jet, and a coast guard Bell 427. He also notes that while he was able to spot Donald Trumps Marine One helicopter with his own eyes, the ADS-B data was not present, indicating that more important military aircraft do not broadcast ADS-B for security reasons.

In the article Laurent makes estimates of the costs of operating these aircraft, and makes some guesses on the type of mission flown by some of the aircraft.

The post Tracking Police and Military Aircraft at the G7 Summit with an RTL-SDR appeared first on rtl-sdr.com.

The team at radarbox24.com recently wrote in and wanted to share some new developments including news about their recently released RadarBox XRange receiver, which is an RTL-SDR based ADS-B receiver. Radarbox24 are an ADS-B aggregation flight tracking website, similar to sites like flightaware.com and flightradar24.com.

The RadarBox XRange receiver costs $649.95 USD and is available on their store. The box appears to include a full computing unit as well as a custom RTL-SDR receiver, and a built in filter and LNA as well. It is sold as a set that includes receiver, power supply, antenna and cabling. Compared to setting up an ADS-B receiver on your own by purchasing an RTL-SDR, ADS-B LNA/Filter, Antenna and Raspberry Pi separately, the XRange is well over three times more expensive. But it may have some value as an easy to set up and ready to go ADS-B receive system. They write:

1- We have release the brand new RadarBox app for iOS and Android where data sharers are able to see what what their own stations receive using the MyStation feature.

2- We've released the brand new RadarBox XRange receiver, RTL SDR based whcih is being sold and placed all over the world to increase network coverage.

3- Our RadarBox24.com flight tracking portal reached 3 millions viewers per month and, together with our apps, is growing really fast by providing an easy way for Raspberry Pi owners or users with our XRange and Micro RadarBox receivers to share flight data with us and benefit from a free Business account.

More information:
- Link to our Store where users can buy the XRange receiver and accessories below:
https://www.radarbox24.com/store

- Link to a real-time listing of newly added stations (Raspberry pi, XRange and all other supported receivers)
https://www.radarbox24.com/stations/new-units

- Link for users to install our software on their Raspberry Pi receivers and start sharing data with us (we get up to 5 new added units added to our network daily):
https://www.radarbox24.com/raspberry-pi

- Link to our worldwide station ranking:
https://www.radarbox24.com/stations

- Link to our MyStation, available to data sharers, where they can monitor their own station aircraft, stats and received aircraft listing:
Example for Texas, US: https://www.radarbox24.com/stations/EXTRPI009148
Example for Sweden: https://www.radarbox24.com/stations/EXTRPI006084
Example for Doha Qatar: https://www.radarbox24.com/stations/PGANRB300567

- The MyStation feature is also available on the Android and iOS apps so users can monitor their stations remotely.

VOR stands for VHF Omnidirectional Range and is a way to help aircraft navigate by using fixed ground based beacons. The beacons are specially designed in such a way that the aircraft can use the beacon to determine a bearing towards the VOR transmitter. VOR beacons are found between 108 MHz and 117.95 MHz, and it's possible to view the raw signal in SDR#.

Over on RadioJitter author Arnav Mukhopadhyay has uploaded a post describing how to decode VOR into a bearing in real time using an RTL-SDR dongle. His post first explains how VOR works, and then goes on to show an experimental set up that he's created using a GNU Radio program.  With the software he was able to decode an accurate bearing towards the VOR transmitter at a nearby airport.

Arnavs post is a preview of an academic paper that he's worked on, and the full paper and code is available by request on the radiojitter post. We've also seen on YouTube that Arnav has uploaded a video showing the software working in action, and we have embedded it below.

JAERO was recently updated by programmer Jonti, and it now supports the decoding of AERO C-Channels which are voice audio channels that exist on both the L-Band and C-Band frequencies of AERO. AERO is a satellite based communications service used by modern aircraft. The information transferred are normally things like aircraft telemetry, short crew messages, weather reports and flight plans. It is similar information to what is found on VHF/HF ACARS.

