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Thread ID: 12570	2001-11-01 11:53:00	laptop modem	Guest (0)	Press F1

Post ID	Timestamp	Content	User
23344	2001-11-01 11:53:00	a mate of mine has bought himself a laptop. however it dissconcts from the line very regulaly. we have ruled out almost everything. at the moment line noise appears to be the culprit(we have a lot of electric fence noise). do laptops normally have problems with line noise? this is with a bay type modem not a serial/usp external.	Guest (0)
23345	2001-11-02 01:51:00	Hi tweak'e, all analogue modems have problems with line noise because if the noise is interpreted as a databit then the block checksum will fail and a transmission error will be counted. when the error count reaches some predefined number, the connection will be terminated. The faster the modem speed the worse it gets so try running at 33.6 Kbps it will probably fix the problem and the reduction in speed will hardly be noticeable if the transmission is more or less error free because less blocks will have to be repeated. Check your modem documentation for an extra value for the initialisation string to set the modem to v34 instead of v90 I think this should limit the transmission speed to 33.6. Telecom recently published a report on electric fence noises saying that if you keep the grass along the fence short enough not to cause earthing of the bottom strand it reduces the amount of noise picked up. Of course thats OK if it's your electric fence that is causing the problem, if it's someone elses fence then tough luck. HTH regards PC.	Guest (0)
23346	2001-11-02 03:47:00	thanks PC (are you the PC in WFD by any chance?)thou the prob here is that the main pc has no probs with the line noise just the laptop. some one mentioned that laptops where a bit more touchy with line noise. don't know if thats true or not. might just change the modem and see. anyone know of a good combo 100mb lan/56k modem card?	Guest (0)
23347	2001-11-02 04:35:00	The fundamental problem is that telephone lines were designed to work on a bandwith of 2400Hz. Modems worked quite well at 300 baud. 1200, 2400, 4800, 9600 needed more and more tweaking, line compensation in the modems, and luck. Now at 56k bits/sec the wonder is that it works at all. Different brands of modem will have different ability to dodge noise (because they use different magic). Spiky noise like electric fence is probably nastiest. You could try, if possible, reducing your packet length (MTU), because the longer the block the greater the chance of a noise burst coming in and ruining it. It's no good getting 'maximum throughput with longer blocks' (less overhead) when the longer blocks are repeated multiple times.	Guest (0)
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