RF amplifier tuning method for coping with expected variations in local dielectric

• US 9,046,461 B1
• Filed: 10/29/2012
• Issued: 06/02/2015
• Est. Priority Date: 02/03/2009
• Status: Active Grant

• Current Assignee: Green Badge, LLC
• Original Assignee: Green Badge, LLC
• Inventors: Sohrabi, Katayoun, Campbell, Jeffrey
• Primary Examiner(s): Lim, Steven
• Assistant Examiner(s): Knox, Kaleria
• Application Number:
  US13/663,442
• Time in Patent Office: 946 Days
• Field of Search: 340/870.02, 340/870.11, 701/220, 702/22, 324/644
• US Class Current: 1/1
• CPC Class Codes: G01N 2033/245 for agricultural purposes
• CPC Class Codes: G01N 22/04 Investigating moisture content
• CPC Class Codes: G01N 27/00 Investigating or analysing materials by the use of electric, electrochemical, or magnetic means G01N3/00 – G01N25/00 take precedence; measurement or testing of electric or magnetic variables or of electric or magnetic properties of materials G01R
• CPC Class Codes: G01N 27/04 by investigating resistance
• CPC Class Codes: G01N 33/24 Earth materials G01N33/42 takes precedence
• CPC Class Codes: G08C 17/02 using a radio link
• CPC Class Codes: H04W 4/00 Services specially adapted for wireless communication networks; Facilities therefor
• CPC Class Codes: Y10T 137/189 Soil moisture sensing

Abstract

A wireless sensor capable of sensing and measuring at least one ambient parameter is disclosed herein. The wireless sensor is capable of transmission of measurement values at a periodic rate, wherein the transmission rate is varied or non-varied. An amplifier varies a power transmission to the antenna based on a real-time soil conductivity value of a soil area and a real-time soil dielectric constant value of a soil area to improve a communication range and communication reliability of the antenna.

Claims

1. A wireless soil sensor comprising:

a microcontroller;

an antenna;

an amplifier;

a probe conducting structure to be placed in the material forming a capacitor connected to a soil moisture circuit;

a soil moisture circuit comprising a high frequency oscillator for applying electrical stimulus to the probe structure, a known reference capacitor connected in series to the high frequency oscillator, and a first voltage meter located between the high frequency oscillator and the reference capacitor;

a soil salinity circuit comprising a low frequency oscillator for applying electrical stimulus to the probe structure, a known reference resistor connected in series to the low frequency oscillator, and a second voltage meter located between the low frequency oscillator and the reference resistor;

wherein the respective circuits connect between the reference capacitor and the reference resistor, at which point the circuits are connected to the probe structure and a third voltage meter; and

wherein the amplifier varies a power transmission to the antenna based on a real-time soil conductivity value of a soil area and a real-time soil dielectric constant value of a soil area to improve a communication range and communication reliability of the antenna.

2. The wireless soil sensor according to claim 1 wherein the microcontroller is configured to measure analog voltages and perform calculations to determine the real-time soil conductivity value and the real-time soil dielectric constant value.

3. The wireless soil sensor according to claim 1 wherein the antenna circuit comprises a plurality of resistors and inductors for tuning the antenna.

4. The wireless soil sensor according to claim 1 wherein the antenna transmits at 2.4 GigaHertz.

5. A method for improving a communication range and communication reliability of an antenna for a wireless soil sensor buried below the surface of a land area, the method comprising:

activating a wireless sensor;

measuring a plurality of soil electrical properties for the land area;

transmitting data from the wireless sensor to at least one receiver above the surface of the land area at a plurality of switchable antenna configurations;

monitoring a signal property of each transmission of data for each of the plurality of switchable antenna configurations;

repeating the above steps every predetermined number of sensor transmission cycle;

creating a map of the signal property for the plurality of switchable antennal configurations;

providing the map to each of a plurality of sensor nodes;

determining from the map the most favorable antenna configuration for the position of the node;

configuring the sensor node to the most favorable antenna configuration; and

transmitting data from the node.

6. The method according to claim 5 wherein the predetermined number of sensor transmission cycles is sixty.

7. The method according to claim 5 wherein the plurality of soil electrical properties comprises soil conductivity and soil dielectric constant.

8. The method according to claim 5 wherein the map is a two dimension map of soil conductivity and soil dielectric constant.

9. The method according to claim 5 further comprising:

determining that a communication link with a wireless sensor has been lost; and

assigning a nearby, reliably communicating sensor to act as a proxy for the sensor with a lost communication link.

10. The method according to claim 5 further comprising:

transmitting a pairing signal from a wireless sensor;

receiving the pairing signal at an irrigation controller; and

pairing the irrigation controller with the wireless sensor.

11. The method according to claim 5 further comprising:

predicting sensor values from wireless sensors when wireless transmissions from the sensors are not received due to radio noise, environmental conditions, dropping battery levels, damaged sensors, etc. based upon at least one of;

the time duration from the previous successfully received sensor value;

the value of the last successfully received sensor value;

observed correlations between the sensor that has not reported and those that are still successfully received;

data from other, non-wireless sensors as well as data from other installations that may be received wirelessly such as nearby weather stations.

12. The method according to claim 5 further comprising:

a plurality of wireless sub-surface sensors;

a receiver for receiving and transmitting data to the plurality of wireless sub-surface sensors; and

a control engine, the control engine receiving the data from the receiver, the control engine having a processor;

wherein algorithms are used to sweep potential antenna configurations and matching components to optimize link budget.

13. The method according to claim 5 further comprising:

a plurality of wireless sub-surface sensors;

a receiver for receiving and transmitting data to the plurality of wireless sub-surface sensors; and

a control engine, the control engine receiving the data from the receiver, the control engine having a processor;

wherein a plurality of antenna configurations and matching components are used within a node to extend a transmissions range.

14. The method according to claim 5 further comprising:

a plurality of wireless sub-surface sensors;

a receiver for receiving and transmitting data to the plurality of wireless sub-surface sensors; and

a control engine, the control engine receiving the data from the receiver, the control engine having a processor;

wherein a plurality of antenna configurations and matching components are used within a node to extend a transmissions range.

15. The method according to claim 5 further comprising:

a water source;

a plurality of wireless controllers for controlling the flow of water through each of a plurality of valves, each of the plurality of wireless controllers at a home in the community; and

a plurality of sub-surface sensors, each of the plurality of sub-surface sensors corresponding to a sub-area of a plurality of sub-areas of a soil area, each of the plurality of sub-surface sensors corresponding to a valve of the plurality of valves, each of the plurality of sub-surface sensors having a probe structure for measuring a moisture content of the corresponding sub-area of the plurality of sub-areas;

wherein the wireless controller is in wireless communication with each of the plurality of sub-surface wireless sensors; and

wherein irrigation data from each home is sent from the wireless controller to a central location so that it can be aggregated into community wide reporting/management of irrigation.