Jonti notes that these C-Channel voice signals are very weak as they are spot beams, so a good antenna system is required to receive them. Over on Jonti's JAERO website there is now some information about these C-Channels (scroll all the way down to the C-Channel heading and read to the end of the page), as well as a frequency list. An excerpt of the information is pasted below:

Inmarsat C and in particular AERO C channels provide circuit switched telephony services to aircraft. The channels of interest are those that carry AMBE compressed audio at a channel rate 8400 bps and voice rate of 4800bps. There is also an older speech codec still in use, LPC at a voice rate of 9600 bps and an overall channel rate of 21000bps.

Telephone channels are two-way duplex. In the from-aircraft direction transmissions are roughly in the 1646 to 1652 Mhz range. The satellite up-converts these transmissions to C band, similar to T and R channel burst transmissions. So it is possible to receive the from-aircraft transmissions although it is significantly more difficult than those in the to-aircraft direction on the L band. So for those who want to get started receiving these transmissions the L band is by far the easiest place to start.

Another aspect of the C channels is that they most often use spot beams rather than global beams which makes it more difficult to receive transmissions for aircraft using a spot beam that is aimed at another region. However if you are inside the spot beam the transmissions are relatively easily received on L band. A 60 cm dish with an LHCP helical and L band LNA will provide excellent results but even with a patch antenna it can be done.

Decoding these channels to audio in JAERO takes a little effort to setup. Due to the uncertain legal status of the digital audio AMBE codec, the codec code needs to be compiled manually first, and then placed into the JAERO directory. Jontio has uploaded the AERO AMBE codec source code at https://github.com/jontio/libaeroambe. Since JAERO is a Windows program, compilation of libaeroambe involves using MSYS2.

Once fully set up with the audio codec, the audio will come out of default soundcard set in Windows audio properties, so ensure that any Virtual Audio Cables are not set as the default device.

On the L-band link you can get conversations from the ground to the plane. The C-band link would get you the plane to ground side of the conversation too, but that is a challenging signal that would require a large dish and Jonti doesn't know of anyone who has managed to receive that before. Typically the conversation topics are things like Medlink which is a multilingual medical support line that can provide backup to doctors or aircrew handling medical emergencies in the air. In Europe the USAF also apparently use C-Channel.

Over on YouTube Fuzz The Pi Guy has uploaded a video tutorial showing how to set up a Broadcastify air traffic control audio feed with RTL-Airband and an RTL-SDR running on a Raspberry Pi. This allows you to publicly share your received air traffic control audio online via sites like Broadcastify.

The video is based on a comprehensive Radioreference text tutorial which takes you through the process from scratch. Setting it up involves installing the Raspbian OS, installing RTL-SDR, installing and setting up RTL-Airband, configuring ezstream and then ensuring that everything runs automatically on boot. It's a fairly involved setup process, but the video helps make things easier.

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.

Thank you to Thierry Leconte (TLeconte) for writing in and submitting his new command line based open source software called vortrack. Vortrack is a simple VOR decoder which calculates the angle towards the VOR. It is compatible with both RTL-SDR and Airspy radios, and runs on Linux.

In the past we've seen several other posts about RTL-SDRs being used to decode VOR signals, but Thierry's implementation appears to be the easiest way to get a bearing straight away. You'll get the most use out of the software if you install it on a portable device like a Raspberry Pi and take it out for a drive as you'll be able to see the VOR angle changing then.

VOR stands for VHF Omnidirectional Range and is a way to help aircraft navigate by using fixed ground based beacons. The beacons are specially designed in such a way that the aircraft can use the beacon to determine a bearing towards the VOR transmitter. VOR beacons are found between 108 MHz and 117.95 MHz, and it's possible to view the raw signal in SDR#.

For ADS-B decoding, dump1090 is an RTL-SDR compatible program that is commonly used. In order to provide information about the aircraft being detected (e.g. icao24 hex address, registration/tail number and sometimes the type of aircraft like A380), dump1090 uses an offline database. Unfortunately this database has not been maintained in a very long time, so it is now out of date, and so cannot display information about many aircraft.

Recently Thierry had the idea to use the data from VDL2 aircraft transmissions to update his dump1090 database. VDL2 is a short data messaging system used by aircraft that will eventually replace the older ACARS messaging system. With an RTL-SDR and vdlm2dec decoder, the VDL2 signal which broadcasts at around 136 MHz can be received and decoded.

