RTL-SDR.com Presentation Slides from Hamvention

During this years 2017 Hamvention convention I was invented by TAPR to present three talks about the RTL-SDR. Several people who watched the talks have requested the slides, so they are uploaded here in PDF format.

The World Of Low Cost Software Defined Radio – Presented at the TAPR Banquet. An introduction to the RTL-SDR and many of the interesting applications that it has been used for.

An Introduction to RTL-SDR – Presented at the TAPR Digital Forum. A brief introduction to the RTL-SDR and a selection of some of the most popular applications.

Introduction to Cheap SDRs for Radio Monitoring – Presented at the Digital Modes Now and In the Future Forum. A brief introduction to the RTL-SDR and a selection of some interesting digital modes that can be monitored.

The talks may be on YouTube in the future. If and when they are they will be posted here too.

A big thanks to all that came to the talks, and all the people who I met at Hamvention. It was a great event and really nice to meet everyone interested in RTL-SDRs and SDRs in general.

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Radio For Everyone: An Easy ADS-B Antenna, ADS-B Advice, and Long Term Results

Over on his blog Akos has uploaded several new posts all relating to ADS-B reception. His first post shows how to build a very simple yet effective “Coketenna” ADS-B antenna which can be built with an empty coke can and some coax cable. This antenna is essentially a 1/4 wave ground plane antenna with the ground plane being a coke can cut in half and mounted upside down. The whip sticking up is simply the coax inner wire. In his post Akos shows exactly how to construct one.

Cantenna and Coketenna
Cantenna and Coketenna

In his second post Akos offers some advice on mounting and positioning ADS-B antennas, discusses the ‘range myth’, talks a bit about LNA’s and filters and shows the differences between a stock RTL-SDR dongle, and one optimized for ADS-B reception like a FlightAware Protstick.

In his third post Akos shows his results from long term ADS-B reception comparisons between a generic RTL-SDR dongle, an RTL-SDR.com V3 dongle with 1090 MHz LNA powered by bias tee, a FlightAware Prostick and a FlightAware Prostick Plus. The V3 dongle with bias tee powered LNA is used as the benchmark receiver and the results show that it received the most signals. The next best was the Prostick Plus, followed by the Prostick and finally the generic dongle.

ADS-B Comparisons between 4 different RTL-SDR setups.
ADS-B Comparisons between 4 different RTL-SDR setups.
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HackRF Receives Negative Press in the UK’s ‘DailyMail’ Newspaper

The HackRF is a $300 USD RX/TX capable software defined radio which has a wide tuning range from almost DC – 6 GHz, and wide bandwidths of up to 20 MHz. It uses an 8-bit ADC so reception quality is not great, but most people buy it for its TX and wide frequency/bandwidth capabilities.

Recently the HackRF received some negative press in the ‘Daily Mail’, a British tabloid newspaper famous for sensationalist articles. In the article the Daily Mail show that the HackRF can be used to break into £100,000 Range Rover car in less than two minutes. The exact method of attack isn’t revealed, but we assume they did some sort of simple replay attack. What they probably did is take the car key far away out of reception range from the car, record a key press using the HackRF, and then replay that key press close to the car with the HackRF’s TX function. Taking the key out of reception range of the car prevents the car from invalidating the rolling code when the key is pressed. 

Of course in real life an attacker would need to be more sophisticated as they most likely wouldn’t have access to the keyfob, and in that case they would most likely perform a jam-record-replay attack as we’ve seen with cheap homemade devices like RollJam. The HackRF cannot do this by itself because it is only half-duplex and so cannot TX and RX at the same time.

We should also mention that the HackRF is not the only device that can be used for replay attacks – potentially any radio that can transmit at the keyfob frequency could be used. Even a very cheap Arduino with ISM band RF module can be used for the same purpose.

