Acoustic obstacle detection with enhanced resistance to systematic interference

An obstacle detection method that comprises:

• sensing an acoustic transducer's response to each acoustic burst in a series of acoustic bursts;
• determining a difference between one of the responses and at least a portion of another one of the responses;
• and
• detecting peaks in the difference at delays corresponding to distances of obstacles reflecting the acoustic bursts.

A controller for an acoustic transducer, the controller comprising:

• a transmitter to drive the acoustic transducer to generate a series of acoustic bursts with signature sequence of frequency displacements;
• a receiver coupled to the acoustic transducer to sense a response for each acoustic burst in the series;
• and
• a processing circuit to derive output data from said responses in part by suppressing any peaks not conforming to the signature sequence.

An obstacle detection method that comprises:

• sensing an acoustic transducer's response to each acoustic burst in a series of acoustic bursts having a signature sequence of frequency displacements;
• combining the responses to obtain a combined response that enhances any peaks conforming to the signature sequence;
• and
• detecting peaks in the combined response at delays corresponding to distances of obstacles reflecting the acoustic bursts.