CONTROLLER ATTENDED RELATED TO 2/4-WIRE CONVERSION

摘要

PROBLEM TO BE SOLVED: To provide a controller that suppresses outputting of the input signal on a 4-wire side into the output of a 4-wire side, which is caused at 2/4-wire conversion. SOLUTION: The controller estimates the attenuation when an input signal level at a 4-wire side is leaked to an output of the 4-wire side on a 4-wire side signal line with two systems of input and output of a 2/4-wire conversion section 1, compares an input signal level and an output signal level of the 4-wire side in an actual circuit, discriminates that a signal denoting an actual attenuation results from a signal leaked to the output side of the 4-wire from an input signal of the 4-wire side when no signal is received from the 2-wire side and the actual attenuation is within an estimated attenuation range and turns off an analog switch 11 connected to the output of the 4-wire side, or discriminates that the signal results from a signal received from at least the 2-wire side when the actual attenuation is the estimated attenuation or over to turn on the analog switch 11 connected to the output of the 4-wire side.