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Standard User Zarjaz
(eat-sleep-adslguide) Tue 16-May-17 12:51:53
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Re: Bridge tap?


[re: WWWombat] [link to this post]
 
You'd hope it signifies a better capability in automatic testing of the line, which can then feed back at the time of sale.

If ISPs can be given a reliable indication of whether the A range or the B range applies, it gives some scope to upsell an engineer install.
Catch 22 though, you cannot make a test for a bridge tap on an FTTC circuit until the service is up and running.

Standard User BatBoy
(sensei) Tue 16-May-17 17:00:17
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Re: Bridge tap?


[re: RobertoS] [link to this post]
 
I think it only appears with the telephone number chacker?
Standard User RobertoS
(elder) Tue 16-May-17 17:28:24
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Re: Bridge tap?


[re: BatBoy] [link to this post]
 
Yes.

My broadband basic info/help site - www.robertos.me.uk. Domains, site and mail hosting - Tsohost.
Connection - AAISP Home::1 80/20. Sync 64513/13170Kbps @ 600m. BQMs - IPv4 & IPv6


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Standard User WWWombat
(knowledge is power) Wed 17-May-17 09:38:45
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Re: Bridge tap?


[re: Zarjaz] [link to this post]
 
In reply to a post by Zarjaz:
Catch 22 though, you cannot make a test for a bridge tap on an FTTC circuit until the service is up and running.


I have to admit that I though a TDR - when employed at the exchange end, say, as part of a test head - would highlight reflections from both the main pair and the tap.
Standard User WWWombat
(knowledge is power) Wed 17-May-17 09:39:11
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Re: Bridge tap?


[re: BatBoy] [link to this post]
 
Ah - that explains why I couldn't see it here frown
Standard User MHC
(sensei) Wed 17-May-17 10:06:07
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Re: Bridge tap?


[re: BatBoy] [link to this post]
 
Think about it ...

As it is referring to a condition on a specific copper pair, it can only be returned on a telephone number check or for a specific line ID.

An address check cannot as there may be multiple lines serving that address.


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

M H C


taurus excreta cerebrum vincit
Standard User WilliamGrimsley
(experienced) Wed 17-May-17 12:00:01
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Re: Bridge tap?


[re: MHC] [link to this post]
 
It shows "N" for our number, which I expected. I presume if it says "Y" then the router is connected to an extension?

Router in use: Billion BiPAC 8800AXL.
Standard User Zarjaz
(eat-sleep-adslguide) Wed 17-May-17 12:31:07
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Re: Bridge tap?


[re: WWWombat] [link to this post]
 
I seriously doubt that, and even then surely a TDR couldn't differentiate between those extensions connected after an SSFP or without.

Standard User MHC
(sensei) Wed 17-May-17 13:07:20
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Re: Bridge tap?


[re: WWWombat] [link to this post]
 
It will certainly highlight the point at which the tap is connected and I too believe there may then be two reflections but discrimination may be difficult.

TDRs can be and are used to locate intercepts (wire taps) on phone lines too.


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

M H C


taurus excreta cerebrum vincit
Standard User WWWombat
(knowledge is power) Wed 17-May-17 13:15:43
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Re: Bridge tap?


[re: Zarjaz] [link to this post]
 
Some bare TDR waveforms can be found here:
http://pe2bz.philpem.me.uk/Comm01/-%20TestEquip/-%20...

The fifth one shows a few small reflections caused by taps, followed by an unterminated end.

The ninth one shows a splitter in use (probably on coax), with reflections for the 2 legs.

In raw terms, I'd expect a TDR to be able to show reflections from every termination of a line.

However, while this ought to apply to bare lines, I don't know how they'd apply to a BT line that properly terminates in a master.

I imagine that a filter (such as an SSFP) does a good job of hiding any taps that occur behind it ... which should be fine. Taps behind filters are good. Taps before filters are the bad ones.
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