An Open-Source Speech Codec at 450 bit/s with Pseudo-Wideband Mode

Start Page
1048
End Page
1051
Article Number
8910691
Citation
European Microwave Conference, EuMC : 8910691 (2019)
Contribution to Conference
49th European Microwave Conference, EuMC 2019  
Publisher DOI
10.23919/EuMC.2019.8910691
Scopus ID
2-s2.0-85076345755
Most modern digital speech codecs are proprietary and do not give insights into their implementations. 'Codec 2' is an open-source codec and opens up the possibility of application-tailored adaptations. In this publication a new 450 bit/s mode is introduced. It includes a pseudo-wideband mode that can be optionally enabled at the receiver without resulting in a higher bit rate. By sorting the codebook vectors a bit error rate of 10-1 is still intelligible. An encoded audio transmission was tested with two low-power Sub-GHz transceivers in the 70 cm amateur radio band achieving a sensitivity of -130 dBm. For proofing the concept, a field test was conducted and compared to a propagation simulation.
Subjects
open source software
radio transceivers
Speech coding
vocoders