FPGA based ToF measurement system for ultrasonic anemometer

The paper describes a way of measuring the wind speed and direction based on Time of Flight. The system uses ultrasonic sound to detect the velocity of the wind. Time of Flight (ToF) is explained as the time taken by the ultrasonic sound waves to travel from one sensor to the other is defined. The propagation of these ultrasonic sound waves is affected by the intensity and direction of wind. If the direction of propagation of wind a n d the direction of propagation of sound is same, the ToF will be less. The lesser the ToF, more is the wind velocity. The system mainly includes Ultrasonic Transceiver, Time to Digital Converters (TDC), Multiplexer, FPGA and user interface. The FPGA communicates with the TDC and multiplexer using SPI protocol. FPGA plays a crucial role in this system. All the control and processing are done using FPGA. The proposed architecture is simulated in Libero IDE and synthesized using Synplify Pro for ProASIC3E Actel FPGA.