Implementation of a Robust 2400 b/s LPC Algorithm for Operation in Noisy Environments

Abstract : A detailed description of the implementation of a robust 2400 b/s LPC algorithm is presented. The algorithm was developed to improve vocoder performance in acoustically compromised environments. Improved robustness in noise is achieved by: (1) increasing the speech bandwidth to 5 kHz; (2) increasing the LPC model order to 12; and (3) doubling the analysis rate. Frame fill techniques are used to achieve the 2400 b/s data rate. The algorithm is embodied in the Advanced Linear Predictive Coding Microprocessor which was developed as a prototype voice processor for in-flight evaluation of narrowband voice communication in the JTIDS communication system. Keywords: Robust vocoding; Frame fill; Linear predictive coding; Speech compression.