Moisture Sensor

The TDR-305N is a modified version of the TDR-310N. The very short waveguide allows this sensor to make very shallow measurements and to be used in higher conductivity environments with a sacrifice in total measurement volume. It has a high voltage waveform output, which makes it effective in taking measurements when the soil electrical conductivity is high. It also consumes more power than the TDR-315H. It is a complete integrated time domain reflectometer that combines ultrafast waveform generating and digitizing functions with a precision 5 picosecond 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 easy vertical installation in an augured hole using a 34 mm flat-bottomed auger. 

It mates with a 1” schedule 40 PVC pipe that acts as a handle in its installation to any desired depth. It provides reading data through a 3-wire SDI-12 interface and is compatible with any data recorder that is compliant with SDI-12 version 1.4 and earlier. 

The TDR-310H is one of Acclima’s H-series sensors, which are very low power and suited perfectly for power-conscious applications. Being part of the Soil Smart Series means that it’s advanced waveform analysis works with all mineral soil types. 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 easy vertical installation in an augered hole using a 34 mm flat-bottomed auger. It mates with a 1” schedule 40 PVC pipe that acts as a handle in its installation to any desired depth. It provides reading data through a 3-wire SDI-12 interface and is compatible with any data recorder that is compliant with SDI-12 version 1.4 and earlier.

Key Features

• Ultra-low power consumption and fast response time
• Housing designed for easy bore hole installation at any depth
• Soil Smart analysis works with all mineral soil types
• Incident Wave Amplitude: 400mV
• 20% to 80% Incident Wave Rise Time: 150 ps
• Waveform Digitizing Resolution: 5 ps
• SDI-12 Interface
• 3-element 10cm stainless steel waveguide
• 5m or 10m 3-conductor waterproof cable (standard)
• Waterproof Epoxy-filled Housing

Measurement Functions

• Volumetric Water Content: 0% to 100%
• Medium Permittivity: 1 to 80
• Medium Bulk Electrical Conductivity: 0 to 2000 µS/cm
• Medium Temperature: -40 to +55 degrees C
• Pore Water EC (Hilhorst Model): 0 to 55000 µS/cm

A fully integrated digital TDR soil water content sensor (a.k.a., soil moisture sensor, probe, or meter) that has demonstrated superb accuracy consistently with excellent repeatability.

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The TDR-310N is a replacement to the former Acclima TDR-310L. It has a high voltage waveform output, which makes it effective in taking measurements when the soil electrical conductivity is high. It also consumes more power than the TDR-310H. 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 easy vertical installation in an augured hole using a 34 mm flat-bottomed auger. It mates with a 1” schedule 40 PVC pipe that acts as a handle in its installation to any desired depth. It provides reading data through a 3-wire SDI-12 interface and is compatible with any data recorder that is compliant with SDI-12 version 1.4 and earlier. 

Key Features

• SDI-12 Interface
• 3-element 10 cm stainless steel waveguide
• 5 m 3-conductor waterproof cable (standard)
• Waterproof Epoxy-filled Housing
• 20% to 80% Incident Wave Rise Time: 300 ps
• Waveform Digitizing Resolution: 5 ps
• Incident Wave Amplitude: 2.3 V

Measurement Functions

• Volumetric Water Content: 0% to 100%
• Medium Permittivity: 1 to 100
• Medium Bulk Electrical Conductivity: 0 to 3000 µS/cm
• Medium Temperature: -40 to +55 degrees C
• Pore Water EC (Hilhorst Model): 0 to 55000 µS/cm

The TDR-310W is a modification to the Acclima TDR-315N. Its shorter rods allow it fit in standard rockwool blocks. 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.

A probe guide is provided to ensure that the waveguide rods are parallel when pushing them into the soil.

It provides reading data through a 3-wire SDI-12 interface and is compatible with any data recorder that is compliant with SDI-12 version 1.4 and earlier.

Key Features

• Designed for easy use with rockwool blocks and smaller grow media
• Large sampling volume with the wide spacing of the 10cm waveguides
• Soil Smart analysis optimized for non-mineral soil types, while still works well in mineral soils
• SDI-12 Interface
• 3-element 10 cm stainless steel waveguide
• 5 m 3-conductor waterproof cable (standard)
• Waterproof Epoxy-filled Housing
• 20% to 80% Incident Wave Rise Time: 300 ps
• Waveform Digitizing Resolution: 5 ps
• Incident Wave Amplitude: 2.3 V

Measurement Functions

• Volumetric Water Content: 0% to 100%
• Medium Permittivity: 1 to 85
• Medium Bulk Electrical Conductivity: 0 to 4500 µS/cm
• Medium Temperature: -40 to +55 degrees C
• Pore Water EC (Hilhorst Model): 0 to 55000 µS/cm

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

This soil moisture sensor kit contains the Acclima Sensor Reader which will read any Acclima SDI-12 soil water content sensor (TDT or TDR soil moisture sensor, probe, or meter), display the readings on an LCD screen, and (if it’s a compatible ‘Waveform Capture’ sensor) it will record and display the waveform. 

