Long-range measurement system using ultrasonic range sensor with high-power transmitter array in air

A long-range measurement system comprising an ultrasonic range sensor with a high-power ultrasonic transmitter array in air was investigated. The system is simple in construction and can be used under adverse conditions such as fog, rain, darkness, and smoke. However, due to ultrasonic waves are well absorbed by air molecules, the measurable range is limited to a few meters. Therefore, we developed a high-power ultrasonic transmitter array consisting of 144 transmitting elements. All elements are arranged in the form of a 12 × 12 array pattern. The sound pressure level at 5 m from the transmitter array was >30 dB higher than that of a single element. A measuring range of over 25 m was achieved using this transmitter array in conjunction with a receiver array having 32 receiving elements. The characteristics of the transmitter array and range sensor system are discussed by comparing simulation and experimental results.