Patent ID: 8554380

Claim:
A controller for controlling an irrigation schedule in an irrigation system, the irrigation system including a plurality of sprinkler heads connected via a plurality of conduits to a water source, the controller comprising: a rain gauge configured to transmit to the controller a signal representing a recent rainfall amount; a thermometer configured to transmit to the controller a signal representing a prevailing temperature value; an input means for permitting a user to enter irrigation parameters into the controller, wherein the parameters include: a Maximum Irrigation Duration; an identifier for identifying a sector in which the irrigation system is located; the current date; a database that includes stored information relating to historical meteorological conditions associated with each of a plurality of sectors located within a geographical area, the information including, for each sector: a historical period-average evapotranspiration rate for a plurality of periods over the duration of a year, a historical average solar radiation level for each month over the duration of a year; a solar radiation for the month of average summer high temperature; an average summer high temperature; wherein, a microprocessor is configured to calculate and apply an amount of time to suspend the next irrigation event due to rainfall, the amount of time being based on measured inches of rainfall divided by the historical period-average evapotranspiration rate for the current period; further wherein the microprocessor is configured to calculate and apply a Next Irrigation Duration being equal to the Maximum Irrigation Duration multiplied by a ratio based on the product of the historical average solar radiation level for the current month and the previous day's measured high temperature, divided by the product of the solar radiation for the month of average summer high temperature and the average summer high temperature; and wherein the microprocessor is configured to respond to a failure in receipt of a signal from at least one of the rain gauge or the thermometer by calculating and applying an Actual Irrigation Duration rather than a Next Irrigation Duration, the Actual Irrigation Duration being equal to the Maximum Irrigation Duration multiplied by a ratio, defined as a Period Reduction Factor, based on the historical period-average evapotranspiration rate for the current period divided by a maximum period-average evapotranspiration rate that occurs in the course of a year.