SOFTWARE GUIDE

Currently, there are multiple software options available for listening and decoding ADS-B signals with the RTL-SDR. Almost all software is free. Note for the Windows based software you will need to have installed the RTL-SDR drivers via zadig first. See the Quickstart guide if you have not done this.

The most commonly used ADS-B decoders are ASDB#, RTL1090 and dump1090.

ADSB# (WINDOWS)

ADSB# is a Windows based 1090 MHz ADS-B decoder developed by the programmer of SDR Sharp. It has a simple graphic user interface and is probably the easiest decoder to use overall. To use ADSB#, download it from http://sdrsharp.com/downloads/adsbsharp.zip.

To install and run ADSB#, all you need to do is extract the zip file into a folder, and then double click on adsbsharp.exe. If your RTL-SDR dongle is plugged into your PC, you should be able to select it under the Device drop down menu. You can then click the start button to begin decoding ADS-B data.

Be sure to also set the gain. Tuner AGC works well for first time testing, but manual gain settings work best after tweaking. Maximum gain with no AGC is usually the best choice.

If you have a good antenna set up, you should begin to see numbers other than zero showing up under Frames/sec. This indicates that you are receiving ADS-B data.

ADSB# decodes the ADS-B data and then sends location data via TCP/IP. Another program such as Virtual Radar Server, ADSBScope or PlanePlotter (explained later) is needed to visualize the data. If you have several antennas in different locations, you can combine your data in this way using the adsbhub.exe program which is part of the ADSB# zip file download.

The frequency correction (ppm) setting is the same as the setting in SDRSharp which is used to correct for the RTL-SDR dongles frequency inaccuracy. Since ADS-B signals are not particularly sensitive to frequency accuracy, this setting won’t make much difference even if you set it correctly. When ADS-B data is received from an aircraft a confidence counter is incremented. The confidence counter rises as more packets from the same aircraft are received. Once the confidence is greater than the confidence set in the GUI, the aircraft location data will be sent over TCP/IP. Confidence is used to prevent false aircraft locations showing up from noise which was accidentally decoded as a valid ADS-B signal. Higher confidence levels may be necessary in noisy environments. The timeout setting defines how long the decoder will wait before checking the confidence of the aircraft again.

RTL1090 (WINDOWS)

Another Windows 1090 MHz ADS-B decoder with graphical user interface is RTL1090 which can be downloaded from http://rtl1090.web99.de. The easiest way to download and install RTL1090 is to use the IMU (Installer and Maintenance Utility), which will automatically download all the required files. The IMU saves the work of having to copy over several dll files and guides you through installing the drivers through zadig. Note if you’ve already installed the drivers through zadig via the Quickstart guide, you can ignore the zadig installation shown in the IMU.

RTL1090 has some special features. It can decode MODE A/C as well as MODE S. Mode A sends an aircraft identification number and Mode C sends the aircraft altitude, MODE S is the one that has the location information. RTL1090 also has a built in spectrum viewer which can be activated by flipping the SISEX switch. Finally, RTL1090 also has a 1-bit checksum error checker built in. The error checker can be activated in the Config menu. It is disabled by default because it can be taxing on older slower PCs. You can access the options screen by clicking the OPEN button in the top left corner of the program GUI. Most people report that RTL1090 has better receive performance compared to ADSB#.

The recent beta 3 version of RTL1090 also comes with a built in graphical radar display.

As with ADSB#, we recommend playing with the manual gain settings or running with Tuner AGC checked and RTL AGC unchecked. Maximum gain with no AGC is usually the best choice.

The authors of RTL1090 also have an experimental version of their software called RTL-DUO, which utilizes two RTL-SDR dongles for improved reception. It can also be downloaded from

http://rtl1090.web99.de.

DUMP1090 (LINUX/MAC/WINDOWS)

This is a Linux/OSX/Windows compatible command line ADS-B decoder. Very useful for Linux based devices such as the Raspberry Pi. With dump1090 you could set up a Raspberry Pi decoder that feeds data to a web server. Most people report that Dump1090 has the best decoding performance out of all the ADS-B decoders.

The latest and most up to date branch of dump1090 can be downloaded from its git repository at

https://github.com/MalcolmRobb/dump1090.

Dump1090 also has a hub mode, which will allow multiple dump1090 instances in different physical locations to connect together and combine data streams. This might be an option if you are not interested in sharing your data publically such as with adsbhub or flightradar24.

Dump1090 also has a graphical display web interface that uses Google maps built into the code. It can be accessed through a web browser.

To install dump1090 on Linux, simply download the zip file from the git repository and unzip the files into a folder or do a git clone on https://github.com/MalcolmRobb/dump1090. Then assuming you have the librtlsdr libraries preinstalled, run ‘make’ at a terminal in that folder. This can also be compiled on OSX, but you will need to ensure that you have a compiler and make-tools installed with access to the dev environment and Xcode. Once compiled you can run the following.

./dump1090 --interactive --net

This will start a Google Maps web server that can display received aircraft. In a web browser go to

http://localhost:8080 to see the map.

You may wish to also enable the --aggressive and --fix flags which will be able to decode more ADS-B packets at the expense of increased CPU usage. The aggressive mode is mainly useful for low traffic areas as it may cause many false positives under high traffic conditions. More options can be found by typing ./dump1090 -h at the terminal. Note that dump1090 automatically chooses the maximum gain setting if no gain is set, which is usually the best choice.

Dump1090 can also receive Mode AC messages together with Mode S by using the flag --modeac To install dump1090 on Windows follow these steps:

1. Download the dump1090 zip file from the GitHub download link.

2. Download the official RTL-SDR Windows release from

http://sdr.osmocom.org/trac/attachment/wiki/rtl-sdr/RelWithDebInfo.zip.

3. Copy the libusb-1.0.dll, rtlsdr.dll and pthreadVC2-w32.dll files from the official RTL-SDR Windows release zip file to the dump1090 folder.

4. Rename pthreadVC2-w32.dll to pthreadVC2.dll. 5. Double click on dump1090.bat.

30002 --net-beast --mlat which starts an interactive web server and beast mode output which will allow programs like Virtual Radar Server (described below) to connect to it using port 30002. You may also wish to experiment with adding the --aggressive and/or --fix flags to the batch file which can be edited with a text editor like Notepad.

MODESDECO

ModesDeco is a Windows/Linux/OSX/Rpi command line based decoder. It can receive Mode S and Mode A/C data simultaneously. Download the latest version from the last page on the forum post at

http://radarspotting.com/forum/index.php/topic,2978.0.html. Note that you may need to install the Visual C++ 2012 Redistributable from http://www.microsoft.com/en-us/download/details.aspx? id=30679, make sure you download the x86 version of the redistributable and not the x64 version.

To start decoding with modesdeco, open a command line prompt from windows, navigate to the directory you’ve extracted modesdeco to and type the following.

modesdeco2.exe --gain 49.6 --net 10001 --sbs10001 --location lat:lon

This mode outputs in the base station format. To output in other formats such as AVR usable by other graphical radar displays use

./modesdeco2 --gain 49.6 --freq-correction 68 --sbs10001 10001 --avr 44044 --msg 30003 --location 43.25:39.33 --filter-nocountry - -rbs --verbose

COCOA1090 (MAC OSX)

This is a ADS-B decoder written for Mac OS X. It can be downloaded from