HSTnet HST Echo HSTnet 1/0 (813) 394-6488 March 1994 FAQ - Fequently Asked Questions Q. Wh

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HSTnet HST Echo HSTnet 1/0 (813) 394-6488 March 1994 FAQ - Fequently Asked Questions Q. What is HST A. HST is a registered trademark of the U.S. Robotics Company (USR). It was originally used to indicate "High Speed Technology." Before USR trademarked HST, it was also used by Microcom to describe modem technology. HST is also the name of the echo that supports users of US Robotics and other make modems based on that technology. Data Race, Concord, Miracom and others have licensed HST technology at one time or other. Q. What is a Courier HST modem? A. The Courier HST was the first high speed modem released by US Robotics. Its primary designed transmission speed was 9600bps. The use of HST error correction increased the maximum transmission speed possible to 11910bps. Actual maximum speeds were in the vicinity of 11700bps. There have been many modems that have been called HST. Gradually the modems increased in speed from 9600 to 14400. The latest version is now 16800 and can be had with facsimile Class 1 and Class 2.0 depending on model. HST is a unique assymmetrical channel configuration. MOST of the usable bandwidth is concentrated in sending data one way at time. Since the vast majority of data transmission is highly asymmetrical in nature, this has proven a very efficient transmission method. Q. What is V.32? A. The Consultative Committee for International Telephony and Telegraphy (CCITT) is a body that sets up compatibility recommendations for various types of electronic equipment. One modem standard set by the CCITT (now known as the ITU 'International Telecommunications Union') is known as V.32. There are many ITU specifications that describe modem protocols. The V.32 spec- ifcation is a 9600 symmetrical protocol that uses MNP for error correction. V.32bis is a faster version of V.32 and operates at 14400 bps. Q. What is V.42, V.42bis, Lap-m A. V.42 is a negotiation protocol for error correcting modems. During the connection process, the modems tell each other which common and desireable features are supported by both modems. The modems will select by default the most efficient error correcting and compression techniques. A more efficient compression technique than MNP5 is called V.42bis. A more efficient error correction technique than MNP1-4 is called Lap-m. When V.42 is executed at the connection phase, it looks for the highest level efficiency both modems can support. The prefered defaults are Lap-m and V.42bis. Q. What is a Bler? A. Bler means Block Error. This is a function of error correction. With an error correcting modem, any data that fails it's verification check is resent. Q. What is ARQ? A. Automatic Resend Request. This is the US Robotics way of labeling the various error checking protocols. The original HST modem used a proprietary technique that was similar to MNP and the resulting connect string sent was 9600/ARQ. All USR modems send connect message of ARQ to indicate an error correcting protocol is detected and in use on both modems. Q What is MNP? A. The acronym stands for Microcom Network Protocol. There are different levels of MNP beginning with level 1. Levels 1 through 4 are in the public domain and can be used in any software or hardware without paying royalties to Microcom. The first three levels apply different techniques for sensing and resending block errors. Q. How do I order a modem on the USR sysops program? A. Call the USR company BBS. The number is 708-982-5092. This is the ONLY way to order a modem on the Sysops program. Q. What do I have to do to qualify for the Sysops program? A. First you have to be operating a BBS for at least six months. You should obtain the latest copy of the Sysops Program offer form USR's BBS. Then you must be willing to accept the conditions of the Sysop's deal in order to be considered to receive a modem at the special Sysops pricing. There are exceptions to this requirement. Owners of the following BBS software have the waiting period waived. PC Board Wildcat Power Board Searchlight Roboboard T.P.Board and Front Door Remote Access Major BBS First Class TeleFinder AmiExpress DLG Celerity/Alarcrity For details see the Sysdeal.TXT file on USR BBS 708-982-5092 Q. Are there requirements to advertise the modem that I buy as a Sysop? A. Yes, you are required to operate the BBS and to carry a notice to all callers that you are using a USR modem, and hopefully which model etc. The time period of this requirement has typically been six months. See the current sysdeal.txt file on USR's BBS for precise details. Q. Why are they so strict? A. Because many non-sysops have attempted to obtain the special pricing which they do not deserve. Q. Why does it take so long to get a USR when I can order other modems and get them almost immediately. A. Frequently USR announces new modems when the production lines are not operating. New modems will have long delays before the first orders are filled. USR also makes a limited amount of modems available to Sysops, and these amounts can run out. There is no retail sales department at USR. They ship on a regular