Tagged: Automatic dependent surveillance broadcast

ADS-B Traffic Analytics with Valo and an RTL-SDR

Valo is a software service for real time big data streaming analytics of data from many sensors.  On their website they explain their service as follows.

Valo is a single platform for streaming (real time) and batch (historical) data analysis. Valo provides multi-paradigm big data storage for both semi-structured and numerical data. Valo contains a powerful analytics engine for processing all of this data. Finally Valo is super simple – a single tool that can be up and running in minutes.

Recently Rémi Selva wrote in to let us know about an interesting use-case for Valo which involves the RTL-SDR. In his post Rémi shows us how he uses an RTL-SDR, Raspberry Pi running dump1090, and Valo to create interesting data visualizations of the ADS-B aircraft data. He not only shows how to visualize the data in Valo, but also how to use queries to dig deeper into the data, looking for patterns.

Valo ADS-B Data Flow
Valo ADS-B Data Flow

Rémi writes that what he’s done is simply a proof of concept that shows the power of Valo. He writes that one such interesting future development could be using Valo to detect FBI/CIA surveillance aircraft. Previously we posted about how an RTL-SDR user discovered these surveillance aircraft by their odd circular flight paths. The analytics engine of Valo could be used to automatically detect odd flight patterns such as from these surveillance aircraft. 

Plotting the history of aircraft coming into land at HK airport
Plotting the history of aircraft coming into land at HK airport

An ADS-B Decoder for the GOMX-3 Satellite ADS-B Repeater

The GOMX-3 is a CubeSat which carries an experimental ADS-B repeater. Since it is a satellite the experimental receiver hopes to be able to receive ADS-B from orbit, then beam it back down to earth at a frequency of about 437 MHz using a GFSK at 19200 baud high data rate transmission protocol. From space the GOM3-X satellite can see many aircraft at one time and space based tracking allows for aircraft tracking over oceans.

Recently the creators of the satellite, GomSpace released a complete decoder for the ADS-B downlink, and now it has also been turned into a GNU Radio flowgraph by Daniel Estevez which can output decoded aircraft position data directly to a KML file which can then be opened in Google Earth or similar. This blog by DK3WN shows several logged decodes of the satellite and shows what the signal looks like in SDR#. Some of his posts also curiously shows what looks to be a Windows decoder, or logger, though we were unable to find a download for it.

Decoding the downlink should give you real time ADS-B data in your area, but the full log of stored stored data is apparently only downloaded when the satellite passes over the GomSpace groundstations which are mostly located in the EU.

[Also mentioned on Hackaday]

The GOMX-3 ADS-B Downlink Signal.
The GOMX-3 ADS-B Downlink Signal.
Aircraft detected by the GOM3-X Satellite ADS-B Receiver.
Logged aircraft detected by the GOM3-X Satellite ADS-B Receiver. Major flight corridors are visible.

A new RTL-SDR based Portable ADS-B Kit for Pilots is on Kickstarter

Back in March we posted about the FlightBox, a portable RTL-SDR ADS-B 1090ES and 978UAT receiver built for use by pilots in small aircraft. 1090ES provides ADS-B which allows a pilot to see on a map where other aircraft are, and 978UAT provides other services such as weather radar. The FlightBox is essentially a Raspberry Pi 2 combined with two RTL-SDR dongles, two antennas, a GPS receiver and is preloaded with the stratux software. The two channel FlightBox receiver currently sells for $250 USD.

Recently a new similar ADS-B product for pilots made by a different company has been released on Kickstarter. The new product is made by a company called RF-Connect and is similar to the FlightBox, but is powered by an Odroid C1. RF-Connect are also the programmers behind the ADS-B on Android app which was one of the first apps to be able to receive FIS-B weather data and display it on a map. 

The product receives 978UAT and 1090ES ADS-B signals using two RTL-SDR dongles, and then transmits the data via WiFi to an Android or iOS tablet running flight navigation software.

The Kickstarter early backer price is $150 USD for a single channel 978UAT only capable receiver or $200 USD for the dual channel 1090ES and 978UAT receiver. This contrasts with the FlightBox price of $200 and $250 USD for similar products, however the standard backer price for the RF-Connect ADS-B receiver is the same as the FlightBox.

