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Author Topic: adsl noise issues and vdsl  (Read 9761 times)

Chrysalis

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adsl noise issues and vdsl
« on: November 26, 2012, 03:48:40 AM »

Hi

If a line has a history of noise itnerference on adsl, is it probable the same isues will disrupt vdsl2?

My history is on adsl/adsl2 my line had 50db attenuation and synced between about 5000 and 6400kbit depending on line conditions.  I had noice interference during weekdays at office hours, where the line would get an initial huge noise spike around 7am followed by on and off moderate noise burst until about 5-6pm.  I had no idea if was local or not, I am hoping was not local so the source is now near the fiber part not copper.  At weekends the line could hold 3-4db margin with a 7000+kbit sync even at night, this gives you an idea the extenct of the noise, but during the noise at say 7am on a monday the line would sync at maybe 3000kbit. (if I synced it at the time).  On any isp that used DLM the service was a nightmare.  It was useable when I was with ukonline who used SRA.

Ok so basically that line got cancelled shortly after ukonline closed shop, as I was annoyed losing SRA and since then I have been on virgin media cable, no noise issues that xDSL has but they have oversubscription issues aka congestion.

Fast forward to now and 2-3 days ago infinity is now available, no other FTTC isp's yet, I have put in an order.

The line is estimated at 65mbit down and 20mbit up, I know where the cabinet is and have guestimated the line route from the cabinet based on address checks I did on the BTw checker, lets just say the copper run is now probably 10% of the original run from the exchange so in my case there should be a huge difference.  There is a even nearer cabinet across the road from me I can see from my window but that isnt my cabinet, I am praying there is no noise source between my cabinet and me, but there is business's on the copper run including a petrol station.
Given what I have said and what should now be a much lower attenuation on the line, is it likely I will keep noise issues or not?  the occurances I read about on the net seem much lower so I have assumed vdsl has higher resistance.
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waltergmw

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Re: adsl noise issues and vdsl
« Reply #1 on: November 26, 2012, 02:10:00 PM »

Hi Chrysalis,


As Ofcom insists, there are many ISP's equally available to supply VDSL services such as Zen, AAISP, Plusnet etc. etc.

It is probably safer to assume that if you have noise problems on ADSL they will not disappear with VDSL, but will probably manifest themselves in different ways.

Kind regards,
Walter

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JGO

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Re: adsl noise issues and vdsl
« Reply #2 on: November 27, 2012, 09:14:00 PM »

Putting my radio engineer's hat on I would expect LOCAL RF noise to be worse since VDSL is ADSL with more REAL bandwidth (i.e. bandwidth in Hz ! ) This means the same cable is a better receiving aerial and whatever is emitting it also has a better aerial. 
This doesn't apply to crosstalk noise between the cabinet and exchange since fibre optic has no external EM field unlike wire cables.
   So it depends !     In my case as blocking bell wire pickup improved the ADSL speed some 50% I suspect local RF noise is quite strong.
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Chrysalis

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Re: adsl noise issues and vdsl
« Reply #3 on: November 28, 2012, 06:18:15 AM »

So basically I have to hope the inteference was on the exchange to cabinet link.  Otherwise I can expect it to be worse right?
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JGO

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Re: adsl noise issues and vdsl
« Reply #4 on: November 28, 2012, 10:36:39 AM »

It will never be 100% one or the other,  but yes if your local interference isn't serious you should be better off. I would be very surprised if ADSL to FFTC didn't gain you something, and in that case the source of interference should be simpler to locate  - just hope nobody treats themself to a plasma TV for Christmas - heard of one which apparently clobbered the FFTC speed by some 95% !
 Good Luck !
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Chrysalis

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Re: adsl noise issues and vdsl
« Reply #5 on: November 28, 2012, 03:11:00 PM »

yeah just seen a youtube video where a guy says he gets 4.5meg sync with plasma tv on.

I assumed better attenuation would make interference harder to interfere but what you say makes sense that there is more of a freqency range for the interference to grab onto :(
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Black Sheep

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Re: adsl noise issues and vdsl
« Reply #6 on: November 28, 2012, 04:13:23 PM »

Attenuation (in laymans terms), is really just the length of the connection from DSLAM to router. Obviously, there's a lot more science behind it.

In a way,you are correct, in as much as a lesser attenuation means less of a distance in which to pick up 'noise' interference. The longer the line, the more 'noise'.

However, you need to be aware that JGO is inferring towards 'REIN' noise, as opposed to the usual' noise' associated with any DSL circuit. This is normally defined as a dB reading against the 'signal' transmitted from the DSLAM, therefore = SNR (Signal to Noise Ratio).

