dan@hrc.UUCP (Dan Troxel VP) (09/30/88)
The company I work for is soon to open a franchise in London, England. We will be communicating back and forth sending about 35,000 bytes worth of compressed data. This could be anywhere from 5 to 20 a day. I have heard that the highest baud rate to communicate out of London is 1200 baud. o Is this true? o If so, WHY? o If so, is there a different way to send the data in a speedily fashion? -- Dan Troxel VP of Computer Operations @ Handwriting Research Corporation - 2821 E. Camelback Road Suite 600 Phoenix, AZ 85016 WK 1-602-957-8870 HM 1-602-435-1240 UUCP : asuvax!hrc!dan
csg@pyramid.pyramid.com (Carl S. Gutekunst) (10/02/88)
In article <311@hrc.UUCP> dan@hrc.UUCP (Dan Troxel VP) writes: >I have heard that the highest baud rate to communicate out of London >is 1200 baud. And that only on *good* days. I dunno why, but dialup to London is awful. The Bell 212A and V.22 modems we've tried were erratic, and V.22bis was out of the question. Even the TrailBlazer has never worked right. (One of these days we may goad Telebit into finding out why.) This is a sharp contrast to Australia, for example, which works exceptionally well with just about anything; and Chile and Argentina, where most modems won't work at all but the TrailBlazers get over 500 cps. Then again, dialup to Germany is terrible, too. Maybe the trans-Atlantic phone links are just outdated? >o If so, is there a different way to send the data in a speedily fashion? X.25 Public Data Network. We have a 9600bps Telenet line here, and most places we call in the U.K. have 9600bps lines to British Telecomm Packet Switch Service (PSS). We get a consistent data rate in excess of 500 characters per second. Unfortunately, X.25 is hideously expensive; Telenet is charging us $1400/month, plus $12 per 64K and $12 per hour of connect time. If you work it out, all you need to maintain is a *reliable* 80 cps on a modem to break even. If the TrailBlazer worked, we'd completely adandon X.25 to the U.K. <csg>
dtynan@sultra.UUCP (Der Tynan) (10/04/88)
In article <41536@pyramid.pyramid.com>, csg@pyramid.pyramid.com (Carl S. Gutekunst) writes: > In article <311@hrc.UUCP> dan@hrc.UUCP (Dan Troxel VP) writes: [All kinds of stuff about horrible bandwidth deleted] > > >o If so, is there a different way to send the data in a speedily fashion? > > X.25 Public Data Network. We have a 9600bps Telenet line here, and most places > we call in the U.K. have 9600bps lines to British Telecomm Packet Switch > Service (PSS). We get a consistent data rate in excess of 500 characters per > second. Unfortunately, X.25 is hideously expensive; Telenet is charging us > $1400/month, plus $12 per 64K and $12 per hour of connect time. If you work it > out, all you need to maintain is a *reliable* 80 cps on a modem to break even. > If the TrailBlazer worked, we'd completely adandon X.25 to the U.K. > > <csg> Pay to the order of USENET: $0.02; I make a *lot* of calls to Ireland, and I can see why the bandwidth isn't there. There are a lot of problems with transatlantic communications. What is really needed, is a modem (Telebit, are you listening?) which is optimized for this type of transfer. With the horrible costs quoted for X.25, someone could make some money, by modifying the TrailBlazer code. Some simple optimizations; 1. Bandwidth is allocated dynamically. For example, a call to London may produce a real low data rate, but a second call a few minutes later may be great. 2. The lines are worse than half-duplex. The primitive switching used to fake full-duplex vox is terrible. I notice delays of up to a second in switching back. This can be fatal to a modem. A small packet size, with a very large window may help. 3. Echo is prevalent, as well as crosstalk. This is something that could be filtered out at the modem. 