| 摘要 |
PROBLEM TO BE SOLVED: To permit a high speed transmitting device and a low speed transmitting device to co-exist without the occurrence of a transmission error and to effectively utilize a power line by permitting a signal component which is used by means of the low speed transmitting means connected to a common power line within the frequency spectrum of a first low transmitting means executing communication to be restricted by means of strength being less than the reception sensitivity of a low speed transmitting means. SOLUTION: The transmission output of a spread spectrum system transmitting device 3a of the high speed transmitting device 3 passes through a filter device 3b and transmitted to the power line 1. The filter device 3b is a low-pass filter, an interrupting frequency is outside the band with the carrier center frequency of the transmitting signal of the low speed transmitting device as the center is set and attenuation in the frequency more than the interrupting one is constituted in 40dB. Since a frequency component to be used by the low speed transmitting device is equal to below a reception threshold value, the signal of the high speed transmitting device is not received. Besides, the transmitting signal of the low speed transmitting device is also inputted to the filter device 3b so as to be attenuated so that erroneous reception does not occur in the high speed transmitting device 3. |
