Hmmmm My Router Stats!!

Can anyone look at the linked image and tell me if that is normal for line statistics?!?!

Upstream Line Attenuation 1037 db !!
Upstream Noise Margin 6553 db !!

However my router syn'd and authenticated without issue (it would appear) because I am writing this to you!!

The n/m is presently 18 db

Is this more likely to be an issue with my router or the line? (Netgear DG843PN with DGTeam 1018)

Any advice appreciated.

Router Line Stats

I presume you are in the building next door to the telephone exchange, based on the downstream figures.

If the 4dB attenuation is sensible, then the upstream is most likely just a bug with the router GUI, when displaying a very small upstream set of figures.

If 4dB downstream attenuation is ok for location, then the sync speed is very poor. Any historical speed data for this line?

In reply to a post by MrSaffron:

I presume you are in the building next door to the telephone exchange, based on the downstream figures.

If the 4dB attenuation is sensible, then the upstream is most likely just a bug with the router GUI, when displaying a very small upstream set of figures.

If 4dB downstream attenuation is ok for location, then the sync speed is very poor. Any historical speed data for this line?

I have always struggled with my 'up to 24 mbit' connection as i think its due to my internal wiring, so i sync at 11 mbit (very stable after my ISP reduced my profile (i think).

They are in the process of upgrading out street cabs for FTTC, so i am about 20 metres from the cabinet (crow flies) or more like <100 as my phone line goes from back of house.

Would this have anything to do with it?

Is a high line attenuation better or worse?
Is a high noise margin better or worse?

Why is my downstream not affected?

Will FTTC have a significant improvement in normal ADSL 2+ connections?

Thanks again

In reply to a post by Anonymous:

In reply to a post by MrSaffron:

I presume you are in the building next door to the telephone exchange, based on the downstream figures.

If the 4dB attenuation is sensible, then the upstream is most likely just a bug with the router GUI, when displaying a very small upstream set of figures.

If 4dB downstream attenuation is ok for location, then the sync speed is very poor. Any historical speed data for this line?

I have always struggled with my 'up to 24 mbit' connection as i think its due to my internal wiring, so i sync at 11 mbit (very stable after my ISP reduced my profile (i think).

They are in the process of upgrading out street cabs for FTTC, so i am about 20 metres from the cabinet (crow flies) or more like <100 as my phone line goes from back of house.

Would this have anything to do with it?

Is a high line attenuation better or worse?
Is a high noise margin better or worse?

Why is my downstream not affected?

Will FTTC have a significant improvement in normal ADSL 2+ connections?

Thanks again

Hmmm, logged in now, I dont like being anonymous!!

Need to know whether the downstream attenuation is actually real? i.e. verify the basic info from another make of router

Low line attenuation is good, but if its really 4dB, then you are not connected to a street cabinet, but about 200m of cable to the telephone exchange building

In reply to a post by MrSaffron:

Need to know whether the downstream attenuation is actually real? i.e. verify the basic info from another make of router

Low line attenuation is good, but if its really 4dB, then you are not connected to a street cabinet, but about 200m of cable to the telephone exchange building

I am at least 1 km from the exchange I would say, more like 2 (15 mins brisk walk each morning takes me pas it)

I will check line stats with my DG834g tomorrow. Thanks

In reply to a post by Anonymous:

Will FTTC have a significant improvement in normal ADSL 2+ connections?

FTTC has nowt to do with ordinary ADSL connections ans cannot affect them.

I was under the impression that FTTC has nowt to do with ordinary adsl, I was more implying that OpenReach are doing work in the area at the moment, and my stats have changed quite significantly:

I have now fired up my trusty old free Sky router (DG834G re-flashed to DG Team f/w), and the (probably more reliable) stats are as follows:


Downstream
Connection Speed - 11003 kbps
Line Attenuation - 26 db
Noise Margin - 14 db


Upstream
Connection Speed - 928 kbps
Line Attenuation - 6 db
Noise Margin - 6 db


So my downstream has improved by about 8-10 db and the upstream by well over db???

I dont know why, but i would like to know if anyone can advise?


Anyway, basically i want to take advantage of this, but my router still syncs at 11000 each time.

According to http://www.kitz.co.uk/adsl/max_speed_calc.php i should be able to sync around 17600 with this line.

What should I ask my ISP (the most excellent ADSL24) to do to try and re-train the line?

Cheers all

The problem there is the downstream noise margin, which I would expect is causing pretty well all of the loss compared to a more usual 6dB.

You haven't said which ADSL24 package you are on, some are set at 9dB rather than 6dB. Could you tell us please?

It seems clear the stats from the other router are incorrect .

With the one you are now using you can tweak the sync-time margin down, so then see what can be achieved and whether or not it is stable. I would suggest a quite aggressive tweak initially, which could bring it down to around 6dB or 7dB. Please read and post the stats immediately after re-sync'ing with that setting.

