Tagged: gqrx

Version 2.6 of GQRX Released

Version 2.6 of the popular SDR program GQRX has just been released (changelog). GQRX is a general signal browsing program similar to programs like SDR#, HDSDR and SDR-Console. However GQRX is designed to run on Linux, MacOS and Raspberry Pi 2 & 3. Note that v2.6 is still a work in progress for MacOS. Apart from the new features and bug fixes, one of the major improvements appears to be reduced CPU usage, meaning that it should run better on older PCs. The changelog is pasted below:

New features

  • 1-2-5 scaling on FFT axis.
  • Audio waterfall.
  • Remember AGC settings between sessions.
  • Right-click on FFT resets frequency zoom.
  • Separate dB ranges for pandapter and waterfall.
  • Raw I/Q mode.
  • Portaudio support.
  • Command line option to set Qt style (fusion, windows, …)
  • Binary packages for Raspberry Pi 2 and 3 (see below)

Bugs fixed

  • Stuttering audio with Pulseaudio backend.
  • Use system font on FFT plot (too small font on high res displays).
  • Broken FUNcube Dongle Pro+ support on Mac OS X 10.11.4.
  • Correct display of negative offsets between -1 and 0 kHz.
  • Reset frequency digits below the one that is being changed.
  • LNB LO could not be set from I/O configuration dialog.
  • Update squelch level when switching between demodulators.
  • Set correct filter range when loading bookmark.
  • White area on waterfall.
  • RFSpace Cloud-IQ support on Mac OS X, RPI binaries and in PPA.

Miscellaneous improvements

  • Input decimator performance.
  • SDRPlay integration through SoapySDR.
  • Only probe for devices when the program is started.
  • Allow user to enter ALSA device name.
  • Set default audio FFT range to -70…0 dB.
  • Restore audio FFT dB scaling between sessions.


Installing GQRX on OSX El Capitan

OSX users often don’t have much choice when it comes to general purpose SDR receiver software for the RTL-SDR or other SDR’s. However, one program that works well on Macs is GQRX. Installing GQRX on OSX can sometimes be difficult as the most common installation method involves using Macports, which won’t always work depending on the version of OSX you are using.

Recently, OSX and RTL-SDR user smittix wrote in to use to let us know that there is now a very easy way for El Capitan OSX users to install GQRX. Basically the GQRX team have now released a DMG file which can be downloaded and installed just like most other easy to use applications. Using the DMG file smittix was able to get up and running within 5 minutes.

GQRX running on El Capitan OSX
GQRX running on El Capitan OSX

Combining the bandwidth of multiple RTL-SDRs: Now working in GQRX!

A few days ago we posted how Oliver, an RTL-SDR experimenter, managed to (incoherently) combine the bandwidths of two RTL-SDR dongles to create a 4.4 MHz FFT display in GNU Radio. Now Oliver has taken this idea further and produced an updated version of his GNU Radio program

Oliver’s GNU Radio program is now capable of combining four RTL-SDR dongles and is now also capable of piping the output via a FIFO to GQRX. With four RTL-SDR dongles you can get a total bandwidth of 8.4 MHz. He also writes that it is even possible to listen to analog signals that are in overlapping areas.

Four RTL-SDRs producing a total of 8.4 MHz of bandwidth in GQRX.
Four RTL-SDRs producing a total of 8.4 MHz of bandwidth in GQRX.

Installing GQRX on Mac OSX

Mac OSX users can have a hard time with the RTL-SDR as there are not many software packages available for it. One software package that is known to work well on OSX is GQRX, which is a general multi mode receiver GUI that is similar to the Windows software SDR#. Over on smittix’s blog, the author has created a post showing how to install the latest version of GQRX on OSX. The installation involves using Macports, a system that allows some open source programs like GQRX to be automatically compiled and installed on OSX.

GQRX running on a Mac Computer
GQRX running on a OSX Computer

RTL-SDR with GQRX Running on an Odroid C1 at 1 MSPS and Max FFT

Over on YouTube user neutron2025 has uploaded some videos showing GQRX running on an Odroid C1. The Odroid C1 is a low cost ($35 USD) mini computer with an Arm Cortex A5 quad core CPU and 1 GB RAM which runs Ubuntu 14.04 or Android KitKat. It is a much more powerful competitor to the Raspberry Pi which also goes for around the same price.

Despite its low cost, the video by neutron2025 shows that the Odroid C1 has enough processing power to run the relatively CPU intensive GQRX SDR software with the RTL-SDR at a 1 MSPS sampling rate and maximum FFT resolution.

To install GQRX, GNU Radio also needs to be installed. Installation of GNU Radio is a lengthy process containing many writes to the file system. The amount of writes that occur could destroy a SDCard. To get around this neutron2025 connected an external hard drive and used that as a swap file while installing GNU Radio. His installation notes can be found on pastebin. He writes that installation took around 8 hours.


Demonstrating GQRX Running on a BeagleBone Black with RTL-SDR

YouTube user Brad Bowers has posted a video showing GQRX running on his BeagleBone Black with an RTL-SDR dongle. The BeagleBone Black is an embedded Linux computer, similar to the Raspberry Pi, but with significantly more processing power. He found that GQRX actually performed quite responsively on the BeagleBone.


HackRF Decoding PICO High Altitude Balloons (HAB)

Blogger g0hww shows us how he used his HackRF to decode Pico high altitude balloon (HAB) transmissions using gqrx and dl-fldigi. Pico balloons are small party sized high altitude balloons, typically launched by hobbyists. They have enough lift to carry a small sized ~60g payload. Since they are so small, they are usually exempt from requiring permission from the authorities, unlike full sized weather balloons.

The cheaper RTL-SDR could also be used to track these balloons.

PICO High Altitude Ballo0n Recevied with HackRF