A network
sensor system is provided that is capable of extremely low-power operation. The network
sensor system implements a communication protocol that allows the sensors to operate at
most times in a
sleep mode, where only a low-power time is active. In this way, each sensor's
receiver,
transmitter, and support circuitry are operated only when strictly necessary. The network has a defined network
time frame, and each device maintains and adjusts its own
clock and relationship with the network time. In this way, each sensor is aware about when it may be sent a message, and opens a short listen window only when such a message is expected. If no message is received, or if the message is addressed to another sensor, the sensor goes back to sleep. The sensor's
transmitter is only activated in the case where the message 1) is received during the listen period, 2) is addressed to the sensor, and 3) requires a transmission action. Otherwise, the
transmitter remains deactivated.