Category: RTL-SDR

GNU Radio Released – First Minor Release Version in Six Years

GNU Radio is an open source digital signal processing (DSP) toolkit which is often used to implement decoders, demodulators and various other SDR algorithms. Several SDR programs are based on GNU Radio code, and it is responsible for a lot of DSP development and knowledge within the SDR and radio community. It is compatible with almost all SDR devices, including the RTL-SDR.

Recently GNU Radio has been updated to version The release is classed as the first "minor" release version in six years, as they are going from version 3.7 to 3.8. That doesn't mean there have been no changes for six years, it just means that over the last six years all releases have remained within the 3.7 version and they have mostly been bug fixes rather than larger changes like added features. Behind the scenes over the last six years developers have been working on these larger changes, and now is the time that they have been officially released.

Marcus Müller from GNU Radio writes:

Witness me!

Tonight, we release GNU Radio

It’s the first minor release version since more than six years, not without pride this community stands to face the brightest future SDR on general purpose hardware ever had.

Since we’ve not been documenting changes in the shape of a Changelog for the whole of the development that happened since GNU Radio 3.7.0, I’m afraid that these release notes will be more of a GLTL;DR (git log too long; didn’t read) than a detailed account of what has changed.

What has not changed is the fact that GNU Radio is centered around a very simple truth:

Let the developers hack on DSP. Software interfaces are for humans, not the other way around.

And so, compared to the later 3.7 releases, nothing has fundamentally modified the way one develops signal processing systems with GNU Radio: You write blocks, and you combine blocks to be part of a larger signal processing flow graph.

With that as a success story, we of course have faced quite a bit of change in the systems we use to develop and in the people that develop GNU Radio. This has lead to several changes that weren’t compatible with 3.7.

The changelog is too long to quote here, but as a summary they have fixed bugs, updated dependencies to newer versions, enabled C++ code generation, changed XML to YAML, moved from QT4 to QT5 and removed a few stale projects. Some of these changes could break compatibility with older GNU Radio tutorials and programs. It also seems that unfortunately due to a lack of updates, support for the Funcube Dongle has been removed.

SignalsEverywhere 10,000 Subscriber Interactive Live Stream with Giveaways on August 10 12PM EST

The SignalsEverywhere YouTube channel is quickly growing in size, and has recently passed the 10,000 subscriber milestone. If you weren't aware, Corrosive (aka KR0SIV aka Harold) who runs the channel has been consistently putting out high quality videos related to the software defined radio hobby. He's also started a podcast which also covers some interesting topics.

Some Recent SignalsEverywhere YouTube Videos
Some Recent SignalsEverywhere YouTube Videos

To celebrate hitting the 10,000 subscriber mark, Harold is planning an interactive 6 hour+ YouTube live stream which will begin on Saturday August 10 12PM EST time (11 hours from the time of this post)If you want to be automatically reminded of the stream, go to the live stream place holder, and click on set reminder.

The stream will be interactive as he is planning on setting up several SpyServer's that will be running across the HF, VHF, UHF and L-Bands. This will allow the audience to use SDR# to connect to his SDRs that are being used on the stream, allowing people to follow along with what Harold is doing on the stream, and ask questions about what they are seeing.

We're also helping to sponsor his stream and will be donating 5x RTL-SDR dongle + antenna kits, 5x RTL-SDR dongles, 1x Radarbox bundle, as well as one KerberosSDR to any giveaways that he plans on doing throughout the stream.

We really like Harolds work on YouTube, and if you are a fan of the content on our RTL-SDR.COM blog, then you really should be subscribed to his channel too.

Interactive SDR Live Stream | 10K Subscriber Celebration and Giveaway!

mySdrPlayback: MacOS Software for Browsing Through IQ Recordings from SDR#, SDRUno and More

mySdrPlayback is a program for MacOS that allows you to easily browse through IQ recordings created from multiple SDR programs. Recently the software's author (@ChrisSmolinski) 
Tweeted that he's added support for SDR# and SDRUno IQ recordings
. The program is described below:

Why use this app? It makes it easy to slog through lots of recording files, looking for interesting signals. Load a file, and a waterfall for the entire file is created. You can scroll around, and if you see anything that looks interesting, you can drag select it, and then demodulate it. You can even save the demodulated audio as a WAVE file, that you can listen to later, send to someone else, or play into your digital decoding software, if it is an RTTY, SSTV, etc. transmission.