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Mike’s SDRuno Tutorial Series

Mike Ladd, one of the top volunteer contributors of the SDRplay community was recently hired by SDRplay officially and has now been working on a fairly comprehensive SDRuno tutorial series over on the SDRplay YouTube channel. SDRuno is the official software for the SDRplay line of SDRs and is a slightly modified version of the ‘Studio1’ software which was previously acquired by SDRplay. SDRuno also supports the RTL-SDR.

SDRuno is a complex piece of software with many features and settings, so it’s great to see a comprehensive video tutorial like this. Mike’s tutorial series currently has 10 episodes, and discusses things like the basic layout and settings of SDRuno, using Virtual Audio Cable (VAC), noise reduction, memories, calibration, DSD, notch filters and FM broadcast with RDS. More videos are probably still on the way.

SDRuno Basic layout and settings - obsolete (MV001)

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XRIT Decoder for GOES Satellites: Supports Airspy R2/Mini and SDRplay RSP2

Over on his blog USA-Satcom has released his XRIT (LRIT/HRIT) decoder for GOES satellites. The software requires a licence and costs $100 USD. GOES-13 (East), GOES-15 (West) and the new GOES-16 are geosynchronous orbiting satellites that broadcast very nice high resolution weather images of the entire visible disk of the earth. The transmit their LRIT/HRIT signals at about 1.7 GHz at fairly weak power, which means that a good LNA and dish set up is critical to be able to receive them. A dish size of about 1 meter, or an equivalent grid or Yagi is recommended as the lowest starting point.

GOES Full Disk Image of the Earth
GOES Full Disk Image of the Earth

USA-Satcom’s decoder is Windows based and comes with a nice GUI. Some portions of the code are based on the Open Satellite Project created by Lucas Teske. It currently supports the Airspy R2/Mini and the SDRplay RSP2 software defined radios.

The software is not free, it costs $100 USD for the licence. To help curb illegal distribution of his software which has been rampant in the past, USA-Satcom also requests that you show some proof of a working setup which is capable of receiving the GOES signal before inquiring about the software.

If you are also interested, USA-Satcom did an interesting talk at Cyberspectrum a few months ago, and he has also recently uploaded his slides.

Screenshot of USA-Satcoms GOES XRIT decoder.
Screenshot of USA-Satcoms GOES XRIT decoder.
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QIRX SDR: A New MultiMode RTL-SDR Program with Built-In DAB+ Decoder

Recently Clem from softsyst.com wrote in and let us know about their new SDR software called ‘QIRX SDR’. This is a multimode receiver currently capable of receiving AM/NFM/WFM and also DAB Plus. It supports the RTL-SDR via an rtl_tcp connection, so it can be used on a local machine, or a remote networked one. The main differentiating features that QIRX has against other multimode receivers like SDR#, HDSDR and SDR-Console etc is:

  • Dual Receiver, within the bandwidth of the frontend. This is most useful e.g. for watching two stations simultaneously in busy airband regions.
  • DAB+ Demodulator, to our knowledge the first one written in C#, allowing for recordings in very good quality (some samples provided for download).

The full list of features are quoted below:

QIRX is an Open Source Software Defined Radio, written in C#, downloadable on this site as a Visual Studio 2013 Solution, offering the following features:

