Hi Adrian and David, Noting the Mumble protocol and looking for a server, I found uMurmur on github
and tried to compile it on my Fedora 29 x86_64 here but am lost in cmake finding the SDL library. To make a cross band codec2 to FM repeater, can you give a quick run down using your software? Alan VK2ZIW On Thu, 17 Oct 2019 22:44:01 +0300, Adrian Musceac wrote > Hi David, > > Wow Adrian it's really coming along quickly! Well done :-) Combined > with the latest crop of duplex SDRs, I can see this work opening up > experimentation in the VHF/UHF bands. > > > Thanks! I've been working full time on this in the last month due to a break > at work that might end pretty soon. > I'm aiming at VHF to SHF work, small, portable and field configurable > repeaters (check out the LimeNet-micro and LimeRFE) > and satellite ops. The IP radio modem in qradiolink might also help point to > point IP link connectivity at low bandwidths but it needs more improvement. > > HF is not out of the question but due to QTH conditions can't really use it. > Telemetry modems (even direct sequence spread spectrum for very low bitrates, > like LoRa) and multi-channel repeaters are the next stop > (after release 1.0). > > Some thoughts: > > 1/ Codec 2 2400A and 2400B were designed to work on VHF/UHF, and 2400A > to substantially outperform FM and current digital voice systems at low > SNRs: > > http://www.rowetel.com/wordpress/?p=5219 > > They're in the FreeDV API already > > > I'll add 2400A for sure. I don't really see a reason to use 2400B with SDRs. > Maybe for testing purposes only with the FM modulator. > > But right now my plate is pretty full trying to test everything already in > and do some packaging. > The 700D modem segfaults in the LDPC encoder with the version of libcodec2 in > Debian stable and I didn't even have time to raise a bug with them. > But I'll add it as well once that's figured out. By the way, can I suggest > for libcodec2 Git tags for stable releases? I could not find any tags in > Github and they would be pretty useful as landmarks. > > 2/ Have you done any BER versus SNR (Eb/No) tests to evaluate the > performance of the modems you are using, e.g. comparing performance to > theoretical? We have found many existing VHF/UHF digital voice systems > have modems that perform poorly. Gains of 10dB are possible with the > right modem/waveform design. > > > Yes. All tests are good. My custom modems are nothing original, they are > based on the knowledge of the GNU radio community, especially Daniel Estevez > and Marcus Mueller but also others. > > Some problems occur with some modems like the DQPSK written by me used with > both Opus and Codec2 > due to some implementation misconfigures. The Doppler correction used for > them tends to interact badly with the rest. > I'll fix that eventually. > > But the FreeDV modems work very well. All numbers check out exactly as you > described in your website. > > 3/ RpiTx would be an interesting option for the TX side: > > https://github.com/F5OEO/rpitx > > > RPiTx is a work of art, but it has some annoyances. It requires a PGA in > front to set the output power (some amplifiers > drive from below 0 dBm). The signals are not exactly clean, but the main > downside is the limited frequency range. > I do SHF (2.4 GHz and 5 GHz) with the PlutoSDR. Options to go all the way up > to 10 GHz with some other MyriadRF hardware. > > There's the https://osmocom.org/projects/osmo-fl2k/wiki project which gives > you a very cheap SDR transmitter as well but with the same limitations. > > Best regards, > Adrian > > Cheers, > David > > On 17/10/19 10:30 pm, Adrian Musceac wrote: > > Hi, > > I made some more progress working on my application[1]. > > First of all, it is now possible to run it headless (maybe even > > daemonized) and control it remotely using a telnet client. > > Second, I have added 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). They operate 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 may cause some small delays. > > > > I haven't really had time to test the cross-mode repeater so could use > > some help there from interested parties. > > > > [1] http://qradiolink.org > > > > Cheers, > > Adrian > > > > > > > > > > _______________________________________________ > > Freetel-codec2 mailing list > > Freetel-codec2@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > > > > _______________________________________________ > Freetel-codec2 mailing list > Freetel-codec2@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > --------------------------------------------------- Alan Beard OpenWebMail 2.53
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