TDR200 Time-Domain Reflectometer
Core of the TDR System
weather applications supported water applications supported energy applications supported gas flux & turbulence applications supported infrastructure applications supported soil applications supported


The TDR200 Time-Domain Reflectometer is the core of the Campbell Scientific time-domain reflectometry (TDR) system. TDR systems accurately determine soil volumetric water content, soil bulk electrical conductivity, rock mass deformation, or a user-specific time-domain measurement. One Campbell Scientific data logger can control multiple TDR200 reflectometers.

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Benefits and Features

  • Low power (half the power of the TDR100)
  • Robust
  • High sensitivity
  • High resolution
  • Low noise
  • Advanced waveform filtering
  • Advanced waveform analysis algorithm
  • Backward compatible with TDR100 systems (CRBasic data loggers only)
  • 60 Hz frequency rejection



Pulse Generator Output 250 mV into 50 Ω
Output Impedance 50 Ω ±1%
Time Response of Combined Pulse Generator & Sampling Circuit ≤ 85 ps
Pulse Generator Aberrations
  • ±16% (within first 1 ns)
  • ±1% (after 1 ns)
Pulse Length 25.5 μs
Waveform Averaging 1 to 128
Operating Temperature Range -40° to +85°C
Power Supply Unregulated 12 Vdc (9.6 to 16 Vdc)
150 mA maximum, USB powered (5 Vdc)
Dimensions 21.6 x 5.1 x 10.7 cm (8.5 x 2.0 x 4.2 in.)
Weight 0.79 kg (1.75 lb)

Waveform Sampling

-NOTE- 20 to 10112 waveform values over chosen length

Distance is Vp=1. Time is one-way travel.
  • 0 to 3800 m (distance)
  • 0 to 27.75 μs (time)
  • 1.35 mm (distance)
  • < 4.4 ps (time)

Electrostatic Discharge Protection

Air ±8 kV @ 2 Ω
Contact ±4 kV @ 2 Ω
Surge ±2 kV @ 2 Ω

Current Drain

During Measurement 120 mA
Sleep Mode 1 mA


PC-TDR v.3.0 (7.34 MB) 15-12-2016

Support software designed for the TDR200 and is also compatible with the retired TDR100 Time-Domain Reflectometer.

View Revision History

FAQs for

Number of FAQs related to TDR200: 2

  1. In applications where TDR probes are used to measure soil water content, the maximum distance from the TDR probe back to the TDR100/TDR200 (even through one or more multiplexers) cannot exceed 15 m (50 ft) when using RG58 coaxial cable; the CS605-L, CS630-L, and CS640-L TDR probes have an RG58 cable. When using low-loss coaxial cable, the distance cannot exceed ≈25 m (80 ft); the CS610-L, CS635-L, and CS645-L TDR probes have a low-loss coaxial cable.

    In slope stability and rock mass deformation applications, the maximum coaxial cable length should not exceed ≈1 mile (5,280 ft). The maximum combined length of all SDM cables in the system should not exceed ≈76 m (250 ft).