Speech optimization at 9600 bits/second. Volume 1: Software simulation

This report describes the design and development of a real-time adaptive transform coder that transmits high-quality speech over a 9600 bps channel with bit-error rates of up to 1% without significant loss of speech fidelity. The report presents the results of our FORTRAN simulations on the adaptive transform coder which maximized the quality of the transmitted speech. Important aspects of the ATC algorithm which are optimized were specification and transmission of the side-band information, accuracy of the pitch and voicing decision, and error-protection of the important transmission parameters. Also included is the system design, detailed documentation, and program listings of the MAP-300 real-time implementation of the optimized ATC speech coder. Finally, the report includes a description of analog equipment GTE built to interface the MAP-300 to telephone handsets and tape recorders and a description of digital circuits (RS 423 compatible) to interface the MAP-300 to a modem. Volume I contains a description of the ATC system and the results of the FORTRAN simulations.