Contained within the data is the icao24 hex address and registration/tail number. By collecting this VDL2 data over a number of days, a new database can be generated which can then be imported into the dump1090 database. It however, doesn't seem to acquire aircraft type data.

RadarBox24.com is a flight data aggregation service similar to sites like FlightAware.com and FlightRadar24.com. They aggregate ADS-B aircraft data obtained from (mostly) volunteer RTL-SDR based feeders based all over the world and use this to power their flight tracking map and flight information database.

Last year RadarBox24 came out with a specialty ADS-B RTL-SDR dongle. This is a custom RTL-SDR which contains a built in 1090 MHz tuned amplifier and filter. We have not tested this dongle yet, but we expect that the design and performance would be very similar to the FlightAware ADS-B dongles. A network analyzer report from RB24 is provided here.

These dongles can only receive 1090 MHz and do so better than a standard RTL-SDR due to the built in LNA and filter. The LNA reduces the noise figure of the dongle leading to greater sensitivity, and the filter removes any strong out of band signals that could overload and desensitize the dongle. This results in greater reception range, and more flights tracked. Please note that these dongles cannot be used as wideband general purpose RTL-SDRs due to the filtering.

Recently in an attempt to gather more volunteer contributors, RadarBox24 has decided to sell their ADS-B dongles at a loss, pricing them at only US$9.95 + shipping (or on Amazon USA with Prime). Shipping appears to be anywhere from US$5-$8 depending where you are in the world, and shipping does not increase with two or more dongles being ordered.

ADS-B data can easily be shared to RadarBox24 with their Raspberry Pi image and RadarBox24 write that if you share data to their site, you will receive the following kickbacks:

• Free Business Account while sharing (worth $39.95 /mo). This allows you to access RAW and historic flight data as well as enabling other features such as more advanced data filtering, and a weather layer.
• Strong and enthusiastic Community on Whatsapp
• Track your own station's flights in real-time not only on website but also on RadarBox apps

Over on Hackaday.io user nathan.matsuda has written about his RTL-SDR based hand held ADS-B aircraft receiver with display and 3D printed enclosure.

His initial idea was to create a flexible and open portable SDR device, however keeping the device open and built for general use meant increased complexity which quickly slowed his progress. Instead [Nathan] decided to focus on just ADS-B for his portable device as living near an airport he’d been interested in aircraft tracking since his first SDR arrived.

The device consists of a Raspberry Zero, RTL-SDR, 3.5″ IPS LCD and a battery pack for portability. For software he uses dump1090 with some custom code for the map plotting. Together with a 3D printed case and some buttons, the result is a very professional looking portable aircraft tracking device.

Hopefully Nathan will continue updating his project page so that others may replicate it on their own.

Over on his YouTube channel Corrosive from the SignalsEverywhere YouTube channel has uploaded a tutorial that shows how to set up ADS-B aircraft tracking with an RTL-SDR, dump1090 and Virtual Radar Server. The decoder software is dump1090 which is a multiplatform command line tool, and Virtual Radar Server is a Windows and Linux compatible program that is used to display the data on Google maps.

ADS-B is used as a more accurate and modern replacement for traditional aircraft radar. Instead of relying on radar reflections, ADS-B simply transmits a radio signal containing plane data such as GPS location, speed, and identification codes. Other aircraft can use this data for collision avoidance, and ground control use it for traffic management. Setting up your own RTL-SDR based ADS-B receiver allows you to see and track on a map almost all the aircraft currently flying in your area.

Over on Reddit freelance investigative journalist Emmanuel Freudenhal has put up a very interesting post about how he is using ADS-B tracking to keep an eye on the travel habits of dictators around the world. If you were unaware, ADS-B is a signal transmitted by aircraft which contains aircraft ID info, and data such as speed, altitude and GPS location. Websites like ADS-B Exchange aggregate ADS-B data from volunteer ground stations that are running (mostly) RTL-SDR dongles. Emmanuel notes that by watching the movements of aircraft registered to dictators, it is possible to keep an eye on their travel habits.

One story that Emmanuel has written using this data is a piece on Paul Biya, Cameroon's president. His article discusses how Paul Biya is often seen in Geneva Switzerland, away on private visits. In a comment, Emmanuel notes that since his story ran, Paul Biya has almost stopped travelling to Switzerland.

