Distance measuring system between train and station - uses phase shift between transmitted and response data telegrams

摘要

The system uses regularly spaced data telegrams. The train determines the clock time of the received data telegram and uses this to transmit a response telegram which is received by the station. The clock time of the response telegram is determined at the station to allow the phase shift relative to the transmission clock of the transmitted data telegrams to be measured. Pref. this phase shift is determined over several clock steps. The data telegram may incorporate one or more characters as the time markings.