Time Domain Reflectometry (TDR) - TDRi Series

Distributed Measurements of Soil Movement

Time domain reflectometry (TDR) is a versatile technique that has several geotechnical applications. It is a reliable tool for the measurement of rock movement. It can improve safety and increase operating speed by providing real-time deformation data.

Why use the TDRi Series ?

The TDRi Series are hassle-free systems that help engineers and mine operators to ensure security and follow the exploitation effects in real time. GKM Consultants’ TDR systems find applications mostly in deformation and stability monitoring of structures, slopes and mines. They have been implemented in open-pit mines to measure bench stability. They are also often used in underground mines as a means to monitor in real time any shaft wall or gallery roof deformation. Other applications include measuring rock breakage from cliffs and excavations, and use in tunnels to measure delamination or shear of rock layers. It can also be used for structural health monitoring to measure deformation in large structures such as roads, bridges or dams. In short, they can be used to measure the position and estimate the amplitude of any kind of deformation in a wide array of media. GKM Consultants provides assistance at every step of the way, from the selection of the right cable to the design and construction of the data acquisition systems and the installation and configuration of the TDRs themselves.

How do they work ?

The TDRi Series work on a similar principle to radar, where an antenna emits radio waves towards items whose position needs to be estimated. By measuring the return time and reflection patterns of the radio wave, we are able to pinpoint the location of an object. Rather than generating radio waves, a TDRi system sends an electrical pulse down a coaxial cable. If the latter is kinked, extended or damaged, the propagation of the electrical pulse is disturbed and some voltage is sent back towards the emitter. By measuring this return time, it is possible to pinpoint the location of any deformation in the cable and evaluate the root cause.


Pulse generator output
250 mV into 50 ohms

Output impedance
50 ohms

Electrostatic discharge protection
Internal clamping

Operating temperature range
-40 °C to +55 °C

Power consumption
300 mA @ 12V DC



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