The semi-duplex method in radiocommunications involves one-way communication at a given time, either for listening or talking, with separate frequencies assigned to the uplink and downlink. It represents a specific variation of simplex operations.

This approach finds application in various scenarios, such as maritime communications. For instance, a ship employs semi-duplex communication, where it alternates between sending and receiving, while the shore-based base station can operate in full-duplex mode, enabling simultaneous two-way communication