How do they work that out?

[UTMonkey]

Hi All,

My workplace is in the final stages of a refurbishment. During the refurb it looks like some phone lines (alarms etc) were cut and likely bricked up or hidden somewhere.

We had a visit from the telecoms people (British Telecom) to rewire it all and they tried looking for the lines.

I was really impressed when they said that they had someone at the exchange check the line and say the length of the line was 476 meters from the exchange.

How on earth could they know that!!!

Mark

 

[blueroomelectronics]

TDR (Time Domain Reflectometry)
http://www.tscm.com/tdr.html

 

[UTMonkey]

Thanks Bill.

Is their anything about electronics you don't know ;-)

 

[blueroomelectronics]

Lots. That's what keeps it interesting

Here's a DIY TDR article from 1973
https://www.scribd.com/doc/267394/An-Inexpensive-TDR

 

[Nigel Goodwin]

Thanks Bill.

Is their anything about electronics you don't know ;-)

Years ago my mothers phone stopped working, and the engineer who came out happened to have a TDR in his van (it's not normal, FAR too expensive, but he had been lent it for a specific job and had 'forgotten' to take it back yet ).

He simply connected it to the line, and it told him how many yards away the break was - nice easy job for him.

 

[dknguyen]

Is TDR like a TOF measurement over a copper wire rather than the air?

 

[blueroomelectronics]

Disclaimer: Avatar for entertainment purposes only.

Do you get PMs about it? Who is she anyway?

 

[dknguyen]

Do you get PMs about it? Who is she anyway?

I disabled my PMs long ago so I wouldn't know. I just have that sig because people (usually students asking for homework help) thinking that the avatar is me and bugging me about it.

Heh, tis is really bugging you isn't it? I think it's the second or third time you've asked and I ignored you. Okay, I'll say.
THis particular girl is Reina Tanaka, a member of a J-pop umbrella group. No one wears outfits that ridiculous in real life...for the most part.

 

[blueroomelectronics]

To the best of my recollection it wasn't me that asked before, but I recall you've been asked
Looked to me like a cosplay costume.
**broken link removed**

 

[dknguyen]

Wow. I can't stop staring at her lips lol. They're picture perfect. Same with ther two teeth lol.

 

[rjvh]

Wow. I can't stop staring at her lips lol. They're picture perfect. Same with ther two teeth lol.

That's what photo shop can do, amazing

Robert-Jan

 

[Hank Fletcher]

I can't stop staring at her lips lol.

That's a dude.

 

[dknguyen]

That's a dude.

THat's one good looking dude.