Author: Alexandru Csete

Embedded software engineer in the satcom industry during the day. Radio amateur and SDR hacker during the night.

[PI-SDR] Raspberry PI 3 + 7″ Touchscreen + RTL-SDR + GQRX

YouTube user Chris D has posted a video showing Gqrx in action on his Raspberry Pi equipped with the 7″ touch screen. Chris uses an rtl-sdr dongle with what appears to be a home made upconverter.

Continue reading “[PI-SDR] Raspberry PI 3 + 7″ Touchscreen + RTL-SDR + GQRX”

Gqrx with the Red Pitaya

Today it was brought to my attention that gqrx works well with the Red Pitaya board running the SDR transceiver code by Pavel Demin. Indeed, looking through the gr-osmosdr commit logs, I could see support was added in December 2015, just around the same time I was packaging gr-osmosdr.

Continue reading “Gqrx with the Red Pitaya”

Gqrx 2.5 released

Only a few weeks have passed since the gqrx 2.4 release, there has been enough development going on to justify a new release. This release includes a few new features as well as important bug-fixes.

Listening on 80 meters with Cloud-IQ and gqrx

New features

  • Read out signal time and frequency on the waterfall (disabled on OS X).
  • Save waterfall to graphics file.
  • Allow user settable waterfall time span (up to 24 hours).
  • Cmake option to build using gr-audio backend (Andrea Merello).

Bug fixes

  • FM stereo (revert to pre-2.4 behavior).
  • Mode selector not updated when selecting a WFM OIRT bookmark.
  • Show correct filter preset when filter LO/HI corresponds to one.
  • Prevent RDS panel from growing by making it scrollable.
  • Use correct audio backend on OS X (app bundle only).

Improvements

  • Button layouts (mostly on Mac OS X).

Details about the new waterfall features

As you may have noticed, new development for this released has been mostly on the waterfall. The adjustable time span allows us capture spectrum data over longer periods and the save functionality provides a convenient way to save the captured data to a graphics file.

The image below shows an example of such capture. It is a ~20 minute capture of the  transponder downlink from the FO-29 amateur radio satellite.

FO-29 orbit 95710 captured with Gqrx and Airspy

Another example for how this feature can be used is spectrum surveillance. The image below shows the 6–16 MHz HF spectrum over an 8 hour time period. It was captured using a HackRF device.

6 - 16 MHz spectrum captured with gqrx and HackRF

As written above, the time span can be up to 24 hours, however, this is only an arbitrary limit and we can increase it should the need arise.

Looking forward to seeing how people will use this feature.

Ubuntu Packages

Updated packages are already available in our new PPA. Instructions for new users are available on the Ubuntu Install page.

Mac OS X binaries

As always, there is an up to date Gqrx package in Macports shortly after the release. There is now also an app bundle available from GitHub or SourceForge. The bundle was built on Mac OS X El Capitan and contains all required third part libraries, as well as the command line utilities that come with the Airspy, RTL-SDR, Hackrf and Bladerf driver libraries. See the included README for details.

Installing from source

The source code can be downloaded from GitHub or SourceForge. Starting with this release, gqrx can also be compiled using cmake, see the README file for details. Building with qmake is still available and will not disappear any time soon, so feel free to use either method.

Have fun!

Gqrx 2.4 released

One year after the 2.3.2 release, Gqrx 2.4 is now available for download. This release includes both new features, important bug-fixes as well as improvements of existing functionality.

Gqrx 2.4 with Funcube Dongle Pro+

New features

  • Bookmarks.
  • FM RDS decoder using gr-rds.
  • Frequency tooltips on the FFT area (disabled on Mac).
  • Filter shape selector (soft, normal, sharp).
  • Slider to aid zooming on the frequency and dB axes.
  • RFSpace Cloud-IQ support (still work in progress).
  • OIRT stereo decoder (Daniil Cherednik).
  • Input decimator.

Bug fixes

  • Prevent crash due to device errors while starting the application.
  • Use hardware frequency in IQ file names.
  • FFT averaging (it can now be disabled).
  • “Could not resolve pattern10600” error messages in the terminal.
  • Antenna selection error with USRP B210 (Ethan Trewhitt).
  • LNB LO value not updated in I/O config dialog.
  • Initial gain of rtlsdr devices is no longer 0 dB.
  • DSP freeze when setting FM de-emphasis time constant to 0.
  • Use correct main category in desktop entry file.

Improvements

  • Support up to 1M point FFT.
  • Fractional PPM correction.
  • AGC performance.
  • FFT performance.
  • Right click on frequency digit to clear digits.
  • Robustness against malformed remote control commands.

Ubuntu Packages

Starting with this release, we have a new PPA that contains only Gqrx binaries and uses MyriadRF PPAs for GNU Radio and SDR driver packages. I realize this is inconvenient for existing PPA users; however, this offloads some of the packaging work from me and will ensure more up to date GNU Radio packages for Ubuntu users in the future.

Please make sure you have the previous PPA disabled and old, obsolete packages removed before using the new PPA as instructed on the Ubuntu Install page. Feel free to contact us if you need help with the PPA transition.

