On Sun, 19 Oct 2003, Maor Meir wrote: > On Sun, 19 Oct 2003, Raindel Shachar wrote: > > > On Sun, 19 Oct 2003, guy keren wrote: > > > 4. in the 'dial-up modems' slide, don't use the word baud - this is > > >incorrect. for example, 14.4Kbps modems still communicated in 2400 > > >bauds. they achieved a higher speed then 2400Kbps modems by using > > >'electrical engineering wizardry' (don't ask me how - ask an electrical > > >engineer). > > > > >From "WordNet (r) 2.0": > > baud rate > > n : (computer science) a data transmission rate (bits/second) > > for modems syn: baud > > > > Therefore, if a modem communicates in 14.4Kbps, it's baud-rate is 14.4Kbs. > > 56000 is the physical maximum limit for dial-up modems (8000 symbols per > > second, each of 7 bits). This limit is implied by the fact that the phone > > line is sampled at the telephony switch at 64Kbps (8000 samples per > > second, each is 8 bit). I am a student in EE :-). > > > > The Jargon file is more elaborate on this issue, and under baud > it lists: "...The technical meaning is `leveltransitions per second'; > this coincides with > bps only for two-level modulation with no framing or stop bits. Most > hackers are aware of these nuances but blithely ignore them." > > The Free On-line dictionary also has more on baud: > <communications, unit> /bawd/ (plural "baud") The unit in > which the information carrying capacity or "signalling rate" > of a communication channel is measured. One baud is one > symbol (state-transition or level-transition) per second. > This coincides with bits per second only for two-level > modulation with no framing or stop bits > .... > > I personally believe using baud as a synonom for Bits per second > is perfectly acceptable, and it is widely used in this fashion. > > Meir
if you like abusing terms - go ahead. i hope some hacker breaks into your system - i don't mind if you want me to call him a cracker - since you don't care about subtletes anyway. ;) since electrical engineers here have failed us(...), i will write what i once was told by an electrical engineering student, who have learned this specific subject, back in the 14.4Kbps modem days. he worked in a technion lab that designed such an 14.4Kbps modem, and he used to know what he was talking about in general, so i pressume the information was correct. the modem still sends data in 2400 baud. however, it super-imposes(is this the right term - to combine several signals together?) several signals on the same link, using phase shifts (e.g. one signal is sent in a +90 degrees phase shift, another in a -90 degrees, etc). this way, they were able to combine 14400 / 2400 = 6 signals on a single carrying signal. a filter on the receiving side would de-compose the carrying signal back to the original 6 signals. i might have gotten the details wrong. here is a site trying to explain modem's modulation with text and graphs: http://www.physics.udel.edu/wwwusers/watson/student_projects/scen167/thosguys/ or this one: http://www-scm.tees.ac.uk/users/a.clements/Async/async.htm so be a sport - don't say the modem works in 56000 baud - say it works in 56000 bps. it's not as if using 'baud' makes people understand you better - the listeners do not care which term you're using. and in such cases, i prefer using the right term. i hope you do, too. -- guy "For world domination - press 1, or dial 0, and please hold, for the creator." -- nob o. dy -------------------------------------------------------------------------- Haifa Linux Club Mailing List (http://www.haifux.org) To unsub send an empty message to [EMAIL PROTECTED]
