cancel
Showing results for 
Search instead for 
Did you mean: 

Plusnet hub One noise margin explanation

malkpm
Grafter
Posts: 29
Fixes: 1
Registered: 14-11-2016

Plusnet hub One noise margin explanation

I have looked through the forum but cant find an explanation.

My noise margin is

8. Noise margin: 6.3 / 4.5
9. Line attenuation: 18.9 / 40.3
10. Signal attenuation: 18.9 / 31.8

What I would like to know is what do the two figures represent either side of the /  .

Am sure there is a simple explanation.

Am on FTTC with Down 5.23  and Up 1.129

 

Thanks for looking.

12 REPLIES
MrSilver
Pro
Posts: 550
Thanks: 88
Fixes: 9
Registered: 05-10-2016

Re: Plusnet hub One noise margin explanation

I believe the same holds for VDSL but this might be worth a read. http://www.kitz.co.uk/adsl/linestats.htm 

the noise margin stats here are how much headroom the link needs to keep it stable, so bigger the number then bigger the margin from the max possible and what you get. (im sure someone can explain  that is better english!)

So the either side is up / down SNR margin (not the Signal to noise ratio but the margin).

 

Are you saying your FTTC has a download speed of 5.23? that is VERY slow, or is that a different number you are quoting?

Plusnet Staff
Plusnet Staff
Posts: 2,123
Thanks: 362
Fixes: 115
Registered: 22-08-2015

Re: Plusnet hub One noise margin explanation

The way I like to explain the noise margin, is by imagining broadband like a set of scales.

There's stability and speed; if the noise margin is low then the line is remaining stable and the DLM is trying to give you the best speed.

However if stability falls and the line drops, the noise margin will increase, lowering your speed to try to make things more stable.

As @MrSilver has pointed out your speed seems incredibly slow for FTTC. It may be due to the length of your line however I'll run a few checks once I'm in the office later today.

I hope this helps.
I've joined the Plusnet Help Team as of May 2017. As such, I have a new forum account. Please direct any queries to @Gandalf. Thanks

 Anoush Mortazavi
 Plusnet Support
jafreer
Rising Star
Posts: 823
Thanks: 45
Registered: 13-10-2012

Re: Plusnet hub One noise margin explanation

@Anoush - There is another scenario where SNRM can be high but your line can still be stable with no DLM intervention. That is when you are syncing at maximum and still have SNRM headroom. So the thing limiting your speed is the maximum rate of the product, not a target SNRM. In these cases, your SNRM can be higher than the target SNRM.

Plusnet Staff
Plusnet Staff
Posts: 2,123
Thanks: 362
Fixes: 115
Registered: 22-08-2015

Re: Plusnet hub One noise margin explanation

True. An example of that would be on a 20CN product that has a maximum sync of 8128 kbps.

I've joined the Plusnet Help Team as of May 2017. As such, I have a new forum account. Please direct any queries to @Gandalf. Thanks

 Anoush Mortazavi
 Plusnet Support
Browni
Seasoned Champion
Posts: 1,618
Thanks: 464
Fixes: 36
Registered: 02-03-2016

Re: Plusnet hub One noise margin explanation

My stats show what @jafreer is describing...

6. Data rate: 19999 / 79903
7. Maximum data rate: 31812 / 95735
8. Noise margin: 15.1 / 10.2
9. Line attenuation: 11.5 / 11.5
10. Signal attenuation: 11.3 / 11.5
I must have been really bad in a previous life. This is my 3rd ISP in a row that uses lithium.
malkpm
Grafter
Posts: 29
Fixes: 1
Registered: 14-11-2016

Re: Plusnet hub One noise margin explanation

Thanks to all for the explanations. Someone has done something today. This is the fastest I have ever seen it. Just hope it lasts.

 

8. Noise margin: 6.2 / 3.8
9. Line attenuation: 18.9 / 39.9
10. Signal attenuation: 18.9 / 32.1

DSL Line Status

Connection Information

Line state: Connected
Connection time: 0 days, 01:45:45
Downstream: 7.206 Mbps
Upstream: 1.133 Mbps
 
malkpm
Grafter
Posts: 29
Fixes: 1
Registered: 14-11-2016

Re: Plusnet hub One noise margin explanation

Thanks for the reply. I think someone has tweaked my settings as speed has increased.

