What even is SDR?
SDR stands for Software Defined Radio. In short, it is a piece of software that runs on your computer and enables you to use your computer’s sound card as a receiver.
If you’re unfamiliar with SDR, then you may not know that it has been around since the 1980’s, and was originally known as direct conversion receivers (DCR). An example of what a modern SDR “kit” looks like is below:
SDRs are commonly used as a hobbyist application. Most people have at least heard of them, and know they do what their name suggests – define radios!
What can you do with an SDR?
You can do various different things using an SDR as follows:
- Receive broadcast radio
- Amateur radio
- Radio astronomy
- Track ships via AIS transmissions
- Track aircraft via Mode S transponder (And this will be today’s project)
- Listen in in “walkie talkies”
Project 1: ADS-B – Tracking Planes
Back in January, I started to play around with SDR, mostly in order to be able to track aircraft using their Mode-S Transponder signals.
Hardware
My ADS-B station is currently running the following hardware:
SDR Dongle: AirNav RadarBox FlightStick
Antenna: AirNav ADS-B 1090MHz External Antenna
Board: Raspberry Pi 3 Model B+
Enclosure: Random box bought at the local supermarket, and some DIY hot-glue stuff
Network connection is currently done via Wi-Fi
Software
This station is currently running the PiAware image, including dump1090-fa (that will out of the box feed data to https://flightaware.com/), with some additional software installed to feed into some other sites:
- adsbexchange-feed, to feed into adsbexchange.com/
- fr24feed, to feed into flightradar24.com
- rbfeeder, to feed into https://www.radarbox.com
- opensky-feeder, to feed into https://opensky-network.org/
Some other websites/services do it the other way around though, by connecting (while having the relevant firewall exceptions) my station to obtain data, instead of the other way around, these services are:
And some other additional software for metrics purposes:
- ADSB Stats Logger, to generate some metrics about the station performance (more on this shortly)
- graph1090, to generate signal and traffic metrics
- timelapse1090, to generate air traffic timelapse
Results
I have been gathering aircraft tracking data since January 2022 with this setup, and these are some metrics of this data, but before sharing the numbers I’ll share my maximum theorical range (according to heywhatsthat.com) at my antenna location, taking terrain into consideration for airborne targets (where red represents the horizon visual range, orange for targets at 10k feet, and the blue line for targets at 30k feet):
Versus my actual range:
If you want to check the live feeds you can do so here:
- RadarBox station EXTRPI015736 (#30 ranked station in Portugal, at the time of writing)
- ADSB Exchange station 5q09vKA4swhy
- FlightRadar24.com by filtering for radar code
T-LPPD20
ADSB Stats Logger:
Data range: 2022-03-08 13:14:53 - 2022-09-03 13:38:11
Unique Flights: 1600
Unique Operators: 522
Max Altitude: Flight SAT408 37.206644315757394 km at 2022-08-19 21:38:10
Max Speed: Flight MEDIC16 1836.0728000000001 kmh at 2022-05-29 22:10:01
Max Station Distance: Flight AFR457 664.5046626435085 km at 2022-07-21 03:33:57
Min Station Distance: Flight RYR2624 0.012642261112371317 km at 2022-05-15 19:38:21
Max Signal: Flight UAL216 -0.9 db at 2022-06-02 11:22:28
Min Signal: Flight AEA194 -28.6 db at 2022-08-04 07:52:23graphs1090 (6 months period)
Whats next?
In the last few weeks I have been playing around with a couple new SDR things to make an upgrade to my SDR setup with a new project, these things are:
AIS Ship Tracking
Listening to Air Traffic Control
I’m currently waiting for Amazon to deliver some adaptors and connectors, so I can connect further gear to my external antenna to develop both these two projects, so stay tuned for future posts about them 🙂
