Right, due to the brilliance of Demon in supplying a USB-only ADSL modem, the only suitable phone cable i have to hand at the moment has to go straight into the wall-socket, so Im not using a microfilter.

Now, I only have one phone socket in the flat, and the only thing plugged in is the broadband, so am I screwing over my connection or not?

Eventually Ill pick up an ethernet modem and the issue will go away, but just wondered in the meantime?

Your usb modem will prob have an element of filter in it that allows the dsl signal to work correctly, so if youre using the dsl signal only generally you dont need an external splitter. If you were to use a straight adaptor and connect a phone (without a splitter) onto the same line youd probs find the phone malfunctioning (or that could affect the dsl signal). B&Q have dsl splitters as well as Maplin and other places.
There are a number of DSL routers (like the Cisco ones) that dont come bundled with a microfilter (bit steep considering theyre Ã,£250), so you might want to check before you get it. The Netgear ones do.

If youre never going to use the phone line dont worry about it. Microfilters are there to stop your phone (which arent particularly well engineered when it comes to electrical cleanliness) from spiking all over your ADSL signal when you pick up/replace the handset.

If you dont use the phone line for making calls then you dont really need one.

And the word from Cisco on why they dont bundle a micro filter is because they feel the market from theyre equipment (rather than Linksys) is business use where typically the line gets used for Internet only and not for phone calls. At least thats what my account manager told me.

Cool, thanks for the help chaps

Water burst at work today so managed to pop out to the shops this afternoon for an appropriate solution, and all is academic now.

The ADSL goes straight through, the filter is on the phone line to stop nasty noises affecting your chat. You didnt need one. oops too late  

I had microfilters coming out of my ears, just not an approriate length cable to reach the PC/Modem, and fit into the fitler. The only cable I had was a modem-to-wall-socket jobby, so thats what i used as a temporary fix.

ADSL splitters do have a low pass filter on the adsl connection; its to stop spikes on the line due to POTS equipment switching transients, its not straight through.

if youve got a sky box then you need the filters or the sky box dialling up will ruin your adsl connection. Ive found.

Matt

Quote from: CeathreamhnanADSL splitters do have a low pass filter on the adsl connection; its to stop spikes on the line due to POTS equipment switching transients, its not straight through.

No, the low pass filter allows the voice frequencies through to the phone, it does not stop them getting to the Modem. it does stop the high frequencies of the ADSL getting through to the phone otherwise there can be clicks or possibly humming on the line on.

QuoteTypical installation for an existing home involves installing DSL filters on every telephone and fax machine in the home, leaving the DSL modem as the only unfiltered device.

http://en.wikipedia.org/wiki/Micro_filter

I wish there was at least accurate information on most of the internet sites, most just say you need them

The filter is supposed to make sure that the line is properly terminated though.

The low pass Im talking about is on the DSL connection AS I said. The telephone equipment generates spikes due to ringing and connection/disconnection. A spike generates higher RF than the DSL connection uses, hence it interferes with it. THIS is why the DSL connection has a low pass filter.

Guess Im going to have to make this simplistic

A low pass filter removes the frequencies above a given limit, letting those below through, thus low pass. A high pass filter allows high frequencies through and blocks low ones.

Thus a  two way speaker has a low pass on the woofer/midrange and a high pass on the tweeter.

For similar reasons if you put a low pass filter on an ADSL line you will remove the high frequencies which is the signal you want.

Quote from: SeriousGuess Im going to have to make this simplistic

A low pass filter removes the frequencies above a given limit, letting those below through, thus low pass. A high pass filter allows high frequencies through and blocks low ones.

Thus a  two way speaker has a low pass on the woofer/midrange and a high pass on the tweeter.

For similar reasons if you put a low pass filter on an ADSL line you will remove the high frequencies which is the signal you want.

You would STILL USE A LOW PASS FILTER serious.

Jeez... As greg said, the interference produced by switching generates HIGHER RF (radio frequencies) than a DSL connection.

THAT is why the dsl connection has a low pass filter.

FFS mun. Its like trying to get a ton of housebricks to do the bloody waltz.

M3ta7h3ad, they do not have one.

If you want to prove it go find some *EVIDENCE*

QuoteThe second socket is the ADSL socket, this is essentially the raw signal, i.e. unfiltered, so an ADSL modem will see the high frequencies, but can just discard the normal voice frequencies.

http://www.adslguide.org.uk/qanda.asp?faq=technical

Voice comes in at below 4khz, ADSL uses the 1.1Mhz band and ADSL2+ the 2.2Mhz band This is far higher than any other signal that might be on the line.

just above that Serious

QuoteAlthough you would never normally use the frequencies outside this range, actions such as picking up the receiver can generate frequencies outside normal voice range. Without the filter, this interference would corrupt data within the ADSL frequency band.

Read it again! The filter is on the line going to the phone, not the line going to the router/modem. It stops the signal coming *BACK* down the line from the phone so it *never* reaches the main line. The ADSL line is clear, no filter.

I havent said "there is no low pass filter" what I have said is its after the split so it is on the phone line and not the ADSL one, this cures both problems.


And from my original post if you dont have a phone on the line there cannot be any of these frequencies so you dont need a filter.