Application of time-to-digital converters to radio-frequency distance measurement

The application of TDCs to wireless distance measurement problems is evaluated by means of experimental tests using a realized system. The system is capable of measuring the round-trip-time of ultra-wideband radio pulses propagating between two active transceivers, utilizing a commercial TDC with sub-nanosecond resolution. The results show an operational range of approximately 30 m in an indoor environment, with a distance-measurement error of less than 0.5 m in approximately 90% of the considered cases. Further, a discussion of the fundamental error sources is provided, analyzing the effect of RF interference, timing jitter, received signal strength, and propagation conditions.