Kitz Forum

Broadband Related => Telephony Wiring + Equipment => Topic started by: ktz392837 on October 21, 2017, 05:42:32 PM

Title: Will Battery Contact Fault Cause Problems With Broadband?
Post by: ktz392837 on October 21, 2017, 05:42:32 PM
Had a sudden big drop in fttc sync so decided to report to ISP and hope to catch them on a good day.  Probably happened in the last few days. They say they have detected a battery contact fault.  Would this have an impact on sync speeds?  Will I get speed back once fixed or could it be other things also?  Thanks
Title: Re: Will Battery Contact Fault Cause Problems With Broadband?
Post by: burakkucat on October 21, 2017, 06:32:38 PM
An xDSL broadband circuit operates in differential mode. A battery contact fault will perturb the status quo of a broadband circuit, certainly the AC balance will be degraded and the potential for RF ingress will become significantly easier.

So "yes" is the one word answer to your first question. As for the subsidiary question, who knows? Get the main problem fixed and then review the situation.
Title: Re: Will Battery Contact Fault Cause Problems With Broadband?
Post by: Black Sheep on October 22, 2017, 09:05:09 AM
With FTTC, a battery contact fault will only affect your circuit (as outlined above ^^), if the fault is on the D-side cable ... ie: from the Cabinet to your premises.

If the contact fault is on the E-side cable, ie: from the Exchange to the Cabinet, then this would only affect your telephony service not the broadband service.
Title: Re: Will Battery Contact Fault Cause Problems With Broadband?
Post by: licquorice on October 22, 2017, 11:19:29 AM
Hmm, not sure about that. The battery contact will still be on the metallic path regardless of whether the fault is on the E-side or D-side.
Title: Re: Will Battery Contact Fault Cause Problems With Broadband?
Post by: Black Sheep on October 22, 2017, 12:19:29 PM
I've not disputed the battery contact will still be on the MPF, however, it will have no effect whatsoever on a FTTC circuit if the battery contact is on the E-side cable.
Title: Re: Will Battery Contact Fault Cause Problems With Broadband?
Post by: licquorice on October 22, 2017, 12:26:48 PM
I still don't understand that, regardless of where the contact originates, it will still be present for the whole length of the metallic path to a degree. I can't see how a (say) 20v contact 5metres along the D-side will affect the circuit but 5 metres back along the E-side it won't.
Title: Re: Will Battery Contact Fault Cause Problems With Broadband?
Post by: Black Sheep on October 22, 2017, 12:32:40 PM
Burakucat or Wombat will be better at explaining it, than I.
Title: Re: Will Battery Contact Fault Cause Problems With Broadband?
Post by: burakkucat on October 22, 2017, 06:18:08 PM
Burakucat or Wombat will be better at explaining it, than I.

As much as I would like to add to this latter discussion, I am very uncertain. I can see both "sides" and both make sense. The best I can "come up with" is an agreement with both!

Let us regard the low-pass filter, present in the "fibre cabinet", as the point where the E-side becomes the D-side.

Let us consider that either a battery contact or an earth contact fault exists 5 metres from the low-pass filter on the D-side. (Audible cross-talk, Ethel nattering to Enid, is noticed for the former fault whilst significant 50 Hz hum is heard for the latter.) The fault is hard and significant. (I suppose we could assume that a sub-standard jumpering task in the PCP was performed by an entity of one of those two sub-contracted companies.) Such a fault will effect the metallic pathway so as to be both telephony and broadband service degrading.

Let us consider that either a battery contact or an earth contact fault exists 5 metres from the low-pass filter on the E-side. The effect will be identical to the above for the telephony service. For the effect upon the broadband service, we have to consider the presence of the low-pass filter. My feeling is that the fault at 5 metres will probably have some effect on the broadband service but probably not so great. Now consider that the fault has its origin at the MDF (perhaps the snipped end of a jumper was accidentally dropped by a frames engineer and was not noticed bridging a pair of tags lower down the frame). I would expect the same effect on the telephony service but a significantly less effect on the broadband service. I postulate that the length of the E-side, coupled with the presence of the low-pass filter, will have offered some degree of "protection" to the broadband service.  :-\
Title: Re: Will Battery Contact Fault Cause Problems With Broadband?
Post by: konrado5 on October 22, 2017, 06:35:53 PM
What is battery contact?
Title: Re: Will Battery Contact Fault Cause Problems With Broadband?
Post by: licquorice on October 22, 2017, 07:31:04 PM
It is when one (or both) leg(s) (wire) of one circuit is in contact (touching) the -50v leg (wire) of another circuit. A telephony circuit consists of 2 wires, one at -50v potential, the other at 0v (earth) potential.
Title: Re: Will Battery Contact Fault Cause Problems With Broadband?
Post by: Black Sheep on October 22, 2017, 08:01:20 PM
As much as I would like to add to this latter discussion, I am very uncertain. I can see both "sides" and both make sense. The best I can "come up with" is an agreement with both!

