20080252475 | Monitoring Method and Apparatus Using Asynchronous, One-Way Transmission from Sensor to Base Station - A monitoring system is disclosed, which includes a base station and at least one sensor unit that is separate from the base station. The sensor unit resides in a dormant state that uses no power, until it is awaked by the triggering of vibration-sensitive switch. Once awakened, the sensor may take a measurement, then transmit to the base station the measurement along with a time stamp of when the measurement was made. The sensor may optionally store the measured quantity and the time stamp for a particular length of time in a suitable storage device, such as with compact flash memory. The sensor transmits the measured quantity and the time stamp to the base station in an asynchronous manner. The transmission is initiated by the vibration-sensitive switch, not by the base station. The time stamp is encoded in a suitable manner, such as with an IRIG-B timing module. Once data is transmitted from the sensor to the base station, the sensor may return to its dormant state. Transmission between the sensor and the base station is one-way, so that the sensor does not receive any information from the base station. There may be multiple sensors for each base station, and the various sensors may optionally measure different quantities, such as current, voltage, single-axis and/or three-axis magnetic fields, that may correspond to physical quantities such as torsional strain, linear strain, temperature, ball valve cycles and linear voltage displacement transducer signals. The sensor may optionally include an energy harvester, such as a solar panel, for reducing and/or eliminating the drain on its battery. | 10-16-2008 |