Support for other SDR recording file formats is possible, you'll need to work with me by providing sample files and details on the format. This program is presently for macOS only. Support for Windows may happen... stay tuned!

mySdrPlayback now supports SDR# and SDRUno IQ Files.
mySdrPlayback now supports SDR# and SDRUno IQ Files.

New LNA + Filter for Radio Astronomy Hydrogen Line Observations Released by NooElec

NooElec have recently released a new LNA + filter combo called the "SAWbird+ H1 Barebones" which significantly lowers the entry bar for new amateur radio astronomers. It's designed to be used with RTL-SDR or other SDRs for radio astronomy, and in particular reception of the Hydrogen line.

The filter is centered at 1.42 GHz with a 70 MHz bandpass region. The LNA has a minimum gain of 40dB. For hydrogen line observations it is important that the LNA have very low noise figure, and this LNA fits the bill with a ~0.5dB to ~0.6dB noise figure. An additional feature on the PCB is an RF switch that is electrically controlled via expansion headers. This switch allows you to switch out the LNA for a 50 Ohm reference which is useful for calibration in more serious radio astronomy work.

This LNA draws 120mA of current meaning that it will work with the RTL-SDR V3 and Airspy's bias tee, but probably not with the SDRplay's bias tee which is limited to 100mA and seems to trip a fuse at higher current draws. For an SDRplay you could use external power instead, although you will need an additional DC blocking cap to prevent power from entering the SDR and destroying the ESD diodes.

If you don't know what the Hydrogen line is, we'll explain it here. Hydrogen atoms randomly emit photons at a wavelength of 21cm (1420.4058 MHz). Normally a single hydrogen atom will only very rarely emit a photon, but space and the galaxy is filled with many hydrogen atoms so the average effect is an observable RF power spike at 1420.4058 MHz. By pointing a radio telescope at the night sky and integrating the RF power over time, a power spike indicating the hydrogen line can be observed in a frequency spectrum plot. This can be used for some interesting experiments, for example you could measure the size and shape of our galaxy. Thicker areas of the galaxy will have more hydrogen and thus a larger spike. You can also measure the rotational speed of our galaxy by noting the frequency doppler shift.

Although this LNA lowers the entry bar, in order to receive the Hydrogen line with the SAWBird+ H1 you will still need a ~1m+ satellite dish and a feed tuned to 1.42 GHz or high gain Yagi, horn or helical antenna. Antennas and feeds like this are not yet available off the shelf, but if you search our blog for "hydrogen line" you'll see many project examples

The NooElec SAWBird+ H1. For Hydrogen Line Observations.
The NooElec SAWBird+ H1. For Hydrogen Line Observations.

An RTL-SDR & SDRplay based WebSDR Designed Specifically for QO-100 (Es’Hail-2) Monitoring

Over on YouTube user [Radio Electronics] has uploaded a useful video showing how to install your own personal SDRplay or RTL-SDR based WebSDR for QO-100 (aka Es'Hail-2) reception. Es'Hail-2 is the first geostationary satellite with amateur radio transponders on board, and is positioned at 25.5°E which covers Africa, Europe, the Middle East, India, eastern Brazil and the west half of Russia/Asia.

The idea behind a WebSDR is to run your RTL-SDR QO-100 receiver on a remote Raspberry Pi (perhaps mounted close to the antenna on your roof etc). The Pi runs custom WebSDR software that has been created from scratch by [Radio Electronics] specifically for monitoring Es'Hail-2. Then you can access your QO-100 receiver from any device on your network that has a web browser (computer/phone/tablet etc). The interface of his WebSDR appears to be quite slick, which multiple QO-100 specific options and labels.

Quite a lot of work must have gone into this software which looks to be of high quality, so it is definitely worth checking out if you are interested in QO-100/Es'Hail-2 monitoring.

