wtm@neoucom.UUCP (Bill Mayhew) (11/06/88)
All this modem comparison and argument seems to be overlooking the most important thing to business. Namely, that of saving money. My site happens to have chosen a T1000 Trailblazer, but we might have picked a USR HST or even a Codex v.32 modem. We bought what we can talk with our uucp neighbor most cheaply. Since our neighbor had a Trailblazer, that is what we got. If he would have had a USR that is probably what we would have. Inside a business where a network is self-contained, it doesn't really matter what the modems are, as long as they save money for the time being, versus something else. I'm not too worried about aour choice to use T1000 modems for high speed. They've cut our uucp feed time to about 1/8 of what it used to be. Given the sale price, we'll have saved the cost of the modem in reduced phone bills in a little under 3 months. Even if we had paid the list price, the modem would have paid for itself in less than 6 months. So, if some really nifty keen v.32 modem comes out a few months from now, I wouldn't feel to terrible. If the v.32 were that much better, we'd buy it. In the three month interim with the T100, we wouldn't have been any worse off than if we would have just stuck with our old v.22 and not used the T1000 at all. Of course we'll have a "free" T1000 to boot. By the way, we do better with our T1000 than we did with a v.32 modem for netnews anyway. Why would I want to switch to a v.32 modem so I could have standard, albeit slower transfers? Anybody with DSP experience know if that TI DSP chip in the T1000 is up to the task of implementing v.32? If so, the upgrade to v.32 for the T1000 shouldn't be too expensive. The upgrade from level 3 to level 4 was about $100 for the older Trailblazer models. I popped the cover off the Codex v.32 modem. There were a whole bevy of DSP chips in there. I think there were 6, but they were an older part type. --Bill
mhyman@cup.portal.com (Marco S Hyman) (11/08/88)
In message <1398@neoucom.UUCP> wtm@neoucom.UUCP (Bill Mayhew) asks: > Anybody with DSP experience know if that TI DSP chip in the T1000 > is up to the task of implementing v.32? ... I > popped the cover off the Codex v.32 modem. There were a whole bevy > of DSP chips in there. I think there were 6, but they were an > older part type. V.32 modems use the full bandwidth of the telephone line in both directions and depend upon echo cancellation in the receiver to mask out what the modem is sending. Given that the echo may arrive at the receiver many milliseconds after it left the transmitter with both phase and frequency shifts I can believe it would take 4-6 DSPs to handle the job. I don't think a PROM update is going to change TBs to V.32 modems. --Marc ...... Marco S. Hyman ...!sun!portal!cup.portal.com!mhyman mhyman@cup.portal.com
brian@cbw1.UUCP (Brian Cuthie) (11/09/88)
In article <1398@neoucom.UUCP> wtm@neoucom.UUCP (Bill Mayhew) writes: [much stuff deleted] > >Anybody with DSP experience know if that TI DSP chip in the T1000 >is up to the task of implementing v.32? If so, the upgrade to v.32 >for the T1000 shouldn't be too expensive. The upgrade from level 3 >to level 4 was about $100 for the older Trailblazer models. I >popped the cover off the Codex v.32 modem. There were a whole bevy >of DSP chips in there. I think there were 6, but they were an >older part type. > >--Bill Even though you didn't specify which of the TI DSP chips was in the T1000, I can tell you that even if it's the 320C25 (TI's most powerful) that it cannot be done. Actually, to my knowledge, no one has been able to impliment V.32 in anything less than two 320C25s. In fact UDS uses six (yes 6!) NEC 7720 DSPs. As I stated in an earlier posting V.32 requires echo cancellation which is a CPU HOG. It cannot be done on *any* of the trailblazers currently available and there is no hope that you will be able to upgrade a current product to do V.32 in the future. This however would not stop me from buying a trailblazer. V.32 is new and someone has already posted an arcticle about problems with his UDS modem. I personally will use a TB+ for a year until V.32 is stable and fewer $$$. Then I'll buy one for a total investment of less money for both modems than I would have made today for a V.32 alone. -brian -- Brian D. Cuthie uunet!umbc3!cbw1!brian Columbia, MD brian@umbc3.umd.edu