Low-rate ultrasonic communications and power delivery for sensor applications

With acoustic-electric channels, it is possible to send data through metallic barriers at very high rates while also transferring power. However, some isolated sensing situations require a lower complexity solution that is both small in size and low-power. This paper describes a simple low-rate communication method optimized for use with a battery-powered wireless sensor using amplitude modulation, envelope detection, and common modules found in commercially available microcontrollers. The data transfer algorithms rely on reduced computational operations making them suitable for microcontroller cores with limited processing power and memory. Additionally, the system is able to transfer power for recharging a battery, eliminating the need for physically accessing the sensor at any time. Bi-directional, half-duplex transfer of data at 2.7 kbps with a low bit error rate (BER) is demonstrated experimentally. A smart sensor that uses the technology, the Autonomous Intelligent Sensor Tracking System ‡ (AISTS), is described.