System Design and Development of a Low Data Rate Voice (1200 bps) Rate Converter
Interim rept. Jul 1991-Jun 1992
NAVAL RESEARCH LAB WASHINGTON DC
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This report presents both a high level and a detailed design for a low data rate voice Rate Converter RC. On the transmit side, converter reduces 2400 bps voice generated by an Advanced Narrowband Digital Voice Terminal ANDVT to a 1200 bps bit stream. On the receive Bide it converts the 1200 bps bit stream back to a 2400 bps stream in ANDVT format. Rate reduction is accomplished with little degradation to the inherent voice quality of the ANDVT. This primary focus is upon the real-time software design which is implemented using VxWorks, a real-time, multi-tasking operating system and development environment. The high level design defines four tasks, each having its own execution thread and its own pipe to facilitate inter-task communication. The Supervisor Task performs initialization and managers input of commands and data to the RC. The Compressor Task reduces a 2400 bps bit stream to 1200 bps while the Decompressor Task converts from 1200 bps back to 2400 bps. The Output Task manages the output of data from the RC. Latter sections of this report describe the software in detail. Low data rate voice, Datavoice integration, Rate conversion.
- Command, Control and Communications Systems