Rowe: FreeDV Robustness

David Rowe, creator of the Codec 2 speech codec (which we discussed briefly in our Linux.conf.au 2013 coverage) has published a three-part series analyzing the performance of Codec 2 and his open source digital radio application FreeDV (part 1, part 2, part 3). The series examines FreeDV and Codec 2 against other HF radio modes, both digital and analog, providing some insight into codec design. "My previous tests show the excitation bits (pitch, voicing, energy) are the most sensitive. The excitation bits affect the entire spectrum, unlike LSPs where a bit error introduces distortion to a localised part of the spectrum. So I dreamt up a new 1300 bit/s Codec 2 mode that has “less” sensitive bits."