Smartlow-cost weather sensor as an example for `multi-component´ sensors

In order to gain the desired information from a sensor and to improve its reliability and selectivity, efforts in different domains can be taken, e.g. determining time dependencies or spectra of measurement results and feature values, observing an object from different locations, measuring at various working points on a sensor characteristics, or increasing the number of sensors and applying a data fusion approach. The generalization of these efforts can be called ´multi-signal´ evaluation, being a fundamental component of a ´multi-component´ sensor as the entirety of sensor elements and signal processing tools combined in a smart sensor. Its potential to increase the usefulness of simple low-cost of-the-shelf-components is shown on behalf of wind and weather sensors made of commonly available temperature-depending resistors. The proposed wind vector sensor consists of three PTC (positive temperature coefficient) elements placed under a known angle to each other around a cylindrical flow body. The wind velocity as well as the wind direction are calculated from output voltages by an optimization procedure. Varying the working points on the I-U characteristics, also the sensor´s state can be monitored on-line. A second example shows how by examining characteristic features of the response of a Platinum temperature-dependent resistor supplied periodically with sufficiently high power, the various sources of influence like the ambient temperature, wind, rain, ice or snow can be separated. Prototype sensors have been developed and evaluated with satisfactory results