System-theoretic analysis and optimization of a novel secondary radar concept for precise distance and velocity measurement

In the last decade, the demand for precise location and tracking of people, vehicles, or objects in real-time has increased tremendously. There are many exciting applications with a huge market potential for wireless location solutions. Today, wireless location systems are widely used in both consumer and industrial applications. This thesis focuses on the analysis and optimization of a novel secondary radar concept for precise distance and velocity measurement. The proposed system is comprised of two active radar stations, a base station and a transponder. It is shown how frequency-modulated continuous wave radar signals are utilized to synchronize the clock of the transponder to the clock of the base station with high precision. After synchronization the distance between the radar stations is measured similarly to the well-known frequency-modulated continuous wave radar principle. A novel extension of the measurement algorithm exploits the Doppler frequency shift of the radar signals to measure the relative velocity of both units as well. Furthermore, novel multiplexing schemes for multiple transponders are derived. To verify the system concept at hand a measurement system was designed and set up within this work. A thorough mathematical analysis of the underlying algorithms for synchronization and distance and velocity measurement provides the basis for the identification of sources of error. The identified errors are then analyzed in detail. The most important sources of error include multipath propagation, the mismatch of the sweep rates of the radar stations, and the signal-to-noise ratio of signals involved in the measurement process. Theoretical calculations as well as simulation and measurement results are used to evaluate the effect of each parameter on the performance of the radar system at hand. Finally, the performance of the measurement system is evaluated in various environments. The results of an extensive measurement campaign prove the excellent performance of the novel system concept investigated in this thesis.