Kitz Forum

Broadband Related => FTTC and FTTP Issues => Topic started by: gt94sss2 on March 23, 2017, 06:26:15 PM

Title: Possible FTTC issues with an alarm
Post by: gt94sss2 on March 23, 2017, 06:26:15 PM
I got a MDWS alert today saying that our FTTC line had disconnected - not a shock in itself as it had been up over a month - until I saw that it had reconnected at 52/3 MB rather than its usual 55/10 (with attainable at 60MB+)

I gather what happened is that my family got their alarm serviced today and discovered the alarm system wasn't connected to the phone line (i.e. all the extensions were disconnected) so the alarm engineer reconnected the extension wiring to the master socket.

I can't get to the socket at the moment to take a picture but was wondering if anyone can tell if the extension is incorrectly connected the extension wiring (or any other issue!) - say before the DSL filter - by looking at the stats for the line on MDWS (user: gt94sss2)?

The Hlog and Quiet Line tests certainly don't look pretty but I'm not an expert on deciphering them

Thanks
Title: Re: Possible FTTC issues with an alarm
Post by: burakkucat on March 23, 2017, 06:56:31 PM
There is certainly some perturbation of the Hlog plot for the lower frequency sub-carriers but it is not something that I have seen before. (Musing, in parenthesis, it looks as something is generating negative attenuation.  ???  )

Likewise, the QLN plot shows a veritable forest in the same lower frequency sub-carrier range.

I suspect that you have already made the correct diagnosis. The alarm circuitry has been incorrectly connected to the circuit.
Title: Re: Possible FTTC issues with an alarm
Post by: gt94sss2 on March 23, 2017, 07:00:32 PM
I note from the stats that my B0 INP reading has gone down slightly and the Interleave Depth seems to have halved - so not sure what is going on with  my line - I would have thought these were 'good things' not that the line should have lost speed as a result?

Edit: my post crossed with burakkucat's above..

How does one get negative attenuation on a line - I see it has fallen slightly..

I will see if I can get some pictures of the inside of the NTE - then just need to work out how to fix whatever it is (am not very gifted in this area:/)
Title: Re: Possible FTTC issues with an alarm
Post by: Black Sheep on March 23, 2017, 07:07:05 PM
The bane of broadband circuits ....... incorrectly connected, alarm system telephony wiring.

If you only have the bog-standard NTE5 configuration (No SSFP), then the alarm engineer should fit an appropriate filter within the alarm system itself. Conversely, if you  do have the SSFP set-up ..... then simply connecting to the lower front-plate will ensure the circuit is wired correctly.
Title: Re: Possible FTTC issues with an alarm
Post by: gt94sss2 on March 23, 2017, 07:11:28 PM
I know we have a Mk3 filter attached to the master socket. No idea how the alarm wiring is set as I was overseas when it was installed but imagine its been connected somewhere to the previously installed internal extension telephone wiring somewhere within the house which was otherwise unused (and disconnected - as I didn't know anything was using it!)

Will try and get some pics
Title: Re: Possible FTTC issues with an alarm
Post by: gt94sss2 on March 24, 2017, 10:01:26 AM
Still need to access the NTE5 so I can fix this but DLM in intervening on the line again this morning.

I am also getting a couple of resync emails from MDWS which don't show up as resync events when I look online:/
Title: Re: Possible FTTC issues with an alarm
Post by: gt94sss2 on March 27, 2017, 11:37:34 PM
Pictures soon I promise!... In the meantime DLM is working on my incorrectly wired line and when it resynced today MDLS reports that my attenuation had dropped to 15.5! :o

No idea how as its usually between 16-16.2 and I have never seen it this low.

Thats some negative attenuation!

Title: Re: Possible FTTC issues with an alarm
Post by: gt94sss2 on October 15, 2017, 12:55:19 AM
Erm.. 7 months might not quite be anyone's definition of soon but I have finally managed to access the relevant master socket and taken some pictures.

The socket usually has a Mk 3 filter on it but I have unscrewed it  which is when I took image 1 attached

After unscrewing the test socket, I then get to the phone/alarm wiring (images 2 and 3 from 2 different angles)

Grateful for any advice on what to do to rectify the alarm wiring without making anything worse (have never done this before so would benefit from simple instructions!) and if I can do it without tools etc or if I need a krone (? or alternative?)..

Title: Re: Possible FTTC issues with an alarm
Post by: Black Sheep on October 15, 2017, 09:08:38 AM
That imagery is too large for me to see it properly, but I think I see two cables connected to the phillips screws on the NTE back-plate ??

If so, one of them will be the 'feed' cable and meant to be there ..... the other will be the alarm cable, which shouldn't be there.

