Ultrasonic anemometer based in cross correlation

This paper describes the development of one axis wind speed measurement equipment, applying cross correlations techniques and ultrasound sensors. It can be used in tubes, climate stations and wind farms where wind speed is necessary. The built prototype is a connected set of a DE0-Nano development board, a signal acquisition printed circuit board and two pairs of ultrasound sensors. The PCB also has circuits for ultrasound sensors exciting and PC communications to store the sampled signals. Inside DE0-Nano board FPGA chip, a system based in NIOS processor was developed and built through QSYS tool. There are some blocks described in VHDL for PCB interfacing. A small wind tunnel was built and a hand anemometer was acquired to validate the proposed system. It is common DSPs and microprocessors inside this type of equipments, but a system developed with a FPGA increases the processing speed due to parallelism. Blocks described in VHDL can be easily replicated inside the FPGA and there is a large collection of libraries, extensive literature and code examples for NIOS. The other advantages are smaller system/prototype developing time and easy development of a System on Chip(SOC) of FPGA based systems, reducing the costs for future commercial product.