FS-1015
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FS-1015 is a secure telephony speech encoding standard developed by the United States Department of Defense and later by NATO. It is also known as LPC-10 and STANAG 4198.
The standard was finished 1984. The algorithm used is a linear predictive coding vocoder. The vocoder enables understandable speech, but the quality is very unnatural and synthetic.
The bit rate of the codec is 2.4 kbit/s. The complexity of the codec is 20 MIPS. 2 kilobytes of RAM is needed. Frame size of the codec is 22.5 ms. Very large lookahead of 90 ms is also required.
Recently an improved version of the standard is introduced. With longer super frame structure and better quantizer the bit rate is reduced to 800 bit/s.[1]
[edit] External links
[edit] References
- ^ Xianglin, Wang; C.-C. Jay Kuo (May 1998). "An 800 bps VQ-based LPC voice coder". The Journal of the Acoustical Society of America 103 (5): 2778. Retrieved on 2007-03-24.
