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Thread ID: 27265	2002-11-18 09:09:00	Broad band ADSl splitters & filters	bk T (215)	Press F1

Post ID	Timestamp	Content	User
99399	2002-11-18 09:09:00	We all 'know' that 'filters' or 'splitters' are required for telephones to operate normally when sharing the same line used by ADSL connection . But, I've tried this afternoon to use the telephone without a filter or splitter and they all work fine! Both the telephone and Jetstream connection are all working OK - connecting to the same Telecom phone line . 1 . Any explanation for the above? 2 . What are the differences between a filter and a splitter? 3 . Shall we use a filter or a splitter? Which is better and recommended, and why? Cheers bk	bk T (215)
99400	2002-11-18 19:05:00	1) My guess is that the phone you have has an incredibly poor high frequency response; perhaps another phone wouldn't work . When I tried a phone directly on the unfiltered line, it sounded like fireworks, and the dsl modem disconnected . 2) Physically a filter has an in and an out connection; a splitter has an in and two outs . For most splitters, the 'ADSL' out is simply a straight through from the in - so you can achieve the same result by using a (cheaper) filter and wiring the feed to all your phones from the 'out' and connecting your modem directly to the unfiltered line . Splitters tend to have a more comprehensive filter (resulting in higher attenuation), but whether this offers any advantage is debateable . (I'm using one 'filter' for all the phones, and it works well) . 3) If you can easily splice a filter inline in the feed to all your phones, while providing a direct unfiltered feed to your ADSL modem, I would try that - it's the most economic and works well for a lot of people .	wuppo (41)
99401	2002-11-18 19:50:00	Phones may work without splitters, however you could expect some "chirps" of interference when data is flowing in the ADSL signal. Often the ADSL will disconnect when a ringing signal comes through, as the spikey nature of the ring cadence disrupts the ADSL	godfather (25)
99402	2002-11-18 20:35:00	godfather, do you mean we have to use a splitter on every phone jack connecting to the same ADSL line? The phones connected to my ADSL line is crystal clear and doesn't affect the ADSL connection when the phone rings. I can use all the phone jacks in the house without any problem. There are 4 phone jacks connected to the same line. Have I wasted my money in buying a splitter /filter where I actually don't need it? Cheers	bk T (215)
99403	2002-11-18 20:43:00	Even with an in-line filter I can *just* hear ADSL chirps. Perhaps your phones have a high frequency roll-off internally? I have covered my whole installation with just 1 filter, by using it similar to a splitter, I wired the installation to allow it. I guess if it works and you don't get disconnected, then it works. I know mine is objectional with no filter. The ringing cadence has a low frequency AC (16.666HZ?) wave superimposed on the system. The external bells here were disconnected, as they did disrupt the ADSL on the ringing signal. Your mileage may vary	godfather (25)
99404	2002-11-18 20:57:00	Just for my information and curiousity, how do you wire the whole installation with just 1 filter? Thanks	bk T (215)
99405	2002-11-19 00:09:00	Bk 1) Find the first connection point inside your house for your incoming line and disconnect the feed to your phone system . 2) Insert the filter in series with the incoming line and your phone system (so that all telephone signals pass throught the filter) . 3) Install a new telephone cable from the incoming side of the filter to a dedicated adsl modem outlet . Do not connect anything else to the adsl outlet . This gives a straight-through line to the modem or router while all telephone, fax & snail modem signals pass through the filter . A splitter is connected the same, only you connect the input to the incoming line, the adsl pair feed your new cable to the dedicated outlet and the other pair feed your phone network . Suitable quick connection terminal units are available from DSE I think . Cheers Billy 8-{)	Billy T (70)
99406	2002-11-19 01:05:00	Billy has answered the howto . . . but there's one question still there: "what's the difference?" . . . . ?:| . . . I've just rubbed out my explanation . :D The best way to learn something is to try to explain it to someone else . Starting again . As far as I can see the terminology is wrong . An "ADSL filter" is intended to be connected between the line and any "telephone" (fax, Vxx modem, etc) . It stops any ADSL signals (in the low megahertz range) from affecting the low frequency stuff (only up to 3400Hz) . Old black HB series dial phones (Bakelite) wouldn't care, the 700 series (the "modern" dial phones) wouldn't care because they didn't have any transisters or microprocessors or CMOS tone generators . That's what you get for your $20 to Dick Smith . An "ADSL splitter", the one you pay Telecom lots of money to install, is not a splitter; it's a filter . It might two filters . . . one to keep the HF out of the telephone output, and one to keep LF out of the ADSL socket . Has anyone looked inside one of these? To be a high pass, it could be just a couple of small capacitors with maybe a resistor to keep a DC path, going to the ADSL output . A splitter is the sort of thing which you must have if you are running multiple television sets off one antenna system . (A diplexer which you might have at the roof to connect your VHF and UHF antennae to a single coax is a different thing again) . A splitter allows multiple loads to be connected without ruining the impedance match of the line to the antenna, which can cause reflections (ghosting) and severe attenuation (making noisy picture) . If your "ADSL splitter" was a splitter it would have multiple telephone outputs -- one for each instrument . Obviously, telephones aren't as fussy about impedance matching as television (partly it's because you have hundreds of millivolts rather than tens (or ones) of millivolts) .	Graham L (2)
99407	2002-11-19 03:26:00	Hi Graham I have long suspected that the Telecom supplied splitter is actually a high pass/low pass filter and I wonder if Peter or any other Telecom type could clarify that for the NZ available products . There are adsl splitters available overseas that utilise both low pass and high pass filtering techniques with 2/4/6 pole passive L/C filter components to effectively isolate each signal frequency band . In my mind that would be ideal as it would protect the adsl signal from lower frequency artefacts that might slow down the service . Cheaper splitters just contain the low pass filtering with the adsl output paralleled to the input terminals and the filter function is a simple low pass L/C type . The absence of any filtering could possibly upset the adsl modem because when directly connected without a high pass filter it is subjected to all the normal garbage on the phone line including ringing tones, fax tones and any other noises such as (occasionally) speech signals . The key issue would probably be the impedance the phone(s) present across the line in parallel with the input to the modem and possibly the cheaper/older the phone and the closer it is to the common point the greater the impact on the adsl signal . Put another way, if your ADSL modem is any good, you could probably get away without a filter/splitter and if you only had one phone plugged in to the line it might all work OK . Me? I played safe and rewired throughout with CAT5-E cable, converted to the 2-wire system Telcom recomends for ADSL (better line balance in the installation I guess, and installed a dedicated outlet to my desk . I brought the Telecom point of supply right into my office then Telecom installed a splitter in the junction/distribution box where all my phone and network cables come together . It works for me, but colour and contents may vary in some boxes :D Cheers Billy 8-{)	Billy T (70)
99408	2006-09-07 09:55:00	So why is it that you need to have telecom install their filter if you have more than 5 jackpoints	thefatralph (2558)
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