| 摘要 |
PURPOSE:To prevent the effects of crosstalks, etc. to other system devices making use of the transport of power lines, by producing and transmitting frequency signals in response to combinations of logical states of plural types of digital data supplied from a digital data input means and discriminating these logical states according to the frequency of a received signal. CONSTITUTION:Both the 1st and 2nd modulation/demodulaton parts 1 and 2 vary their output frequencies according to the logic of the transmission data B. Analog switches 3 and 4 are switched in response to the logic of the data A and turned on and off in a complementary relation at all times. The outputs of both switches 3 and 4 are sent to a transmission part 5, and the frequency signals sent from both switches 3 and 4 are superposed on the power supply voltage on a power line 6 and transmitted. The frequency signal received at a reception part 7 is applied to the part 1 as well as to the part 2. Then the output of each comparator is supplied to an OR circuit 9 to obtain OR. Thus the data B is extracted. |
