Tagged: planeplotter

RTL-SDR Tutorial: Cheap ADS-B Aircraft RADAR

The RTL-SDR can be used as a super cheap real time air radar. Modern planes use something called an ADS-B (Automatic Dependent Surveillance-Broadcast) Mode-S transponder, which periodically broadcasts location and altitude information to air traffic controllers. The RTL-SDR can be used to listen to these ADS-B signals, which can then be used to create your very own home aircraft radar system. Compared to dedicated commercial ADS-B receivers which can go for between $200 – $1000, the $20 RTL-SDR is very attractive for the hobbyist in terms of price. However, note that the RTL-SDR probably shouldn’t be used for ADS-B navigation in a real aircraft for safety reasons. 

ADS-B broadcasts at a frequency of 1090 MHz. It has been discovered by the RTL-SDR community, that the RTL-SDR with R820T tuner has the best sensitivity at this frequency. The E4000 and other tuners perform poorly in comparison. So it is recommended that you obtain an R820T tuner if you want to set up ADS-B decoding with the RTL-SDR. Recently there has also been talk about the R820T2 tuner, which seems to have slightly better performance too. See the Buy RTL-SDR dongles page for more information on where to purchase.

We also now note that recently new higher end SDR’s like the $199 Airspy have developed very good ADS-B receivers that are several times more sensitive that the RTL-SDR.

Examples of RTL-SDR used as an ADS-B air radar

In this video, YouTube user Superphish shows a timelapse of air traffic over New Zealand using RTL-SDR, ADSB# and Virtual Radar Server.


Continue reading

RTL-SDR Tutorial: Receiving Airplane Data with ACARS

What is ACARS?

ACARS is an acronym for Aircraft Communications Addressing and Reporting System which is a digital communications system that aircraft use to send and receive short messages to and from ground stations.

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.


Continue reading