New features in QRadioLink 0.8.2


In release 0.8.2 (which is currently being tested) there will be some new features:

  • it is now possible to run it headless/no GUI (maybe even daemonized) and control it remotely using a telnet client.
  • support for mixed mode repeater (Codec2/FM or viceversa or any combination of modes like wideband Opus/Codec2/FreeDV/SSB etc.).
  • The repeater can be connected to a VOIP server using the low latency Mumble voice protocol (known especially for high-performance gaming). So it is possible now to connect multiple repeaters together by putting them on the same VOIP channel (this can be controlled via telnet as well, although it’s stil work in progress). It operates in full duplex mode, so a VOIP user can talk at the same time as a radio user and the two audio streams will be mixed together and broadcast. The FreeDV/Codec2 radio frames are transcoded to Opus at very high bitrates (~48 kbit/s) for VOIP transport. This, along with multiple stream mixing may cause some small delays.
  • USB FTDI (FT232) relay control for automatically operating RF switches, power amplifiers and filter boards (two relays supported currently, up to 8 planned).

Right now the test target is Pluto’s Zynq while waiting for the LimeNet Micro and LimeRFE to hit the market. The goal here is portable low power repeater using the LimeNet’s four core ARM CPU.
Bugs are still being identified so no date set in stone for final 0.8.2 release.

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0.8.2 is released.
Excerpt from the changelog 0.8.1 to 0.8.2:

  • Fixed CTCSS not being transmitted
  • Fixed broken IP modem
  • Fixed issues in relay controller
  • Faster memory scan by not changing modes and CTCSS if unnecessary
  • Skip memory channel scan setting
  • Update GUI when changing channels during scan
  • Added 2FSK mode with Codec2 700C, all 2FSK modes now have RRC filtering
  • Added IP modem burst mode setting to GUI
  • Increased resilience of DQPSK modes
  • Re-enabled logging facility
  • Night mode UI theme
  • Change sound devices without requiring restart
  • Audio mixing
  • Remote control via network
  • Remote control via Mumble private text messages
  • Run headless (no graphical user interface) for terminal usage on
    embedded platforms like the Raspberry Pi or similar boards without any screen
  • Mixed mode repeater (e.g. FM to Codec2 and viceversa, or FM to Opus
    and viceversa or any combination of voice modes)

This will probably be the last stable release for this year. Distribution packaging won’t happen unfortunately due to lack of compatibility with GNU radio 3.8.
There is a new branch called gr_3.8_port. If anyone wants to work on this port feel free to submit pull requests against this branch, I’m currently not able to do this.



My stuff is still packed up. Did you by chance check for HF TX? Not bugging you, just asking.

Thank you,


Ed, sorry but no, wasn’t able to check for that.
After the upgrade to Debian Buster packages, I get some errors from the LMS driver, probably because I’m forced to use an older version of LimeSuite and SoapySDR 0.6 modules instead of latest versions:
[ERROR] SetPllFrequency: timeout, busy bit is still 1
[INFO] LMS7002M calibration values caching Disable
[ERROR] SetPllFrequency: timeout, busy bit is still 1
[INFO] RX LPF configured
[ERROR] SetPllFrequency: timeout, busy bit is still 1
[INFO] RX LPF configured
[ERROR] SetPllFrequency: timeout, busy bit is still 1
[INFO] RX LPF configured
[ERROR] Rx calibration: MCU error 5 (Loopback signal weak: not connected/insufficient gain?)
[ERROR] SetPllFrequency: timeout, busy bit is still 1

The receiver works in the VHF-FM range, but I get all these errors I did not get before. Turns out mixing software versions is not such a good idea.
But anyway, the filter widening code is there, FWIW.