Emmanuel has also been running a Twitter bot that uses ADS-B data to automatically tweet when a dictator aircraft is detected at Geneva airport. A list of known dictator aircraft is kept on a publicly accessible Excel file.

Now he is hoping to expand his tracking operation, and is asking for more people to feed the ADS-B Exchange aggregation website. ADS-B Exchange is the site recommend to feed because it is the only ADS-B aggregation website that does not censor any aircraft. Other aggregation sites such as Flightradar24 and FlightAware have come under scrutiny in the past for their willingness to upon request censor and block the tracking of military/political aircraft and private jets owned by several companies. In particular several aircraft owned by dictators are reportedly censored. However, the counter argument is that not censoring aircraft may result in ADS-B tracking eventually being made illegal, or that costly legal suites may be brought against ADS-B aggregation companies.

On the Reddit post Emmanuel writes:

I'm a freelance investigative journalist (www.emmanuel-freudenthal.com / @emmanuelfreuden). I'm getting into SDR/ADSB and very glad I found this group because I need your help to track aircrafts!

With a colleague, we started a project to look into the travels of dictators around the world. It's an evolution of a Twitter bot (https://twitter.com/GVA_Watcher) started a few years ago. This bot tweets every time an aircraft owned by a dictatorship lands or takes off at the Geneva airport, Switzerland. And dictators visit Geneva, a lot. There's secretive banks and good healthcare, enjoyed by Algeria's departing president or Cameroon's president Paul Biya.

We want to expand this project to all of the world's airports. See our place-holding website: https://dictatoralert.org(which will get expanded soonish). To do so, we've partnered with ADSB-Exchange, which as you probably know, is the only website that doesn't censor flights. Usually the planes owned/chartered by dictatorships don't show up on flightaware or flightradar24 (anyone can asked to be removed). Some planes also don't share their GPS coordinates (e.g. Mode S) and so they don't show up.

In addition to the Dictator Alerts, we'll also use the data to do investigations into dictatorships, human rights violation and corruption.

The idea is to allow everyone to keep tabs, so the data will be available publicly, via Twitter bots and on a dedicated website (with e.g. a page per dictatorship and per airport).

To succeed, we need a lot more antennas! So, it'd be great if you could feed ADSB-Exchange. You can do that in addition to feeding other services. See how to do it here: https://www.adsbexchange.com/how-to-feed/ If you want to feed, please contact me on emmanuel.freudenthal@gmail.com, my twitter DM are open. It's quite important that you contact me before feeding, so that we also capture aircrafts that don't share their GPS coordinates.

That also means, you'll be able to see ALL of the data that you're collecting online.

What do you think? Would you be keen to participate? Any questions?

Your feedback is very welcome, i'm still learning!

Best,

Emmanuel

Other stories of interest: A similar story we ran last year was about tracking police and military aircraft at the G7 summit with an RTL-SDR, and three years ago we ran a story about tracking World Economic Forum Attendees with an RTL-SDR.

Recently Arstechnica ran an in depth story about how a $600 USRP software defined radio could be used to trick an aircraft that is making use of the Instrument Landing System (ILS). ILS is a radio based system that has been used as far back as 1938 and earlier. It's a very simple system consisting of an array of transmitter antennas at the end of a runway and a radio receiver in the aircraft. Depending on the horizontal and vertical position of the aircraft, the ILS system can help the pilot to center the aircraft on the runway, and descend at the correct rate. Although it is an old technology, it is still in use to this day as a key instrument to help pilots land especially when optical visibility is poor such as at night or during bad weather/fog.

Researchers from Northeastern University in Boston have pointed out in their latest research that due to their age, ILS systems are inherently insecure and can easily be spoofed by anyone with a TX capable radio. Such a spoofing attack could be used to cause a plane to land incorrectly. In the past ILS failures involving distorted signals have already caused near catastrophic incidents.

However, to carry out the attack the attacker would require a fairly strong power amplifier and directional antenna lined up with the runway. Also as most airports monitor for interference the attack would probably be discovered. They write that the attack could also be carried out from within the aircraft, but the requirements for a strong signal and thus large power amplifier and directional antenna would still be required, making the operation too suspicious to carry out onboard.