schedule. Other companies sell retail from the factory. Q. If I can buy a modem direct from other modem makers, why does USR have such a strict policy? A. One reason is to protect the distributors and dealers who sell USR modems. Some companies will sell modems in competition to their dealers and distributors. Such companies dealers are not likely to view the sysop as a customer but as a competitor who has taken away profit. Sysops using USR modems who advertise those modems on their BBS's provide a service that is likely to benefit USR modem dealers. And such sysops are much more likely to recieve support from dealers for the advertising the Sysops perform. Q. What is V.32TERBO? A. Terbo is NOT a V. Standard. It is a protocol that was developed by AT&T. It is a version of V.32. The V.32bis version of V.32 encodes more data bits in a pattern refered to as the Constellation. Several of the "bits" in the constellation are used to provide a kind of error correction in a technique known as Trellis Coded Modulation. This is a type of "forward looking" error correction that adds approximately 2.5 db to the Signal to Noise (S/N) ratio that a modem required in order to recognize the waveform pattern and its encoded data bits. Since the telephone lines were found to have enough bandwidth (frequency width, usually from 300-2700 hz) the V.32bis protocol was created and will under ideal conditions achieve data transmission rates of 17100 bps. When line noise occurs errors occur, and the amount of data bit encoding is reduced. V.32bis has fallback speeds of 12000, 9600 and 7200 bps. This occur as each data bit encoding is dropped, which in turn allows the use of a narrower bandwidth, increases the effective S/N ratio, and tend to allow transmission to continue. TERBO, also refered to as V.32terbo takes several of the data bits in the Constellation that the CCITT did not think should be used for data, and attempts to use them as data. Under nearly perfect line conditions the Terbo technique can be used to transmit as fast as 19200 bps or 21600 in USR terbo. Since the bandwidth is increased, the sensitivity to noise decreases from 3 to 3.5 db. Q. What is the fastest modem protocol? A. Right now, the Telebit Super PEP modem has a carrier rate of 23,000 bps and can do speeds above 24,000 bps reliably on many more difficult telephone line conditions than TERBO or V.FC. This is a rating of absolute bit density, which is how most BBS operators consider speed. If sending of compressed data is considerd (which is rare on a BBS) then the Hayes V.FC is the current top speed modem with compressed bit densities of up to 230,000 bps claimed. Q. Can I upgrade my old HST modem (9600, 14400 or 16800 bps) A. Yes you can. Several upgrades may be in effect from time to time. One such upgrade for the very old HST9600 modems is to Dual Standard (9600HST/V.32 9600) for $150. At various times other upgrades or trade in programs are in effect. The best way to be sure is to call USR. Q. How do I contact USR directly? A. You can use a modem to call their BBS at 708-982-5092. The BBS runs a Total Control rack mount with 8 Courier Dual Standard TERBO modems on it. There is a section where you can download information on the Sysops program, products, pictures of modems, and technical tips. There is also a section taht contains a local USR message area for questions to USR. This is the ONLY BBS where you can expect to receive an answer from USR technical personnel. You can also call USR at 800-342-5877 and talk to sales. Or you can call Technical support at 708-982-5151. Be prepared to wait to talk to anyone as they are quite busy. USR personnel answer several thousands of questions per week. Q. If I prepay will I get my modem sooner? A. Probably not. There have been several instances where modems were prepaid and arrived after months of waiting. I don't recommend prepayment, unless by credit card, and only if the shipping date is soon and promised. Then if the modem does not arrive on time, the charge can be cancelled and refused at your bank. Q. Is the Courier modem really upgradable? How is this done? A. In the past all modems were made to do one thing at one speed. For the past several years, modem technology has improved so rapidly that the ONLY way to ensure a modem could be upgradable was to make sure the processors could be changed as needed. USR Courier modems have all the necessary parts to perform the modem protocol functions on a small seperate printed circuit board that can be replaced with more powerful processors as needed. Many modem buyers were highly disappointed after having purchased a bargain modem to find out that a newer modem was now available that was 50% or more faster, or more robust. Some current modem makers are providing very powerful modems, but sending them out with slow speed protocols in them. Then those buyers are required to download the higher speeds protocols and run a program to "upgrade" their modems. (Why not just ship them ready to run at high speed?) This makes such modem less competitive as they have to be priced comparable to slower modems, even though built with the processors of the faster modems.


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