Which term describes the carrier wireless signal used to convey information when modulated?

• A. Carrier wave
• B. Local oscillator
• C. Noise
• D. Reference signal

Answer: (A)

A carrier wave is the high‑frequency signal that carries information in a modulated transmission. In modulation, the information from the control or data signal is applied to the carrier by changing one of its properties—amplitude, frequency, or phase. This transformation encodes the information onto the carrier so it can travel through the air and be retrieved later by demodulation.

The local oscillator, on the other hand, provides a stable frequency reference used in mixing to convert frequencies, not the signal that directly conveys the information. Noise is random unwanted interference that can distort the signal. A reference signal is a separate signal used for synchronization or calibration in some systems, not the primary carrier carrying the data.