PURPOSE: To prevent mixing with noises by a method wherein a temperature sensor detection signal and a humidity sensor detection signal are mixed to be outputted to a power source line as one signal and the signal is extracted through a power source series impedance.
CONSTITUTION: A first sensor modulation circuit 32 performs a frequency modulation by a frequency corresponding to a quantity of electricity of a first sensor 32a and a second sensor modulation circuit 34 performs an amplitude modulation so that an output signal S1 of the circuit 32 gives an amplitude corresponding to the quantity of electricity of a second sensor 34a. Modulation signals S1 and S2 are mixed to be outputted to a power source line 22 via a signal output circuit 35. The signal S1+S2 obtained by the mixing is transmitted to a power source series impedance 23 via an extension 11 and a voltage signal generated between both ends thereof is picked up. The signal thus picked up is separated into temperature information and humidity information. This can reduce the number of wires connecting a control center to a temperature/humidity measuring point while preventing mixing with noises.
NAGANO KENTARO
MORIYA YOSHIO
NIHON PARKERIZING
| JPS5995450A | 1984-06-01 |