Patent ID: 11885874
Assignee: SEMICONDUCTOR COMPONENTS INDUSTRIES, LLC
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. An acoustic distance measuring circuit, comprising:
a frequency generator having an output for providing a chirp signal;
a transmitter amplifier having an input coupled to the output of the frequency generator, and an output adapted to be coupled to an acoustic transducer;
a sensing circuit having an input adapted to be coupled to the acoustic transducer, for receiving an input signal and providing an in-phase portion and a quadrature portion of the input signal, filtering the in-phase portion and the quadrature portion, calculating a phase of the input signal in response to filtered in-phase and filtered quadrature portions, and determining a frequency slope of the input signal in response to the phase; and
a controller having an input coupled to the sensing circuit, wherein the controller is operable to compare the frequency slope of the input signal to a chirp signal frequency slope and to detect an object if the frequency slope of the input signal is approximately equal to the chirp signal frequency slope, wherein the controller is also operable to determine a distance of the object corresponding to a frequency shift of the frequency slope of the input signal and an extrapolated chirp signal frequency slope extended from the chirp signal.