| 摘要 |
PURPOSE:To simplify the configuration of terminal equipment, and to form the data communication system of low cost as a total system in a radio data transmission system using a spread spectrum system. CONSTITUTION:The transmission circuit of the transmitting part 10 of the data transmitting part 1 of a central device 20 is constituted by a narrow-band modulation system, and the reception circuit of the receiving part 51 of the data transmitting part 5 of a terminal side 30 is constituted by the narrow-band modulation system. On the other hand, the transmission circuit by the transmitting part 50 of the terminal equipment 30 is constituted by a spread spectrum system, and the reception circuit of the receiving part 11 of the data transmitting part 1 of the central device 20 is constituted by the spread spectrum system. Namely, transmitted data from the central device 20 is modulated by the narrow-band transmitting part 10, and is sent as modulated data, and is received by the terminal equipment 30, and is demodulated by the narrow-band receiving part 51. On the other hand, returned data from the terminal equipment 30 is spectrum-spread by the spread spectrum transmitting part 50, and is sent as spread data, and is received by the central device 20, and is received by the spread spectrum receiving part 11, and is restored. |
