Frequency ___domain sensor: Difference between revisions

Revision as of 14:41, 29 October 2009

Revision as of 11:56, 4 December 2009

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* ''Electrical [[Electrical impedance|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 blaatwithto [[time ___domain reflectometer]] (TDR), FD sensors are cheaper to built 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.

==References==