Category: RTL-SDR

An online Software Defined Radio training course

We’ve recently found what looks to be a new online video based course that uses the RTL-SDR to teach basic software defined radio topics. The course is not free, it is priced at $29.99, but the first three videos are free. Judging from the first three videos the content appears to be quite basic, but is presented in a very clear way that may be useful for beginners. Currently the lessons include:

  1. Course Overview 

    Welcome to the exciting world of Software Defined Radio. In this video, we’ll discuss what SDR is, and why it’s such a hot button topic right now.

  2. Setting up the environment

    In this module, we’ll setup our environment for development. If you’re already very comfortable with Ubuntu, you might want to just follow the guide below.

  3. Browsing the spectrum 

    In this module, we’ll cut our teeth on GRQX, and learn a little about the radio spectrum.

  4. Signals Intelligence

    In this module, we’ll learn how to find transmissions in the frequency domain, and capture them to disk for offline analysis.

  5. Modulations

    In this module, we’ll learn how to identify two types of basic digital transmissions, and talk a little about the history of radio.

  6. Demodulation – Part 1

    In this module, we’ll practice capturing signals in the wild, identifying the modulation, and demodulating the signal with GNU Radio.

  7. Demodulation – Part 2

    In this module, we’ll learn about clock recovery. And we’ll pull out packets from the garage door remote.

It also appears that they plan to have some live classes in the future.

We note that there are also alternative SDR training courses available such as Micheal Ossmanns lessons at greatscottgadgets.com/sdr.

sdrtrainingonline

rtl_power_fftw: An improved version of rtl_power designed for radio astronomy

As the RTL-SDR’s maximum usable bandwidth is about 2.8 MHz, programs like rtl_power were written to scan over wider bandwidths by quickly hopping between different swaths of the frequency spectrum and then stitching the data together.

Now a new improved version of rtl_power called rtl_power_fftw has recently been developed and released. This version is designed for radio astronomy use, but also overcomes several issues general users may encounter with rtl_power. One of the authors, Klemen wrote in to us with this information:

I would like to tell you about a program we have been developing at Astronomical Society Vega – Ljubljana, namely one for measuring power spectrum with rtl dongles.

It addresses several shortcomings of the rtl_power program shipped with librtlsdr. The most notable is that it uses a much faster FFT algorithm (from the fftw3 library) and separate threads for acquiring data and FFT processing. This means that even the lowly raspberry pi is capable of processing spectra of sizes up to ~1024 bins in real-time (no slower than data acquisition). This enables the user to sample spectrum continuously and more efficiently.

The other benefit is the output format: data is presented in a gnuplot-friendly way, so plotting is simple, and no data is mangled to make an illusion that spectral hopping is not needed: FFT of each frequency hop is output separately, and user can make and informed decision on how to process data – the program stays out of this, to preserve the accuracy of the gathered data.

The program was developed for use in radio astronomy where all these things matter. Code is available on Github:

https://github.com/AD-Vega/rtl-power-fftw

New Mini RTL-SDR Dongle Available from Nooelec

The Nooelec store have recently come out with a new small RTL-SDR model called the Nano 2, which appears to an improved version of the old tiny square dongles. These new ones are sized at 24mm x 21mm x 8mm and come in a new plastic case with vent holes to prevent overheating. They also come with the newer R820T2 tuner chip. This appears to be a good improvement over the older models which were reported to have overheating and thermal frequency drift issues.

These small dongles look to be great for embedded or mobile phone applications that have space restrictions.

The new dongle is currently selling for $24.95 USD + $1.99 shipping.

The Nano 2 with vent holes in the case.
The Nano 2 with vent holes in the case.
The Nano 2 circuit.
The Nano 2 circuit.

Hak5: Reverse Engineering Radio Protocols with SDR and the Yardstick One

Over on YouTube the popular security and hacking themed channel Hak5 have created two videos together with Mike Ossmann (creator of the HackRF and Yardstick One) that give a good introduction and overview on reverse engineering unknown radio protocols. In the video they show how to use a SDR like the RTL-SDR or HackRF to initially capture the radio signal, and then how to use the Yardstick One to reverse engineer and recreate the signal. Using this process they reverse engineer the radio protocol for a wireless liquor cabinet lock.

The Yardstick One is a computer controlled wireless transceiver (but it is not an SDR). The Yardstick One understands many radio protocols by default and can be programmed in Python, lowering the learning barrier for reverse engineering signals.

