What are the two modes of a transmitter?

• A. Sine Wave
• B. Square Wave
• C. Amplitude Modulated
• D. Continuous Wave and Pulsed Wave

Answer: (D)

The key idea is how the transmitter delivers energy over time. Transmitters can emit energy either continuously or in bursts, which are the two basic modes.

In continuous wave mode, RF energy is sent out all the time while the transmitter is energized. The carrier can be unmodulated or modulated, but the defining feature is a constant presence of the signal while it’s on. This mode was classically used for Morse code by turning the carrier on and off, but the energy that’s on remains continuously present in time.

In pulsed wave mode, RF energy is emitted in short bursts or pulses with defined widths and repetition rates. The transmitter is off between pulses, so the energy is not continuous. Pulsed transmission allows high peak power with lower average power and is common in radar and other timing or signaling systems. Shorter pulses also spread the signal over a wider bandwidth due to the time–domain confinement.

The other options describe waveform shapes or modulation methods rather than how the transmitter operates over time, so they don’t define the modes of operation. Continuous wave and pulsed wave are the two modes of a transmitter.