Date: Fri, 17 Dec 1999 19:55:24 +0100 From: Juergen Lock <nox@jelal.kn-bremen.de> To: Poul-Henning Kamp <phk@critter.freebsd.dk> Cc: freebsd-isdn@FreeBSD.ORG Subject: Re: 300 Baud V.21 modem for I4B Message-ID: <19991217195523.A23681@saturn.kn-bremen.de> In-Reply-To: <2844.945164580@critter.freebsd.dk> References: <199912140200.DAA20856@saturn.kn-bremen.de> <2844.945164580@critter.freebsd.dk>
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On Tue, Dec 14, 1999 at 10:43:00AM +0100, Poul-Henning Kamp wrote: > In message <199912140200.DAA20856@saturn.kn-bremen.de>, Juergen Lock writes: > > > > But shouldn't just about any analog modem still be able > >to talk V.21 too? Or do the recent ones no longer? > >(Could be you have to send some command to allow > >non-error-corrected connections.) > > I don't know of any modems which can't do V.21. > Me neither, but then i haven't installed one (or even read comp.dcom.modems...) for a long time. (My old V.32b one certainly does, and it does V.23 too.) > > I wonder if i still have that 1200/75bps atari sio driver > >somewhere that i had to hack for V.23... (yup that was an > >asymmetric standard, and the uart had only one clock for both > >directions so the 75 bps had to be done in software.) > > As far as I recall V.23 is also a FSK standard, Yup it is! There also seems to be another 300 bps FSK modem standard, Bell 103... > and as such it > should be easy to adapt my code to do it (since the uart is already > done in software). But I don't have any of the "old" V.* documents, > I only have them from V.32 and forward... I did a quick altavista search and found some information here, http://computer.org/cspress/CATALOG/BP05697/chapter5.htm and here, (description of an FSK chip that does V.23) http://www.ampr.poznan.pl/users/sp3uqs/tcm3105/index.html At least the frequencies etc. are there, not sure if you need more? What may also be interesting are the FSK modulations used by the various TDD/TTY/EDT etc. devices that deaf people use to `talk' over the phone, here are a few links i found about those: http://www.phone-tty.com/ttyinfo.htm http://tap.gallaudet.edu/TTY-Basics.htm http://www.totse.com/files/FA055/ham02.htm Regards, -- Juergen Lock <nox.foo@jelal.kn-bremen.de> (remove dot foo from address to reply) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isdn" in the body of the message
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