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- Frequency_domain_sensor abstract "Frequency domain (FD) sensor is an instrument developed for measuring soil moisture content. The instrument has an oscillating circuit, the sensing part of the sensor is embedded in the soil, and the operating frequency will depend on the value of soil's dielectric constant.There are two types of sensors: Capacitance probe, or fringe capacitance sensor. Capacitance probes use capacitance to measure the dielectric permittivity of the soil. The volume of water in the total volume of soil most heavily influences the dielectric permittivity of the soil because the dielectric of water (80) is much greater than the other constituents of the soil (mineral soil: 4, organic matter: 4, air: 1). Thus, when the amount of water changes in the soil, the probe will measure a change in capacitance (from the change in dielectric permittivity) that can be directly correlated with a change in water content. Circuitry inside some commercial probes change the capacitance measurement into a proportional millivolt output. Other configuration are like the neutron probe where an access tube made of PVC is installed in the soil. The probe consists of sensing head at fixed depth. The sensing head consists of an oscillator circuit, the frequency is determined by an annular electrode, fringe-effect capacitor, and the dielectric constant of the soil. Electrical impedance sensor, which consists of soil probes and using electrical impedance measurement. The most common configuration is based on the standing wave principle (Gaskin & Miller, 1996). The device comprises a 100 MHz sinusoidal oscillator, a fixed impedance coaxial transmission line, and probe wires which is buried in the soil. The oscillator signal is propagated along the transmission line into the soil probe, and if the probe's impedance differs from that of the transmission line, a proportion of the incident signal is reflected back along the line towards the signal source.Compared to time domain reflectometer (TDR), FD sensors are cheaper to build and have a faster response time. However because of the complex electrical field around the probe, the sensor needs to be calibrated for different soil types. Some commercial sensors have been able to remove the soil type sensitivity by using a high frequency.".
- Frequency_domain_sensor wikiPageID "6239416".
- Frequency_domain_sensor wikiPageRevisionID "595567366".
- Frequency_domain_sensor hasPhotoCollection Frequency_domain_sensor.
- Frequency_domain_sensor subject Category:Hydrology.
- Frequency_domain_sensor subject Category:Impedance_measurements.
- Frequency_domain_sensor subject Category:Measuring_instruments.
- Frequency_domain_sensor subject Category:Physical_chemistry.
- Frequency_domain_sensor subject Category:Soil_mechanics.
- Frequency_domain_sensor subject Category:Soil_physics.
- Frequency_domain_sensor type Artifact100021939.
- Frequency_domain_sensor type Device103183080.
- Frequency_domain_sensor type Instrument103574816.
- Frequency_domain_sensor type Instrumentality103575240.
- Frequency_domain_sensor type MeasuringInstrument103733925.
- Frequency_domain_sensor type MeasuringInstruments.
- Frequency_domain_sensor type Object100002684.
- Frequency_domain_sensor type PhysicalEntity100001930.
- Frequency_domain_sensor type Whole100003553.
- Frequency_domain_sensor comment "Frequency domain (FD) sensor is an instrument developed for measuring soil moisture content. The instrument has an oscillating circuit, the sensing part of the sensor is embedded in the soil, and the operating frequency will depend on the value of soil's dielectric constant.There are two types of sensors: Capacitance probe, or fringe capacitance sensor. Capacitance probes use capacitance to measure the dielectric permittivity of the soil.".
- Frequency_domain_sensor label "Frequency domain sensor".
- Frequency_domain_sensor sameAs m.0fyclx.
- Frequency_domain_sensor sameAs Q5502864.
- Frequency_domain_sensor sameAs Q5502864.
- Frequency_domain_sensor sameAs Frequency_domain_sensor.
- Frequency_domain_sensor wasDerivedFrom Frequency_domain_sensor?oldid=595567366.
- Frequency_domain_sensor isPrimaryTopicOf Frequency_domain_sensor.