The RF-Connect ADS-B Receiver transmitting data to a tablet.
The RF-Connect ADS-B Receiver transmitting data to a tablet.
The parts inside the ADS-B Receiver. Two RTL-SDR dongles, GPS receiver, two antennas, WiFi dongle, Odroid.
The parts inside the ADS-B Receiver. Two RTL-SDR dongles, GPS receiver, two antennas, WiFi dongle, Odroid.

RF-Connect have also uploaded a video showing their ADS-B on Android app in action.

RTLSDR4Everyone: ADS-B Bias-T Filter and External amplification

Akos from the RTLSDR4Everyone blog has recently come out with a new post where he explains how to get the best ADS-B reception with an LNA and filter. In his experiments he uses an LNA4ALL low noise amplifier and and ADS-B Filter, both of which are sold by Adam 9A4QV. New versions of the filter sold by Adam now also include a built in bias-tee circuit which allows you to easily power the LNA4ALL over the coax cable, allowing you to place it externally.

In the post Akos shows where to optimally place the LNA and how you can use your Raspberry Pi together with the ADS-B filter with bias-T in order to power an antenna mounted LNA4ALL. The post also discusses what the cheapest solution is for European customers attempting to optimize their ADS-B reception.

ADS-B Setup including a filter, bias tee, LNA and Raspberry Pi.
ADS-B Setup including a filter, bias tee, LNA and Raspberry Pi.

Comparing ADS-B Reception with the RTL-SDR, Airspy and Beast Receivers

Over on satsignal.eu the author has set up a page showing live statistics of his ADS-B reception for the RTL-SDR and Airspy software defined radios, and also for the Beast ADS-B receiver. The Airspy is a $199 software defined radio that many consider as a next stage up from the RTL-SDR, and the Beast is a ~$270 USD dedicated ADS-B receiver.

Unsurprisingly the results clearly show that the Airspy receives ADS-B signals significantly better than the RTL-SDR. However, what comes as a surprise is that it is actually appears to be outperforming the dedicated Beast receiver. In the tests with the outside vertical antenna, the Airspy running on a Raspberry Pi appears to receive a significant higher number of messages and also sees planes out to a further range.

Not too long ago the Airspy team released their ADS-B software for the Raspberry Pi 2. They write that this software uses the full 10 MHz bandwidth and can even decode messages that are overlapping one another. We’ve also been told by the Airspy team that the Airspy is already in professional use as an ADS-B receiver amongst several small airports.

In the future we hope to compare the Airspy against the RTL-SDR on ADS-B reception ourselves, and also compare it against the 8 MHz bandwidth SDRplay whose development team have also recently released a new ADS-B decoder, as well as the recently released FlightAware ADS-B Prostick RTL-SDR.

Beast and Airspy comparison on ADS-B Reception.
Beast and Airspy comparison on ADS-B Reception.

FlightAware ProStick: A new ADS-B optimized RTL-SDR with built in LNA

The FlightAware team have today announced the release of the "ProStick", an RTL-SDR dongle that they write has been modified for improved ADS-B reception. The new FlightAware RTL-SDR's main defining feature is that it comes with a built in low noise amplifier (LNA) on the front end. The built in LNA is optimized for the ADS-B frequency of 1090 MHz and has 19 dB of gain with a 0.4 dB noise figure and an OIP3 of +39dB. They claim that the new unit will give a 20-100% performance boost in terms of range for Mode S reception when compared to a standard RTL-SDR.

As the increased gain and amplifier non-linearities can cause overload and intermodulation to more easily occur, the FlightAware team stresses that you must use the new device with a 1090 MHz filter, such as their FlightAware filter. In a previous post we reviewed the FlightAware filter and antenna and found that they performed very well and are great value for money.

The new unit is priced cheaply at $16.95 + shipping on Amazon for US buyers, and $24.95 + shipping on eBay for international buyers.

So far we haven't seen any circuit photos or news about which LNA chip has been used, but we intend buy a unit and do a review when it arrives.