What JGO is saying is, if you are suffering now with normal SNR levels, your circuit may well die if a REIN source induces into your circuit !! Plasma's are a known source of this.

I would request an engineering visit to check the integrity of your MPF (Metallic Path Facility).
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Ezzer

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Re: adsl noise issues and vdsl
« Reply #7 on: November 28, 2012, 09:10:24 PM »

Attenuation is like having a conversation with some one.
If the're close by then you can hear them load and clear (low attenuation), further away their voice is heard to be fainter (high attenuation)

And if further away then the odds of some other backround noise/s (SNR) getting in over the conversation becomes greater.
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Chrysalis

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Re: adsl noise issues and vdsl
« Reply #8 on: November 30, 2012, 02:55:46 AM »

Ezzer yes thats what I meant.

So since FTTC improves attenuation by shortening the copper run my initial thoughts were that the DSL signal would then more likely drown out the interference noise.

My copper run on ADSL is approx 3.5km due to hideous line routing between cabinet and exchange far from direct.
The copper run from cabinet to me is much more direct and of course shorter estimated around 200metres.

Also my interference wasnt a local plasma tv and I am also fairly sure it wasnt local, as the same interference used to affect someone a mile away from me.
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Black Sheep

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Re: adsl noise issues and vdsl
« Reply #9 on: November 30, 2012, 11:27:07 AM »

Not quite right, Chrysalis. Although the copper/ali 'run' is shorter on NGA, the 17a bandwidths being sent down them is far, far greater than the ADSL bandwidths.

I said it earlier, i'll say it again, request an engineering visit if you suspect your circuit isn't right.
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Chrysalis

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Re: adsl noise issues and vdsl
« Reply #10 on: December 05, 2012, 04:13:45 PM »

ok I have been connected all day, the old adsl issues happened during office hours and all day today I have seen no indications of errors or instability so early signs are VDSL is not havng the issues suggesting the interruption was on the E side.

Full 80/20 sync.

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Black Sheep

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Re: adsl noise issues and vdsl
« Reply #11 on: December 05, 2012, 06:39:18 PM »

I'm not getting this at all ??? The E-side used on your old ADSL link will be (or should be) exactly the same as the one used on your new VDSL connection ??
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Chrysalis

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Re: adsl noise issues and vdsl
« Reply #12 on: December 05, 2012, 06:46:31 PM »

E-side is exchange side of cabinet right?

that part is now fiber so immune to interference.

However I do know there is 2 routes from exchange to my cabinet a short and long route.

My old line was on the short route, my new one is on the long route (which if I was on adsl I would be unhappy about), so my new line is now also taking a different route.

All this aside tho, what reasons from your knowledge would make sense to you why noise issues on adsl go away with vdsl?

Do you reject the theory that when the dsl signal is noiser/stronger (better attenuation) it is more resistant to noise?
« Last Edit: December 05, 2012, 06:49:55 PM by Chrysalis »
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Black Sheep

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Re: adsl noise issues and vdsl
« Reply #13 on: December 05, 2012, 07:09:02 PM »

No, the bit that's fibre, is from the Exchange to the new cabinet.  Your complete VDSL connection, still begins it's journey at the Exchange on it's old and original Copper/Ali pair of wires.

If you can picture it, the dial tone leaves the Exchange on the original metallic path you had for ADSL. This dial tone then 'appears' at the old, original cabinet. The same dial tone is then sent to the new cabinet to have VDSL added to it, then both frequencies (Dial tone and VDSL) are sent back to the old cabinet to be connected to the D-side wires, which continue on their way to the telegraph pole, etc ...

You could have an extremely faulty E-side that you are introducing to the VDSL signal, and would be 'seen' by the DLM and actioned appropriately.

When we convert from ADSL to VDSL, we don't supply new E-sides, we use existing ones, so I don't see the correlation between you moving from a short route to a long route (Exchange to Cabinet) ????

To answer your question, audible noise issues don't just go away when conversion is carried out. There could have been a HR connection at the cabinet that has been inadvertently cured during the course of the conversion. Same with any internal wiring or socket issues. In short, a fault on ADSL will generally be magnified on VDSL, rather than 'go away'.   
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JGO

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Re: adsl noise issues and vdsl
« Reply #14 on: December 05, 2012, 07:12:37 PM »

Is the important point Crysalis' "Interference WAS on E side ". i.e. with FFTC,  pickup on the exchange to cabinet isn't there any more so hence better results ?
Yes if you include "E side" as also at exchange, ISP's server and perhaps on trunk line, that would be the same.
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