line attenuation... should it change??

[markusbrodie]

hi all,

apologies if this has been answered somewhere else or is a daft question, but basically, i've had my Sky BB since late June/early July this year. Though not in the master socket (i've tested there and got almost exact same results) the Router has been plugged in to the same socket the whole time (other than the test mentioned above). However, i've noticed a change in line attenuation and noise stats of late and i'm a bit confused.

basically, after original connection and DLM process, downstream line attenuation was at 52.0db, upstream 31.0db, with noise margin 9.7db downstream and 13.0db up.
However recently the line attenuation is now saying 55.5db downstream and 29.9db up.... i thought this was to do with the amount of cabling i.e. distance from the exchange... so surely this should remain static?? the worry being that if the line attenuation is increasing (for whatever unknown reason) then my already paltry connection speed, currently 3mb, will drop... or again, is that completely wrong and i'm getting myself confused??

any advice/info greatly appreciated.

thanks

[Isitme]

The attenuation is a measurement of the length and condition of your line. The two main reasons it may increase is if there is a fault on the line or if you have been moved from G.DMT to ADSL2+. If you post your stats, using only the ADSL cable supplied by Sky, preferably from your Test socket, we may be able to give some more advice.

[markusbrodie]

please see attached stats pics.. the slightly better line attenuation are from the test socket, the other is from master, which is again very slightly better than the socket i've always used that's recently changed...

[mjstokes85]

If attenuation is a measure of length then why is the downstream and upstream attenuation always different even though it's the same line?

[Isitme]

the slightly better line attenuation are from the test socket, the other is from master, which is again very slightly better than the socket i've always used that's recently changed..

It is quite normal to see a slightly lower attenuation in the Test socket. The only thing I can think of as to why you are seeing a higher attenuation in the socket you normally use is that something is interfering with the signal. If at all possible you should fit and use a filtered faceplate, this would give you the best possible signal.

@mjstokes85
Saying it was a measurement of length was probably not quite correct. It is more an indication of the length. Attenuation is the gradual loss of signal through the cable, the longer the cable, the greater the attenuation will be. Any degrading of the quality of the cable will also add to the total attenuation. I am not sure why the upstream attenuation is always lower than the downstream, but I think it may be because the upstream part of the signal uses a lower part of the frequencies available and attenuation is greater in the higher frequencies. This is one of the reasons that the attenuation increases when moving from G.DMT to ADSL2+. G.DMT(ADSL1) uses the lower frequencies so the attenuation is lower..

[mjstokes85]

It is quite normal to see a slightly lower attenuation in the Test socket. The only thing I can think of as to why you are seeing a higher attenuation in the socket you normally use is that something is interfering with the signal. If at all possible you should fit and use a filtered faceplate, this would give you the best possible signal.

I must admit one of the best things BT did for me was install a filtered faceplate, for a start it looks much tidier than having the microfilter hanging out the socket, and secondly, I was told that they filter out a lot more noise than a standard filter. My attenuation has dropped by 0.5 of a db since the filtered faceplate.