How do they work that out? - Electronic Circuits Projects Diagrams Free

UTMonkey · 29th April 2008, 07:54 PM

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 · 29th April 2008, 08:02 PM

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

UTMonkey · 29th April 2008, 08:05 PM

Thanks Bill.

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

blueroomelectronics · 29th April 2008, 08:06 PM

Lots. That's what keeps it interesting

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

**Nigel Goodwin** · 29th April 2008, 08:20 PM

Quote:

Originally Posted by UTMonkey

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 · 29th April 2008, 10:08 PM

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

blueroomelectronics · 29th April 2008, 11:03 PM

Quote:

Disclaimer: Avatar for entertainment purposes only.

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

dknguyen · 29th April 2008, 11:45 PM

Quote:

Originally Posted by blueroomelectronics

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 · 30th April 2008, 03:03 AM

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.

dknguyen · 30th April 2008, 08:44 AM

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

rjvh · 30th April 2008, 09:05 AM

Quote:

Originally Posted by dknguyen

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 · 30th April 2008, 08:53 PM

Quote:

I can't stop staring at her lips lol.

That's a dude.

dknguyen · 30th April 2008, 08:58 PM

Quote:

Originally Posted by Hank Fletcher

That's a dude.

THat's one good looking dude.

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29th April 2008, 07:54 PM	(permalink)
UTMonkey	How do they work that out? 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

29th April 2008, 08:02 PM	(permalink)
blueroomelectronics	TDR (Time Domain Reflectometry) http://www.tscm.com/tdr.html __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

29th April 2008, 08:05 PM	(permalink)
UTMonkey	Thanks Bill. Is their anything about electronics you don't know ;-)

29th April 2008, 08:06 PM	(permalink)
blueroomelectronics	Lots. That's what keeps it interesting Here's a DIY TDR article from 1973 http://www.scribd.com/doc/267394/An-Inexpensive-TDR __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

29th April 2008, 10:08 PM	(permalink)
dknguyen	Is TDR like a TOF measurement over a copper wire rather than the air? __________________ NO, that picture isn't me so don't bother asking if we can be friends.

30th April 2008, 03:03 AM	(permalink)
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. __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

30th April 2008, 08:44 AM	(permalink)
dknguyen	Wow. I can't stop staring at her lips lol. They're picture perfect. Same with ther two teeth lol. __________________ NO, that picture isn't me so don't bother asking if we can be friends.