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[ben_strange]

Hello,

I've been trying to get my grandparents internet fixed for nearly six months now. Openreach suspected REIN. They've been out 6+ times now, and the more recent times have been one of their best engineers in the area.

So far they have:

Replaced the master socket,
New overhead cable from the house to the pole,
That didn't make it any better, so they ran a new cable straight to the DP pole, bypassing the closer carrier pole,
Still didn't make it any better, they ended up finding the line sat in a pool of water in poor condition in a manhole about 500m away. Since then, it has been much better, more consistent speeds and far less dropouts.

I've recently fitted an unlocked HG612 3B modem to try and do some of my own logging using a Raspberry Pi. So far, going well. It's picked up huge spikes in ES and FEC's, and also large dips in the SNR. I've just been playing around with DSL Stats some more tonight, and was just looking at the bit loading graph (attached) would somebody be able to tell me if it looks normal or not?

Thank you very much,
Ben

[Weaver]

Welcome, Ben!

[burakkucat]

I've recently fitted an unlocked HG612 3B modem to try and do some of my own logging using a Raspberry Pi. So far, going well. It's picked up huge spikes in ES and FEC's, and also large dips in the SNR. I've just been playing around with DSL Stats some more tonight, and was just looking at the bit loading graph (attached) would somebody be able to tell me if it looks normal or not?

A profile 17a G.993.2 service has 4096 sub-carriers available for use. The image you have shown is truncated at about sub-carrier 2220 so we do not have the full picture. However what we can see is reasonable . . . I guess it is the big "notch", centred at about sub-carrier 270, that has you wondering. Yes, that is normal. It is the down-stream power back-off, which is related to the distance between the cabinet and its serving telephony exchange.

[Weaver]

What Burakkucat said ^^^^.

My understanding of it, which is limited since I am not lucky enough to have VDSL2, is :

I think that notch is a policy thing, a rule or restriction which limits the transmit power your line gets at certain frequencies, and this restriction is to prevent your line, which is acting as a transmitting antenna, from creating too much interference for other users.

I think it was Kitz who enlightened me on this, hope I remember correctly.