| 摘要 |
<p>PURPOSE:To reduce noise in the environment of a station by eliminating a broadcast sound unnecessarily large in volume, by controlling the sound volume of a broadcasting unit according to the passing speed of a train. CONSTITUTION:Speed-detecting Doppler radars 41 and 42 are provided away from station 1. As a result, the speed of a train traveling in section 5 is detected and speed information is supplied to calculator 8 and gain controller 7. On the basis of the speed information, gain controller 7 judges whether the train is stopping or passing by slowly or at a fixed speed or above. On the basis of the speed information, calculator 8 obtains information on the information when the train reaches the station. Then, gain control amplifier 10 is controlled to optimum volume on the bais of those pieces of information.</p> |
