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TDR100 Time-Domain Reflectometer
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The TDR100 Time-Domain Reflectometer is the core of the Campbell Scientific time-domain reflectometry system. This system is used to accurately determine soil volumetric water content, soil bulk electrical conductivity, rock mass deformation, or user-specific time-domain measurement. Up to 16 TDR100s can be controlled using a single Campbell Scientific datalogger. PC-TDR software is used with our TDR100-based systems during system setup and troubleshooting. It can be downloaded from the Downloads section of the web page.

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Ventajas y características

  • Reflectómetro compacto y económico
  • Diseñado para uso en aplicaciones remotas
  • Determina el contenido volumétrico de agua y conductividad eléctrica del suelo y otros medios porosos
  • Compatible con dataloggers CR300, CR800, CR850, CR1000 y CR3000


Descripción detallada

The TDR100 (1) generates a short rise time electromagnetic pulse that is applied to a coaxial system that includes a TDR probe for soil water measurements and (2) samples and digitizes the resulting reflection waveform for analysis or storage.

The elapsed travel time and pulse reflection amplitude contain information used by the on-board processor to quickly and accurately determine soil volumetric water content, soil bulk electrical conductivity, rock mass deformation or user-specific, time-domain measurement.

The data logger collects a 250-point waveform and analyzes it in approximately two seconds. Each waveform can have up to 2,048 data points for monitoring long cable lengths used in rock mass deformation or slope stability. Averaging up to 128 readings makes accurate measurements possible in noisy environments.


Salida generador de pulsos 250 mV into 50 Ω
Impedancia de salida 50 Ω ±1%
Tiempo respuesta combinado generador pulsos y circuito muestreo ≤ 300 ps
Longitud del pulso 14 µs
Timing Resolution 12.2 ps
Promediado forma de onda 1 to 128
Electrostatic Discharge Protection Internal clamping
Fuente alimentación Unregulated 12 V (9.6 to 16 V)
300 mA maximum
Rango temperatura funcionamiento -40° to +55°C
Aberraciones generador pulsos
  • ±5% (within first 10 ns)
  • ±0.5% (after 10 ns)
Dimensiones 23.6 x 5.9 x 12.6 cm (9.3 x 2.3 x 5.0 in.)
Peso 726 g (1.6 lb)

Muestreo forma de onda

-NOTA- 20 to 2048 waveform values over chosen length

Distance is Vp=1. Time is one-way travel.
  • -2 to 2100 m (distance)
  • 0 to 7 µs (time)
  • 1.8 mm (distance)
  • 6.1 ps (time)


Durante la medida 270 mA
Modo reposo 20 mA
Standby Mode 2 mA


Nota: lo siguiente muestra información de compatibilidad notable. No es una lista de todos los productos compatibles.


Producto Compatible Nota
CR1000 (retired)
CR200X (retired)
CR216X (retired)
CR3000 (retired)
CR3000 (retired)
CR3000 (retired)
CR3000 (retired)
CR5000 (retired)
CR800 (retired)
CR850 (retired)
CR9000X (retired)

Equipos para montajes

Producto Compatible Nota


Producto Compatible Nota
21X (retired)
CR10 (retired)
CR10X (retired)
CR23X (retired)
CR500 (retired)
CR510 (retired)
CR9000 (retired)

Información de compatibilidad adicional

Data Logger Considerations

To control the TDR100, the data logger uses TDR100 instruction in CRBasic or Instruction 119 in Edlog. All CR800-series, CR1000, and CR3000 operating systems (OS) are compatible with the TDR100. The CR10X operating system (OS) should be version 1 rev. 13 or higher and the CR23X OS should be version 1 rev. 10 or higher.

Enclosure Considerations

The TDR100 requires a desiccated, non-condensing environment; a Campbell Scientific enclosure is recommended. The TDR100's case has mounting flanges for attachment to the 1 in.-on-center hole grid of Campbell Scientific enclosures.


TDR100 OS v.0.9724 (60 KB) 15-08-2012

Current TDR100 Operating System. PC-TDR must be connected to TDR100.

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.

Historial revisiones

Preguntas frecuentes

Número de FAQs relacionadas con TDR100: 19

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  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).

  2. Theoretically, yes, this can be done. However, it is more common to use a second datalogger both for resilience reasons and because there are advantages in keeping TDR cables short. It is best to distribute the systems across the test site rather than trying to centralize everything.
  3. Yes. The data logger can be programmed to send commands to the TDR100 and to store the measurement results. A flag can be used in the program to initiate measurement and store these results.

  4. These three multiplexers all use the same relay board, but the housing differs. The multiplexers are described side-by-side on page 2 of this brochure.

    The most popular model is the SDMX50SP, followed by the SDMX50.

  5. PC-TDR is a free download in the Downloads section of the PC-TDR web page.

  6. The TDR100 ships with the items listed in the Ships With box on the right side of this page.

    In addition, consider purchasing the ENCTDR100 TDR System Enclosure. This enclosure ships with many items necessary for a TDR100 Data Acquisition System. See the Ships With box on the right side of this page.

  7. Campbell Scientific offers six soil probes that have different rods and connector cables, allowing them to be used in diverse soil types and with a variety of cable lengths. For more details, see the listed TDR100 probes.

  8. Slope stability/rock mass deformation instrumentation is used to detect slope movement and rock mass deformation associated with landslide, mining, and construction activities. In many applications, the ground movement readings are processed by a data logger.

    Application engineers at Campbell Scientific can provide a list of geotechnical system integrators who can offer guidance and/or support for TDR cable selection, installation, waveform interpretation, and alarm condition set points.

  9. Yes. The datalogger can be programmed to store time-series data from the TDR100. The time-series data can then be viewed using PC400 or LoggerNet. For program examples, see the TDR100 Instruction Manual.

Casos de aplicación

Illinois: Automating a Data System
The McCook Reservoir is a ten-billion-gallon reservoir located in La Grange, Illinois. The Metropolitan Water......leer más
Illinois: Automating a Data System
The McCook Reservoir is a ten-billion-gallon reservoir located in La Grange, Illinois. The Metropolitan Water......leer más
San Diego: Slope Monitoring
The North County Transit District (NCTD) of San Diego County, California, determined that three segments......leer más
Ohio: Monitoring Sinking Highway
When the Ohio Department of Transportation (Ohio DOT) was preparing to widen Interstate 77, they......leer más