Position finding based on multiple doppler sensors

Nowadays knowledge about the position of persons indoors is relevant for a huge number of problems. An increasing number of modern applications and services is based on information referring to the users actual position and in some cases also on its velocity. In addition to these location based services also safety and security relevant tasks require these informations, e.g. critical infrastructure (CI) or small area surveillance. In outdoor scenarios the GPS-System is often used, but not all of the already existing wireless infrastructure is capable of providing the position information needed, especially in indoor environments. For this case several approaches can be found in the literature. Most of them adopt the GPS-principle thus needing additional infrastructure and objects actively participating in the position finding task. We will present a system that is based on doppler measurement and only analyses a relative distance information between the object to be detected and four very basic sensors. Therefore no cooperation of the object is needed which is very important for the mentioned security relevant applications. The design of a 4-channel demonstration system will be shown and practical results obtained with this demonstration system will be given.