Mike Ossmann has also been slowly releasing very detailed video tutorials about DSP and radio related topics. If you are interested in reverse engineering radio signals it is a very helpful series to watch.

Radio Hacking: Reverse Engineering Protocols Part 1 - Hak5 1913

Radio Hacking: Reverse Engineering Protocols Part 2 - Hak5 1914

Using the RTL-SDR as a Panadapter for a Kenwood TS-570D

Over on YouTube user SA6 HAM has uploaded a video showing how to modify a Kenwood TS-570D so that an RTL-SDR dongle can be connected to its first IF stage in order to create a low cost panadapter. A panadapter is a device that allows you to visually view RF signals with an FFT or waterfall display on a regular analogue hardware radio. Some radios have IF output ports on the case, but older radios tend to need internal modification to expose the IF as a port.

In the video SA6 HAM opens up his Kenwood TS-570D radio and shows exactly where to connect the RTL-SDR dongle’s antenna connector on the inside.

Kenwood TS-570D Panadapter modification with an 820T2 RTL SDR dongle

Raspberry Pi Docker Images for ADS-B and ACARS with the RTL-SDR

Docker is a Linux based platform which allows you to build and deploy complex applications into a self contained “container” package that contains all the needed applications and dependencies. The container is completely preconfigured to just work as soon as you install the application without the need for any extra configuration.

Over on his blog SysRun has been developing an ADS-B ready docker image for use with the RTL-SDR on a Raspberry Pi embedded computer. His post shows how he prepared and built the docker image on the Pi and how to run the docker image.

In addition he has also uploaded another post showing how to prepare, build and run an ACARS decoding based docker image on the Raspberry Pi.

In the future SysRun also hopes to upload an AIS Docker tutorial.

Raspberry Pi + Docker + RTL-SDR
Raspberry Pi + Docker + RTL-SDR

SpyVerter Upconverter now for sale

The team behind the Airspy software defined radio (as well has the popular SDR# software package) have just released the SpyVerter upconverter for sale. Upconverters shift HF frequencies (0 – 30 MHz) “up” by a fixed amount, giving receivers that can’t tune that low like the RTL-SDR and the Airspy the ability to receive HF signals.

The SpyVerter extends reception all the way down to DC and has a 60 MHz low pass filter. Its main selling point is its H-Mode architecture which provides excellent IIP3 performance. This basically means that strong HF signals are unlikely to cause overloading in the up-conversion stage. The good IIP3 performance should improve HF reception when compared to other upconverters even with lower end SDR’s like the RTL-SDR. The reason is that when hit by strong HF signals many other upconverters will overload in the upconversion mixing stage, before even reaching the SDR, thus requiring the need for attenuators or antennas with less gain.

Another selling point is its good performance down to DC, making it ideal for VLF reception.

SpyVerter is designed for optimal performance with the Airspy and can be powered directly by the Airspy’s bias tee. However, RTL-SDR users can also use the SpyVerter by powering it through the micro USB connector, or by using it with one of our RTL-SDR Blog units with the activatable bias tee. 

The SpyVerter sells for $59 USD and comes in a metal enclosure with three bonus SMA adapters. There is a $9 USD discount for Airspy owners.

At these prices combined with its claimed performance and metal enclosure we now generally recommend the SpyVerter over any other upconverter. The designers of the SpyVerter have sent us a sample unit and we will review it after testing it out over the next few weeks, but our initial tests already show good performance.

The SpyVerter upconverter.
The SpyVerter upconverter.

Using the GPIO Ports on the RTL2832U Chip

The RTL-SDR uses the RTL2832U chip as its ADC and USB interface processing chip. It also has 8 GPIO (General Purpose IO) ports available which are by default unused by the original DVB-T dongle application. However, which the right modifications to the SDR drivers, these GPIO ports can be activated and potentially used for applications such as antenna, filter, pre-amplifier and attenuator switching.

Over on his web site S57UUU has been experimenting with these GPIO ports and has put up a short tutorial/set of notes on how to connect to the ports and how to modify the RTL-SDR drivers to set the state of each pin. You will need basic programming and compilation knowledge to understand how to activate these pins in the drivers, as well as good surface mount soldering skills to be able to connect wires to the pins.

Connecting to the GPIO ports requires good SMT soldering skills.
Connecting to the GPIO ports requires good SMT soldering skills.