Over on YouTube user Shortwave Bavaria has uploaded a video that demonstrates HFDL reception. HFDL is short for High Frequency Data Link and is a signal used by aircraft to communicate short messages with ground stations over long distances. It is often used in place of VHF ACARS when flying over oceans.

In his video Shortwave Bavaria uses a 26.5m end fed wire, and a Cloud-IQ SDR. But we note that any HF capable SDR can be used to receive HFDL. SDR-Console V3 is used as the receiver, and MultiPSK Professional edition as the decoder. Many HFDL messages contain location data, so aircraft can be plotted on a map and he demonstrates this using Google Earth. In the video he notes how amazing it is that flights from across the globe can be received with his set up.

Recently the company Stratux released a new ADS-B/UAT diplexer PCB. This is useful if you have a single antenna and want to feed two RTL-SDR dongles, with one receiving 1090 MHZ ADS-B and the second receiving 978 MHz UAT. The filter consists of a splitter and two SAW filters.

ADS-B is short for Automatic Dependant Surveillance Broadcast and is used to help track aircraft in the sky. It is transmit at 1090 MHz and the signal contains aircraft data such as the location, speed, altitude and aircraft call sign. ADS-B is utilized worldwide.

UAT is short for Universal Access Tranceiver and is transmit at 978 MHz. Like ADS-B it is used to keep track of aircraft, however UAT is only available in the USA and only for aircraft that fly below 18,000ft. It is a little cheaper and unlike ADS-B, UAT transmissions can also contain weather and traffic data.

US aircraft owners/operators that fly below 18,000ft can choose to install either UAT or ADS-B transmitters in their aircraft, so in the US a complete monitoring solution needs to monitor both 1090 MHz and 978 MHz.

The Stratux Diplexer board is currently available on Amazon for $24.99.

A while back we posted about flight tracking company RadarBox.com who had launched their 1090 MHz ADS-B optimized RTL-SDR. Like other ADS-B optimized RTL-SDR's, the dongle contains a 1090 MHz filter and a low noise amplifier that reduces the noise figure, resulting in better SNR, and thus more planes spotted at further distances.

We spoke with RadarBox and asked if they could provide a low cost RTL-SDR + Antenna bundle for us. That bundle is now available in our store for $49.95 + shipping. Shipping takes about 2-3 weeks and costs between $10 - $25 depending on your country. Shipping costs will automatically added to the cart on checkout. Please note that due to the larger size this will be shipped in a cylindrical package from a separate Chinese warehouse, and tracking info will come a few days later in a separate email.

The bundle includes:

• 1x RadarBox ADS-B 1090 MHz SMA Outdoor Antenna with mounting brackets
• 1x RadarBox ADS-B Optimized 1090 MHz RTL-SDR

The antenna is a has 7 dBi gain, 50 (+-5) Ohm impedance, and is made from fiberglass and aluminum. It is fully waterproof and outdoor rated. This is a great set at a great price to get started tracking planes with ADS-B.

To purchase, please click the Add to Cart button below or visit our store at www.rtl-sdr.com/store. Please note we only have limited stock of this product.

Financial news site Bloomberg recently ran an article about how hedge fund managers are using ADS-B to track private company aircraft in order to help predict the next megadeal between companies. They explain with an example:

In April, a stock research firm told clients that a Gulfstream V owned by Houston-based Occidental Petroleum Corp. had been spotted at an Omaha airport. The immediate speculation was that Occidental executives were negotiating with Buffett’s Berkshire Hathaway Inc. to get financial help in their $38 billion offer for rival Anadarko Petroleum Corp. Two days later, Buffett announced a $10 billion investment in Occidental.

There’s some evidence that aircraft-tracking can be used to get an early read on corporate news. A 2018 paper from security researchers at the University of Oxford and Switzerland’s federal Science and Technology department, tracked aircraft from three dozen public companies and identified seven instances of mergers-and-acquisitions activity. “It probably shouldn’t be your prime source of investing information, but as a feeder, as an alert of something else what might be going on, that’s where this work might be useful,” says Matthew Smith, a researcher at Oxford’s computer science department and one of the authors.

