Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!mstar!mstar.morningstar.com!bob From: bob@MorningStar.Com (Bob Sutterfield) Newsgroups: comp.dcom.modems Subject: New Modems, Telebit Fails under impairments in PC Magazine tests Message-ID: Date: 28 Nov 90 22:03:01 GMT References: <1715@chinacat.Unicom.COM> <1990Nov19.191023.11581@nstar> <1990Nov21.221114.11850@unixland.uucp> <1990Nov23.185029.2663@nstar.rn.com> <1990Nov26.010656.20883@virtech.uucp> <1990Nov26.024835.13024@ux1.cso.uiuc.edu> <1990Nov26.062122.24546@sbcs.sunysb. Sender: usenet@MorningStar.COM (USENET Administrator) Organization: Morning Star Technologies Lines: 189 The modem comparison article in the December 11 1990 issue of PC Magazine has stimulated some interesting discussion, particularly regarding the poor showing of the Telebit T2500 in their comparison tests. I went through the article with a highlighter and thought I'd offer a few impressions. First, a few key excerpts, first from the comparison test description, page 329: "Unfortunately, the Telebit modems were not able to complete the data transfer tests under any of the EIA-standard impairment conditions. We saw similar problems using these modems under their native PEP mode." then from the individual modem review, page 336: "The unit gave us a few headaches while we were trying to set up for V.32/V.42/V.42bis testing. Because the default configuration tries to connect with another Telebit modem using PEP first, we needed several phone calls to technical support to get the modem configured for our performance tests... It was not successful for any of our 24 impaired line tests, despite repeated tries and extensive consultation with the company." Now, some responses to things said here: In article <1990Nov19.191023.11581@nstar> larry@nstar (Larry Snyder) writes: The Telebit modems will hold the line better than the dual standard... This is the "conventional wisdom" held by many modem users, particularly those who have used Telebits alongside other modems in difficult environments. In article <1990Nov21.221114.11850@unixland.uucp> bill@unixland.uucp (Bill Heiser) writes: Interesting -- did you see PC Magazine's comments about the T2500? They "couldn't recommend it" because it wouldn't hold the line on noisy connections. This is the fundamental disagreement between PCMag and modem users. In article <1715@chinacat.Unicom.COM> chip@chinacat.Unicom.COM (Chip Rosenthal) writes: Then they did not run their tests in PEP mode. According to PCMag, they tried both V.* and PEP, with similar results. Note: They tried but were apparently unsuccessful at actually *running* the tests in both universes. In article <1990Nov23.185029.2663@nstar.rn.com> larry@nstar.rn.com (Larry Snyder) writes: That's not what happens in real applications - ask around - and you'll find Telebits maintaining links around the world. Again, the conventional wisdom contradicts PCMag's results. The telebit's lost out [in PC Week's review] primarily due to their lack of supporting a DTE speed of 38400... One might expect that Telebit would quickly catch up and offer a 38.4Kb DTE interface. In article <5@ivysoft.UUCP> tonyl@ivysoft.UUCP (Regular Tony Lin id as normal user) writes: If you want to use your high speed modem for UUCP, wouldn't the TELEBIT be a better choice because it has PEP protocal support? But be aware of the fact that PC Magazine said it failed in their impaired line tests. Yes, be aware of that fact. Question both the modem and the tests. In article <1990Nov26.010656.20883@virtech.uucp> cpcahil@virtech.uucp (Conor P. Cahill) writes: I'm not sure what mode they were using it in, but in PEP mode the T2500 holds the line better than any of the V.32s that I have tried (including the T2500 itself in v.32 mode). That's true if they were successful in setting up their modems, and were actually using PEP correctly. If they had "a few headaches" setting up their modems, and didn't do it right, then one might expect the results they reported. In <9842@discus.technion.ac.il> devil@techunix.BITNET (Gil Tene) writes: Well, I wonder If they plugged it in right, or did thay plug it in at all? ;-) You might be getting close! I am using a TB2500 for an overseas connection 1/3 the way around the globe. The line is VERY noisy, it has my TB running at "only" 350-700 Bytes/sec. I can get a connection almost every time and hardly ever loose it. Another empirical data point to support the conventional wisdom. It's beginning to sound more and more as if PCMag might not have configured their T2500s as carefully as you did yours, eh? I have tried several other connections, including 