Exactly my thoughts. He is an `engineer` and after rewiring my sockets he was getting no signal at all where I was previously using an adsl router so something was not right. he then proceeded to using a different pair and got signal. But even then I was asking him questions about fibre he was not very clued up about it I could not have an interesting conversation with him about the tech at all. Maybe he was having a bad day who knows.

And on a side note. My appointment was between 8-1pm. He never turned up on time and then I had to ring my provider for them to make sure that he was still coming. An hour and twenty minutes later a phone call..
He was coming after all. He said that my job only appeared on his thingy at around 1pm. How is that for organising the works at BTO.

There would be no way for me to prove a fault. The connection istelf was still decent enough and my gut feeling would not warrant a visit from bt. Just proves the point that sometimes the simplest solutions can make a huge difference. 5 minutes and one screwdriver + punch tool =

12-13 meg incresae in max attainable.
Sync up from 36-37 to 39996
SNRm up to above 8 from 4-6
Almost no errors

Two days later still nothing exploded so it might be alright

In reply to a post by Zarjaz:

Polarity is only important after the master socket, so no need to touch anything before it any way.

After master but before modem? How and where could this be done?

The polarity mentioned only affects telephony, and very rarely at that too. Faint faults on cordless phones, and constant bell ringing on older corded phones. This being due to an A/B reversal after the NTE.

So its possible that re-sitting wires did the trick then. Cheers

It could well be, maybe just poorly terminated by the engineer originally. Let's hope it all stays hunky dory from now on.

And by proxy, if it's incorrect before the master socket, it's likely to be incorrect after it...

How would you influence the polarity after the master socket, extensions excluded?

Paul

Edited by deleted (Thu 28-Aug-14 09:56:37)

Morning Kamil

I had a some-what similar experience many years back, when installing two DEC VT 102 Terminals, by "Current-Loop" to a DEC PDP 1/11 Computer.

Not identical though.

The CL Cable had two pairs of colour-coded insulated wires and one bare earth wire.

Works Engineering ran two cables in through the false ceiling void, to the far end of the mainly open-plan office, one terminating in that main area and the other in a private office almost immediately adjacent. So a lot of disturbance etc.

I terminated and connected the shorter cable, no problems of any sort.

But I just could not get the slightly longer cable to function, testing it for continuity etc - but limited in part by the distance separating the ends.

Fortunately, the office incumbent was not particularly keen to have a working terminal, so I gave up etc.

Some months later, that incumbent moved to a new job (Managing Director); and his replacement insisted on having a working terminal.

I tried for some time to get the cable to function - to no avail.

In desperation, I swapped over the two pairs of wires at the terminal end.

Hey Presto, IT WORKED.

Whilst some strange mix-up in the middle of that local cable run could explain the result,. I suspect that there was an inadvertent swap somewhere in the very much longer and convoluted run back to the Computer Room.

In reply to a post by Kamil:

Can someon please tell me if my interleaving depth is substantial or fairly small?

The depth is actually pretty irrelevant: Depth is a value negotiated by the modems in order to meet the requirements laid down by DLM. Those requirements are the things that are much more interesting.

DLM has set INP=3.0 and delay=8ms downstream, and nothing upstream. This is a fairly standard setting by DLM, usually used as the first attempt to improve quality/reduce errors. It shows that DLM has intervened, but it hasn't had to go further.

With these settings by DLM, the modems then choose (during sync negotiation) the interleaving depth & width (parameters D and I) to match these INP and delay factors... but you get to see the real impact in the form of the additional delay in the extended ping times (ie the 8ms).

Some other parameters negotiated by the modem also tell you more than the raw depth. The R and N parameters tell you how much FEC (self-correction) overhead is being used.

Downstream, you have 16 bytes out of every 74, or roughly 22% of your capacity. This is used to give the Impulse Noise Protection (INP) of 3.0 symbols when combined with the 8ms of interleaving.

Upstream, the modems have chosen to add 16 bytes of overhead in every 254 bytes, or roughly 6%. DLM has not asked for this protection, but it seems that modems often incorporate this during negotiation when there is spare capacity available. Note that this is just FEC protection upstream, but without any interleaving (D=1).

And by proxy, if it's incorrect before the master socket, it's likely to be incorrect after it...

The salient point being that polarity is only ever an issue on extension wiring, the polarity before the NTE matters not one iota*. The only thing that requires 'influence' is the termination on the extension socket, the polarity is was it is from the NTE's out put.






*There is a minuscule amount of earth calling lines running to VERY old PABX systems on which are polarity conscious. These lines are rarer than hens teeth these days.