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From: "Michael Painter"
Subject: Re: FILTER for Computer Phone Line
X-Newsreader: Microsoft Outlook Express 6.00.2720.3000
Date: Sat, 04 Jan 2003 05:40:13 GMT
NNTP-Posting-Date: Sat, 04 Jan 2003 05:40:13 GMT
Organization: AT&T Worldnet
"Howard Davis" wrote in message
> I'm having dial-up ISP disconnect problems due to phone line noise, and
> to design a lowpass filter (3 pole; -18 db/octave) that will minimize
> out-of-band noise but not slow downloads or uploads. I would greatly
> appreciate the technical information I need to do this:
> Optimum cutoff frequency (-3db).
> Source impedance of phone line.
> Input impedance of a 56K hardware modem.
> Is a Butterworth (maximally flat) or Bessel (phase linear) filter response
> most desirable?
First thing to do is check where your phone comes into the house. Since
you're writing in winter I'm betting you have one of the old lard wired
(should be hard but it fits) blocks with carbon filters in them.
Clean them out. Spiders and bugs like them and then it rains...
It is *never* the phone companies fault but most of the good techs don't
If you have the old type call and complain about line problems. When the
tech gets there be friendly. Mine changed out the old one for the new type.
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