Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!sdd.hp.com!mips!dimacs.rutgers.edu!rutgers!cbmvax!drysdale From: drysdale@cbmvax.commodore.com (Scott Drysdale) Newsgroups: comp.sys.amiga.datacomm Subject: Re: 19200bps Message-ID: <21448@cbmvax.commodore.com> Date: 9 May 91 17:58:08 GMT References: <1991May5.185645.12902@cunixf.cc.columbia.edu> <1991May5.201708.452@cec1.wustl.edu> <942@cns.SanDiego.NCR.COM> Reply-To: drysdale@cbmvax.commodore.com (Scott Drysdale) Organization: Commodore, West Chester, PA Lines: 34 In article <942@cns.SanDiego.NCR.COM> dltaylor@cns.SanDiego.NCR.COM (Dan Taylor) writes: >In dillon@overload.Berkeley.CA.US (Matthew Dillon) writes: > >> A normal phone line has a bandwidth of around 38KBaud. As any > >There are still a LOT of subscriber lines with 3KHz filters. That is >NOT a misprint, 3000 Hz. Some urban subscriber lines have 38KHz, but >not many. The higher data rates are achieved by compressing the >information in various ways, and using schemes like "trellis coding" to >send more "bits per second" than the phone lines can normally stand. Of >course, leased point-to-point lines are not normally filtered like this. >That's why the older "high-speed" modems worked on them, long before >most subscriber lines could. The FAX people have this problem, too. >Their machines have many graceful fallback modes. > >Personally, I WANT an optical ISDN connection as my subscriber line. optical doesn't buy you diddlysquat for 2B+D service. 2B+D only needs 192Kbits per second, and the encoding and decoding process only requires about 1/3 that frequency to be on the wires between you and the central office. optical connections are useful for multi-megahertz stuff, or very long distances. the wires between you and the phone company (or a termination box) are less than 1 mile long (1/2 mile, i think it is). >Dan Taylor --Scotty -- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Scott Drysdale Software Engineer Commodore Amiga Inc. UUCP {allegra|burdvax|rutgers|ihnp4}!cbmvax!drysdale PHONE - yes. "Have you hugged your hog today?" =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=