z@rocksvax.UUCP (02/24/84)
Is anyone out there using the Vadic 2400 baud modems? The price
of one of these beasties is about $2000 and supposedly they can be
combined with the Vadic autodialer (VA811). Any experience? Comments?
Is anyone currently using 2400 baud for news?
--
//Z\\
James M. Ziobro
Ziobro.Henr@parc-maxc
{rochester,rocks34,amd70}!rocksvax!ztom@uofm-cv.UUCP (Tom Libert) (03/05/84)
An interesting article describing modem concepts appeared in the Fall 1983 edition of IEEE Potentials. The article was written by Arthur J. Carlson of Anderson Jacobson. In this article the author describes the AJ 4048, which operates at 4800 bps in full duplex over the switched telephone network. The author recommends "Principles of Data Communication" by Lucky, Salz, and Weldon, McGraw-Hill, 1968, and "Data Transmission", Bennet and Davey, McGraw-Hill, 1965. He claims that the best source of current information on modems is articles in IEEE Communications Society magazine and "Communications", the technical journal of the IEEE Com. Society. BTW, the AJ 4048 was introduced in September, 1982. They might have a 9600 bps version by now. Tom Libert Dept. of EE and CS U of Michigan ...mb2c!uofm-cv!tom ~p ~v
jeffm@hammer.UUCP (Jeff McMeekin) (03/06/84)
Concord Data Systems (617-890-1394) makes a 2400 bps modem that works over normal phone lines. It is also 212 compatible. Price is $900 to $1000.
rjk@mgweed.UUCP (Randy King) (03/06/84)
As we move into higher data rates on the switched network,
designers and manufacturers must begin to concern themselves with
the perils of noise that is sure to come from the BOCs since the
breakup. No longer ruled by the iron fist of "Ma", the BOC's will
do pretty much what they please.
This is evidenced by the fact that the source of my "{" data noise
problem was found - a "cheaper" version of a D4 channel group at
the back end of a T1 multiplexor; the signal is not synchronized
with the other end and digital slip occurs every 30 seconds.
And the "new" BOC says to me: "You can talk on it? Good. That's
where our responsibility ends." In a few years network service
provided by the local BOC's is going to be so bad that it will
hardly be worth the money.
What about alternates? Satellite? Cellular radio? Cable?
Whatever it is, the data devices have got to incorporate error
detection/correction or they will not be any good.
Randy King
AT&T/CP-MG
ihnp4!mgweed!rjkberry@zehntel.UUCP (03/06/84)
#R:ucbcad:1654967196:zinfandel:4700001:000:627 zinfandel!billn Mar 4 10:38:00 1984 I have two Concord Data Systems 2400/1200 baud modems. Cost was about $900 per. They work great at 2400 baud and are also great at auto-fallback to 1200 in either answer or originate mode. Actually, they xmit (as answer unit) at 2400 and receive at 1200, giving the impression of 2400. They supposedly have an auto-dialer too, though mine arn't. I've had them about 6 mo. and no probs. I normally use them about 2-3 hours at a time, sometimes all day. Concord Data Systems 303 Bear Hill Road Waltham, Ma. 02154 (617) 890-1394 They have a distributor in somewhere in darkest Sunnyvale whose buisness card I've lost.
sid@linus.UUCP (Sid Stuart) (03/06/84)
Concord Data Systems 303 Bear Hill road Waltham, MA 02154 617-890-1394 1200(212a)/2400(ccitt) modem, cost $1000. Same modem with autodial, $1,195 I tested the non-auto-dial modem for a week. It was very nice. I have 3 on order and intend to use two of them for uucp connections, so I will know more about their reliability in 3 or 4 months. According to the salesman it is compatible with the other modems coming on the market that follow the ccitt standards. sid stuart sid@linus.uucp
lmc@denelcor.UUCP (Lyle McElhaney) (03/07/84)
By the way, does anyone have Anderson-Jacobsen's address and/or phone number? Thanks... -- Lyle McElhaney (hao,brl-bmd,nbires,csu-cs,scgvaxd)!denelcor!lmc
kho@hou2a.UUCP (S.KHO) (03/07/84)
The following vendors have 2400 baud aync modems: 1. Anderson Jacobson - Model AJ4048, Full Duplex, Not compatible with anyone, Price $3495. 2. Codex - Model 224, Full Duplex, Compatible with Bell 212A, CCITT V.22 and V.22bis, Price $1195. 3. Concord Data Systems - Model CDS224, similar to Codex 224, Price $995. Samuel Kho hou2a!kho
cyrus@symplex.UUCP (03/08/84)
CAjustSE There is a company called "Concord Data Systems", based in Mass., that is currently selling 2400 bps (not baud!!) modems. I believe they have automatic fallback to 1200 bps and can adaptively syncronize to both 1200 and 2400 bps in dial-up. I know these modems have been selling like hot cakes since Concord is one of the few in the market quoting reasonable deliveries (don't ask me what reasonable is). The auto-detection of 1200 and 2400 makes the upgrade path very smooth (how many outside sites use 2400 bps modems at this time?). PS: let us all remember a "baud" is not a "bit". -Cyrus Azar (415) 591-1667 fortune!dsd!symplex!cyrus Symplex Communications 1625 El Camino Real Suite 4 Belmont, CA. 94002
kho@hou2a.UUCP (S.KHO) (03/08/84)
The phone number you can use to reach Anderson Jacobson is (408)-263-8520. Samuel Kho hou2a!kho
dya@unc-c.UUCP (03/08/84)
References: uofm-cv.510
Not Art Carlson of WKRP in Cincinatti -:)
Seriously, 4800 bps FULL DUPLEX over the PSTN? More, more, please !!!
David "Last of the Analog" ....( (akgua,decvax)!mcnc!urp!dya )bam@sdchema.UUCP (03/15/84)
Racal-Vadic is soon to release a relatively inexpensive 2400 baud modem. Inexpensive for them seems to be around $1600. The devices is surprisingly noise resistant and seems to work reasonably well over sprint and MCI lines. Bret Marquis sdchema!bang!bam -- Bang World Communication Center - San Diego.
sysman@glasgow.UUCP (System Manager) (03/15/84)
Jaguar Communications Ltd
Elton House
London Rd
St Albans
Herts AL1 1LJ
ENGLAND (+44 727 32983)
sell a 2400 baud modem. This is essentially their V22 modem with error
correction added to increase the speed. It is supposedly capable of working
with another V22 modem at 1200 baud too. Price under 900 pounds. I think they
just retail the modem which is actually built by somebody else.
Zdravko Podolski, Comp Sci Dept, Univ. of Glasgow, Scotland
{...!decvax!mcvax | ...!vax135 }!ukc!edcaad!edee!glasgow!{ zp | sysman }
or better still: glasgow!zp%edee%rco%ucl-cs@CSNet-Relayjimbo@ucbcad.UUCP (03/17/84)
I've heard that some company has a 2400 bps full-duplex modem for $900. It isn't compatible with any other format at all. I wish I new the name of the company! If any of you out there have heard of it, please send it along. Jim Kleckner ( jimbo@Berkeley, ucbvax!jimbo )