Thread View: comp.protocols.misc
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Started by Christopher Ward
Mon, 20 May 1991 14:29
Using High Speed Modems
Author: Christopher Ward
Date: Mon, 20 May 1991 14:29
Date: Mon, 20 May 1991 14:29
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Greetings friends in netland. I am currently evaluating some in-house software for a client and would like some "in reality" information on a communications product they are using. Perhaps you can help on one of the questions listed below. Your interest in appreciated. 1) They will be using US Robotics HST/V.42bis 14.4K data compression modems for communications, these modems automatically step down to slower speeds if the line is of poor quality. The sites may be anywhere in the US. Does anyone know approx % of connections or time that modems will slow down, and to what extent (perhaps there has been a study in ..?) E.g. 5% of connections can be expected to only operate at 4.8K. 2) Again, with the modems above. I was experimenting by sending data records between stations. The data was 1K records of mostly spaces which I would have thought would be compressed. Just for kicks I decided to change the records to be random characters instead (random typing on the keyboard). Suprise! The transfer times were exactly the same. It would seem that either the compression algorithm is very efficient or not working! And yes, I did have the modem's compression enabled (&K3 for those in the know). Any ideas? I will follow up with any pearls of wisdom I receive. Thanks Chris Ward -- INTERNET: wardc@eng.auburn.edu US-MAIL: CSE Dept. Auburn University, Auburn, AL 36847 PHONE: (205) 844-6320
Re: Using High Speed Modems
Author: John Grohol
Date: Sat, 25 May 1991 16:18
Date: Sat, 25 May 1991 16:18
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wardc@banana.cse.eng.auburn.edu (Christopher Ward) writes: >1) They will be using US Robotics HST/V.42bis 14.4K data compression >modems for communications, these modems automatically step down to >slower speeds if the line is of poor quality. The sites may be anywhere >in the US. Does anyone know approx % of connections or time that modems >will slow down, and to what extent (perhaps there has been a study in >..?) E.g. 5% of connections can be expected to only operate at 4.8K. From my own personal experience, as well as what I've read in USR's manual and magazine articles, you can expect most xfers to go through at 19.2k or higher. Of course your long distance carrier may be an important factor in this chain, so it may be worth your while to change ld carrier if you do indeed find that your modems are often stepping down because of line noise. -- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- John M. Grohol || Nova University - Ft. Lauderdale, FL Internet: grohol@novavax.nova.edu || Center for Psychological Studies "So when you see a man who's broken, pick him up & carry him." - L. Anderson
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