Patent ID: 6248068
Filing Date: 2001-06-19
Classification: G01S

Abstract:
An apparatus for the non-contact monitoring of the movement or non-movement of an object comprising:(a) a generator for generating an electrical reference signal;(b) an ultrasonic transmitter coupled to said generator to receive and to convert said electrical reference signal into an ultrasonic emitted wave and to direct said emitted wave towards the object to be monitored, the emitted wave striking the object and being reflected therefrom to form a reflected ultrasonic wave;(c) an ultrasonic receiver located in a position to receive the reflected ultrasonic wave and to convert the reflected ultrasonic wave into an electric signal of the same frequency as the reflected wave;(d) a preliminary amplifier coupled to said ultrasonic receiver to receive and to amplify the electric signal supplied by said ultrasonic receiver and to form an amplified electric signal of increased amplitude;(e) a first electrical circuit forming a first channel coupled to said generator for receiving said electrical reference signal and also coupled to said preliminary amplifier for receiving and processing the amplified electric signal from said preliminary amplifier;(f) said first circuit introducing a phase shift of 45.degree. to said amplified electric signal from said preliminary amplifier to provide a first shifted amplified signal;(g) said first circuit including means for multiplying the first shifted amplified signal by the electrical reference signal supplied by said generator;(h) a second electrical circuit forming a second channel coupled to said generator for receiving said electrical reference signal and also coupled to said preliminary amplifier for receiving and processing the amplified signal from said preliminary amplifier;(i) said second electrical circuit introducing a phase shift of -45.degree. to said amplified signal from said preliminary amplifier to provide a second shifted amplified signal, with the total phase shift between said first and second shifted amplified signals being equal to 90.degree. and their amplitudes being the same;(j) said second circuit including means for multiplying the second shifted amplified signal by the electrical reference signal supplied by said generator;(k) an alarm circuit;(l) an adder connected to said first and second electrical circuits and to said alarm circuit;(m) said adder including means for adding the direct current voltages produced by said first and second electrical circuits and amplifying the result;(n) said amplified signal from said adder when the voltage is below a preset voltage actuating said alarm circuit thereby indicating that the movement of the object has terminated;(o) said amplified signal from said adder when producing an output voltage greater than said preset voltage maintaining said alarm circuit inactive thereby indicating that movement of the object has not terminated.