Acclima Digital True TDR-315H Soil Moisture Sensor

A fully integrated digital TDR soil water content sensor, the 315H consumes a fraction of the energy than that of its soil moisture sensor siblings in the N series, but still maintains a 150 pico-second rise time for superb accuracy. Not intended for soils with high clay content or bulk EC above 1800 µS/cm.

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The TDR315H is a true Time Domain Reflectometer soil moisture sensor designed to provide highly accurate Volumetric Water Content Measurements in soils and other porous media. It incorporates the same basic TDR components found in console-based TDR instruments costing 20 times more – housed inside the small enclosure that also supports the 15 cm waveguide. 

The patented TDR function is coupled directly to the waveguide, thus eliminating the coax cable associated with conventional TDR devices. The absence of the coax cable provides the TDR315H with higher bandwidth waveform data thus improving its resolution and sensitivity over expensive conventional TDRs.

The TDR-315H is the replacement to the former Acclima TDR-315 and TDR-315L soil moisture sensors. It is fully compatible with those sensors but incorporates several improvements. It is a complete integrated time domain reflectometer that combines ultra-fast waveform generating and digitizing functions with a precision 5 pico-second resolution time base and highly sophisticated waveform digitizing and analyzing firmware that provides true time domain analysis of soil-propagated waveforms. Its form factor is designed for shallower horizontal installations where it is forced into the sidewall of a trench that has been dug to the desired measurement depth. 

Its main improvements over the 315L soil moisture probe are its faster rise time, its shaped incident wave, its lower power consumption and its very fast response time. Its rise time is as fast as the TDR-315 but its power consumption is much lower than the TDR-315 and its price is also lower. 

Key Features

• True Waveform Digitizing TDR: 5ps Resolution Measures Water Content up to 1.00 m3/m3 
• Reads Soil Bulk EC: 0 to 2000 µS/cm
• VWC Readings not affected by Bulk EC (under 1.8 dS/m for this low power model) 
• VWC Readings not affected by Compaction 
• Soil Specific Calibration not required 
• Accurate Soil Temp Measurements: <±0.25°C
• Supports Time Domain Waveform Download
• Ultra-Fast Incident Wave Rise Time: 150ps 
• Fast Measurement Response: typ. <0.25 sec
• Supports Long Battery Life: .09 J per Reading 
• Low Sleep Current: < 10 µA 
• SDI-12 Interface

Measurement Functions

• Volumetric Water Content: 0% to 100%
• Medium Permittivity: 1 to 85
• Medium Bulk Electrical Conductivity: 0 to 2000 µS/cm (Ɵ, ɛ repeatability degrades above 2000 µS/cm BEC)
• Medium Temperature: -40 to +55 degrees C
• Pore Water EC (Hilhorst Model): 0 to 55000 µS/cm

Applications

• In-Situ Soil Water Monitoring for
  Agriculture
• High Credibility Data for CloudBased Analysis
• Gold Standard VWC Reference
• Replacement for Neutron Probes
• Portable Measurements using
  Acclima Reader
• Laboratory and Field Research
  Instrumentation