| 摘要 |
PROBLEM TO BE SOLVED: To facilitate detection of a phase change corresponding to train control information of an ATC signal transmitted from the ground side to an on train side.SOLUTION: A phase detection means that detects a phase of a carrier wave of an amplitude modulated signal transmitted from ground equipment and outputs phase information is composed by including: an A/D converter 31 that converts amplitude modulated signals into digital signals; a multiplier group 32 comprising N pieces of multipliers that multiply a digital amplitude modulated signal from an A/D converter 31 by internal carrier waves that are displaced the phase by 2&pgr;/N by same amplitude and frequency of the basic carrier wave; a low-pass filter group 33 comprising N pieces of low-pass filters that extracts DC components of output values of each multiplier; and a phase difference detection means 34 that detects the phase of the internal carrier wave where the low pass filter output value of intermittent each signal part of the amplitude modulated signals becomes the maximum, detects the relative phase difference of internal carrier waves between signal parts mutually adjoined, outputs the phase information based on the relative phase difference. |
