ULTRASONIC DETECTING DEVICE AND ULTRASONIC DETECTING METHOD

An ultrasonic detecting device may include a transmitter, a receiver, a motor, and processing circuitry. The transmitter may transmit a sequence including a first pulse wave and a second pulse wave separated by a time interval shorter than a time required for an ultrasonic wave to make a round trip underwater to a detection range. The receiver may convert reflection waves of the first and second pulse waves into echo signals. The motor may rotate the receiver. The processing circuitry may acquire, from the echo signals, a first echo signal and a second echo signal, generate first image data based on the first echo signals and second image data based on the second echo signals, and generate synthesized image data based on an angular position of the receiver when the first image data is generated, and an angular position of the receiver when the second image data is generated.