The Spectrum Monitor: The ABCs of ADS-B and Airband Reception using Software Defined Radio

Thank you to Mario Filippi (N2HUN, WQWL238) for submitting news about his latest article that has been published in the March 2020 edition of The Spectrum Monitor magazine. The article is titled "The ABCs of ADS-B and Airband Reception using Software Defined Radio", with the description reading:

Ever wonder about all the planes you see in the sky overhead where you live? What flight is that; where is it going; how high and how fast is it? All of these planes transmit on one frequency: 1090 MHz and you can monitor them all as Mario shows us. He tells us what receiver to use, which antenna (hint: you can build a better ADS-B antenna than you can buy), which software to use and how to assemble your own desktop virtual radar screen.

The article isn't free to access as it's published in the Spectrum Monitor magazine, however the magazine only costs $3 and contains a number of other airband related articles too.

The Spectrum Monitor: 2020 Aviation Edition
The Spectrum Monitor: 2020 Aviation Edition
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Demonstrating Solar Inverter Noise Cancelling with a Timewave ANC-4 and Airspy HF+

At his house W1VLF found that his solar inverter was causing huge amounts of interference on the HF bands, essentially making any hope at receiving shortwave or amateur radio signals impossible on his Airspy HF+ Discovery . However, over on his YouTube channel he's demonstrated a solution that allows him to almost completely cancel the noise.

The solution involves using a Timewave ANC-4 noise canceler, which is as analog noise cancelling device available from the manufacturer for US$209.95. To use the device you also need a noise probe which can be a small loop antenna. The noise probe is connected to the ANC-4 and placed near the source of the noise, which in W1VLF's case was just on the solar inverter enclosure mounted on the outside of his house. Then by tuning the gain and phase knobs on the ANC-4 the noise can be cancelled out of the signals received by the main antenna. 

In the video W1VLF demonstrates how effective noise cancelling with the ANC-4 can be by showing the before and after results with his Airspy HF+ Discovery.

Kicking Solar inverter noise in the A$$ with noise cancelling

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OneSDR New Posts: RF Filter Primer, Bias Tees, SDR Precautions

Over on onesdr.com a new SDR tutorial website, the authors have put up three new posts. The first post is part 2 of their "How Not to Break your Software-defined Radio (SDR) Hardware" series. This post covers mechanical strain considerations on connectors and reference clock input voltages. 

The second post titled "Software-defined Radios and Bias Tees" covers the use of bias tee's and the different voltage and current specs of bias tee's on different SDRs. They explain how these specs affect which LNA's you can use, and how some bias tee's are protected against over-current damage.

The third post is titled "A Primer on RF Filters for Software-defined Radio". In this post they cover topics like types of filters, insertion loss and preselectors on SDRs. 

OneSDR's Image used to explain Band Pass filters.
OneSDR's Image used to explain Band Pass filters.
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GQRX Updates: GR3.8, New Color Maps, Bug and Performance Fixes

Since mid-January 2020 the popular Linux and Mac compatible SDR program GQRX has seen a number of new code commits over on it's git repository. Some of the updates include moving to GNU Radio 3.8, new color maps, as well as various bug and performance fixes.

At the moment these updates only appear to be available on the latest git code, so to get them you'll need to install GQRX from source via the instructions on the git readme.

Also thank you to @devnulling for providing us with the screenshot posted below which shows off the various new color maps available for the FFT waterfall.

GQRX Updated Color Schemes
GQRX Updated Color Maps
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ADSBExchange now using tar1090: Historical Flight Tracks, Military Aircraft Filters and more

ADSBExchange is an aircraft tracking website service which aggregates ADS-B data from contributors running RTL-SDR's or similar receivers worldwide.

However, unlike other flight tracking sites such as flightaware and flightradar24, ADSBExchange sets themselves apart by proudly refusing to censor the tracking of military and private jets that have requested privacy. One area where this refusal to self-censor helps is with the "Dictator Alert" service. This is a service that automatically tracks the movements of private aircraft owned by authoritarian regimes via the ADS-B data collected and shared by ADSBExchange. 

Recently ADSBExchange upgraded their web interface moving from the old Virtual Radar Server system to tar1090 which is a more fully featured open source display for dump1090. This new interface has some great features, like the ability to view the complete flight track history of any aircraft on a particular day, the ability to display only military aircraft and the ability to filter by altitude and aircraft type. 

