I have DSL, and I noticed today, that in all of my phones I have horrible screeching noises. Could the filters be bad? I noticed the problem when I first installed DSL, and I find it hard to believe all three filters are bad.
Does it still happen when the modem is disconnected?
Try unplugging each phone and or filter to isolate if its a filter problem, a phone problem, or some other wiring problem.
If it’s happening on all phones, it would seem more likely that the filter on the line where the modem is attached is the faulty one. Are you experiencing loss of connection at times?
I’ll bet it’s a single filter problem. My parents’ house, despite its other flaws, is really really well-wired for telephones for a house built in the 1960s (one of the previous owners had put in a second line and there are jacks in practically every room in the house.) There were like 5 different phones plugged in at different parts of the house, all of which had a DSL filter. When one of them failed you got the noise on all the phones, not just the one the filter had failed on. I’d get a new filter and try replacing filters one by one, seeing if that fixes it. And do check to make sure that the filter in the modem works.
Ther shouldn’t be any filter at the modem, or you’ll have a heck of a time trying to get the thing to sync up.
Unplug all the phones and their filters. One by one, re-connect phones with the filters. When the noise returns, you’ve found the bad filter.
Huh? Maybe it depends on the filters, but all of mine have two outputs, for phone and for ADSL.
Maybe I’m just complicating matters even further (but at least I drew a diagram). Anyway, when I had DSL, I used one fillter for the whole house. Connect the modem ahead of the filter then connect the entire house wiring. (see diagram. )
Oh and you don’t need any fancy filter. One ordinary filter will be enough for the whole house.
The ADSL output is unfiltered, for obvious reasons.
I second the ‘huh’. Unless ADSL works differently in other parts of the world, everything must be filtered; the filter splits the line into two frequency bands; the modem takes one and the voice traffic goes on the other; If you leave the modem unfiltered, it will not be confined to its band and problems will occur; to wit: screeching on the line and/or loss of connection when a call is made.
The Audience says no… (In Australia) The modem remains unfiltered. Any and all devices that are not the modem, and that use the telephone use the filters to separate their lower frequency, and keep the line clear for the modem to go through. The modem has a clear line, because filtering does affect the sync to the DSLAM by interfering with the signal.
A properly filtered line should be able to support an unfiltered modem, without any extraneous noise. If you’ve got filters on your phones, and still have noise, you either have too many devices on the line which are all interfering with each other, or your filters are insufficient for the signal that the phones put out. Cordless phones are often a culprit of this, sometimes requiring different filters from your average cord-in-the-wall handsets.
At least that’s the way it works over here shrug
Hmmm. That’s certainly not the way it is in the UK; here is a typical setup, and here it is from BT; the filter goes into the wall socket and itself provides two output sockets; one for voice and the other for the modem. AFAIk, all UK ISPs stipulate that filters must be installed at all points, including the modem.
Mangetout, those look like filter/splitters. They are a mixed filter and splitter for use when you only have one line to plug both your modem and the analogue device in. The part of the filter that the ADSL is plugged in to is unfiltered.
That may be the case, but UK ISPs are pretty insistent that you use them on every extension, even the one that only hosts a modem.
Actually… short of buying an extra cable, it’s physically impossible to plug a DSL modem into an unfiltered socket here in the UK; the cable that comes with the modem is invariably an RJ-11 at both ends; this won’t plug directly into a standard BT telephone socket.
However… you are right.
It appears that the modem takes care of confining its communications within its own band; of course this is to be expected, but I did think it might not do this to absolute perfection and that a filter would be required on both halves, but as you say, this is not the case (cite for this being true in the UK: http://www.adslguide.org.uk/qanda.asp?faq=install#Q191 )
So… I learned something today