TDR and Microcontrollers 1

[Rockjoint]

Greetings.

Does anyone have experience with TDR for geotechnical applications (e.g., detecting shear plane in a borehole)? Or perhaps TDR knowledge and microcontroller interfacing?

I am looking into designing a SIMPLE, portable system for use in the field. I would appreciate any suggestions or comments.

Thank you.

 

[itsmoked]

You are refering to:

The Dragon Reborn
Troubled Debt Restructuring
Terrace Dining Room
Terminal Doppler Radar
Tactical Data Radio
Transfer Data Records
Torque-Differential Receiver
Test Deficiency Report
Total Defect Rate
Training in Tropical Diseases
Training Device Requirement
Toxicology Desk Reference
Tokyo Disney Resort
Tonnage Distribution Roster
Time Delay Relay
or
Time-Domain Reflectometry?

 

[felixc]

The volume of geotechnical instruments sold to the market is surprisingly low. Companies selling these readout boxes are usually the same ones that are selling and installing the instruments themselves. Companies like Roctest have started selling TDR instrumentation. But TDR instruments being relatively recent (versus vibrating wire instruments which have a 75-year track record for example), it is unlikely that some will want to take the risk of using TDR without any sort of exit door with another backup technology.
But I remember borehole shearplane detectors as quite prehistoric, unprecise and unreliable material, so maybe that you'd have a chance with TDR if you already have a customer or a precise target application.

 

[Comcokid]

TDR is frequently used for detecting ground moisture, and there have been a few applications in civil applications for detecting stress/fracturing in reinforced structures by embedding a coaxial line in concrete.

The key to many TDR sensor applictions is the selection and design of the transmission line probe. This would also be the case for detecting the shear plane location in a borehole.

For experiementation, you could start with a used cable-type TDR tester. There are many TDR circuits in the public domain, as well as some technologies that can be licensed (

http://www.getradar.com).

The simplest interface to a microcontroller is usually comparators that are triggered by the return, and using the microcontroller to time the comparator signals.

 

[Rockjoint]

itsmoked:
From the context of the post, it was most likely The Dragon Reborn.

Comcokid and felixc:
Thanks for the suggestions. They are most appreciated.