FIPS 137 explained

FIPS 137, originally issued as FED-STD-1015, is a secure telephony speech encoding standard for Linear Predictive Coding vocoder developed by the United States Department of Defense and finished on November 28, 1984.^[1] It was based on the earlier STANAG 4198^[2] promulgated by NATO on February 13, 1984.

FED-STD-1015 was re-designated as Federal Information Processing Standard (FIPS) Publication 137, (FIPS PUB 137) on October 20, 1988.

It is also known as "LPC-10".

The codec uses a bit rate of 2.4 kbit/s, requiring 20 MIPS of processing power, 2 kilobytes of RAM and features a frame size of 22.5 ms. Additionally, the codec requires a large lookahead of 90 ms.

In 1998, an improved version of the standard was introduced. With a longer super frame structure and better VQ quantizer, the bit rate is reduced to 800 bit/s.^[3]

External links

• CELP-3.2a and LPC-10
• Various Speech Coding Links
• LPC10 presentation, Soo Hyun Bae, ECE 8873 Data Compression & Modeling, Georgia Institute of Technology, 2004

Notes and References

1. Web site: FIPS PUB 137, Analog to Digital Conversion of Voice by 2,400 Bit/Second Linear Predictive Coding. . National Institute of Standards and Technology . 2018-08-17.
2. Web site: PARAMETERS AND CODING CHARACTERISTICS THAT MUST BE COMMON TO ASSURE INTEROPERABILITY OF 2400 BPS LINEAR PREDICTIVE ENCODED DIGITAL SPEECH . North Atlantic Treaty Organization . 2018-08-17.
3. Xianglin . Wang . C.-C. Jay Kuo . C.-C. Jay Kuo . May 1998 . An 800 bit/s VQ-based LPC voice coder . The Journal of the Acoustical Society of America . 103 . 5 . 2778 . 10.1121/1.422247 . 1998ASAJ..103.2778W . 14294667 . 2007-03-24 . https://archive.today/20130223071802/http://link.aip.org/link/?JASMAN/103/2778/1 . 2013-02-23 . dead .