He's now begun a new series on his channel where he will be exploring the world of software defined radio in more depth. The first video that he's uploaded today is an overview where he overviews EMS communications, aircraft signals, military air signals, maritime signals, space signals, as well as other interesting signals he's received like wireless earpieces for musicians at concerts and TV studio talkback links. He writes:
The 2020 SDR Guide Episode 1 has just been released. It serves as an introduction to the incredible world of Software Defined Radio and will be of interest to both beginners and more advanced users.
Over the next few weeks, Frugal Radio will be exploring various aspects of using SDRs within the hobby. These include :
His idea was to receive ADS-B signals with his Yagi and a dipole antenna, then compare the data received in order to determine in which directions the Yagi receives better than the dipole. To do this he first creates a standard 2D map of plane tracks collected over a 24hr period for both the dipole and Yagi. A gaussian blur is applied to the two maps in order to fill in blank space and the data is normalized. Then he simply subtracts the dipole plot from the Yagi-Uda plot. The resulting difference plot reveals a mapping of where the Yagi receives better or worse compared to the dipole in a 2D plane.
Back in March we posted about the release of OpenEar, a standalone TETRA decoder for the RTL-SDR. Since then OpenEar has undergone massive developments, not only improving upon the TETRA decoder, but adding DMR, ADS-B and POCSAG decoders as well as a waterfall display.
Recently Tech Minds reviewed this software on his YouTube channel. In the video he shows how to download the software, install the rtlsdr.dll file, and run and use the software. He then demonstrates reception of an amateur radio DMR repeater, reception of POCSAG pager messages and finally reception of ADS-B aircraft messages.
OpenEar Digital Decoder - DMR TETRA P25 ADSB POCSAG RTL-SDR
Over on YouTube we've recently discovered a live stream by channel Information Zulu that has created a virtual live 24hr view of LAX airport air traffic by piping ADS-B data into a flight simulator game. The stream also combines this with live air traffic audio and arrivals and departures information. Other videos on his channel show highlights like go arounds.
We're not sure what he's using to pipe ADS-B data into the simulator or exactly what simulator this is, but in the video description he notes that he uses a Pi 4, RTL-SDR blog V3 with ADS-B LNA, and an AirNav antenna to receive the ADS-B data.
During the recent George Floyd BLM protests police and military aircraft have been playing a large part in the surveillance of protestors. All these aircraft are required to transmit ADS-B which of course can be monitored with an RTL-SDR or other SDR. Many volunteers around the world use RTL-SDRs to upload ADS-B data to an online aggregation service, so flight data from all over the world can be accessed in one place. However, most ADS-B aggregation services like FlightAware and FlightRadar24 censor police and military aircraft from the raw ADS-B data received from the RTL-SDRs. ADS-B Exchange is the only service that has a policy to not censor any aircraft.
As mentioned in a previous post, ADS-B Exchange recently updated their interface and backend, and they now run tar1090, which is a fully featured ADS-B mapping platform that can display the historical tracks of any tracked aircraft.
We also note that on Twitter John Wiseman @lemonodor also runs several "advisory circular bots" that make use of ADS-B Exchange data to automatically tweet a notification when aircraft are detected as having a circular flight path.
The Unidentified Aerial Phenomenon Tracking Network (UAPTN) is an effort to set up crowd sourced Raspberry Pi powered cameras all over the world in order to record videos of "unidentified aerial phenomena" AKA UFOs. In order to rule out false positives from known aircraft, they are recommending that contributors install a FlightAware RTL-SDR in their system for aircraft tracking.
For this purpose doing your own ADS-B flight tracking would be required as most commercial flight tracking sites censor military and private jets. The only site that does not censor data is ADS-B Exchange. However, of course military aircraft conducting operations are always able to turn ADS-B off if required for the mission which is what the UAP network will probably detect the most.
If UFO tracking does not interest you, then you might instead be interested in creating a RTL-SDR based GhostBox to talk to spirits!
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.
ADSBExchange is an aircraft tracking website service which aggregates ADS-B data from contributors running RTL-SDR's or similar receivers worldwide.
However, unlike other flight tracking sites such as flightaware and flightradar24, ADSBExchange sets themselves apart by proudly refusing to censor the tracking of military and private jets that have requested privacy. One area where this refusal to self-censor helps is with the "Dictator Alert" service. This is a service that automatically tracks the movements of private aircraft owned by authoritarian regimes via the ADS-B data collected and shared by ADSBExchange.
Recently ADSBExchange upgraded their web interface moving from the old Virtual Radar Server system to tar1090 which is a more fully featured open source display for dump1090. This new interface has some great features, like the ability to view the complete flight track history of any aircraft on a particular day, the ability to display only military aircraft and the ability to filter by altitude and aircraft type.