In reply to a post by RobertoS:

The problem there is the downstream noise margin, which I would expect is causing pretty well all of the loss compared to a more usual 6dB.

You haven't said which ADSL24 package you are on, some are set at 9dB rather than 6dB. Could you tell us please?

It seems clear the stats from the other router are incorrect .

With the one you are now using you can tweak the sync-time margin down, so then see what can be achieved and whether or not it is stable. I would suggest a quite aggressive tweak initially, which could bring it down to around 6dB or 7dB. Please read and post the stats immediately after re-sync'ing with that setting.

My ADSL24 package (setup in Nov 2009) is "LLU ADSL2+ Home Special".

When you talk about "the one you are now using you can tweak the sync-time margin" are you talking about my router? Can you tell me where/how to do this (especially whether I increase or decrease the values!)?

When the line was first set up there as some instability, so (from what i can remember) i logged it with ADSL24 and they (increased/decrease?) the margin in order for my router to sync at a slightly slower speed and since then i can go a week or more without a disconnect.

Will my changing my router config not be impacted by that?

It's a long time since I used DGTeam, but it is on one of the pages.

However, you now have something else to consider. You have confirmed earlier instability, and that the noise margin was raised to stabilise the line. Raising the sync-time (connection time) margin reduces the sync speed and improves stability. Lowering the sync-time margin increases speed but makes the line less stable.

That's what it is for.

So if you lower it you are undoing what ADSL24 did to help you.

Not good .

If the instability was with the other router, that gave the dodgy stats, I suggest the first thing is to you see if you stay connected for considerably longer now than you did with that one.

If you do, then it would point to the router being faulty in other ways, and it is safe to try a bit of tweaking as earlier. If that works and also stays stable then ask ADSL24 to reduce it at their end.

If and when you do try a tweak, you can try any number between the 10 I suggested, and 90, and see what is stable. They are percentages but it's a logarithmic scale, so discussion gets complex. Basically 50% of the ISP end setting will reduce it by 3dB and 200% of the ISP setting will add 3dB.

In reply to a post by RobertoS:

If and when you do try a tweak, you can try any number between the 10 I suggested, and 90, and see what is stable. They are percentages but it's a logarithmic scale, so discussion gets complex. Basically 50% of the ISP end setting will reduce it by 3dB and 200% of the ISP setting will add 3dB.

If the sync is capped by rate, rather than noise margin, how do such tweaks work? Can they even overcome the cap?

I'm not saying this is necessarily the case here (although I think it might be). I've just never tried a tweak in such circumstances, and always wondered about this...

If sync is rate caped then no fiddling with target noise margin in the modem will change things

In reply to a post by RobertoS:

They are percentages but it's a logarithmic scale, so discussion gets complex. Basically 50% of the ISP end setting will reduce it by 3dB and 200% of the ISP setting will add 3dB.

It's not too tricky to do a direct calculation ; )

So, if you need precision and want to change the target noise margin by x dB, then just punch the following into Google, and this is the % you need to enter: 10^(x/10+2)

Eg you want to reduce the target noise margin from 14dB to 6dB. This is a change of -8dB. 10^(-8/10+2) = 15.8%

In reply to a post by MrSaffron:

If sync is rate caped then no fiddling with target noise margin in the modem will change things

Thanks. Makes sense, lol.

In reply to a post by vimto_girl:

In reply to a post by RobertoS:

They are percentages but it's a logarithmic scale, so discussion gets complex. Basically 50% of the ISP end setting will reduce it by 3dB and 200% of the ISP setting will add 3dB.

It's not too tricky to do a direct calculation ; )

So, if you need precision and want to change the target noise margin by x dB, then just punch the following into Google, and this is the % you need to enter: 10^(x/10+2)

Eg you want to reduce the target noise margin from 14dB to 6dB. This is a change of -8dB. 10^(-8/10+2) = 15.8%

That might be a little difficult for over 90% of the posters here I'm afraid. Many won't even know what a logarithmic scale is, or have a clue what your notation means.

A simpler method which suffices for the case in point, is to assume the target noise margin is 15dB, as it is usually set in 3dB steps. Then a simple iteration gives 6dB at 12.5%, based on what I posted earlier of halving or doubling equating to a 3dB change. As the tweaker in question works in 10% steps ....

Oh, by the way, punch the following "what" into google?

In reply to a post by RobertoS:

Oh, by the way, punch the following "what" into google?

She means the arithmetic expression after the colon in said sentence. Google will evaluate arithmetic expressions presented to it rather than doing a search. There is no reason it should present any difficulty to any poster here; they are quite capable of "punching" it in blindly w/out knowing anything about logarithmic scales or the notation employed. All they have to do is decide the x dB increase they wish to achieve.

BTW: Her formula is the inverse of one I showed you earlier in PMs.

Edited by XRaySpeX (Fri 13-Jan-12 00:40:59)

I mis-read the relevant paragraph in her post.