SDSL and microfilters
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- Re: SDSL and microfilters
SDSL and microfilters
10-09-2007 7:28 AM
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Re: SDSL and microfilters
10-09-2007 8:29 AM
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You shouldn't need to use a filter for SDSL, as you will have a dedicated line for the SDSL connection.
Re: SDSL and microfilters
17-09-2007 8:14 PM
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But you would be asked to plug one in if you ever had any problems with your connection
Re: SDSL and microfilters
18-09-2007 3:01 AM
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I've never used one - I save mine for telephones etc
"In The Beginning Was The Word, And The Word Was Aardvark."
Re: SDSL and microfilters
18-09-2007 9:56 AM
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SDSL should be a managed install with SSFP (Service Specific Faceplate) as far as I'm aware, I'll just double check this though. SDSL comes with a dedicated phoneline so there should/will be no need for additional filtering.
Re: SDSL and microfilters
18-09-2007 10:39 AM
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the filter is used to separate the two different kind of signals to ensure that both work at an optimal level. If there is interference between the two you can see poor speed levels or at a more extreme level, intermittent or complete loss of broadband connection and in some cases, oddness around the broadband connection dropping when the telephone receiver is lifted and so on.
Re: SDSL and microfilters
18-09-2007 1:30 PM
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In the case of ADSL, I don't think it uses the low frequencies used by telephones. In addition all non-active filters introduce a slight signal loss and AFAIK a some amount of delay.
I get a good stable sync ratel anyway.
"In The Beginning Was The Word, And The Word Was Aardvark."
Re: SDSL and microfilters
18-09-2007 3:06 PM
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The main purpose of the filter is to prevent the line impedance changing every time a phone goes on or off hook, otherwise this would force a resync. The secondary purpose is to prevent DSL signals interfering with phone equipment.
Re: SDSL and microfilters
18-09-2007 4:23 PM
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Quote from: James when you have broadband activated, you have a digital signal applied to the phone line so that you can use a high speed internet connection.
My understanding is no digital signals are applied to the phone line but modulated signals on a carrier seperated approximately at 4.3kHz intervals.
Perhaps a better analogy is to think of the filter as a radio tuner. With it tuned in to the voice components of the signal so stopping interference from other stations (DSL part of the signal).
Re: SDSL and microfilters
18-09-2007 4:29 PM
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http://www.adslnation.com/support/filters.php
This provides details of a number of filters available.
Re: SDSL and microfilters
18-09-2007 4:38 PM
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Re: SDSL and microfilters
18-09-2007 4:47 PM
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Re: SDSL and microfilters
18-09-2007 4:51 PM
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Quote from: itsme 1st harmonic will be quarter size bricks so some of these will pass through the half brick size holes
and these are created as the whole bricks bump into each other as they are thrown off the scaffold.............
Re: SDSL and microfilters
18-09-2007 4:57 PM
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Note that the upstream ADSL signal occupies the portion of the spectrum just above telephones - so harmonics of the half bricks are not a problem (because the upstream S/N ratio is usually excellent).
"In The Beginning Was The Word, And The Word Was Aardvark."
Re: SDSL and microfilters
19-09-2007 9:02 AM
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Quote from: James_H
Quote from: oliverb all the filters I've seen do nothing to the DSL signal, it just passes straight through.
You've clearly not seen them all then!
I'll try to remember to post up some pics later on, but basically you don't *need* to filter the DSL signal, but in many situations its beneficial to do so, as filtering the DSL signal may eradicate interferance coming from just below the wavelengths used by ADSL equipment.
I think the low frequencies are [usually] removed by digital filtering, they just end up in the bottom of the spectrum that the DSL modem is programmed not to use. I think the only exception would be if the signal was enough to saturate the converter, in which case you'd have major voice service problems too.
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