New FTTC install with pre existing HR fault..

My FTTC is scheduled to be installed on the 9th but I have a long standing intermittent HR fault on the line that started about 2 years ago and has been getting worse and more frequent ever since..

I have never been able to convince my ISP to get an engineer out despite providing them with a TDR graph showing the location of a possible HR dis, all i end up doing is going around the usual testing that ends up masking the problem for a few weeks..

Will the FTTC engineer test the cable pair and pick this fault up before providing the FTTC connection, last thing i need is a [censored] FTTC connection..

if you lucky the fault is on the exchange to cabinet run and FTTC will then bypass it.

Where did the fault show? Between you and the cabinet (D-side), or the cabinet and exchange, (E-side)?

Sounds like an ideal time to cancel that upgrade and migrate, unless you already are doing so, as if FTTC doesn't cure it you are really stuck for at least 12 months . WHich ISP is it?

I can only estimate the cable run to the cab but i get it to about 250 meters the HR shows up at about 301 meters on the TDR but 301 meters is almost exectly where a BT box on the payment is located so it looks like its on the D-side

To be honest i`m no expert at TDR testing I just have a ADSL tester that has TDR function for work

I`m moving to FTTC with BT from Be.

Be to be fair have been great but all that ends up happening after jumping through all the hoops we end up just masking the problem until the fault re-appears.

Sounds as though it could be in the cabinet. Does your estimate for distance include, up the pole, the additional cable in the overhead catenary, the run into the house?

If in te cabinet then there isa good chance any connection will be remade.

As MHC says.

In case you don't know, for FTTC the phone line (PSTN) from the exchange has to be connected in the phone cabinet (PCP) to a copper pair that goes to the FTTC cabinet. On the DSLAM in that the fibre feed and PSTN get onto a return copper pair to the PSTN cabinet and from there a connection is made onto the cable from you to it. So I imagine every connection, (to do with you), in the cabinet is remade.

So is there some sort of termination or filter to stop the VDSL2 signal from propagating up the D side so a HR fault on the D side would not affect the E side ?

If that question makes sense

In reply to a post by TimLaduk:

So is there some sort of termination or filter to stop the VDSL2 signal from propagating up the D side so a HR fault on the D side would not affect the E side ?

If that question makes sense

Depends on what you mean by d-side and e-side?

sorry was going of what rebertos said but i got it the wrong way round

Between you and the cabinet (D-side), or the cabinet and exchange, (E-side)?

That reads as though you have E-side and D-side mixed up, or at least as I was referring to them, which was in terms of your existing line.

Both MHC and myself are suggesting the fault could possibly be a connection within the PCP, and that all your connections in there could change, so curing it as a side-effect.

But if the fault is on the D-side, ie between you and the PCP rather than inside it, then your FTTC will be probably be affected.

If the fault is on E-side now, between the PCP and the exchange, there is a high probability that although it will still be there it will not affect the FTTC. In time it would probably get worse and in time the phone will fail and they will fix it, but I would expect the FTTC, (I don't know), would carry on regardless even then.

We have a PSTN E-side problem which used to really hurt the ADSL, but on FTTC things are fine.

(Edit - got interrupted by a phone call, so didn't see your correction, but leaving this post here ).

Edited by RobertoS (Mon 02-Jan-12 15:02:31)

No thanks that really help i`m convinced the fault is at the PCP or just E-side so i`m optimistic

Just ask the guy to check when he installs it - the problems you have had in the past are related to getting an engineer out. Now you'll have one in your house, so just talk to him...

Our neighbour's installation took a while, as the engineer had to fix a problem with their line (between home & cab).

I will my wife was going to stay in for the BT engineer but i have booked the day off now should be interesting to see what he says..

Well it was installed today and i`m getting the ful 40/10 service so i`m very happy...

I dint ask the guy to look at the possible line fault he looked totally stressed out i was his second of 5 FTTC installs today, so i just let him get on with it...

Good luck with it.

No doubt you will be back before long if it does play up, but if it doesn't I wouldn't mind knowing when it has been long enough to be pretty certain to be OK.

Then there will be two of us with evidence for any doubters.

Can you retest with the TDR and see if it shows up.

Fault could always have been somewhere between the cabinet and exchange so that would disappear with FTTC as that section of the line is no longer carrying the DSL signal.

Good thinking. Presumably it would if it is e-side, and not if it was within the cabinet as the two of us thought possible?

Edited by RobertoS (Mon 09-Jan-12 17:36:06)

Another way of seeing if the HR was in the cab, if the OP can run the TDR again, the DSLAM cabinet will be clear as it shows as a pulsing 'spike' on the TDR in the DSLAM terminations.

