Two-Wire Irrigation Decoder With Adaptive Baud Rate
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Solution Overview
Problem
Existing two-wire power and communication systems for irrigation systems are limited by sensitivity to power surges, electrolysis issues, and reduced functionality due to voltage drops and increased resistance over long distances, leading to high costs and limitations in system size and decoder numbers.
Innovation Solution
A two-wire power and communication system that includes a gateway for transmitting firmware updates, decoders that can receive messages with irrigation start and run times, and a communication protocol that adjusts baud rate for reliability, along with solenoids that sense plunger movement and relay status, minimizing voltage fluctuations and enhancing system control and scalability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If decoders use fixed resistor circuits to switch to a circuit path with a resistor between the common current and ground, then the decoder can communicate with the central controller, but any reduction in voltage causes a proportional reduction in the current pulse, causing the gateway to not recognize the acknowledgment pulse
Solution Approach 1:
The patent changes the electrical parameters of the decoder circuit by replacing fixed resistor circuits with transistor-based switching circuits. The transistor acts as a variable resistor controlled by the microprocessor, allowing the circuit to maintain sufficient current pulse strength for acknowledgment even when voltage drops occur over long wire distances. This parameter change enables reliable communication in extended system configurations.
2Area of stationary object
If decoders are installed further away from the gateway, then system coverage area increases, but the resistance of the power and communication wires becomes significant and reduces the voltage available across the decoder
Solution Approach 1:
The patent employs parameter changes in the decoder's switching circuitry to compensate for voltage drops over long distances. The transistor-based circuit can maintain adequate current levels for communication even when supplied with reduced voltage from long wire runs, enabling expanded system coverage without sacrificing reliability.
3Adaptability or versatility
If large numbers of decoders are installed, then system functionality increases, but large numbers of decoders further reduce voltage and increase resistance on the power and communication wires
Solution Approach 1:
The patent uses parameter changes in the transistor switching circuits to maintain adequate current levels even when multiple decoders are connected to the same communication bus. Each decoder's transistor-based switching circuit can operate effectively with the reduced voltage levels that result from having multiple devices on the bus, enabling expanded system functionality.
4Extent of automation
If traditional two-wire systems use DC current to power and control components, then control functionality is achieved, but heavy use of DC current may cause electrolysis issues with electrical components
Solution Approach 1:
The patent employs periodic action by using AC power for the two-wire system instead of continuous DC current. The system uses the alternating current to power decoders and superimposes communication signals on top of the AC waveform. This periodic AC-based operation eliminates the continuous DC current flow that causes electrolysis, while maintaining full control functionality through the alternating current cycles and superimposed signal modulation.
5Extent of automation
If decoder circuitry listens for communications on the two-wire system, then digital control communication is achieved, but decoder circuitry are sensitive to power surges by lightning, requiring expensive external surge devices
Solution Approach 1:
The patent merges the power and communication functions into a single integrated two-wire system using AC power. By combining these functions and using AC instead of DC, the system reduces susceptibility to surge damage. The AC-based design with proper isolation and signal coupling provides inherent protection against lightning-induced surges while maintaining digital communication capability.
Data Source
AI summary
A decoder for a two-wire irrigation system is disclosed, having the ability to be remotely updated with new firmware over the two-wire network, the ability to download irrigation commands that can be executed at a later time, the ability to adjust its data speed when data corruption is encountered, and the ability to sense the position of an attached solenoid plunger.