1200, 2400 (w and w/o MNP) and 9600 V.32, I have not been able to keep anything other than a TB2500 with PEP on the line for more than 30 seconds This is typical of reports from non-North American users. In article <1990Nov26.024835.13024@ux1.cso.uiuc.edu> msp33327@uxa.cso.uiuc.edu (Michael S. Pereckas) writes: The PC Mag article is primarily about V.32. It is not clear to what extent they tested PEP. They apparently tried, but unsuccessfully. What is your experience with V.32? You must have missed the rest of his description. Mr Tene tried V.32, but he didn't mention whether he used MNP4 or V.42 or any other noise suppression method, nor whether that would have helped him maintain a carrier. In article <1990Nov26.062122.24546@sbcs.sunysb.edu> altman@sbstaff2.cs.sunysb.edu (Jeff Altman) writes: The PC Mag test was measuring the ability to hold the line when using V.32/V.42/V.42bis and not PEP. This makes all of the difference. The article was about the standards, but they also tested HST and tried to test PEP. With the T2500, they reported that they were unsuccessful at almost everything they tried that exercised the modem in interesting ways. In article <8353@gollum.twg.com> david@twg.com (David S. Herron) writes: By *ALL* reports I've heard, and *ALL* the testing I've done with telebit's they work excellently on "impaired lines". ...another empirical data point that contradicts what the PCMag testing lab had to say. The only downfalls of PEP are 1-- it's not a "standard" True, this is a major problem. 2-- It's half-duplex. In-modem protocol spoofing and careful protocol design (e.g. TCP header compression) make this less important if the modem is not to be used for simple typing. In article <326@comtst.UUCP> mdv@comtst.UUCP (Mike Verstegen) writes: We have used Trailblazer+ modem (close relative of the T2500) for inbound and outbound, domestic and international with no problems from the modem. Are we just lucky, or did Telebit get a bad review? I have come to believe the latter. The experiences commonly reported by Telebit users so contradict the PCMag review results that I am inclined to doubt the test procedure. And a few key clues from the article support my conclusion. The problems described in the article all appear to be addressed by the modem's user documents. When using a modem that's nearly Turing-complete, it helps to RTFM. The testers were apparently unable to decipher the documentation for S50, 92, S94, perhaps S95, S97, S106, S107, and maybe even S98. While the documentation does require study, it's frankly not that tough. I find that the modems come with register settings that are fairly close to what I want to use most of the time. For any variations or oddities, a couple hours of playing almost invariably get me on the air. Lacking the ability to decipher TFM, they "needed several phone calls to technical support to get the modem configured for our performance tests," and even after "repeated tries and extensive consultation with the company," couldn't do the tests they wanted. I have found Telebit's technical support to be quite capable over the several years I have used their modems. They have helped me when I've listened to what they've had to say. I wonder whether Telebit's inability to help PCMag's reviewers with the modems might not have been related more to the reviewers than to the customer support staff or to the modems? We've all dealt with users who, despite our best efforts, heard only what they wanted to hear and were uninterested in accepting our advice. As often as not, the user will storm out of the office and grumble loudly to anyone in earshot that "the system is a pile of junk and the user support staff aren't interested in helping me get my work done." It's at least plausible that PCMag's review lab and Telebit's customer support staff interacted in this way - it would explain their results, which are so obviously different from those of regular Telebit users. And the shame of it is, PCMag went to print before their testing problems were resolved (if they ever were), and that article has by now been photocopied and shoved into folders all over the world, to be treated as an authoritative reference manual to choosing high-speed modems. I don't know who fared worst from that article: Telebit, or companies like Intel whose modems didn't even make it into the review. (I have no connection with Telebit or any other modem company, other than as a very satisfied user. I just don't like seeing good products and good companies getting an unfair shake; and I don't like seeing users making purchase decisions based on misinformation.)