James Michael Keba

Low bit rate real‐time half duplex LPC vocoder utilizing minimal random access memory

A low bit rate real‐time half duplex LPC vocoder was constructed based upon the Texas Instruments TMS32010 digital signal processor IC. Approximately 2700 words of external ROM were used for program and tables. The 144 words of onboard RAM were the only words of RAM used. The analysis was performed on preemphasized windowed speech using autocorrelation accumulation and the LeRoux‐Gueguen method to generate reflection coefficients and gain. A modified Rabiner‐Gold pitch algorithm was used for pitch and voicing. The software was split into foreground computations done on each speech sample and background computations done on each frame. There were 54 LPC information bits generated per frame.