The kit comes with a rugged carrying case, a 32-gigabyte (GB) thumb drive with micro and standard USB connectors for storing readings and updating the reader, a digital True TDR-315H soil moisture sensor (soil moisture meter or probe) with Waveform Capture and terminated with an M12 connector, and a convenient international power adapter kit for charging the unit. 

Firmware updates are freely available via the button under downloads below.

Acclima’s TDR Sensors are Integrated Time Domain Reflectometers that contain an

ultra-fast step

function generator, an ultra-fast waveform digitizer and a precision time base. The

step function

generator and waveform digitizer are connected directly to a waveguide of length

5 cm, 10 cm or 15 cm

without an intervening coaxial cable. The key to their operation is a patented

waveform digitizing

hardware and firmware set that has an effective digitizing rate of 200 billion samples

per second. The

step function generator launches a voltage step on the waveguide with a 20%/80%

rise time of 150

trillionths of a second. The digitizer acquires a digital image of the incident wave and

its returning

reflections with 5 trillionths of a second resolution. The image is then analyzed to

determine the roundtrip propagation time between the incident wave and the first

reflected wave. Using the propagation

equation that governs the speed of light through a medium the permittivity of the

medium is then

calculated as:

                        E = t2/4l2

where t is the round trip propagation time, l is the length of the waveguide and E is

the relative

permittivity of the medium though which the wave has passed. The fact that

propagation time is

independent of soil electrical conductivity leads to the fact that the calculated

permittivity is also

independent of soil electrical conductivity. This is the main advantage of digitized

waveform time

domain sensors over all non-time domain electronic sensors. Volumetric Water

Content can be derived

from permittivity using the Topp equation or a suitable dielectric mixing model.

Electrical Conductivity in

soils is affected by compaction and hence non-TDR sensors tend to be very sensitive

to both installation

compaction and follow-on soil settling. TDR sensors report the true volumetric water

content

independent of soil electrical conductivity, compaction and settling.

An 80 MHz floating point processor inside the sensor is used to process the

waveform image. The total

time required to send a measurement command to the sensor, acquire the digitized

waveform image,

process the image and calculate the soil permittivity, water content and conductivity

is 0.25 seconds.

The sensors require a power supply from 3.5 volts to 15 volts. The current draw

during a reading ranges

from 88 mA at 3.5 volts to 32 mA at 15 volts. The idle current is less than 10 uA.

Because of the very fast

operation time the total energy consumed from a battery is only 0.1 Joule per

reading. A typical goodquality 18650 Li-Ion battery stores about 40,000 Joules.

Used worldwide, this TDT soil water content sensor (a.k.a., soil moisture sensor, probe, or meter) accurately measures VWC, Bulk EC, and temperature. Temperature accuracy is within 0.5˚C.

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The Acclima Digital TDT® soil moisture sensor represents a revolutionary advance in the irrigation industry. It is the first soil moisture sensor to incorporate the accuracy of digitized Time Domain Transmissometry (TDT) in a low-cost instrument providing highly accurate absolute readings of soil moisture under all conditions of temperature and soil chemistry that crops will grow. No other TDT soil water content sensor on the market matches its accuracy and stability. Independent test data from leading soil physicists verify these claims and are available upon request.

This Digital TDT sensor incorporates a modified SDI interface capable of connecting directly to Acclima data loggers or any other third-party SDI version 1.4 compliant device. The Acclima modified SDI interface is also capable of auto-detection and addressing collision repair with Acclima data loggers.