4. Ireland is currently switching over to a digital system. Some of the larger cities are now digital, and the clarity is pretty good. Some of the others, however, are probably using cans! If possible, make the connection to a large metropolitan area. 5. Most of the common-carriers have links to London. Check each of them (and post the results!). AT&T may be giving you the old "under-the-sea" cables, whereas someone else may let you use their ultra-super sattelite for the same cost. There are probably hundreds more optimizations. What *I'd* like to see, is some sort of short-wave link (TDMA?), that we could all use, sans licence. As a hard-and-fast rule, however, whatever common-carrier you choose, will charge you the same for a lousy quality line, as they will for a good one. For this reason, the modem should dump the line and restart if the error rate is pitiful. Of course, then again, the line quality *should* be better during business hours (when it is more expensive). BTW; Carl, you should think about sub-letting some of your X.25 bandwidth, and spreading the overhead. - Der -- Reply: dtynan@sultra.UUCP (Der Tynan @ Tynan Computers) {mips,pyramid}!sultra!dtynan Cast a cold eye on life, on death. Horseman, pass by... [WBY]
paul@csnz.nz (Paul Gillingwater) (10/04/88)
In article <311@hrc.UUCP> dan@hrc.UUCP (Dan Troxel VP) writes: > >I have heard that the highest baud rate to communicate out of London >is 1200 baud. > >Dan Troxel VP of Computer Operations @ >Handwriting Research Corporation - 2821 E. Camelback Road Suite 600 >Phoenix, AZ 85016 WK 1-602-957-8870 HM 1-602-435-1240 I have regularly called London using a V.22bis (2400 bps) modem with few problems - and I'm calling from New Zealand - can't get much further away! If you use a nice sliding-windows protocol such as Zmodem, you'll get maximum throughput. Of course, you'll do even better if you have a Trailblazer plus running at both ends. The TB+ is made by Telebit, who license it to Dowty in the UK (Dowty have just bought out Case, who also supply modems). -- Paul Gillingwater --> Path: ...!uunet!vuwcomp!dsiramd!csnz!paul Computer Sciences of New Zealand Ltd. Domain: paul@csnz.co.nz Magic Tower BBS (24 hrs) NZ +64 4 753-561 (V21/V23/V22/B103/B212A)
rick@seismo.CSS.GOV (Rick Adams) (10/05/88)
We manage to get 7-8 k bps between Washington, DC and Suffolk, England with Telebit Trailblazer modems. I would expect traffic to London to be similar. ---rick
davidsen@steinmetz.ge.com (William E. Davidsen Jr) (10/05/88)
In article <2556@sultra.UUCP> dtynan@sultra.UUCP (Der Tynan) writes: | 4. Ireland is currently switching over to a digital system. Some of | the larger cities are now digital, and the clarity is pretty good. | Some of the others, however, are probably using cans! If possible, | make the connection to a large metropolitan area. One of the people locally tells me that they had two weeks of really bad connections to their middle east office, although the connections were usually good. It seems that the operator was sick and the replacement operator kept listening in to see if the call was done. Perhaps the relay switches taken out of Ireland will go to some of the really bad places in the world. -- bill davidsen (wedu@ge-crd.arpa) {uunet | philabs}!steinmetz!crdos1!davidsen "Stupidity, like virtue, is its own reward" -me
henry@utzoo.uucp (Henry Spencer) (10/06/88)
In article <2556@sultra.UUCP> dtynan@sultra.UUCP (Der Tynan) writes: >... What *I'd* like to see, is >some sort of short-wave link (TDMA?), that we could all use, sans licence. It would be nice if there was enough radio spectrum for something like this to be practical and useful. There isn't. (Incidentally, if you think transatlantic phone lines are bad sometimes, short wave is often worse.) -- The meek can have the Earth; | Henry Spencer at U of Toronto Zoology the rest of us have other plans.|uunet!attcan!utzoo!henry henry@zoo.toronto.edu
snoopy@sopwith.UUCP (Snoopy T. Beagle) (10/10/88)
In article <2556@sultra.UUCP> dtynan@sultra.UUCP (Der Tynan) writes: | Of course, then again, the line quality *should* be better | during business hours (when it is more expensive). Why should the line quality be better during the day just because you are paying more for it? Charges are lower at night to encourage people to shift their calls to the night. This extracts more useful work out of the telco equipment which would otherwise be mostly idle at night. It also reduces the peak load during the day, which reduces the amount of equipment needed. Dig out your old Econ 101 book, and look up the chart labeled "Supply and Demand". You pay more during the day because that's when the demand is, not because the phone lines magically have greater bandwidth and/or signal/noise then. _____ /_____\ Snoopy /_______\ |___| tektronix!tekecs!sopwith!snoopy |___| sun!nosun!illian!sopwith!snoopy