cancel
Showing results for 
Search instead for 
Did you mean: 

Plusnet 1mb DSL and Attenuation query

N/A

Plusnet 1mb DSL and Attenuation query

I had the IPStream 1000 service activated on my line in the second week of october - so probably one of the early Plusnet trial connections. I've been using a Speedtouch 510v4 router, and within the first week of getting the connection up i checked the line noise information as given by the router. I had an attenuation downstream of 36dB, whereas when i checked it just today it gave me a value of 50 which is way outside the line noise limit! This is what the router gave me today:

Downstream Upstream
Margin [dB] : 19 27
Attenuation [dB] : 50 27
OutputPower [dBm] : 19 11

Ive resync'd the line but it still stays at 50dB (even flashed the router with new firmware). Funny thing is, i still get 960 odd on the PlusNet speed test now as i did earlier and 12-13ms pings to www.jolt.co.uk. Could it just be a faulty reading from the router? I suppose i could ask PlusNet to perform a woosh test on my line - but if it turns out the 50dB is correct i don't want my line to be cancelled as its working perfectly fine as it is.

Cheers for any thoughts,
nick
14 REPLIES
Community Veteran
Posts: 3,181
Thanks: 19
Fixes: 2
Registered: 31-07-2007

Plusnet 1mb DSL and Attenuation query

Could be cause of:


  • A faulty filter
  • Fault on your phone line
  • Damage to your cable from the router to the socket, causes = your Kids/Pets/Mice? Mice cause they have moved in now for the winter if your bordering a green belt, so if you have a old house with old ventialtion bricks could be you have mice. Had that 5 years ago they had completely ruined the line from the street to the main socket
Unvalued customer since 2001 funding cheap internet for others / DSL/Fibre house move 24 month regrade from 8th May 2017
Community Veteran
Posts: 14,469
Registered: 30-07-2007

Plusnet 1mb DSL and Attenuation query

Have you tried with just the modem connected to the master socket - i.e. without any filters, phones or extension sockets connected.

Lines can degrade over time and they can also be rerouted / changed by BT.

The fact that you still get good speeds just goes to show BT were conservative in their db figures for >512K ADSL capability or the figures you are getting are wrong. Ask Plusnet to do a Whoosh test on your line via contact us just in case your modem is giving false info (i.e. it's testing could now be faulty not the line).

Cheers

Peter Cool
N/A

Plusnet 1mb DSL and Attenuation query

I think you will find it is the damp weather conditions of late. This can play havok with any mechanical connection down the line (on your local telegraph pole, green street corner box etc) and add to the Db loss figure. Generally, a loss figure obtained due to extra capacitance as caused by damp conditions does not decrease the signal to noise ratio.
If your SNR (signal to noise ratio) has dropped as well, then PANIC.
N/A

Plusnet 1mb DSL and Attenuation query

where do i find the SNR?
N/A

Plusnet 1mb DSL and Attenuation query

I am not 100% sure, as I do not know the Speedtouch 510. However, I would guess it is the "margin" figure you have already quoted. Although, there would normally be an upstream and downstream figure quoted.
The 19db or so you quote is not bad, indicating a signal over 70 times stronger than the background noise on the line.
The higher the SNR figure the better as it indicates the signal strength over the background noise.
The opposite is true for the attenuation figure, here the lower the better as it indicates the signal loss between you and the exchange.
If the attenuation Db increases and the SNR DB reduces, your modem and the exchange will have increasing difficulty decoding the signal to such a point that you will have more retries than transfered data and increased loss of sync.

If it's still working for you, remember the saying - if it ain't bust, dont fix it.
N/A

Plusnet 1mb DSL and Attenuation query

hmm - just removed all other devices and plugged the router in without a filter - still says 50 for attenuation.

very strange... is it worth asking PlusNet to do a woosh test? if they find that the line is in fact at 50dB, will they put in a cease order?
N/A

Plusnet 1mb DSL and Attenuation query

Where did you get this idea that Plusnet would put a cease
order on your line ?
If your line was faulty and you had a poor result from
your whoosh test they would simply advise you that
if the matter was put to BT to investigate further, THEN
there would be a possibility that BT might cease the service,
not Plusnet. Ive heard this happen to people who have had very
high attenuation figures around 60dB but not as low as yours.
If your line is working fine then you really don't have a problem
even if the result IS 50dB.
Plusnet Staff
Plusnet Staff
Posts: 12,169
Thanks: 18
Fixes: 1
Registered: 04-04-2007

Plusnet 1mb DSL and Attenuation query

Hi,

If woosh shows your line loss as out of limits then we won't automatically cease the line.

However, if you later have a problem on the line and in the course of the investigation BT find the line loss to be over 45dB and they can't do anything to bring it back down and back within the limits then they may downgrade the service back to 512kbps (so long as it is under 64dB).
N/A

Plusnet 1mb DSL and Attenuation query

hehe nice to see people still up Smiley

Ok, well ive just raised a ticket explaining the situation and asking for a woosh test..

funny that though - i still manage to get 956k from adslguide speedtests!
N/A

Plusnet 1mb DSL and Attenuation query

Most common effect is loss of sync and constant
disconnections especially at peak times.
However thats a pretty fine router you have and
things really need to get bad, before it lets go . Lol
Good luck with the woosh test.
Plusnet Staff
Plusnet Staff
Posts: 12,169
Thanks: 18
Fixes: 1
Registered: 04-04-2007

Plusnet 1mb DSL and Attenuation query

Just finished work at midnight, which is why I'm still up.. Cheesy

It might just be your router reporting the loss incorrectly, I've seen differences of up to 15dB from a router to woosh. Sometimes they aren't that accurate, simply because the testing software can never be as good as woosh.

If you look at the design specification of G.DMT (the UK implementation of ADSL) it may allow 1Mbps to work at slightly greater distances and line loss to 2Mbps (not a lot, maybe 0.5-1km or 3-5dB), although at present BT don't differentiate between the 1 & 2Mbps services. So if your line loss figure is accurate, this may explain why you have a decent speed.
Community Veteran
Posts: 6,983
Thanks: 8
Registered: 10-04-2007

Re: Plusnet 1mb DSL and Attenuation query

Quote

Downstream Upstream
Margin [dB] : 19 27
Attenuation [dB] : 50 27
OutputPower [dBm] : 19 11



The figure called "Margin" is in your case the SNR (Signal to Noise Ratio) and looks fairly healthy.

The results diplayed by ADSL Modem or Routers can be quite a way out.
Where did you get the original figures from? was it the from the same modem.?
Have a Whoosh test done and ask for the results but bear in mind that the figure from the Whoosh test is up to 4 dB higher then the real figure. So if the test shows say 50 dB then your line is realy 46 dB.
N/A

Plusnet 1mb DSL and Attenuation query

the router gave me the initial numbers (a downstream attenuation of 36dB)

My ticket has had a "please test" note added to it, so hopefully ill know for sure in a little while Smiley
N/A

Plusnet 1mb DSL and Attenuation query

they told me the woosh test stuff wasnt working so ill have to ask again a little later...