Ultrasonic sensor system and method having input capture for echo processing

Abstract

An ultrasonic sensor system ( ) has a transducer ( ) that emits an ultrasonic signal ( ), in response to an electrical excitation signal ( ) from driver/receiver circuitry ( ), and outputs an electrical response signal ( ), in response to receipt of a reflected ultrasonic signal ( ) from an object, such as a vehicle occupant ( ). The response signal ( ) is an oscillating signal that has a voltage amplitude indicative of the strength of the reflected ultrasonic signal ( ). A receiver circuit ( ) of driver/receiver circuitry ( ) processes the response signal ( ) from said transducer ( ) and outputs an analog, non-oscillating signal ( ). The analog signal ( ) has a voltage amplitude indicative of the voltage of the electrical response signal ( ). A comparator ( ) of a comparator preprocessor ( ) compares the voltage of the analog signal ( ) to a predetermined reference voltage (V ) and outputs a digital signal ( ). The digital signal ( ) is indicative of whether the voltage of the analog signal ( ) is greater or less than the reference voltage. A controller ( ) processes the digital signal ( ) for determining distance between the transducer ( ) and the occupant ( ). Preferably, the controller ( ) controls a protection module ( ).