After various people expressed interest in the ZyXEL modem CELP specs... Tyrone.Horton@p101.f701.n202.z1.fidonet.org replied:

As far as CELP, ZyXEL will not be releasing the specs.

OK. In that case, it's up to us to figure it out. :-) I saw the following post about 4800 CELP on another newsgroup and thought it might help someone here get closer to figuring out how ZyXEL's 9600 CELP works. PLEASE: the following message mentions a source of CELP source code that's free. Rather than everyone calling all at once, I suggest: (1) If you live in the D.C. area, maybe go ahead and call anyway and then post the results in this newsgroup. Otherwise (2) If you have a high interest and it's likely you'll actually do something with the information, POST A NOTE TO THIS NEWSGROUP saying so and wait a couple of days so we can all see who else is interested. (3) When the dust settles, the most interested, and/or those nearest Washington, D.C., call to get the source code and then post it to the newsgroup (if permitted). (Unfortunately, you may have to consider U.S. export restrictions, but since the author says the code "is available for worldwide distribution", I don't expect this to be a problem.) -WBE --------------------------------------------------------------------------- From: jpcampb@afterlife.ncsc.mil (Joe Campbell) Newsgroups: comp.compression.research Subject: Re: CELP vocoder refs Date: 17 Jan 93 21:38:07 GMT Organization: The Great Beyond Hi, I hope that the following information answers your questions. Joe The U.S. DoD's Federal-Standard-1016 based 4800 bps code excited linear prediction voice coder version 3.2 (CELP 3.2) Fortran and C simulation source codes are available for worldwide distribution at no charge (on DOS diskettes, but configured to compile on Sun SPARC stations) from: Bob Fenichel National Communications System Washington, D.C. 20305 1-703-692-2124 1-703-746-4960 (fax) Example input and processed speech files, a technical information bulletin, and the official standard "Federal Standard 1016, Telecommunications: Analog to Digital Conversion of Radio Voice by 4,800 bit/second Code Excited Linear Prediction (CELP)" are included at no charge. The following articles describe the Federal-Standard-1016 4.8-kbps CELP coder (it's unnecessary to read more than one): Campbell, Joseph P. Jr., Thomas E. Tremain and Vanoy C. Welch, "The Federal Standard 1016 4800 bps CELP Voice Coder," Digital Signal Processing, Academic Press, 1991, Vol. 1, No. 3, p. 145-155. Campbell, Joseph P. Jr., Thomas E. Tremain and Vanoy C. Welch, "The DoD 4.8 kbps Standard (Proposed Federal Standard 1016)," in Advances in Speech Coding, ed. Atal, Cuperman and Gersho, Kluwer Academic Publishers, 1991, Chapter 12, p. 121-133. Campbell, Joseph P. Jr., Thomas E. Tremain and Vanoy C. Welch, "The Proposed Federal Standard 1016 4800 bps Voice Coder: CELP," Speech Technology Magazine, April/May 1990, p. 58-64. The U.S. DoD's Federal-Standard-1015/NATO-STANAG-4198 based 2400 bps linear prediction coder version 53 (LPC-10e v53) Fortran or C simulation source codes are available on a limited basis upon written request to: Tom Tremain Department of Defense Ft. Meade, MD 20755-6000 USA The U.S. Federal Standard 1015 (NATO STANAG 4198) is described in: Thomas E. Tremain, "The Government Standard Linear Predictive Coding Algorithm: LPC-10," Speech Technology Magazine, April 1982, p. 40-49. There is also a section about FS-1015 in the book: Panos E. Papamichalis, Practical Approaches to Speech Coding, Prentice-Hall, 1987. The voicing classifier used in the enhanced LPC-10 (LPC-10e) is described in: Campbell, Joseph P., Jr. and T. E. Tremain, "Voiced/Unvoiced Classification of Speech with Applications to the U.S. Government LPC-10E Algorithm," Proceedings of the IEEE International Conference on Acoustics, Speech, and Signal Processing, 1986, p. 473-6. Copies of the official standards "Federal Standard 1015, ...", and "Federal Standard 1016, Telecommunications: Analog to Digital Conversion of Radio Voice by 4,800 bit/second Code Excited Linear Prediction (CELP)" are available for US$ 2.50 each from: GSA Rm 6654 7th & D St SW Washington, D.C. 20407 1-202-708-9205 Realtime DSP code for FS-1015 and FS-1016 is sold by: John DellaMorte DSP Software Engineering 165 Middlesex Tpk, Suite 206 Bedford, MA 01730 1-617-275-3733 1-617-275-4323 (fax) dspse.bedford@channel1.com DSP Software Engineering's FS-1016 code can run on a DSP Research's Tiger 30 (a PC board with a TMS320C3x and analog interface suited to development work) or on Intellibit's AE2000 TMS320C31 based 3" by 2.5" card. DSP Research Intellibit 1095 E. Duane Ave. P.O. Box 9785 Sunnyvale, CA 94086 McLean, VA 22102-0785 (408)773-1042 (703)442-4781 (408)736-3451 (fax) (703)442-4784 (fax) -- ............................................................................. ; Dr. Campbell N3JBC jpcampb@afterlife.ncsc.mil 74040.305@compuserve.com ; ; My opinions are mine! Happiness = Reality - Expectations, Click & Clack ; ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~