Does this look right?

Went live with fttc recently was expecting 60Mbps+ as quite close to the cab and from what the checker indicated.

Had a noisy line with a constant buzz on it that the engineer that fitted the new faceplate mentioned, we'd put up with it for years because of solid 8mbps and didn't want shafting with £100+ bill.

Anyway engineer said all the lines in our estate seem to do it, then went away and said he'd found a spare pair and buzz is now gone. Line stats below using a fritz box 7490:

http://postimg.org/image/40gv4vklj/

How close? If you "guess" the route the line takes, how far is it?

From those speeds I would guess you are around 600-650m or so.

Certainly the drop in upstream to around 12Mbps ties in with a mid 50's downstream.


What did the original line check estimates give? for Clean and Impacted?

Also, can you post a link to the images under the spectrum tab?

It's about what I'd expect given the attenuation on the line. Almost identical to my stats and indicates a line length of 6-700 metres from the cabinet assuming typical 0.5mm diameter copper phone wire.

(I see that it's one of those boxes which miss labels noise margin/SNR margin as Signal to Noise Ratio. Although they are closely related, there's an important distinction).

These are my stats

6. Data rate: 11605 / 52689
7. Maximum data rate: 11516 / 60648
8. Noise margin: 6.0 / 6.1
9. Line attenuation: 29.4 / 20.7
10. Signal attenuation: 29.2 / 20.0

Note that both would seem to have interleaving turned on.

Edited by deleted (Sun 25-Jan-15 15:37:46)

In reply to a post by TheEulerID:

(I see that it's one of those boxes which miss labels noise margin/SNR margin as Signal to Noise Ratio. Although they are closely related, there's an important distinction).

I gave up with that many years back! Does any device give the real Signal to Noise Ratio? Internally they know what it is but never display it

SNR, SNR Margin/noise Margin and I even saw something like Excess Margin or Excess SNR. The latter was the amount of margin remaining after the operational margin was removed!

It's only an average of some kind or other across the frequencies anyway. IIRC DMT use to give them in the CSV file if you ticked the right box.

Of course it has to be a (presumably) weighted average of some sort, and it will vary across the frequency range (trending worse with increased frequency). The same with attenuation. However, the method must surely be defined within the relevant xDSL standards or we'd get big variations.

But none of this is an excuse for mislabeling the noise margin as signal-to-noise ratio.

From the relevant page on my website:-

Noise Margin is the non-technical term for Signal to Noise Ratio Margin (SNRM). Domestic standard modems and ADSL routers often use the terms Noise Margin or SNR when reporting on its value.

The value reported by these, unless they give both, is never the SNR (Signal to Noise Ratio).

The Signal to Noise Ratio, as its name implies, is the ratio between the strength of the signal and the level of noise on the line. That ratio is a major factor in determining the connection speed, as the higher the ratio the higher the possible speed.

The SNRM is a margin which by which the noise level can rise before connection is lost.

(That's been there since Jan 2010).

We certainly do get variations in attenuation reported depending on the modem manufacturer, so I expect they also vary on noise margin. Netgear and Thomson modem/routers were different - I was able to swap them with consistent results, and had more than one of each so it wasn't a particular unit.

Also all my Netgears would hold sync to 0dB reported margin, whereas all my Thomsons (which had the higher attenuation and gave lower sync) packed in around 3dB.

How do you get interleaving turned off, is it a wait it out or does it need resetting?

Wonder if it got turned on due to the noisy line when it first went live

Just wait it out - should be off in a couple of weeks.

In reply to a post by Rich44:

http://postimg.org/image/40gv4vklj/

Wow, I like this connection stats as it got the most important stats are G.INP, G.Vector and Impulse Noise Protection.

Not many VDSL2 modems and routers doesn't have that!