"Alternative data" collection firms like Quandl Inc. have services like "corporate aviation intelligence", where they use ADS-B data to keep tabs on private aircraft, then sell their data on to hedge funds and other investors who are hoping to gain an edge in the stock market.

Popular flight tracking sites that aggregate ADS-B data like FlightAware and FlightRadar24 censor data from private jets on their public maps upon the request of the owner, but it's not known if they continue to sell private jet data on to other parties. ADS-B Exchange is one ADS-B aggregator that promises to never censor flights, however the data is only free for non-commercial use. The value from using companies like Quandl is that they probably have a much more accurate database of who each private jet belongs to.

The Bloomberg article also mentions another use case for tracking private flights, which is  tracking the movements of known dictators via their private jets. We previously posted an article about this too. We've also in the past seen ADS-B data used to track world leaders, and help United Nations advisers track flights suspected of violating an arms embargo.

ADS-B data is typically collected these days with a low cost SDR like the RTL-SDR. We have a tutorial on setting up your own ADS-B home tracker here.

ADSB Flight Tracker is an Android App that allows you to display ADS-B flight data in either 2D or 3D. It works either with data shared from others over the internet via aggregation sites like adsbexchange.com, or via your own home ADS-B receiver data coming from an RTL-SDR and dump1090 server on your home network. You can also directly connect to an RTL-SDR that is running on your phone and this will allow you to get data faster with less lag. Using data shared by others from the internet could have a delay of a few seconds.

In order to keep using the 3D and RTL-SDR features you'll need to unlock them for a small in-app purchase of $2 for each feature. Initially you get about 30 minutes trial time however.

Some interesting 3D videos were also recently posted to the apps Twitter page @ADSBFlightTrkr. 

Over on Reddit u/tsimola has posted about his remote ADS-B station that is accessed via an LTE connection. When an opportunity came up to install a remote ADS-B station on a tall building with unobstructed 360 degree views, tsimola decided to build the best ADS-B monitoring station that he could, and make sure that it would be easily to maintain and monitor from afar.

He notes that his ADS-B station consists of a FlightAware Prostick Plus and 16-element collinear coaxial antenna. The following components are also used:

• Raspberry Pi 3 booting and running from SSD drive (Raspbian and ADSB Receiver Project package)
• Power via UPS (1 hour and 45-minute runtime) and text message controlled power socket (for hard reboots)
• Powered USB hub with three basic RTL-SDR dongles (ACARS, VDL Mode 2 and voice)
• Three temperature sensors and one humidity sensor, 80 mm exhaust fan (filtered air intakes)
• Magnetic switch for push notifications if the lid is opened (IFTTT and Webhooks)
• LTE/4G router for Internet connection

In addition to the ADS-B station, tsimola has also added ACARS, VDL2, and AM voice air traffic control monitoring with a second station in the same location that utilizes three RTL-SDR dongles. This second airband station is connected to a 128 MHz tuned airband dipole antenna, with an LNA4all and GPIO labs airband filter.

As well as descriptions of the hardware, tsimola's post goes over his software choices and explains how it is securely accessed. We think that this is a very well put together build that should be replicated in other locations too.

[Also seen on Hackaday]

Arun Venkataswamy has recently completed a write up about his system which automatically captures images of passing aircraft. It works by using a Raspberry Pi and RTL-SDR to listen to ADS-B broadcasts from aircraft. These broadcasts contain the live current location and altitude of all aircraft in his area. When a landing aircraft is detected to be passing near his house, the Raspberry Pi sends a signal to another Raspberry Pi connected to a camera on his balcony, and that snaps a photo of the passing aircraft.

In terms of software, Arun uses dump1090 as the ADS-B decoder. For communications between the two Raspberry Pi's he uses Node-RED and Mosquitto in order to communicate with MQTT. On the second Raspberry Pi, gPhoto2 captures images from the camera, and then ImageMagick is used to write some text about the aircraft and photo on the image. Arun's post goes in further detail about the code and conditions he uses to determine when a photo should be snapped.

In the past we've posted about a similar project where an RTL-SDR and Raspberry Pi based ADS-B tracker was used with a servo mounted video camera to track and record video of passing aircraft.