Which process involves shifting the carrier between two different frequencies by opening and closing a key?

Which process involves shifting the carrier between two different frequencies by opening and closing a key?

• A. Modulation
• B. Keying
• C. Ionosphere
• D. Propagation

Answer: (B)

Keying is the act of using a switch (a key) to control the RF transmitter, turning the carrier on and off or switching it between defined states to encode information. When the setup shifts the carrier between two frequencies by opening and closing the key, you’re performing discrete state changes that convey data—the essence of keying. This is different from modulation in general, which is about varying a carrier parameter continuously to carry information. The ionosphere and propagation describe the environment and path the signal takes, not the signaling method itself.

Keying is the act of using a switch (a key) to control the RF transmitter, turning the carrier on and off or switching it between defined states to encode information. When the setup shifts the carrier between two frequencies by opening and closing the key, you’re performing discrete state changes that convey data—the essence of keying. This is different from modulation in general, which is about varying a carrier parameter continuously to carry information. The ionosphere and propagation describe the environment and path the signal takes, not the signaling method itself.