Question

In which of the following digital modulation carrier wave switches between 0 and 1 based on applied input?

• A. Amplitude Shift Keying
• B. Phase Shift Keying
• C. Frequency Shift Keying
• D. Phase Shift Keying and Frequency Shift Keying

Hint:

On-Off Keying (OOK). A simple form of Amplitude Shift Keying (ASK) where the presence of the carrier (amplitude '1' or A) represents a binary '1', and the absence of the carrier (amplitude '0') represents a binary '0'.

Answer 1

The Correct Option is A

Digital modulation techniques represent binary data (0s and 1s) by varying a parameter of a carrier wave
- Amplitude Shift Keying (ASK): The amplitude of the carrier is varied
In the simplest form (On-Off Keying or OOK), the carrier is transmitted with a constant amplitude to represent a '1' and turned off (amplitude 0) to represent a '0'
This directly matches the description of switching between 0 and 1 (amplitude levels)
- Phase Shift Keying (PSK): The phase of the carrier is shifted to represent data
- Frequency Shift Keying (FSK): The frequency of the carrier is shifted to represent data
Therefore, ASK (specifically OOK) is the modulation where the carrier wave switches between a non-zero amplitude (representing '1') and zero amplitude (representing '0')