In reply to a post by Zarjaz:

Another way of seeing if the HR was in the cab, if the OP can run the TDR again, the DSLAM cabinet will be clear as it shows as a pulsing 'spike' on the TDR in the DSLAM terminations.

Im assuming that's a positive spike ?? i will try and do it tonight if i have the time, its just a pain getting behind the tv cab to get to the master socket..

Yes, well it is with both the TDR's I use.

In reply to a post by TimLaduk:

In reply to a post by Zarjaz:

Another way of seeing if the HR was in the cab, if the OP can run the TDR again, the DSLAM cabinet will be clear as it shows as a pulsing 'spike' on the TDR in the DSLAM terminations.

Im assuming that's a positive spike ?? i will try and do it tonight if i have the time, its just a pain getting behind the tv cab to get to the master socket..

It is, when a 301C is used.

Ok well good news the HR has gone !!! and it looks like it was in the cab

so here is the last TDR i did ( that i showed Be* ) i marked the HR at 301 meters it could be less because may not be using the correct cable settings..

http://img69.imageshack.us/img69/8205/tdrtest.jpg

Here is today's TDR i can see a joint at 301 meters but no HR and the FTTC cab is at 356 meters witch is totally consistent with where it is..

http://img853.imageshack.us/img853/9868/jan102057tdr...

So this tell me something either the last engineer that came out to look at this 2 months ago did not change the jellys in the cab like he said or the corrosion had gone up the cable and he needed to cut more off...

In reply to a post by TimLaduk:

My FTTC is scheduled to be installed on the 9th but I have a long standing intermittent HR fault on the line that started about 2 years ago and has been getting worse and more frequent ever since..

I have never been able to convince my ISP to get an engineer out despite providing them with a TDR graph showing the location of a possible HR dis, all i end up doing is going around the usual testing that ends up masking the problem for a few weeks..

Will the FTTC engineer test the cable pair and pick this fault up before providing the FTTC connection, last thing i need is a [censored] FTTC connection..

All my problems (that 2 engineers visits couldnt fix) vanished in to thin air after moving to FTTC.

In reply to a post by Alnath:

All my problems (that 2 engineers visits couldnt fix) vanished in to thin air after moving to FTTC.

Even the credit card balance?

Robertos did you check my tdr graphs i posted ?

Yes, but they are beyond my ken. I was expecting one of the engineers who had responded to comment, but most of them have something called a job to do, so maybe they will in time .

In reply to a post by RobertoS:

Yes, but they are beyond my ken. I was expecting one of the engineers who had responded to comment, but most of them have something called a job to do, so maybe they will in time .

This maybe of an interesting read to you then, judging by all the tech stuff on your site..

http://documents.exfo.com/appnotes/anote168-ang.pdf

That's great, thanks for the link.

When I'm in the mood I shall see if the relevant brain cells still work and read it thoroughly.

The graphs are very interesting. What TDR equipment are you using?

It's hard to see because of the graph scaling. but it looks like you are getting a phase-reversed echo at ~300 metres. That would suggest a short circuit.

Can you change the scale on the Y axis to get a better look at the characteristics of the reflected pulse?

cheers, a

Are you looking at the original graphs, or the new ones now all the cab connections have changed?

The first link looks very much the screen of an Exfo tester, and since there was something in the other link mentioning Exfo as well ........

I concur. You need to increase the gain if possible to get a good reading (and depends on the quirks of the TDR itself - used 5 different ones extensively each had own unique ways of reading things).
The negative dip does imply a short circuit fault (a dis or hr dis would be positive and a joint a sideways s shape) - if it was HR you can measure each leg by earthing one leg of the pair and tester and then swapping to other pair doing same - if reading doesnt change it is just a joint - if only on one leg it shows which leg is faulty and of course the distance.
Impossible to say without a suite of tests and or voice symptoms, but I would deduct from the graphs that you had a rectified loop (partial short) which has been resolved by upgrading to FTTC as the jumper wires and connections would have to be renewed. I have seen old jumper wire get this way (as rubs against metal rings in cab over time) - especially old red / white type.

One good bit of news for non tdr weilding users is that the BT test system is being upgraded with CIDT test head which when testing towards a working dsl modem can detect the previously hidden HR faults - so if you think you have a HR fault ring your ISP and ask top run a line test.
Oh, you need to measure by swapping from each leg of the pair with one wire from tdr to line - one to earth, and the untested leg of line to earth (didnt make very clear above).
- Telecom Engineer

Yes indeed its an EXFO and I still have no idea how to get the best out of it, I mainly use it for ADSL testing and finding bridge taps on internal wiring in old buildings that could be causing problems..

thanks for the extra info for testing, i think it will be a while before CIDT will be rolled out nation wide they have only just finished the trial

Just what I could do with - both the EXFO and CIDT

Wouldn't have a clue what to do with the EXFO though, despite the info provided