My cabinet is 1 mile away. I am not living in the countryside. I did ask Openreach last September if they knew of any plans to install a new cabinet. I feel I had a brush off no. The trouble with large organisations is that you cant get to right person. I suppose they would tell me that I am not their customer.

 

Thanks again for your time.

 

DSL Line Status

Connection Information

Line state: Connected
Connection time: 0 days, 01:45:45
Downstream: 7.206 Mbps
Upstream: 1.133 Mbps
 
Plusnet Staff
Plusnet Staff
Posts: 2,123
Thanks: 362
Fixes: 115
Registered: 22-08-2015

Re: Plusnet hub One noise margin explanation


malkpm wrote:

Thanks to all for the explanations. Someone has done something today. This is the fastest I have ever seen it. Just hope it lasts.

Happy to hear your speed is better. I'd love to take the credit, however I've just looked into your account now. Not aware anyone else has opened your account today. Glad to hear it, all the same.

 

Testing your fibre, the router is in sync at 7.2 Mbps which is at the top end of the estimate. However, just from looking at your connection, there appears to be an issue somewhere as there more drops than I'd like to see.

 

 

I'd advise to try connecting your router into your test socket (if you haven't already and if you have one). Explained here: https://community.plus.net/t5/Library/Testing-From-The-Master-Socket/ba-p/1322242

 

Possibly to then raise a fault to us at http://faults.plus.net if the drops continue.

I've joined the Plusnet Help Team as of May 2017. As such, I have a new forum account. Please direct any queries to @Gandalf. Thanks

 Anoush Mortazavi
 Plusnet Support
malkpm
Grafter
Posts: 29
Fixes: 1
Registered: 14-11-2016

Re: Plusnet hub One noise margin explanation

Thanks Anoush. I am always connected to the master socket. And yes, I have been having dropouts. 

Plusnet Staff
Plusnet Staff
Posts: 2,123
Thanks: 362
Fixes: 115
Registered: 22-08-2015

Re: Plusnet hub One noise margin explanation

I'd probably advise to raise a fault to us to investigate. Smiley
I've joined the Plusnet Help Team as of May 2017. As such, I have a new forum account. Please direct any queries to @Gandalf. Thanks

 Anoush Mortazavi
 Plusnet Support
jafreer
Rising Star
Posts: 823
Thanks: 45
Registered: 13-10-2012

Re: Plusnet hub One noise margin explanation

I think one of the reasons you are seeing speed variations could be because of SNRM fluctuations combined with your frequent disconnections. I don't know what is causing the disconnections or whether that is related to the fluctuating SNRM but consider the following...

SNRM is not a fixed value and can fluctuate depending on a number of factors (atmospheric conditions, rain, time of day, noise, switching of time clocks, street lighting etc). When you sync to the cabinet (power cycle the modem for example), the speed you will connect at will be based on your current SNRM (along with other factors, e.g. banding if it is applied). Also, on a stable connection, the connection usually holds even in fluctuating SNRM conditions (as long as they don't drop too low). However, once you add frequent disconnects into the equation, your connection speed will come back based on whatever the SNRM currently is. Which could be lower or higher than your previous connection speed.

For example, I have a stable connection that rarely ever drops. I also have some fluctuation of SNRM but it never falls low enough to drop the connection. So if I monitor my SNRM and choose a point in time where it is higher than the nominal 6dB, and I disconnect, I will reconnect at a faster sync rate than I just had. That is because on reconnection, the SNRM will again be reset to 6dB, giving me a little more speed. Conversely, if I pick a point in time where my SNRM is lower than the nominal 6dB, and disconnect, on reconnection my sync speed will be lower than it was.

Now, If I wasn't paying any attention to SNRM values, and my connection dropped for some reason, it could come back with a nice speed increase (or a speed decrease), or somewhere in between.

So unfortunately this does not answer the question as to what is causing your disconnects, but it may explain why you are seeing speed fluctuations.

malkpm
Grafter
Posts: 29
Fixes: 1
Registered: 14-11-2016

Re: Plusnet hub One noise margin explanation

Just a follow up. My speed is now the best ever. Not sure who did what but a BIG THANK YOU.

Still some disconnects but I will put up with them if I get this speed.

DSL Line Status

Connection Information

Line state: Connected
Connection time: 1 days, 05:37:54
Downstream: 7.555 Mbps
Upstream: 1.129 Mbps