This paper describes the development of several methods for the dynamic measurement of error distribution for positioning systems. When a user moves along a path at an unknown speed, it is no longer feasible to calculate the distance between the measured and real positions. We outline three applications using different positioning systems and apply our methods to the evaluation of the performance of these systems. Two indoor ultrasonic positioning systems are described and compared with the use of the GPS system outdoors. Alternative options for the placement of sensors/ antenna on the human body are evaluated.