Abstract: A directional coupler for duplex transmission for use with a transmitter/receiver unit is described. It includes a memory unit for providing a correction signal and a compensation circuit to which the correction signal is applied to supress that portion of the received signal which is derived from the transmitter. The memory unit is capable of storing values of the correction signal, the values being assigned to the different possible varients within a selected period of time, of time functions coming from the transmitter, and a decoder connected between the transmitter and the memory unit for detection of actual, transmitted signal variants. The decoder includes means for selection in the memory unit of the values of the correction signal assigned to the actual signal variants.