Sensor system

• US 4,941,501 A
• Filed: 02/06/1989
• Issued: 07/17/1990
• Est. Priority Date: 02/06/1989
• Status: Expired due to Term

• Current Assignee: Ann S. Wachtler Separate Property Trust, First Westinghouse Ventures Corporation
• Original Assignee: AquaMetrics, Inc.
• Inventors: Bireley, Richard L.
• Primary Examiner(s): CHAMBERS, A MICHAEL
• Application Number:
  US07/306,392
• Time in Patent Office: 526 Days
• Field of Search: 137/78.3, 239/63, 239/64
• US Class Current: 137/78.3
• CPC Class Codes: E02B 13/00 Irrigation ditches, i.e. gravity flow, open channel water distribution systems retaining waterborne material in irrigation canals E02B5/085; other distribution systems for watering or spraying gardens, fields, sports grounds, or the like, A01G25/00; built-in irrigation means for sports grounds E01C13/083
• CPC Class Codes: F17D 5/06 using electric or acoustic means
• CPC Class Codes: G01M 3/16 using electric detection means G01M3/045, G01M3/06, G01M3/12, G01M3/20, G01M3/24, G01M3/26 take precedence
• CPC Class Codes: Y10T 137/189 Soil moisture sensing

Abstract

A sensor is disposed in an earth patch for sensing the amount of moisture in such patch by providing a capacitance having a variable value dependent upon the sensed moisture. The variable capacitance is included in an oscillator which produces a signal at a frequency variable in accordance with variations in the capacitive value. The oscillator is energized by a direct potential passing through a cable from a potential source at a central station. A rectifier and a filter capacitor prevent the signal produced in the oscillator from interfering with the energizing of the oscillator by the direct potential. The signal from the oscillator passes through the cable to a stage at a controller. The incoming signal is prevented from interfering with the energizing voltage source by a filter inductor. A first controller stage reestablishes the incoming signals relative to a ground potential. The signal is the converted to a direct voltage which varies as a function of signal frequency. This voltage is then introduced to a comparator. A second voltage obtained from the voltage source and adjustable to indicate a desired amount of moisture in the monitored area of earth is also introduced to the comparator. The comparator produces an output dependent upon the relative values of the direct voltage obtained from the variable frequency signal and the adjustable direct voltage. This output controls the energizing of a solenoid at that position. When the solenoid is energized, it operates the valve for producing a watering of the patch of earth.

Claims

1. In combination for controlling the watering of a patch of earth in accordance with the amount of moisture in the patch of earth,

a central station displaced from the patch of earth,

first means at the central station for providing a direct potential,

second means at the patch of earth for sensing the amount of moisture in the earth and for producing a capacitance having a value dependent upon the amount of such moisture,

a coaxial cable extending between the patch of earth and the central station,

third means at the central station for introducing the direct potential to the coaxial cable,

fourth means responsive at the patch of earth to the direct potential passing through the cable and responsive to the capacitance for producing signals at a frequency dependent upon the value of the capacitance and for introducing such signals to the coaxial cable,

fifth means responsive at the central station to the signals passing through the coaxial cable for producing a voltage related to the frequency of the signals, and

sixth means responsive at the central station to the voltage produced by the fifth means for controlling the watering of the patch of earth.

2. In a combination as set forth in claim 1,

means associated at the patch of earth with the coaxial cable and the fourth means for preventing the direct potential from affecting the operation of the fourth means.

3. In a combination as set forth in claim 1,

means associated at the central station with the coaxial cable and the fifth means for preventing the direct potential from affecting the operation of the fifth means.

4. In a combination as set forth in claim 3,

means at the central station for introducing the direct potential to the fifth means to energize the fifth means, and

means at the central station for preventing the signals from the fourth means from affecting the energizing of the fifth means to provide for the production by the fifth means of the direct voltage having the magnitude related to the variable frequency of the variable frequency signal.

5. In combination for controlling the watering of a patch of earth in accordance with the amount of moisture in the patch of earth,

a central station displaced from the patch of earth,

a coaxial cable having ungrounded terminals and extending between the central station and the patch of earth,

first means at the central station for providing a direct potential,

second means at the patch of earth for providing a capacitance having a value dependent upon the amount of moisture in the patch of earth,

third means responsive at the patch of earth to the value of the capacitance for producing signals having a frequency dependent upon such value,

fourth means at the patch of earth for introducing the direct potential through the coaxial cable to the third means to energize the third means,

fifth means at the central station for controlling the watering of the patch of earth in accordance with the frequency of the signals from the fourth means, and

sixth means at the central station for passing the signals through the coaxial cable to the fifth means to obtain the operation of the fifth means in controlling the watering of the patch of earth in accordance with the frequency of the signals from the third means.

