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From: Jay Miller (jnmiller, cryptofreak dot org) Date: 2001.03.08 - 22.16 MST
X-Mailer: Mutt 1.2.5i - Words by Michael Dwyer <mdwyer, timestreamtech dot com> [010308 21:21]: > Anyway, I made a mistake -- you sample every /other/ zero crossing. Zis is what I have been saying! > The first pixel is the zero-crossing between ...ahem... tits. It is > rising. (+) The next time it touches zero is where the phase shifts > (actually, the whole polarity, but I digress). The next zero crossing > is when the signal is falling. (-). Next is a little tit, then a > rising signal (+). > > +-+ or 101 or 010. Yes, I believe this is right, but do you guys see how there are two possibilities in the counting? We know we're supposed to mark a 1 or a 0 when the wave *crosses zero*. That does not include the tits "touching zero", as it were. Here.. here's the first four bits as it shows up on the sheet: 1 2 3 4 | | | | /\ /\| |/\ /\| /\| |\/ \/| |\/ |\/ The pipes indicate the points at which we record a bit. Now, according to http://wheelie.tees.ac.uk/users/a.clements/Async/async.htm, each phase change indicates a *HIGH* signal. See figure 4. So that would result in a '1110' reading of the above bits. But, looking over at figure 5 in http://www.rad.com/networks/1994/modems/modem.htm, we see that each phase change indicates a reversal, ie. if signal was low, go high - and vice versa. On that reading, the result becomes '1010'. See the dilemma? Any thoughts? -- Jay Miller ICQ: 32123421 | YM: ladenedge | http://www.cryptofreak.org PGP: 0xedc9bb8d | 41a6428c 46abd36b 6b259b68 8a28ca4c edc9bb8c -- This is the mod-chal mailing list. To unsubscribe, email majordomo, cryptofreak dot org with message body 'unsubscribe mod-chal'. Or, for more information, visit http://www.cryptofreak.org/.
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