Let us regard the low-pass filter, present in the "fibre cabinet", as the point where the E-side becomes the D-side.

Let us consider that either a battery contact or an earth contact fault exists 5 metres from the low-pass filter on the D-side. (Audible cross-talk, Ethel nattering to Enid, is noticed for the former fault whilst significant 50 Hz hum is heard for the latter.) The fault is hard and significant. (I suppose we could assume that a sub-standard jumpering task in the PCP was performed by an entity of one of those two sub-contracted companies.) Such a fault will effect the metallic pathway so as to be both telephony and broadband service degrading.

Let us consider that either a battery contact or an earth contact fault exists 5 metres from the low-pass filter on the E-side. The effect will be identical to the above for the telephony service. For the effect upon the broadband service, we have to consider the presence of the low-pass filter. My feeling is that the fault at 5 metres will probably have some effect on the broadband service but probably not so great. Now consider that the fault has its origin at the MDF (perhaps the snipped end of a jumper was accidentally dropped by a frames engineer and was not noticed bridging a pair of tags lower down the frame). I would expect the same effect on the telephony service but a significantly less effect on the broadband service. I postulate that the length of the E-side, coupled with the presence of the low-pass filter, will have offered some degree of "protection" to the broadband service.  :-\

Thank you for taking the time to compose that, B*cat ............... like you say, the low-pass filter has to play a part in minimising the affect on DSL frequencies to a point where it is absolutely negligible.
 
I always use real-life experiences where possible, and I cannot ever recall an E-side battery contact issue affect the EU's FTTC service !!

As always, I'm open to having my knowledge enhanced though. :)

 
Title: Re: Will Battery Contact Fault Cause Problems With Broadband?
Post by: konrado5 on October 22, 2017, 08:37:54 PM
Has battery contact any influence on Hlog?
Title: Re: Will Battery Contact Fault Cause Problems With Broadband?
Post by: burakkucat on October 22, 2017, 08:41:17 PM
Thank you for taking the time to compose that, B*cat ............... like you say, the low-pass filter has to play a part in minimising the affect on DSL frequencies to a point where it is absolutely negligible.

It was no problem . . . and an interesting situation to consider. I shall await for 3W to give us his opinion.
Title: Re: Will Battery Contact Fault Cause Problems With Broadband?
Post by: burakkucat on October 22, 2017, 08:45:31 PM
Has battery contact any influence on Hlog?

Truthfully, I am unable to give an answer to your query.

I'll expand on that response to say that I am unaware of seeing any abnormal looking Hlog plot where the abnormality was proven to be the result of either a battery contact or an earth contact fault. 
Title: Re: Will Battery Contact Fault Cause Problems With Broadband?
Post by: ktz392837 on October 22, 2017, 09:17:25 PM
To add to the weirdness I would say the quality of my voice line is no different than usual (good quality) but broadband has a significant percent loss of speed. 

Do you ever get a false positive on a test or is there definitely a battery fault?

Thanks
Title: Re: Will Battery Contact Fault Cause Problems With Broadband?
Post by: Black Sheep on October 22, 2017, 09:31:52 PM
Our old field technicians 'Bible' (The black book), actually quoted that up to 30 volts of battery contact fault would see minimal impact on PSTN services.
Of course, that would be devastating for DSL services.

Regarding test results ... you can't have a false positive with a contact result test, if one has been found then one exists.

You can however have a false negative result, this occurs when we have a 'Tapping battery contact' ... in other words the fault is there one minute then gone the next, and so on.
With any remote testing (ie: by the ISP/CP), the test they perform is a 'One-shot test' which basically means if the fault isn't there at the specific moment in time the test is run, it will return a LTOK (Line Tests OK) result. Literally a second later and the fault could be back. 
Title: Re: Will Battery Contact Fault Cause Problems With Broadband?
Post by: konrado5 on October 22, 2017, 10:40:06 PM
kitz392837: Could you attach your Hlog and QLN? I'm curious what is battery contact influence on these graphs.