Which of the following is not a basic transmission method?

Duplex-plus is not considered a basic transmission method. The fundamental transmission methods typically include simplex, half duplex, and full duplex, each defining how signals are transmitted over a communication channel.

Simplex allows data transmission in only one direction, such as a keyboard sending data to a computer without any feedback. Half duplex supports bi-directional communication but allows only one direction at a time, similar to walkie-talkies where one party talks while the other listens, but they cannot communicate simultaneously. Full duplex permits two-way communication where both parties can send and receive data at the same time, much like a telephone conversation where both participants can talk and listen without interruption.

Duplex-plus, while it may refer to extended features or enhanced modes of communication, is not recognized as a standard basic transmission method. Therefore, it stands apart from the more common transmission types, which form the foundation of communication principles.