This paper describes a real-time implementation of a multirate (2.4, 4.8, 8 and 16 Kbit/sec) speech codec designed to fulfil the requirements of the telecommunication sub-system for HERMES spacecraft. Considering these requirements, our choice turned to the Multi-Pulse Excited Linear Predictive Coding (MPLPC) approach (except for the 2.4 Kbit/sec emergency rate which is based on the standard LPC-10 algorithm). In the first part of the paper, emphasis is put on coding aspects, in order to achieve effectively the expected bit rates. In particular, the encoding of the pulses is carefully studied. Then, details are given about hardware and software developments. Lastly, system complexity is discussed.
Bibliographic reference. Lefevre, Jean-Paul / Viola, Roberto (1989): "Real-time multirate speech codec for manned spacecraft communications", In EUROSPEECH-1989, 1294-1297.