What does the abbreviation "PSK" mean?

The abbreviation "PSK" stands for Phase Shift Keying. This is a modulation scheme used in communication systems, where the phase of a carrier signal is varied based on the data being transmitted. By changing the phase of the signal, different bits of information can be represented, which allows for efficient and reliable data transmission.

Phase Shift Keying is particularly useful in digital communication because it can effectively utilize bandwidth while maintaining resistance to noise and interference. The method allows for multiple symbols to be sent in the same channel by shifting the phase of the carrier wave to represent different data states.

The other options do not accurately describe the PSK modulation scheme. While there are various forms of keying used in digital communications, none of the other choices correctly identify the established terminology for Phase Shift Keying. Thus, the correct answer is linked to the recognized and widely utilized modulation technique in the realm of amateur radio and data communications.