6. In a combination as set forth in claim 5,

means at the patch of earth for preventing the signals from the third means from affecting the energizing of the third means by the direct potential.

7. In a combination as set forth in claim 5,

means at the central station for preventing the direct potential from passing through the coaxial cable to affect the operation of the fifth means in responding to the signals from the third means.

8. In a combination as set forth in claim 7,

means at the central station for introducing the direct potential to the fifth means to energize the fifth means for the control of the watering of the patch of earth in accordance with the frequency of the signals form the third means.

9. In a combination as set forth in claim 8,

means at the central station for preventing the signals passing through the third means from affecting the energizing of the fifth means by the direct potential.

10. In a combination as set forth in claim 7,

means at the central station for preventing the direct potential from passing through the coaxial cable to affect the operation of the fifth means in responding to the signals from the third means, and

means at the central station for preventing the signals passing through the third means from affecting the energizing of the fifth means by the direct potential.

11. In combination for controlling the watering of a patch of earth in accordance with the amount of moisture in the of earth,

a central station displaced from the patch of earth,

a coaxial cable extending between the central station and the patch of earth,

first means at the central station for providing a direct potential,

second means at the patch of earth for producing signals having a variable frequency representative of the amount of moisture in the soil,

third means at the central station for introducing the direct potential through the coaxial cable to the second means to energize the second means for the production of the signals of variable frequency,

fourth means responsive at the central station to the passage of the variable frequency signals through the coaxial cable for processing the variable frequency signals, without any effect from the passage of the direct potential through the coaxial cable, to provide a controlled watering of the patch of earth in accordance with the variations in the frequency of such signals, and

fifth means at the central station for energizing the fourth means with the direct potential without any effect from the variable frequency signals in the coaxial cable.

12. In a combination as set forth in claim 11,

the second means including a sensor constructed to be disposed in the patch of earth and to produce a variable capacitance having a value dependent upon the amount of moisture in the patch of earth and further including means responsive to the variable capacitance for varying the frequency of the signals in accordance with the variations in the value of the capacitance, and

means at the patch of earth for preventing the variable frequency signals from affecting the energizing of the second means by the direct potential passing through the coaxial cable.

13. In a combination as set forth in claim 11,

means at the patch of earth for preventing the second means from affecting the energizing of the second means by the direct potential.

14. In a combination as set forth in claim 11,

means at the central station for preventing the direct potential from affecting the operation of the fourth means in processing the variable frequency signals to provide a controlled watering of the patch of earth in accordance with the variations in the frequency of such signals.

15. In a combination as set forth in claim 12,

means at the central station for preventing the second means from affecting the energizing the second means by the direct potential,

means at the central station for preventing the direct potential from affecting the operation of the fourth means in processing the variable frequency signals to provide a controlled watering of the patch of earth in accordance with the variations in the frequency of such signals,

the fourth means being operative to convert the variable frequency signals to a direct voltage having a magnitude related to the variable frequency of such signals, and

means responsive at the central station to the magnitude of the direct voltage for obtaining a controlled watering of the patch of earth,

16. In a combination for controlling the watering of a patch of earth in accordance with the amount of moisture in the patch of earth,

a central station displaced from the patch of earth,

a coaxial cable having a first terminal and a second terminal which is earthed, the coaxial cable extending between the central station and the patch of earth,

first means at the patch of earth for producing alternating signals having characteristics representing the amount of water at the patch of earth,

second means at the central station for providing a direct potential and for introducing the direct potential through the coaxial cable to the first means to energize the first means for the production of the alternating signals,

third means at the central station for passing the alternating signals through the coaxial cable without interference from the direct potential, and

fourth means responsive at the central station to the alternating signals passing through the coaxial cable for processing the signals to provide a controlled watering of the patch of earth in accordance with the characteristics of the alternating signals,

17. In a combination as set forth in claim 16,

the fifth means including sixth means at the central station for establishing, relative to the potential of the earth, the signals passing through the coaxial cable and further including seventh means for converting such signals to a direct voltage without interference from the direct potential passing through the coaxial cable, and

means at the central station for energizing the seventh means with the direct potential without interference from the alternating signals passing through the coaxial cable.

18. In a combination as set forth in claim 17,

comparator means at the central station,

eighth means responsive at the central station to the direct potential for providing an adjustable direct voltage,

means at the central station for introducing the direct voltage from the seventh means to the comparator means for comparison with the adjustable direct voltage, and

means responsive at the central station to the output from the comparator means for obtaining a controlled watering of the patch of earth,

19. In a combination as set forth in claim 18,

means at the patch of earth for providing for an energizing of the first means by the direct potential without interference from the first means.