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Previously on "Looking for an expensive DSL filter"
I had a rummage the other day and came across a parallel printer cable. Do you reckon these will come back into fashion one day or should I just chuck it.
You never know
Shhh! Keep this to yourself, but global warming may see the resurrection of old technology as the high tech producers like Korea and Japan etc. fall back into the days of dark age feudalism, causing the western world to fall back on their own capabilities.
Just out of curiosity I went quickly through my spares (Junk) cupboard.
I have:
11 spare DSL filters
9 Assorted Harddrives
2 5 1/4 floppy drives
4 3.5 floppy drives
about 30 kilo of assorted cables
6 power packs
and a large box of assorted memmory, vid cards etc
Well!
It may come in useful one day
I had a rummage the other day and came across a parallel printer cable. Do you reckon these will come back into fashion one day or should I just chuck it.
Due to the way it uses the frequency spectrum, ADSL deployment presents some issues. It is necessary to install appropriate frequency filters at the customer's premises, to avoid interference with the voice service, while at the same time taking care to keep a clean signal level for the ADSL connection.
In the early days of DSL, installation required a technician to visit the premises. A splitter or microfilter was installed near the demarcation point, from which a dedicated data line was installed. This way, the DSL signal is separated earlier and is not attenuated inside the customer premises. However, this procedure is costly, and also caused problems with customers complaining about having to wait for the technician to perform the installation. As a result, many DSL vendors started offering a self-install option, in which they ship equipment and instructions to the customer. Instead of separating the DSL signal at the demarcation point, the opposite is done: the DSL signal is filtered at each phone outlet by use of a low-pass filter for voice and a high-pass filter for data, usually enclosed in what is known as a microfilter. This microfilter can be plugged directly into any phone jack, and does not require any rewiring at the customer's premises.
A side effect of the move to the self-install model is that the DSL signal can be degraded, especially if more than 5 voiceband devices are connected to the line. The DSL signal is now present on all telephone wiring in the building, causing attenuation and echo. A way to circumvent this is to go back to the original model, and install one filter upstream from all telephone jacks in the building, except for the jack to which the DSL modem will be connected. Since this requires wiring changes by the customer and may not work on some household telephone wiring, it is rarely done. It is usually much easier to install filters at each telephone jack that is in use.
DSL signals may be degraded by older telephone lines, surge protectors, poorly designed microfilters, radio frequency interference, electrical noise, and by long telephone extension cords. Telephone extension cords are typically made with small-gauge multi-strand copper conductors which do not maintain a noise-reducing pair twist. Such cable is more susceptible to electromagnetic interference and has more attenuation than solid twisted-pair copper wires typically wired to telephone jacks. These effects are especially significant where the customer's phone line is more than 4 km from the DSLAM in the telephone exchange, which causes the signal levels to be lower relative to any local noise and attenuation. This will have the effect of reducing speeds or causing connection failures.
Last edited by Spacecadet; 18 December 2009, 09:46.
Having established that my DSL filter is on the blink, I need a replacement. (Well it has always blinked irritatingly, but I mean is now almost knackered.)
However, a quick web search established that these are ridiculously cheap, only a couple of quid, and I wonder if there are perhaps better models available for a bit more, for example with multiple sockets.
Crazy as it may seem, I don't feel comfortable paying such a pittance.
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