Which description matches simplex operation?

• A. Uses one frequency to transmit and receive
• B. Uses two frequencies and allows one way communication
• C. Uses two frequencies and allows simultaneous two way communication
• D. VoIP with push to talk for radios and non radio devices over IP

Answer: (A)

Simplex operation relies on a single frequency channel for both transmitting and receiving; radios share the same frequency and take turns to talk or listen rather than using separate channels. That’s why describing one frequency being used to transmit and receive best matches simplex. Using two frequencies implies a duplex arrangement, which can support one-way or simultaneous two-way communication depending on the system—these are not simplex characteristics. The option about VoIP over IP describes digital networking rather than how RF channels are used, so it doesn’t describe simplex either.