Mac OS X binaries

As always, there is an up to date Gqrx package in Macports. There is now also an app bundle available from GitHub or SourceForge. The bundle was built on Mac OS X El Capitan and contains all required third part libraries, as well as the command line utilities that come with the Airspy, RTL-SDR, Hackrf and Bladerf driver libraries. See the included README for details.

Installing from source

The source code can be downloaded from GitHub or SourceForge. Starting with this release, gqrx can also be compiled using cmake, see the README file for details. Building with qmake is still available and will not disappear any time soon, so feel free to use either method.

Have fun!

Meteor scatter reception with RTL-SDR and Gqrx

Meteor scatter, or meteor burst communications, is a challenging field within amateur radio communication, where the operators use the ionized trails of meteors for reflection of radio waves.

George Smart, M1GEO, has posted a very nice write-up on his website describing the setup that he uses for meteor scatter reception. The setup uses an RTL-SDR dongle with Gqrx as receiver, and WSJT or MSHV for decoding.

Meteor Scatter reception setup by M1GEO. Image credit: M1GEO.
Meteor Scatter reception setup by M1GEO. Image credit: M1GEO.

Check out Meteor Scatter Reception on RTL-SDR.

Satellite telemetry decoding on Linux

Are you interested in receiving and decoding telemetry from amateur radio satellites? Then check out this excellent article by Jan PE0SAT called Unix TLM (Telemetry) decoding, where Jan gives a description of his setup.

In his Linux setup, Jan uses Gqrx as SDR front-end and Gpredict to track the satellites. As we wrote earlier, Gqrx has a Hamlib-compatible TCP interface so that we can use Gpredict to adjust the receiver frequency with Doppler corrections.

PE0SAT Linux telemetry receiver setup. Image credit: PE0SAT.
PE0SAT Linux telemetry receiver setup. Image credit: PE0SAT.

Jan also takes advantage of the Audio/UDP interface in Gqrx as well as the audio routing capabilities of modern Linux desktops to route the demodulated audio from Gqrx to external decoder applications.

All in all, this is a very nice setup that demonstrates well how Gqrx can be hooked up with external applications to get new functionality.

Gqrx 2.3.0 released

Someone has pointed out to me that it’s been almost a year since gqrx 2.2.0 was released. There have been a few snapshot releases since 2.2.0 and some of them got even included in distributions. However, considering the large number of improvements and bug fixes since 2.2.0 I felt it was appropriate to tag a new release.

The changes since version 2.2.0 include:

  • Support for setting analog bandwidth.
  • Support for setting gain stages individually.
  • Remember visibility status of main toolbar.
  • Restore the geometry of the main window between sessions.
  • Restore the state and placement of the dock windows.
  • Nuand BladeRF support.
  • RF Space SDR-IQ, SDR-IP and Netsdr support.
  • Airspy support.
  • Peak detection on the FFT plot.
  • Max hold on the FFT plot.
  • Audio streaming over UDP socket.
  • Remote control through TCP socket.
  • Set squelch level from current signal/noise level.
  • Command line option to list existing configurations.
  • I/Q recording and playback.
  • Incorrect handling of decimal values in LNB LO frequency.
  • Correctly apply initial LNB LO frequency.
  • Audio output device selection on Mac OS X.
  • Properly store settings when using Save As function.
  • Crash when recording audio with no rec directory set.
  • Only allow audio playback while DSP is running.
  • Ensure DSP is stopped when we exit.
  • Freeze when switching modes after audio recording.
  • Toggling “ignore limits” changes frequency.
  • Include gqrx.dekstop file.
  • Rename scope.svg to gqrx.svg to avoid confusion.
  • Gqrx can fit on small screens (900×600 pixels).
  • Better color gradient for the waterfall.
  • FFT presentation at high rates and high sizes.
  • Make release news available through the Help menu.

Many of these changes are contributed by others as can be seen in the list of contributors.

The source code is available through Github or Sourceforge. Ubuntu packages for Trusty and Utopic are in the PPA. Mac version is expected to be available through Macports soon.

This is probably the last version I am going to release for a very long time, perhaps ever, as I neither have the time nor the interest to continue down this road. Hopefully we can find somebody else to take over further development and maintenance.

Controlling gqrx from a remote host

Starting with version 2.3 gqrx can be controlled remotely using a simple TCP connection. Currently, the remote control functionality is limited to setting and reading a few parameters but more handles might be added in the future.

Continue reading “Controlling gqrx from a remote host”

Streaming audio over UDP

Starting with version 2.3 gqrx has an option to stream the audio over UDP to a remote host. This can be used to send the audio to external data decoders or for remote monitoring. This post describes the streaming functionality in gqrx and provides a few examples for how to use it.

Continue reading “Streaming audio over UDP”

Ubuntu packages for armhf architectures

Just a quick note that we have got armhf builds enabled for our gqrx/snapshots repository. Armhf refers to ARM architecture with hardware floating point support.

For now I have rebuilt all packages for Ubuntu 12.04 as this seems to be most common Ubuntu used on ARM devices. Later I will also rebuild for Ubuntu 13.04 but there are limits on how much resources one can use when building for armhf and I have to watch out not to abuse this service.

I can imagine that gqrx may not be very useful on all arm devices; however, I hope that at least the driver libraries, the command line tools and maybe even gnuradio itself will be useful.

Feedback is welcome.