What does FM stand for in modulation?

What does FM stand for in modulation?

• A. Frequency Multiplexing
• B. Flux Modulation
• C. Finite Modulation
• D. Frequency Modulation

Answer: (D)

FM stands for Frequency Modulation. In this scheme, the information signal causes the instantaneous frequency of a carrier to vary over time, while the carrier’s amplitude stays essentially constant. So the carrier wiggles in frequency in step with the input signal, encoding the data in how fast or slow the carrier oscillates, not in how tall the wave is. The amount of frequency change is set by the modulation index, which ties the strength of the input signal to how far the frequency swings. This naming is the standard one used in communications, because it describes exactly what the modulation does: modulates the carrier’s frequency. The other phrases aren’t recognized modulation methods—Frequency Multiplexing describes combining signals on different frequencies rather than naming a modulation type, and Flux Modulation and Finite Modulation aren’t standard terms for modulation.

FM stands for Frequency Modulation. In this scheme, the information signal causes the instantaneous frequency of a carrier to vary over time, while the carrier’s amplitude stays essentially constant. So the carrier wiggles in frequency in step with the input signal, encoding the data in how fast or slow the carrier oscillates, not in how tall the wave is. The amount of frequency change is set by the modulation index, which ties the strength of the input signal to how far the frequency swings.

This naming is the standard one used in communications, because it describes exactly what the modulation does: modulates the carrier’s frequency. The other phrases aren’t recognized modulation methods—Frequency Multiplexing describes combining signals on different frequencies rather than naming a modulation type, and Flux Modulation and Finite Modulation aren’t standard terms for modulation.