Patent ID: 6192752
Filing Date: 2001-02-27
Classification: G01F,G01N

Abstract:
A sensor system for use in characterizing contents of a container, wherein said sensor system analyzes microwave frequency electromagnetic signals generated therefrom to thereby determine characteristics of the container contents, said system comprising:an electromagnetic sensor which is disposable on a container, and which is capable of transmitting the microwave frequency electromagnetic signals, wherein the electromagnetic sensor is a microwave frequency multi-port coupler which includes an input port and at least two output ports, wherein a high common mode rejection ratio is used to thereby reduce electromagnetic sensor activity by having a first output port and a second output port;a detector circuit which is electrically coupled to the electromagnetic sensor to thereby detect the perturbations in the microwave frequency electromagnetic signals, and which processes each signal from the first and the second output ports by rectifying, integrating, and then comparing the rectified and integrated signals using a differential amplifier circuit;a processing device which is electrically coupled to the electromagnetic sensor, wherein the processing device develops the microwave frequency electromagnetic signals to be transmitted, analyzes the transmitted microwave frequency electromagnetic signals to thereby detect perturbations therein, and provide a human perceptible alarm when the detected perturbations indicate that an alarm condition is met;wherein the processing device includes an oscillator which is electrically coupled to the electromagnetic sensor, and which develops the microwave frequency electromagnetic signals for transmission therefrom;a controller for activating the oscillator and the detector circuit when the electromagnetic sensor is in a sensing mode, and for deactivating the oscillator and the detector circuit when the sensor system is in a sleep mode, and wherein a duration of the sensing and the sleep modes is programmable; anda power supply for supplying electrical current to the sensor system.