Very simple fix indeed. Simply terminate the alarm cable onto the NTE front-plate onto terminal 2 & 5 ... they are not polarity conscious so it doesn't matter which way round you connect the wires.
Then put the MK3 filter back in place and screw the whole thing back together.
Title: Re: Possible FTTC issues with an alarm
Post by: RealAleMadrid on October 15, 2017, 11:12:02 AM
Quite difficult to see from the pictures but there looks like there could be 2 white/blue wires on one of the terminals but only 1 blue/white on the other with a disconnected blue/white which appears to have come away from the terminal. Needs sorting as BS has suggested.
Title: Re: Possible FTTC issues with an alarm
Post by: gt94sss2 on October 15, 2017, 01:06:25 PM
Many thanks for all the advice and sorry about the poor quality of the pics

I have removed the white/blue wire belonging to the alarm and tightened the 'feed' one again but have not yet connected the alarm back yet.

On reconnecting MDWS shows my attainable speed has gone up but that my attenuation is also the highest it has ever been.

Is there something I should be doing to make sure the attenuation doesn't increase like this? Just so I can address everything at once..

Edit: the Hlog and Quiet Line graphs also look a bit worse?

Edit 2: the SNR also falls when I put a dial tone on the line?
Title: Re: Possible FTTC issues with an alarm
Post by: gt94sss2 on October 28, 2017, 01:36:00 AM
Just to ask another very basic wiring question:

When reconnecting the feed cable to the phillips screws on the NTE back-plate how 'tight' does the screw have to be? (and what happens if its to tight/loose?)

Title: Re: Possible FTTC issues with an alarm
Post by: banger on October 28, 2017, 02:13:09 AM
I may not be understanding the question but loose = intermittent connection tight = good connection but not so tight you break the wires or take the head off the Philips screw.
Title: Re: Possible FTTC issues with an alarm
Post by: gt94sss2 on October 29, 2017, 04:43:06 AM
Thanks - the question was that basic.  :D

My line has held sync for almost 2 weeks since I removed the alarm wiring so hope DLM will act soon  to reduce the level of INP etc (currently 57!) but after that will check how 'tight' I have connected the wires.

Am trying to determine why my line attenuation went up 0.5dB by removing the alarm wires to the highest its ever been - before I properly connect the alarm to the master socket - as I understand the lower the attenuation, the higher my maximum attainable speed will be.

Title: Re: Possible FTTC issues with an alarm
Post by: Black Sheep on October 29, 2017, 08:37:39 AM
Thanks - the question was that basic.  :D

My line has held sync for almost 2 weeks since I removed the alarm wiring so hope DLM will act soon  to reduce the level of INP etc (currently 57!) but after that will check how 'tight' I have connected the wires.

Am trying to determine why my line attenuation went up 0.5dB by removing the alarm wires to the highest its ever been - before I properly connect the alarm to the master socket - as I understand the lower the attenuation, the higher my maximum attainable speed will be.

Because you had the router disconnected whilst performing the wiring task, when you've plugged it back in the 'handshake' process can sometimes see 0.5dB swings. It really is nothing to concern yourself over, as the speed increase would be negligible.

I believe, and someone may confirm or deny this ..... that plugging the router in during low contention times (ie:early morning), can sometimes see the router achieve a higher speed connection ??
Title: Re: Possible FTTC issues with an alarm
Post by: Deathstar on October 29, 2017, 04:40:18 PM
I would have thought contention would have no effect on cable attenuation.
The measured attenuation is calculated based on the physical reasons, power, resistance etc.
Contention is going to be based on the available bandwidth at any given time.

Could you have over stressed the cables when you were re-terminating them? We know the cables are of an extremely small cross section, so there is a potential that by bending the cable you could have created a week point, and a small increase in resistance?

Just a thought.

Sent from my SM-G930F using Tapatalk

Title: Re: Possible FTTC issues with an alarm
Post by: ejs on October 29, 2017, 05:21:08 PM
I think it will depend on what frequencies the attenuation figure is calculated over. If it's calculated based on the frequencies in use, and the improvement to the wiring has allowed higher frequencies to be used, then it would be expected for both the bandwidth and attenuation to increase, with the increase in attenuation not indicating any problem.
Title: Re: Possible FTTC issues with an alarm
Post by: Black Sheep on October 29, 2017, 06:24:15 PM
I would have thought contention would have no effect on cable attenuation.

Sent from my SM-G930F using Tapatalk

I never said that contention effects attenuation.
Title: Re: Possible FTTC issues with an alarm
Post by: Deathstar on October 29, 2017, 06:46:02 PM
I never said that contention effects attenuation.
Possible misread as I was in the pub

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Title: Re: Possible FTTC issues with an alarm
Post by: Black Sheep on October 29, 2017, 07:43:31 PM
Best place to be. Just got back myself.  :)