| 摘要 |
PROBLEM TO BE SOLVED: To reduce a calculating load of transmission and reception by transmitting and receiving railway detection signals and railway control signals with one transmitter/receiver. SOLUTION: This transmitter/receiver processes signals of a digital filter, frequency conversion, modulation, and demodulation using a processor for calculation. In a process of signal processing of a receiving system, inputs from a track are digitally converted by A/D41, and inputted into a decimation (thinning) filter (FIR(finite impulse response) type) 42 in order that a sampling frequency fs is converted from fs1 to fs2 (fs1>fs2). This output is inputted into a frequency converter 43, and inputted into a decimation filter 44, in order that the frequency fs is converted from fs2 to fs3 (fs2>fs3). Thereafter, a receiving level is outputted by a level calculator 46, and digital data RXD is simultaneously outputted by a demodulator 48. In this manner, the sampling frequency is gradually changed in the process of signal processing. COPYRIGHT: (C)2005,JPO&NCIPI
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