PURPOSE: To receive a micro receiving signal by adjusting an energy quantity held by the pulse of one side polarity of positive negative polarity pulses which is an alternate mark inverting signal and the energy quantity held by the pulse of other side polarity and balancing the energy quantity of both polarity pulses.

CONSTITUTION: The title circuit has a separating means to separate a transmitting means and a receiving means, is included in a data transmitting device to execute the half duplex communication with an opponent station and executes the base band transmission of an alternate mark inverting signal to the opponent station. At this time, an output part to output a transmitting pulse, a receiving signal reproducing part 25 to reproduce a receiving signal 24, and a signal adjusting means to adjust the energy quantity held by the pulse of one side polarity of the positive-negative polarity pulses which are the alternate mark inverting signals and the energy quantity held by the pulse of other side polarity and balance the energy quantity of the pulse of both polarities are provided. Namely, a signal adjusting means 18 adjusts the energy quantity held by the pulse of one side polarity of the positive negative polarity pulses as the alternate mark inverting signal and the energy quantity held by the pulse of other side polarity and balances the energy quantity of both polarity pulses. Thus, the micro signal can be received.