The American Radio Relay League (ARRL) a.k.a The American National Association for Amateur Radio has put online a freely available ADS-B tutorial featured in their monthly QST magazine, written by Robert Nichols, W9RAN. The tutorial focuses on using an R820T RTL-SDR dongle to receive ADS-B signals, and then using computer software to decode the signals and create a virtual aircraft radar.
ADS-B is a protocol used by most modern aircraft to broadcast their position and altitude which is determined via GPS. ADS-B is intended to supplement and eventually replace traditional radar.
In this ADS-B tutorial, they show how to create a weatherproofed 1090 MHz collinear antenna from RG-6/U coax and PVC pipe and how to use the ADSB# and virtual radar server software to decode and visualize aircraft positions, like a radar.
To use the app, you will need an Android device that supports USB OTG, which most Android devices on Android 4.0+ should support. You will also need a USB OTG cable, and an RTL-SDR dongle. You may want to consider a USB OTG cable that has a second port for external charging capabilities, as the RTL-SDR can drain the battery quickly.
The app is cheaply priced at under $2, so give it a try!
Over on YouTube user adsbrus shows us his project which is an in car ADS-B aircraft tracker using a Raspberry Pi mini computer and an RTL-SDR. The system uses an LCD screen mounted where the car radio usually is to show aircraft identifier, altitude, and speed information in text.
ADS-B in CAR (Raspberry PI & USB TV RTL2832U+R820T)
In order to do this he used the Linux based dump1090 ADSB-B decoder and hub software on his main PC. Lui was even able to compile and run the ADS-B hub portion of dump1090 on his Windows PC using Cygwin, but was unable to get the decoder part to work. It doesn’t matter though because the dump1090 hub can receive data from any ADSB decoder, such as ADSB#. His results look very promising as can be seen by the timelapse of plane traces in the image below.
Standard ACARS transmits at a frequency of 131.550 MHz, which is in the receivable range of the RTL-SDR. The RTL-SDR software radio can be used as a radio scanner for listening to these digital messages, and with the help of some decoding software, can be used to decode and display the messages. The messages you can receive will be from nearby aircraft and ground stations. Most messages will be unreadable data intended for computers, but you can find out what is flying near you by decoding the flight number and aircraft registration details sent with every message.
There is also HF ACARS, which is used for long distance communications. In this article the focus will be on VHF ACARS, as receiving HF ACARS is a little different.
Examples of the RTL-SDR being used to decode ACARS
YouTube user Superphish shows a timelapse over 5 hours of ACARS traffic and decoding using SDR# and decoding program acarsd. He used a J-Pole antenna. (2021 Update: please see note regarding acarsd no longer working as expected below in the tutorial)
ACARS Decoding with RTL SDR (RTL2832), SDR Sharp and ACARSD