Es'Hail-2 QO-100 WebSDR
Es'Hail-2 QO-100 WebSDR

In the first video he first talks about various methods for downconverting the 10489.550 MHz QO-100 CW signal into a range receivable by the RTL-SDR or SDRplay. He then goes on to show the exact steps to install and run his WebSDR software on a Raspberry Pi 3.

In the second video he goes on to demonstrate the web browser interface highlighting the QO-100 specific features that he has implemented such as being able to compensate for any LNB frequency drift via a feature that can lock to the QO-100 PSK beacon.

es-hail-2 QO-100 WebSDR Part-1: INSTALLATION

es-hail-2 QO-100 WebSDR Part-2: OPERATION

KerberosSDR App Update: Heatmap + Precise TX Localizing & Turn by Turn Navigation Demo Videos

We have just released an updated version of the KerberosSDR Android direction finding app. If you didn't already know KerberosSDR is our experimental 4x Coherent RTL-SDR product. With it, coherent applications like radio direction finding (RDF) and passive radar are possible. Together with the KerberosSDR direction finding Android app it is possible to visualize the direction finding data produced by a KerberosSDR running on a Pi3/Tinkerboard.

The KerberosSDR hardware is currently in preorder status on Indiegogo for the second production batch, and we expect it to be ready to ship out this month. If you preorder then you'll be able to purchase a KerberosSDR at a reduced price of USD$130. After shipping for batch two begins the price will rise to USD$150.

The new version of the KerberosSDR Android app adds the following features:

  1. Heatmap Grid Plotting
  2. Precise TX location pinpointing when enough data points are gathered
  3. Turn by turn navigation to the RDF bearing direction / TX location
  4. Bearing moving average smoothing

To understand what these features are, we've released two demo videos showing them in action. In the first video we use the new features to find an 858 MHz TETRA transmitter, and in the second video we find a 415 MHz DMR transmitter. The first video explains the new features so we recommend watching that first.

KerberosSDR Radio Direction Finding: Heatmap + Auto Navigation to Transmitter Location Demo 1

KerberosSDR Radio Direction Finding: Heatmap + Auto Navigation to Transmitter Location Demo 2

SignalsEverywhere: Creating a DIY Upconverter with a HackRF and RF Mixer

Over on YouTube Corrosive from the SignalsEverywhere channel has uploaded a new video showing us how you can make a DIY upconverter using a HackRF as a signal source and a cheap $10 RF Mixer. An upconverter converts lower frequencies into higher frequencies. For example, an upconverter is commonly used to convert HF signals into VHF, so that VHF/UHF only SDRs can receive HF.

In the video he uses the HackRF as a local oscillator source, a cheap RF mixer on a breakout board, and an Airspy as the receiver. In most circumstances if you needed and upconverter you'd just purchase one like the Ham-it-up, or the Spyverter for ~$40. However the interesting advantage of using a versatile signal generator like the HackRF is that it results in an upconverter that can upconvert HF to almost any frequency. Even without any filtering (which is recommended to remove signal images), Corrosive fings that he has excellent HF reception.

This video is an excellent way to learn about how upconverters work.

HackRF and RF Mixer = DIY RTL SDR Up-converter | Basics of the Passive ADE Mixer


SignalsEverywhere: Windows 10 usb_open_error -12 Fix

The process to install an RTL-SDR dongle on Windows involves the simple step of running Zadig and installing the generic WinUSB drivers to the RTL-SDR, which shows up as "Bulk-In, Interface (Interface 0)" in Zadig.

However we find that people sometimes accidentally use Zadig to install WinUSB to "Bulk-In, Interface (Interface 1)" by mistake. Installing WinUSB to this interface can break your installation, and it can cause the RTL-SDR to display a "usb_open error -12" on command line software, and can cause problems connecting to the device on GUI software like SDR#.

Over on YouTube Corrosive from the SignalsEverywhere YouTube channel uploaded a very useful video that shows how to fix this problem.

RTL SDR Drivers On Windows 10 2019