Campbell Scientific TDR Probes CS605, CS610, CS630, CS635, CS640, CS645 - Manual (Page 7)

TDR Probes CS605, CS610, CS630,
CS635, CS640, CS645
1. Introduction
This document presents descriptions and instructions for Campbell Scientific
Time Domain Reflectometry (TDR) probes and includes some TDR principles.
Consult the TDR100 operating manual for comprehensive TDR instructions.
A single TDR probe can be connected directly to the TDR100 or multiple
probes connected via the SDMX50-series Coaxial Multiplexers.
Before using the TDR probes, please study:
• Section 2, Cautionary Statements
• Section 3, Initial Inspection
2. Cautionary Statements
• Care should be taken when opening the shipping package to not damage or
cut the cable jacket. If damage to the cable is suspected, consult with a
Campbell Scientific application engineer.
• The CS605 and CS610 are shipped with rubber caps covering the sharp
ends of the rods. Remove the three caps before use.
• The TDR100 is sensitive to electrostatic discharge damage. Avoid
touching the center conductor of the panel BNC connector or the center
rod of TDR probes connected to the TDR100.
3. Initial Inspection
• Upon receipt of a TDR probe, inspect the packaging and contents for
damage. File damage claims with the shipping company.
• The model number and cable length are printed on a label at the
connection end of the cable. Check this information against the shipping
documents to ensure the correct product and cable length are received.
4. Overview
TDR probes are the sensors of the TDR measurement system and are inserted
or buried in the medium to be measured. The probes are a wave guide
extension on the end of coaxial cable. Reflections of the applied signal along
the waveguide will occur where there are impedance changes. The impedance
value is related to the geometrical configuration of the probe (size and spacing
of rods) and also is inversely related to the dielectric constant of the
surrounding material. A change in volumetric water content of the medium
surrounding the probe causes a change in the dielectric constant. This is seen
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