Lossy Transmission Line Component Calculation

[ohmrun]

I need to determine the R, L, C, and G of a lossy transmission line at various frequencies below 1 MHz. I have only one access point at an end. Any suggestions would be appreciated. My first attempt was to determine the input impedance and set it equal to sqrt{(R+jwL)/(G+jwC)} and solve simultaneously for real and imaginary parts. It seemed messy and tended to blow up.
Thanks

 

[nbucska]

How long is the line ? At 1 MHz most likely the ohmic
parts are negligeable, unless the line is very long. <nbucska@pcperipherals.com>

 

[ohmrun]

This is not an ordinary transmission line. It is actually an insulated pipe in the earth of unknown length. The particular line that I am testing is about 250 feet long before it makes a connection to the main line; it then continues several miles.

 

[nbucska]

What are you trying to do ? Using TDR to trace the pipe ?
detect leakage or break ?
<nbucska@pcperipherals.com>

 

[ohmrun]

Tracing pipe by injecting a signal and tracing the resulting magnetic field. I am attempting to detemine the how different frequencies respond.

 

[nbucska]

Public utilitis do this rutinelly -- why don't you find out
what they use.

You may also search for patent at

http://wwww.USPTO.GOV

<nbucska@pcperipherals.com>

 

[Lewish]

The telephone guys do this all the time. Why don't you see if you can borrow a test set for DSL line trouble-shooting. DSL frequencies can go up to several megahertz. The better testsets will return all the values you are looking for.

Lewis