Remote wireless moisture sensors for irrigation
First Claim
1. A moisture sensor insertable into soil, the moisture sensor comprising:
- a printed circuit board having an upper end and a lower end and having a front surface and a rear surface;
a first capacitive sensor positioned on one of the front surface and the back surface of the printed circuit board and positioned in a first selected location with respect to the upper end of the printed circuit board, the first capacitive sensor having a first capacitance responsive to moisture content of soil proximate to the first capacitive sensor;
a second capacitive sensor positioned on one of the front surface and the back surface of the printed circuit board and positioned in a second selected location with respect to the upper end of the printed circuit board, the second selected location farther from the upper end than the first selected location, the second capacitive sensor having a second capacitance responsive to moisture content of soil proximate to the second capacitive sensor;
a third capacitive sensor positioned on one of the front surface and the back surface of the printed circuit board and positioned in a third selected location with respect to the upper end of the printed circuit board, the third selected location farther from the upper end than the second selected location, the third capacitive sensor having a third capacitance responsive to moisture content of soil proximate to the third capacitive sensor; and
a processing and transmission subsystem positioned on at least one of the front surface and the back surface of the printed circuit board proximate to the upper end of the printed circuit board, the processing and transmission subsystem coupled to each of the first, second and third capacitive sensors, the processing and transmission subsystem generating a first data value responsive to the first capacitance, generating a second data value responsive to the second capacitance and generating a third data value responsive to the third capacitance, the processing and transmission subsystem transmitting the first, second and third data values via a radio frequency output signal.
1 Assignment
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Accused Products
Abstract
A remote wireless moisture sensing unit is insertable into soil. The sensing unit includes at least three capacitive sensors positioned at three spaced apart levels with respect to the surface of the soil. The capacitance of each sensor increases in the presence of increased moisture content of the soil proximate to the sensor. An analog multiplexer selectively routes each sensor to an input to a capacitively-controlled oscillator to cause the oscillator to generate a clock signal having a frequency responsive to the capacitance of the currently connected sensor and thus responsive to the moisture content proximate to the currently selected sensor. A processor generates a respective data value for the frequency corresponding to each sensor and transmits the data values for the sensors via a radio frequency transceiver. The data values are processed to determine the moisture content of the soil at the three sensor levels.
18 Citations
10 Claims
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1. A moisture sensor insertable into soil, the moisture sensor comprising:
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a printed circuit board having an upper end and a lower end and having a front surface and a rear surface; a first capacitive sensor positioned on one of the front surface and the back surface of the printed circuit board and positioned in a first selected location with respect to the upper end of the printed circuit board, the first capacitive sensor having a first capacitance responsive to moisture content of soil proximate to the first capacitive sensor; a second capacitive sensor positioned on one of the front surface and the back surface of the printed circuit board and positioned in a second selected location with respect to the upper end of the printed circuit board, the second selected location farther from the upper end than the first selected location, the second capacitive sensor having a second capacitance responsive to moisture content of soil proximate to the second capacitive sensor; a third capacitive sensor positioned on one of the front surface and the back surface of the printed circuit board and positioned in a third selected location with respect to the upper end of the printed circuit board, the third selected location farther from the upper end than the second selected location, the third capacitive sensor having a third capacitance responsive to moisture content of soil proximate to the third capacitive sensor; and a processing and transmission subsystem positioned on at least one of the front surface and the back surface of the printed circuit board proximate to the upper end of the printed circuit board, the processing and transmission subsystem coupled to each of the first, second and third capacitive sensors, the processing and transmission subsystem generating a first data value responsive to the first capacitance, generating a second data value responsive to the second capacitance and generating a third data value responsive to the third capacitance, the processing and transmission subsystem transmitting the first, second and third data values via a radio frequency output signal. - View Dependent Claims (2, 3, 4, 5)
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6. A method for determining moisture content of soil at three spaced apart levels below the surface of the soil, the method comprising:
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inserting a moisture sensing unit into the soil with a first capacitive sensor at a first level below the soil surface, with a second capacitive sensor at a second level below the soil surface, the second level farther below the soil surface than the first level, and with a third capacitive sensor at a third level below the soil surface, the third level farther below the soil surface than the second level; selecting the first capacitive sensor as an input to a capacitively controlled clock generator during a first time duration, the clock generator generating an output clock signal at a first frequency, the first frequency responsive to a capacitance of the first capacitive sensor, the capacitance of the first capacitive sensor responsive to the moisture content of soil proximate to the first capacitive sensor at the first level; selecting the second capacitive sensor as an input to the clock generator during a second time duration, the clock generator generating the output clock signal at a second frequency, the second frequency responsive to a capacitance of the second capacitive sensor, the capacitance of the second capacitive sensor responsive to the moisture content of soil proximate to the second capacitive sensor at the second level; selecting the third capacitive sensor as an input to the clock generator during a third time duration, the clock generator generating the output clock signal at a third frequency, the third frequency responsive to a capacitance of the third capacitive sensor, the capacitance of the third capacitive sensor responsive to the moisture content of soil proximate to the third capacitive sensor at the third level; determining the first frequency and generating a first data value responsive to the first frequency; determining the second frequency and generating a second data value responsive to the first frequency; determining the third frequency and generating a third data value responsive to the third frequency; and transmitting the first, second and third data values via a radio frequency signal as representations of the moisture content of the soil at the first, second and third levels, respectively. - View Dependent Claims (7, 8, 9, 10)
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Specification