Abstract: Acoustic touch detection (touch sensing) system architectures and methods can be used to detect an object touching a surface. Position of an object touching a surface can be determined using time-of-flight (TOF) bounding box techniques, or acoustic image reconstruction techniques, for example. Acoustic touch sensing can utilize transducers, such as piezoelectric transducers, to transmit ultrasonic waves along a surface and/or through the thickness of an electronic device. Location of the object can be determined, for example, based on the amount of time elapsing between the transmission of the wave and the detection of the reflected wave. An object in contact with the surface can interact with the transmitted wave causing attenuation, redirection and/or reflection of at least a portion of the transmitted wave. Portions of the transmitted wave energy after interaction with the object can be measured to determine the touch location of the object on the surface of the device.

Abstract: An electronic device may be provided with antenna structures. Proximity sensors and other sensors may be used in determining how the electronic device is being operated. Wireless circuitry such as a radio-frequency transmitter associated with a cellular telephone communications band, a wireless local area network band, or other communications band may be used in transmitting radio-frequency signals through the antenna structures at a transmit power. Control circuitry may adjust the wireless circuitry to ensure that the transmit power is capped at a maximum transmit power. The maximum transmit power may be adjusted dynamically by the control circuitry based on data from the proximity sensors, data from a magnetic sensor that detects whether a cover is present on the device, a connector sensor that detects whether the device is coupled to a dock or other accessory, and other sensors.