Abstract: A communication method, applied to a master device, includes: determining, according to the number of controlled devices and a preset time slot length, detection cycles and detection timing of various controlled devices in a detection cycle; receiving, in a time slot in the detection cycle, an ultrasonic sweep signal sent by the controlled device; and determining, according to the detection timing and the ultrasonic sweep signal, a detection result of the master device and a controlled device.

Abstract: A sending time determination method includes: determining a transmission duration and a synchronization error of signal transmission between the device to be measured and a goniometric device; determining a receiving time slot for the goniometric device to receive ultrasonic goniometric signal sent by the device to be measured, where the goniometric device is configured to receive ultrasonic goniometric signals sent by a plurality of devices to be measured, and the goniometer device receives the ultrasonic goniometric signals sent by different devices to be measured in different receiving time slots; and determining a sending time of the ultrasonic goniometric signal according to the receiving time slot, the transmission duration and the synchronization error.