Apparatus for performing a fast Fourier transform on real-time samples of a received signal

摘要

A railway vehicle safety system, wherein a frequency modulated signal is transmitted to a vehicle informing, inter alia, of a safe maximum speed, which speed is represented by the carrier modulation frequency, which may possess one of a number of alternative frequencies. Also disclosed is an apparatus for analysing received signals to identify the carrier frequency and the modulation frequency employs a fast Fourier transform processor.