"i) A higher quality mode in the 2400 bit/s range. Maybe wideband audio. We could get this into 2000 Hz of RF and SNRs of less than 10dB."
This is exactly what the masses are waiting on. Having an HF mode that would provide good voice quality with fallback to 700D robustness at the click of the mouse would be the cat's meow. Mel K0PFX -----Original Message----- From: David Rowe [mailto:[email protected]] Sent: Wednesday, June 06, 2018 5:38 PM To: [email protected] Subject: [Freetel-codec2] High Quality 2400 bits/s (or so) prototype Hello List, OK, so we have FreeDV 700D which is competitive to SSB at low SNRs. This is comprised of the Codec 2 700C speech, powerful Forward Error Correction (FEC), and the new OFDM modem. I am now taking a look at improving speech quality with some new Codec 2 modes, the idea is to drop these new modes into the LDPC/OFDM modem framework that is working so well. Modes I am considering: i) A higher quality mode in the 2400 bit/s range. Maybe wideband audio. We could get this into 2000 Hz of RF and SNRs of less than 10dB. 2400 bit/s would also be useful for UHF/VHF work, if competitive to FM and AMBE. ii) Improving the 700C Codec quality, in particular robustness to different microphones and speakers. Here is a first pass, comparing Codec 2 1300 (the codec used for FreeDV 1600), a simulation of SSB at 10dB SNR, and a prototype of a new 2400 bit/s (ish) mode: http://rowetel.com/downloads/codec2/proto/ Readers who are fans of SSB noise cancellation, please run the SSB sample through your system and post results here. Cheers, David ---------------------------------------------------------------------------- -- Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2 ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
