| 摘要 |
<p>PURPOSE:To provide train detection and ATC information of a high noise-proof characteristic by supplying a first and a second PN codes, demodulating a train detecting signal and a modulated train control signal to extract-detect a signal including the second PN code, and demodulating a control signal obtained by generating the same PN code as the second PN code. CONSTITUTION:When a train (a) exists in a closed terrotory T, a rail T is short-circuited by the axles W of the train (a), and this is detected by a receiver 10. An onboard receiver 20 receives a second PN code (PN2) from the rail T through an antenna A, and a demodulating circuit 23 demodulates a signal of the same frequency as train control carrier wave (fATC). The coincidence degree of the sampled signal with the second PN code (PN2) is then detected by a matched filter 26, and the same PN code as the second PN code (PN2) is generated from a fourth PN code generator 28 through a synchronous holding circuit 27. Using this code, the signal received by the onboard receiver 20 is processed by an onboard inverse diffusion circuit 29 and decoded by a control signal decoder 32 through an FSK demodulator 31.</p> |
