Patent ID: 6259372
Filing Date: 2001-07-10
Classification: G01M,G08C

Abstract:
A wireless transducer comprising:a housing adaptable to monitor an external physical condition of an external structure;an energy conversion source mounted within the housing to sense the external physical condition and create a power and characteristic signal in response to the external physical condition, the power and characteristic signal having a characteristic of the external condition;a transmitter mounted in the housing and connected to the energy conversion source to receive the power and characteristic signal and transmit a monitoring signal, the transmitter receiving power only from the energy conversion source as a source of power;wherein the power and characteristic signal is an A.C. voltage signal and wherein the wireless transducer further comprises a rectifier circuit to rectify the A.C. power and characteristic signal;an energy storage device and a energy level detector, the energy storage device is connected to the energy conversion source and the energy level detector is connected to the energy storage device, and wherein the energy storage device is capable of storing the rectified A.C. power and characteristic signal at least until the energy level detector detects a predetermined energy level; andwherein the energy storage device is a capacitor, the capacitance of which is selected to set a pulse width of the monitoring signal such that a number of wireless transducers can each produce a unique monitoring signal, and the energy level detector comprises a voltage comparator having a hysteresis in which the monitoring signal is transmitted.