Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!pacific.mps.ohio-state.edu!linac!att!pacbell.com!tandem!zorch!ditka!teda!netcomsv!gandrews From: gandrews@netcom.COM (Greg Andrews) Newsgroups: comp.sys.amiga.datacomm Subject: V.32 (was Re: Is there a 9600 baud standard?) Summary: No compression - that's something else. Message-ID: <1991May5.174424.26844@netcom.COM> Date: 5 May 91 17:44:24 GMT References: <1991May4.030943.20676@rodan.acs.syr.edu> Sender: netnews@netcom.COM (USENET Administration) Organization: Netcom - Online Communication Services UNIX System {408 241-9760 guest} Lines: 37 In article bobl@graphics.rent.com (Bob Lindabury - SysAdm) writes: > >The standard in the entire industry and the world for 9600 bps modems >is V.32. V.32bis will probably supercede V.32 in the next year. >V.32 gives you a 9600 baud carrier with compression giving you up to >4 times that speed in theory. V.32bis will give you a 14,400 baud >carrier with the same 4 times increase (theoretically) with >compression. > > InterNet: bobl@graphics.rent.com | Raven Enterprises Hi Bob, V.32 doesn't have compression. That's handled by an entirely different set of standards. V.32 (and V.32bis) are simply the modulations that allow the modems to fling bits back and forth through the telephone line. V.32 runs at 9600 bps, and V.32bis at 14400 bps. There are 'fallback' speeds if the line is impaired, but they are all slower than the bit rate which the standards are known for. Whether you can get 4:1 compression depends on what compression method the modems achieve, and what kind of data is sent through them. If the modems only get MNP5 compression, they will not be able to compress much higher than 2:1. 4:1 compression is possible with the V.42bis method. Mentioning compression in the same breath as a modulation probably isn't that good an idea. Compression is achieved through extensions to error correction protocols, and is not directly related to the modulation. Linking compression and a modulation without mentioning the error correction step in between them can lead to confusion. -- .------------------------------------------------------------------------. | Greg Andrews | UUCP: {apple,amdahl,claris}!netcom!gandrews | | | Internet: gandrews@netcom.COM | `------------------------------------------------------------------------'