Key Features

• Works in all soils
• Highly stable under a wide range of soil conductivity and temperature
• Range of 0 -100% volumetric water content
• Made with durable inert materials
• Very low-power, battery operable
• SDI-12 version 1.4 compliant
• Low cost

CharacteristicsPhysical

• Dimensions (without cable): 20 cm x 5.33 cm x 1.5 cm
• Weight (with 5m cable): 299 grams
• Composition: Type 304 stainless steel, crystalline-epoxy
• PVC (insulation) cable: 3 conductor, 22 ga PVC sheath, 5
  meters

Environmental

• Operating temp range: 1 ̊C to 50 ̊C for VWC (no ice), -20
• ̊C to 50 ̊C for the other data
• Storage temp range: 20 ̊C to 75 ̊C
• Lightning and surge protection: 6 kV @ 3 kA, 8/50 µs

Operating

• Volumetric water content: 0 to 100%
• Resolution: 0.06% VWC
• Absolute VWC accuracy: ±2% typical
• VWC soil EC stability: ±1% of full scale 0 to 5 dS/m BEC
• Temp reporting accuracy: ±2 ̊C from +1 ̊C to +50 ̊C
• EC reporting accuracy: ±0.2 dS/m 0 to 5 dS/m BEC

Architectural

• Technology: Waveform digitizing time domain transmissometer
• Effective acquisition bandwidth: 200 giga-sample/second
• Propagation time resolution: picosecond
• Waveform propagation resolution: 1.5 mm in air, 0.16 mm in water
• Waveguide length: 30 cm
• Permittivity to VWC calculation: Modified dielectric mixing model
• Propagation waveform bandwidth: >2 GHz

Communications

• Communication protocol: SDI-12 Revision 1.4
• Maximum cable length: 60 meters

Power

• Operating Voltage Range: 6–15 VDC
• Listening/Sleep Mode Current: 60 µA at 50 ̊C
• Communications Current: 6 mA typical, 8 mA max
• Read Moisture Comm Time: 425 ms total for each read cycle
• Moisture Sense Current: 84 mA at 12VDC input, 98 mA at 8 VDC input, 110 mA at 6 VDC input
• Moisture Sense Time: 450 ms each sensing operation

A fully integrated digital TDR soil water content sensor (a.k.a., soil moisture sensor, probe, or meter) that has demonstrated superb accuracy consistently with excellent repeatability between six different soils including potter’s clay.  It is the first release of Acclima’s Soil Smart moisture sensors.  Allows for waveform capture.

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The TDR-315N is a replacement to the former Acclima TDR-315L. It has a high voltage waveform output, which makes it effective in taking measurements when the soil electrical conductivity is high. It also consumes more power than the TDR-315H. 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. 

A probe guide is provided to ensure that the waveguide rods are parallel when pushing them into the soil. It provides reading data through a 3-wire SDI-12 interface and is compatible with any data recorder that is compliant with SDI-12 version 1.4 and earlier.

Key Features

• Designed for easy use in shallower horizontal applications
• Highest accuracy Acclima sensor configuration
• Soil Smart analysis works with all mineral soil types
• SDI-12 Interface
• 3-element 15 cm stainless steel waveguide
• 5 m 3-conductor waterproof cable (standard)
• Waterproof Epoxy-filled Housing
• 20% to 80% Incident Wave Rise Time: 300 ps
• Waveform Digitizing Resolution: 5 ps
• Incident Wave Amplitude: 2.3 V

Measurement Functions

• Volumetric Water Content: 0% to 100%
• Medium Permittivity: 1 to 85
• Medium Bulk Electrical Conductivity: 0 to 3000 µS/cm
• Medium Temperature: -40 to +55 degrees C
• Pore Water EC (Hilhorst Model): 0 to 55000 µS/cm

The TEROS 10 soil water content sensor is a ruggedized version of our basic, no-frills soil moisture sensor. Its 70-MHz frequency minimizes salinity and textural effects, making it accurate in most soil or soilless media. With a tough, epoxy body, the TEROS 10 is designed to withstand some of the harshest field conditions, which means problem-free measurements over the longevity of your research. We’re so confident about the long life of our TEROS sensor line, we’ve increased our standard warranty from one to three years.

Feature

•  0-200 Centibar range
•     Stainless steel enclosure
•    Will not dissolve in soil
•    Not affected by freezing temperatures
•    Internal compensation for commonly found salinity levels
•    Inexpensive
•    Easy to use

•    No maintenanceWATERMARK sensors require a reading device designed specifically to read them. For other devices which can read standard analog sensors, we offer adapters to allow easy integration:

  
   200SS-SDI Adapter - SDI module that reads three WATERMARK and 1 200TS Soil Temp Sensor
   200SS-VA Adapter - Adapter reads one WATERMARK and outputs standard 0-3V analog signal

  For directly integrating WATERMARK sensors in to your device project, our integration guide covers best practices and includes an example Arduino implementation: