Abstract: A monitoring system is disclosed, which includes a base station and at least one sensor unit that is separate from the base station. The at least one sensor unit resides in a dormant state until it is awakened by the triggering of a vibration-sensitive switch. Once awakened, the sensor may take a measurement, and then transmit to the base station the measurement. Once data is transmitted from the sensor to the base station, the sensor may return to its dormant state. There may be various 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.

Abstract: An in situ health monitoring apparatus may include an exciter circuit that applies a pulse to a piezoelectric transducer and a data processing system that determines the piezoelectric transducer's dynamic response to the first pulse. The dynamic response can be used to evaluate the operating range, health, and as-mounted resonance frequency of the transducer, as well as the strength of a coupling between the transducer and a structure and the health of the structure.

Abstract: An in situ health monitoring apparatus may include an exciter circuit that applies a pulse to a piezoelectric transducer and a data processing system that determines the piezoelectric transducer's dynamic response to the first pulse. The dynamic response can be used to evaluate the operating range, health, and as-mounted resonance frequency of the transducer, as well as the strength of a coupling between the transducer and a structure and the health of the structure.

Abstract: 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.