Category: Airband

Modesdeco: Now Supports Simultaneous Reception of Mode S and Mode A/C

Modesdeco is a Windows/Linux/OSX/RPi compatible command line ADS-B Mode S decoder built for the RTL-SDR. It natively supports the BaseStation format and so can be used with the BaseStation software without the need for com port converters.

Modesdeco has recently been updated to allow for the simultaneous reception of Mode S and Mode A/C. Mode S provides location data for ADS-B while Mode A provides an identification code and Mode C provides the aircraft’s pressure altitude.

Effect of a Filter on RTL-SDR ADS-B Reception

Over on YouTube user Adam Alicajic has posted a video showing the effect of a filter tuned for 1090 MHz used on ADS-B reception. Adam switches the filter in an out showing the difference in the number of received ADS-B frames. With the filter enabled he is able to receive around 1200 messages per second and without only around 800 messages per second.

A filter (aka preselector) can help to reduce out of band interference from strong signals.

DVB-T dongle receiving the ADS-B using the filter

Receiving VDL2 with MultiPSK and an RTL-SDR

Over on YouTube user Frank K2NCC has posted a video showing the reception of VDL2 (VHF Data Link mode 2). He uses MultiPSK to receive and decode VDL2 signals and VDL2-Display to nicely display the received messages.

VDL2 is a transmission mode used on aircraft for sending short messages, position data (similar to ADS-B) and also for allowing traffic controllers to communicate to pilots via text and data. Earlier we has a post about a VDL2 reception tutorial.

Hak5: ADS-B on a Quadcopter carrying a Wifi Enabled Linux Computer, RTL-SDR and Coaxial Collinear Antenna

Over on YouTube, Hak5 a electronics enthusiast channel has posted a video showing an interesting ADS-B project they undertook.

The Hak5 team took a quadcopter up on top of a high mountain, attached to it a WiFi Pineapple (a small WiFi equipped Linux computer), an RTL-SDR dongle and a coax collinear antenna and then flew it up high. They ran dump1090, a Linux based ADS-B decoder on the WiFi pineapple and then broadcast the decoded information back to a laptop on the ground.

Although the results were less than favourable, it is still an interesting project to explore. Their poor results may be due to a nearby RF broadcast tower which could have been overloading the dongle, or EMF from the quadcopter motors.

Tracking Aircraft over 300 miles away! Mountain + Drone + SDR, Hak5 1609

Interest Check for an ADS-B Folded Monopole Antenna

Adam, manufacturer of the LNA4ALL and LNA4HF is putting out an interest check for an ADS-B folded monopole antenna. The antenna can efficiently cover the 1030 MHz to 1090 MHz frequencies that are used by ADS-B.

The major advantage to Adams antenna is that it uses a DC grounded design, eliminating static build up problems that can potentially fry your LNA or RTL-SDR dongle.

If there is sufficient interest, Adam will sell the antenna for 20 Euros.

ADS-B Folded Monopole Antenna
ADS-B Folded Monopole Antenna

Aircraft Messages with HFDL, MultiPSK and the RTL-SDR

Over on YouTube user k2nccvids has posted two videos showing how he was able to decode High Frequency Data Link (HFDL) packets using the RTL-SDR, Ham-it-up upconverter, MultiPSK and HFDL Display. HFDL is a service similar to ACARS but sent over HF frequencies. It is used to sent short messages to and from aircraft and ground stations.

In the first video k2nccvids uses MultiPSK with the RTL-SDR directly and also uses the add on software HFDL Display to more clearly view received HFDL packets. In the second video he uses SDR-CONSOLEv2 to monitor three HFDL frequencies simultaneously, with MultiPSK and HFDL Display still being used for decoding and display.


Receiving VDL Mode 2 with MultiPSK and the RTL-SDR

The VHF Data Link mode 2 (VDL2) is a new transmission mode used on aircraft for sending short messages, position data (similar to ADS-B) and also for allowing traffic controllers to communicate to pilots via text and data. VDL2 is intended to eventually replace the standard ACARS modes. It is found at 136.975 MHz.

Recently, a wiki page explaining how to decode VDL2 using MultiPSK, Planeplotter and the RTL-SDR has been put up. MultiPSK is a sophisticated software program that can decode a wide range of amateur radio digital signals as well as several professional modes like VDL2. To decode most professional modes like VDL2 however, the paid version of MultiPSK is required, but a 5 minute per use trial of VDL2 decoding can be used for testing. Newer versions of MultiPSK can now even directly connect to the RTL-SDR dongle.

The wiki page shows how to set up the RTL-SDR dongle on MultiPSK to receive VDL2 signals, and then shows how to connect it to PlanePlotter in order to plot the aircraft positions on a map.

MultiPSK with VDL2
MultiPSK with VDL2
PlanePlotter with VDL2 Data
PlanePlotter with VDL2 Data

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