An ultrasonic sensor comprising: a two-dimensional array of ultrasonic transducers comprising a plurality of sub-arrays (2550a, 2550b, 2550c) of ultrasonic transducers, wherein a sub-array of ultrasonic transducers of the plurality of sub-arrays of ultrasonic transducers is independently controllable, and wherein a sub-array of ultrasonic transducers has an associated receive channel; a plurality of shift registers configured to select a receive pattern of ultrasonic transducers of the two-dimensional array of ultrasonic transducers to activate during a receive operation; an array controller configured to control selection of the ultrasonic transducers during the receive operation according to the receive pattern and configured to shift a position of the receive pattern within the plurality of shift registers such that the receive pattern of the ultrasonic transducers activated during the receive operation moves relative to and within the two-dimensional array of ultrasonic transducers; characterized in that the ultrasonic sensor further comprises switches at boundary regions between adjacent sub-arrays, wherein the switches are controlled to direct a received signal for an ultrasonic transducer to a selected receive channel during the receive operation, wherein the array controller is configured to control the switches responsive to the receive pattern overlapping at least two sub-arrays of the plurality of sub-arrays of ultrasonic transducers, wherein the array control logic directs the received signals for all ultrasonic transducers of the receive pattern to the selected receive channel during the receive operation. a two-dimensional array of ultrasonic transducers comprising a plurality of sub-arrays (2550a, 2550b, 2550c) of ultrasonic transducers, wherein a sub-array of ultrasonic transducers of the plurality of sub-arrays of ultrasonic transducers is independently controllable, and wherein a sub-array of ultrasonic transducers has an associated receive channel; a plurality of shift registers configured to select a receive pattern of ultrasonic transducers of the two-dimensional array of ultrasonic transducers to activate during a receive operation; an array controller configured to control selection of the ultrasonic transducers during the receive operation according to the receive pattern and configured to shift a position of the receive pattern within the plurality of shift registers such that the receive pattern of the ultrasonic transducers activated during the receive operation moves relative to and within the two-dimensional array of ultrasonic transducers; characterized in that the ultrasonic sensor further comprises switches at boundary regions between adjacent sub-arrays, wherein the switches are controlled to direct a received signal for an ultrasonic transducer to a selected receive channel during the receive operation, wherein the array controller is configured to control the switches responsive to the receive pattern overlapping at least two sub-arrays of the plurality of sub-arrays of ultrasonic transducers, wherein the array control logic directs the received signals for all ultrasonic transducers of the receive pattern to the selected receive channel during the receive operation.