Smart two-element PTC wind sensor

A smart, low-cost wind sensor consisting of just two self-heated PTC (positive temperature coefficient) elements is described. Placing the elements asymmetrically in a cylindrical shell, the wind vector can be reliably measured in two dimensions. Inherent measurement errors due to incipient soiling of the sensor surface, ohmic bridges, shortcuts and ageing of the electrical parameters, are detected with an automatic self-calibration procedure and effectively compensated for. The instants for automatic recalibration are determined without any additional assistance, when identical signals from both sensor elements are observed. The parameters of the PTC sensor model are then determined from the element´s I-U-characteristics and used to correct all measured data during operation.