Acclima TDT hygrometer + EC/temperature sensor

Acclima TDT hygrometer + EC/temperature sensor


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 in a low-cost instrument providing highly accurate absolute readings of soil moisture under all conditions of temperature and soil chemistry where crops will grow.
No other TDT sensor on the market matches its accuracy and stability.
Independent test data from leading soil physicists verifies this extraordinary claim 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.

Main 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


Physical characteristics:


  • Dimensions (without cable): 20cm x 5,33cm x 1,5cm
  • Weight (with 10m cable): 480g
  • Composition: type 304 stainless steel, crystalline-epoxy
  • PVC (insulation) cable: 3 conductor, 22ga PVC sheath, 10m long


Environmental characteristics:


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


Operating characteristics:


  • 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 5dS/m BEC
  • Temperature reporting accuracy: ±2°C in the range of +1°C to +50°C
  • EC reporting accuracy: ±0.2dS/m 0 to 5dS/m BEC


Architectural characteristics:


  • Technology: waveform digitizing time domain transmissometer
  • Effective acquisition bandwidth: 200 Giga-sample/s
  • Propagation time resolution: ps
  • Waveguide length: 30cm
  • Permittivity to VWC calculation: modified dielectric mixing
  • Propagation waveform bandwidth: > 2GHz


Communications characteristics:


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


Power characteristics:


  • Operating voltage range: 6–15 VDC
  • Listening/sleep mode current: 60µA at 50°C
  • Communications current: 6mA typical, 8mA max
  • Read moisture communication time: 425ms total for each read cycle
  • Moisture sense current: 84mA at 12VDC input, 98mA at 8 VDC input, 110mA at 6 VDC input
  • Moisture sense time: 450ms each sensing operation