Abstract

A communication method and a data collection and transmission system are provided having at least one remotely located monitoring station. A central computer is arranged for bidirectional communication with each of the monitoring stations. Each of the monitoring stations includes a storage and forward unit for communicating with the central computer and at least one sensor unit for monitoring a predetermined geographically proximate variable and for processing and storing predetermined operational data. The storage and forward unit includes a real time clock that is arranged to accurately maintain a real time indicative signal. A local area network connects the storage and forward unit and each of the sensor units. A coded message having a predetermined sequential data format is used for bidirectional communications between the storage and forward unit and the sensor units. A real-time coded message is provided by the storage and forward unit to the sensor units. The storage and forward unit includes a counter for counting at a predefined rate for identifying a delay time period prior to the transmission of the real-time coded message. Each sensor unit includes a counter for counting at the predefined rate to identify a second time delay period responsive to a received real-time coded message from the storage and forward unit. The real-time coded message includes the first identified time delay period that is combined with the second identified time delay period to determine the current time value by the sensor unit.