One criticism about this unit that we can already see is that it should be understood that good RF design teaches us to always place the LNA as close to the antenna as possible to overcome cable loss and keep the noise figure low. Placing the LNA at the antenna vs at the receiver makes a huge difference in performance, depending on how long and lossy your coax cable run is. Furthermore, integrating an LNA into the receiver ruins the system for optimal performance with an LNA placed by the antenna due to the reduced linearity caused by the additional internal LNA. The post at http://ava.upuaut.net/?p=836 explains optimal LNA placement very well. We think that perhaps selling an external LNA and bias tee module would have been a significantly better idea to optimize ADS-B reception. However, the additional LNA should help to reduce the noise figure of the dongle by a few dBs which will result in improved ADS-B reception as long as signal saturation does not occur. 

The new FlightAware ADS-B optimized RTL-SDR.
The new FlightAware ADS-B optimized RTL-SDR.
The new FlightAware dongle running on a PiAware Raspberry Pi system.
The new FlightAware dongle running on a PiAware Raspberry Pi system (actual unit uses SMA).

ADS-B Decoder for the SDRplay RSP Now Available

A new ADS-B decoder for the SDRplay RSP has recently been released by the SDRplay programmers. The SDRplay is a $149 USD software defined radio with a 0.1 – 2000 MHz range, 12-bit ADC and up to 8 MHz of bandwidth. In a previous review we compared it against the Airspy and HackRF.

The SDRplay team have based their new decoder on the multi-platform compatible dump1090 code, which is an ADS-B decoder that was originally written for the RTL-SDR. The Windows version can be be downloaded from http://www.sdrplay.com/windows.html, and the code for other platforms can be downloaded from https://github.com/SDRplay.

To help with the installation procedure the SDRplay has also provided a manual (pdf) which shows exactly how to download and set up the required ADS-B software on a Windows system. They also write that the software is fairly new and is still being optimized for best performance.

In the future after the software is further optimized we hope to compare the RSP against the RTL-SDR and Airspy on ADS-B reception.

The SDRplay compatible version of dump1090 deceiving ADS-B data.
The SDRplay compatible version of dump1090 deceiving ADS-B data.

FlightBox: Commercial RTL-SDR Based ADS-B (1090ES & 978UAT) Receiver for Pilots

For some time now, small aircraft pilots who don’t have access to expensive ~$1000+ ADS-B gear have been successfully using an RTL-SDR and Raspberry Pi combination to receive ADS-B and UAT to display aircraft and weather data on an iPad. The first time we posted about this was back in August 2015.

The full implementation uses two RTL-SDR dongles to receive both 1090ES aircraft position information and 978 UAT to receive weather radar information. Both dongles are used on a Raspberry Pi mini computer that runs a program called Statrux. Stratux takes the ADS-B information received by the RTL-SDR’s and re-transmits the data out via WiFi. Then an iPad running special pilot navigation aid software such as ForeFlight can interface with the WiFi signal and receive the ADS-B and weather information.

Assembly of a Stratux box requires the purchase of each individual component or a Raspberry Pi kit that includes the stratux software image on an SD card, RTL-SDR and WiFi adapter. However, setting up a Stratux box may be a little difficult for pilots who do not have any electronics DIY skills.

To solve this, a new product called FlightBox recently ran a successful Kickstarter campaign. FlightBox provides a ruggedized plastic case, a Raspberry Pi 2 preloaded with software, two nano RTL-SDR dongles, two pigtail adapters, a 10Hz WAAS GPS module, and two customized ADS-B whip antennas (one for 978 MHz and one for 1090 MHz).

The FlightBox costs $200 for single band operation and $250 for dual band (1090ES and 978UAT). They are currently accepting pre-orders for delivery in late March/April.

For more information about Stratux see the active discussion forum at reddit.com/r/stratux.

The FlightBox: An RTL-SDR based ADS-B 1090ES and 978UAT receiver for Pilots.
The FlightBox: An RTL-SDR based ADS-B 1090ES and 978UAT receiver for Pilots.
Components used in the FlightBox, including two RTL-SDR dongles.
Components used in the FlightBox, including two nano RTL-SDR dongles.