Fig. 15 shows the ATS-P system configuration. Wayside information such as signal aspect status are transmitted via a repeater and a ground coil to the cab coil of a passing train after being code processed. Then the receiver of the train generates a "speed pattern" corresponding to the wayside information, and passes it on to the controller which controls train speed.
The ATS-P uses 3 frequencies; 1.7 MHz for cab-to-ground information, 3.0 MHz for ground-to-cab information, and 245 kHz for power transmission, and adopting the FSK (Frequency Shift Keying) modulation method, transmits information at the speed of 64 kbit/s. An information data frame consists of 80 bits, of which 16 bits are used for synchronizing, 16 bits for CRC checking, and the remaining 48 bits for actual information use (Fig. 16).
Fig. 15 Configuration of ATS-P system
Fig. 16 Transmitting frequencies/fundamental data frame configuration
