PDC half-rate speech coding, standard and a real time operating prototype
Tomoyuki Ohya, Toshio Miki, Hirohito Suda · NTT review · 1994
The Pitch Synchronous Innovation-CELP (PSI-CELP), proposed by NTT Mobile Communications Network, Inc. (NTT DoCoMo) in 1993, has been adopted as the Japanese half-rate PDC (Personal Digital Cellular) speech coding standard. This algorithm is based on CELP (Code Excited Linear Prediction) with a pitch synchronized excitation source. It uses 3.45 kbit/s out of 5.6 kbit/s for speech coding and the remaining 2.15 kbit/s for error protection. This paper summarizes the PSI-CELP algorithm and mentions the techniques to improve speech quality, reduce computational complexity, and reduce memory requirements. A prototype based on this algorithm that operates in real time is also described