| Forum Home | ||||
| Press F1 | ||||
| Thread ID: 145395 | 2017-10-22 19:31:00 | ADSL line filter question | Tony (4941) | Press F1 |
| Post ID | Timestamp | Content | User | ||
| 1440991 | 2017-10-22 19:31:00 | Another from the "helping my tech-challenged neighbour" file: There is supposed to be an ADSL filter on every phone connection, right? So my question is, if there is one missing, does that affect the quality of the phone line, the broadband line, or both, and how does the effect show up? |
Tony (4941) | ||
| 1440992 | 2017-10-22 20:25:00 | Yes it can but is largely dependent on how many split offs there are in the line. Generally speaking if you have multiple splits daisy-chained off the main incoming line and the cabling is old there will be some degradation in the signal transmitted over the lines. Symptoms of this are regular DSL sync issues (i.e.Internet disconnects) and static on the phone line. Also whilst not a true and tested measure... it's best to use the same type of filter on all the jack points. Another thing to consider as well is the age of the filters, some of them can degrade over time which can lead to signal degradation as well on the line. You may want to replace all the filters rather than trying to figure out which one is faulty as this can be hard to troubleshoot. Cheers, |
chiefnz (545) | ||
| 1440993 | 2017-10-22 20:39:00 | The issue is not that one may be faulty (although that may still be the case), rather that she has been complaining of static and it turns out she has two phones connected and only one has a filter on it. I've put a filter on and after one trial things seem to be better. She is of the opinion that it is worse with the first call of the day and after that it is better - which seems unlikely. She has been blaming her new phone, so I have temporarily swapped hers with one of mine, and hers seems fine at my place. Of course this means I have violated the scientific principle (only change one thing at a time) so we'll swap them back tomorrow and see what happens then. I'll also give her a new filter to replace her original one. I have no idea of the configuration of her house, though the wiring is probably going to be pretty old. AFAIK she doesn't get too many internet disconnects. |
Tony (4941) | ||
| 1440994 | 2017-10-22 23:16:00 | There does not need to be one on every jack. It is only used to keep your phone within its frequency range. Having extra devices on your line actually degrades it but its probably not noticeable. Your adsl modem does not need a filter and can plug directly into the phone socket. Filters are for phones and other devices that make use of the line, fax, sky, etc |
Kame (312) | ||
| 1440995 | 2017-10-22 23:29:00 | From another point of view, a phone is a low impedance device that takes low frequencies, so the filter is a low pass device and has high impedance to high frequencies. If you have 2 phones and only 1 has a filter, then high frequency ADSL will be "shorted out" in a manner of speaking by the unfiltered phone. There must be a filter for each phone unless a master filter or 'splitter' is fitted feeding all the phone jack points, and a separate unfiltered feed to the modem. | Terry Porritt (14) | ||
| 1440996 | 2017-10-22 23:47:00 | Having extra devices on your line actually degrades it but its probably not noticeable.Is that why phones etc used to (and may still) have a "ringer value" that could not in total exceed some number? | Tony (4941) | ||
| 1440997 | 2017-10-23 00:26:00 | Ringer value has to do with capacitance and the amount of load the ring current is capable of driving, too many devices and they won't ring reliably. Seldom a problem these days. Cordless phones in particular have a very low impact overall. As to the filter question it's been pretty well answered, but to add my 2c. The broadband signal is audible so it needs to be filtered off the phone line so you won't hear it. Filters are only needed where a phone is connected. A master filter in the ETP and a dedicated xDSL jackpoint is by far the best solution, but if you use plug in filters there does need to be one in every jackpoint that has a phone or other device that uses the phone line. Also the plug in filters are a common point of failure so it's worth swapping them around or replacing them when problems occur to see if it's one of the filters While the filter is mainly for the phones benefit having an unfiltered phone connected can cause the xDSL connection to be unstable particularly when the phone is in use. |
dugimodo (138) | ||
| 1440998 | 2017-10-23 01:11:00 | Another:2cents: When there is more than one phone filter, they are effectively in parallel, so the high impedance presented to the ADSL signal is reduced which can degrade the ADSL. That is why more than 3 filters are not usually recommended. | Terry Porritt (14) | ||
| 1440999 | 2017-10-23 01:20:00 | does that affect the quality of the phone line, the broadband line, or both, and how does the effect show up? Yes. But from what I have found it causes noise on the phone mainly. |
pctek (84) | ||
| 1441000 | 2017-10-23 02:14:00 | Thanks everyone for the help. I'll report back on what we end up with. | Tony (4941) | ||
| 1 | |||||