Which of the following describes combining speech with an RF carrier signal?

• A. Demodulation
• B. Modulation
• C. Mixing
• D. Filtering

Answer: (B)

Combining speech with an RF carrier signal is referred to as modulation. This process involves altering one or more properties of the carrier signal (such as its amplitude, frequency, or phase) in accordance with the information being transmitted, which in this case is the speech signal.

Modulation is essential in radio communications because it enables the efficient transmission of information over longer distances and through various mediums. By modulating the carrier, the speech signal can be transmitted at radio frequencies, allowing it to travel more effectively and be received by a radio receiver, which will then demodulate it back into a format we can understand, such as audible sound.

Other terms like demodulation refer to the reverse process of extracting the original information from the modulated carrier, while mixing generally involves combining different signals without necessarily maintaining the original information integrity. Filtering typically pertains to removing unwanted frequencies from a signal rather than combining speech with a carrier. Therefore, modulation distinctly describes the process of fusing the speech with the RF carrier signal.