The Turkish Narrow Band Voice Coding and Noise Pre-Processing NATO Candidate
Ahmet M. KONDOZ, H. Palaz · Defense Technical Information Center (DTIC) · 2001
Robust and low power communication systems are essential for battle field environment in military communication which require bit rates below 4.8kb/s. In order to benefit from the new advances in speech coding technologies and hence upgrade its communication systems, the NATO has been planning to select a speech coding algorithms with its noise pre-processor. In this paper we describe a speech coder which is capable of operating at both 2.4 and 1.2kb/s, and produce good quality synthesized speech. This coder will form the basis of the Turkish candidate which is one of the three competing. The rate of the coder can be switched from 2.4kb/s to 1.2kb/s by increasing the frame length for parameter quantization from 20ms to 60ms. Both rates use the same analysis and synthesis building blocks over 20ms. Reliable pitch estimation and very elaborate voiced/unvoiced mixture determination algorithms render the coder robust to background noise. However in order to communicate in very severe noisy conditions a noise pre-processor has been integrated within the speech encoder.