Category: Airband

Acarsdec 2.0: A Multi-Channel Realtime Linux ACARS Decoder which supports RTL-SDR

Acarsdec is a recently released open source, multi-channel realtime ACARS decoder for Linux. It supports direct input from an RTL-SDR dongle, and with the RTL-SDR can listen to four ACARS channels simultaneously. It’s official feature list includes

– up to four channels decoded simultaneously
– multithreaded
– error detection AND correction
– input from sound file , also sound card or software defined radio (SDR) via a rtl dongle

Acarsdec Terminal Output
Acarsdec Terminal Output

Studying VOR Signals with the RTL-SDR

VHF Omni Directional Radio Range (VOR) signals are used in aviation as a short range radio navigational system. Amateur radio hobbyist F4GKR decided to study these VOR signals by recording them using his RTL-SDR, and then analyzing them in MATLAB. On his post he shows his method of analysis and discusses his results.

VOR Spectrum and Waterfall
VOR Spectrum and Waterfall

RTL_ACARS Updated

The rtl_acars console based ACARS decoder which is based on rtl_fm has been updated by a new author, gat3way on Reddit. The new updates include decoder sensitivity improvements and the following:

  • Multiple frequencies scanning is now supported (by providing multiple -f arguments at command line and -l ). Since there is no audio output and it’s hard to determine right squelch level, a squelch debug option (-r) is implemented. Use it to experiment with squelch value, it’s simple: good squelch values flood stdout with “hopping freq!” messages yet avoid too high squelch levels. In general, values between 20-30 work good with my setup (big city, lots of radio interference, NOAA turnstile which gives -3db due to rhcp polarization).
  • Aircraft and airline databases now supported (using the acarsdec builtin ones). DBs are text files using simple format, so you may easily update them. I would very much appreciate your help to keep that up-to-date.
  • Certain improvements in frequency hopping code as compared to rtl_fm, but don’t expect wonders, it takes time to retune so data loss is not avoidable especially if you provide lots of frequencies to scan or huge ranges.
  • A simple Makefile to make it simpler 🙂

In the future gat3way hopes to support the decoding of multiple ACARS channels as well. The updated rtl_acars software can be downloaded from github here.

Simplified RTL1090 Installer

The popular RTL-SDR ADS-B decoder RTL1090 requires the rtlsdr.dll and libusb.dll files to be manually downloaded and then placed into the RTL1090 folder. However, now the author of RTL1090 has created an automatic installer which will download and install all the required files automatically.

This internet based utility helps you with setting up a complete RTL1090 installation with almost no manual intervention. It automatically downloads the relevant files as rtlsdr.dll, zadig.exe and helps to configure zadig with a built in tutorial.

The installer is called the IMU (Installer and Maintenance Utility) and can be download from the RTL1090 website at rtl1090.web99.de.

News via sonicgoose.com.

ADS-B Virtual Radar RTL-SDR Tutorial in the ARRL QST Magazine

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.

If interested, we also have an ADS-B virtual radar tutorial that can be found here.

ADS-B Virtual Air Radar Tutorial by the ARRL
ADS-B Virtual Air Radar Tutorial by the ARRL

ADS-B Decoder for the RTL-SDR now available for Android

A (beta version) of an ADS-B decoder and display app for the RTL-SDR dongle for Android has been released. This app allows you to receive the ADS-B radio signals emitted by modern aircraft, which contain information such as flight number, latitude, longitude and altitude, essentially giving you a live portable aircraft 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!

ADS-B Decoding on Android
ADS-B Decoding on Android

ADS-B Active PCB Antenna for the RTL-SDR

This ADS-B antenna by amateur radio hobbyist F5ANN combines a 30dB LNA preamplifier, bandpass filter and antenna tuned for 1090MHz together on a single PCB board. The LNA preamplifier helps boost weak signals, whilst the bandpass filter helps to remove interference from others signals such as GSM. The novel thing about this antenna is that everything is neatly packaged into a single PCB board, which makes this antenna very compact, and yet have high performance.

F5ANN uses his combined antenna together with an RTL-SDR dongle and the RTL 1090 ADS-B decoding software with PlanePlotter, and was able to receive 194 simultaneous aircraft signals with a message rate of 556 messages a second at distances of up to 250 nm.

Active PCB Antenna
Active PCB Antenna