  • TCP/IP Based: QIRX accepts 8-bit I/Q-Data either from TCP/IP sources or from pre-recorded files containing the I/Q-data. It is designed to cooperate with RTL-SDR dongles and the widely available rtl-tcp.exe as I/Q-data server. Both QIRX and rtl-tcp may run on the same machine or on separate ones. The rtl-tcp.exe might be started automatically without additional user actions, also when used remote via a LAN.
  • Dual Receiver: Within the selected bandwidth, e.g. 2.56MHz QIRX is able to operate two independent receivers simultaneously.
  • Squelch: For each receiver, QIRX provides a digital squelch, enabling to monitor the selected stations – when not transmitting – without annoying background noise.
  • Simplest Operating Principle: QIRX – using its AM, NFM or WFM demodulators – is purely FFT-based, with a NF lowpass filter only. This might change in a future version.
  • Scanner: QIRX provides for Receiver 1 a simple scanner, being able to scan large frequency areas. This is still in an experimental state.
  • HF and NF Spectrum: For each receiver, QIRX provides a spectrum viewer being able to show the HF and the NF spectrum. No waterfall spectrum yet. For DAB+, it shows the constellation.
  • DAB+ Receiver: QIRX provides a comfortable DAB+ receiver ( Transmission Mode I ). It is -to the best of our knowledge- the first C# based SDR providing this facility. Some standard libraries like the Viterbi decoder are used as C/C++ packages, accessed via P/Invoke.
  • File Recorder: For all demodulators, the audio output can be saved to .wav files, independently for each of the both receivers. For DAB+ this allows for high-quality audio recordings.

    Additionally, the I/Q raw data can be saved to a file. It is possible to replay recorded I/Q-data files.

QIRX SDR: A new multimode receiver with DAB+ decoding
QIRX SDR: A new multimode receiver with DAB+ decoding
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The New England Workshop for SDR (NEWSDR) Accepting Poster Submissions

Thanks to Michael Rahaim a Postdoctoral Researcher at Boston University for letting us know about the New England Workshop for SDR (NEWSDR) which will be held on June 1 & 2 and Tufts University in Medford, MA. They write:

A few of my colleagues and I are organizing the New England Workshop for SDR (NEWSDR) next month and we are currently accepting submissions for poster presentations. The event will be held at Tufts University and is sponsored by MathWorks, Ettus/NI, MediaTek and Analog Devices. It is the 7th time we’ve held the workshop and we typically have attendance of 80-100 people from industry, academia, and government.

This seems to be mostly an academic and industry conference type event, but a few people reading this blog may be interested. Registration is free.

This year as well as the poster presentations there will be a tutorial and introduction to using the PlutoSDR, which is an (as of yet unreleased) TX & RX capable SDR that will be priced at around $149 USD. It looks to be like a way to get started with SDR TXing very cheaply. During the workshops they are also providing tutorials on using USRP SDR devices with MATLAB Simulink, and with FPGAs. In 2016 they also had some interesting presentations including “Wireless Beyond RF: From Underwater to Intra-body Ultrasonic Software Defined Radios” and a tutorial on “Identifying Mystery Waveform Using Simulink and RTL-SDR”

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A 3D Printed Case for the DIY Outernet Kit

Thanks to Manuel (aka Tysonpower) for writing in and sharing his 3D printed ‘Universal Outernet Case’. Outernet is a satellite file casting service that uses an RTL-SDR based solution for reception. With an Outernet set up you can receive things like daily news, weather updates, books, Wikipedia pages and more all for free. About 20 MB of data can be transmitted in one day.

The DIY Outernet kit consists of an RTL-SDR ‘SDRx’ board, patch antenna and C.H.I.P single board computer. The patch antenna needs to point roughly in the direction of the Inmarsat/Alphsat satellite in your area. This can be a problem because the Outernet patch antenna doesn’t come with a stand or mounting solution.

Manuel solved this problem with his 3D printed Outernet enclosure. The enclosure houses the patch antenna, SDRx and C.H.I.P, and also doubles as a stand for pointing the patch antenna. Inside he’s also fitted a small 30mm fan to keep everything cool while inside the enclosure as the C.H.I.P is known to have overheating problems.

The 3D printed Outernet enclosure.
The 3D printed Outernet enclosure.

Over on YouTube Manuel has uploaded a video explaining how the enclosure is made with 3D printing, demonstrates the assembly steps and finally shows the final product. The video is narrated in German, but it has English subtitles available. The design files required for 3D printing the case are also available on thingiverse.

[EN subs] Outernet Case aus dem 3D Drucker (Universal elv. Winkel) - für DIY Kit

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