ADSBExchange.com new tar1090 interface
ADSBExchange.com new tar1090 interface
Viewing the tracks of 1-day of police helicopter activity in the new ADSBExchange tar1090 interface.
Viewing the historic tracks of 1-day of police helicopter activity in the new ADSBExchange tar1090 interface.
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New 978 MHz UAT Specialty RTL-SDR and Antenna and Dual 1090 & VHF Antenna from RadarBox

Over on Amazon we've recently seen the release of a 978 MHz UAT specialty RTL-SDR and 978 MHz tuned antenna by the flight tracking service known as AirNav RadarBox. The RTL-SDR appears to be similar to their 1090 MHz RTL-SDR version, which contains a SAW filter and LNA onboard the RTL-SDR. Due to the built in filter, this dongle will only work at the 978 MHz frequency. Like the 1090 MHz version, the dongle itself is priced at only US$14.95, and the antenna at US$49.95.

Universal Access Transceiver (UAT) is an alternative to ADS-B that is available only in the USA. It is typically used by smaller aircraft, transmits at 978 MHz, and apart from it's tracking system it has some additional advantages for pilots over 1090 MHz ADS-B, like the ability to receive alerts, weather data and radar plots. With an RTL-SDR and appropriate software these data services can also be received.

In addition they have also released some other interesting products including a 1090 MHz ADS-B with 118-136 MHz VHF airband antenna stacked on top of the ADS-B element for US$49.95, and an external ADS-B 1090 MHz filter for only US$14.95.

As an alternative to an RTL-SDR UAT receiver, we note that the Stratux has a hardware radio based UAT receiver available which has significantly lower power consumption. Although the receiver itself appears to be currently out of stock.

We note that we also currently have our 1090 MHz AirNav Radarbox Antenna + ADS-B optimized RTL-SDR set on sale for only US$39.95 + shipping, which is cheaper than you can find it elsewhere. Visit our store for ordering information.

The AirNav RadarBox 978 MHz UAT Optimized RTL-SDR and Antenna.
The AirNav RadarBox 978 MHz UAT Optimized RTL-SDR and Antenna.
New RadarBox 1090 MHz Filter and 1090 MHz & VHF Antenna single antenna.
New RadarBox 1090 MHz Filter and 1090 MHz & VHF Antenna single antenna.
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OpenAstroTracker: 3D Printed DSLR Tracking Mount may be useful for Antennas Too

OpenAstroTracker is a recently published open hardware 3D printed tracking mount designed to move DSLR cameras for astrophotography. The mount supports heavy long lenses, so we think that this mount could also have the ability to move long directional antennas for satellite tracking. It could also be interesting to modify it for automatic aircraft photography, similar to what we've seen in this previous post where a Raspberry Pi camera on a pan-tilt mount was used with ADS-B data from an RTL-SDR to track aircraft in the sky with the camera.

The 3D printer files are available on Thingiverse, and the mechanical and electronics build guide, and Arduino code is available on GitHub. The build seems to be quite a bit easier compared to a SatNOGS rotator which is another 3D printed open hardware rotator, but it is yet to be seen what sort of antenna sizes it could rotate.

OpenAstroTracker: Could be modified for satellite tracking.
OpenAstroTracker: Could be modified for satellite tracking.
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Opening a Parking Barrier with a HackRF Portapack and a Replay Attack

Over on YouTube user kwon lee has uploaded a video demonstrating a replay attack against a parking barrier arm. The tools he uses are a HackRF and Portapack running the Havok firmware. A replay attack involves recording a control signal with the HackRF+Portapack, and then replaying it later with the transmit function of the HackRF. If no wireless security mechanism like rolling-codes are used, simply replaying the signal will result in the transmission being accepted by the controller receiver.

As he has access to the remote control he records the transmission that is sent when the open button is pressed on the remote. Later once outside he shows how transmitting with the HackRF+Portapack results in the barrier arm opening.

This reminds us of a previous post where we noted how a HackRF was used to jam a garage door keyfob to prevent people from leaving in the TV show "Mr. Robot".

RF Replay Attack _ Parking-Breaker via HackRFone+Portapack+havoc

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