How does simplex transmission work?

• A. Two ways at any time
• B. One way
• C. Two way, but only one at a time
• D. A signal can be modulated for distance

Answer: (B)

Simplex transmission means one-way communication: the signal goes from the sender to the receiver, and there is no return path on that same link for the receiver to send data back. This is why broadcast systems like radio or TV fit simplex—the audience receives content without replying on the same channel. If two-way communication is needed, you’d use a different mode: two-way but not simultaneous (half duplex) or two-way simultaneously (full duplex) on either the same or a separate channel. Modulating a signal to extend distance doesn’t address the direction of flow, so it doesn’t describe simplex.