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Carrier wave properties: Does a carrier wave itself carry information before modulation is applied?

Difficulty: Easy

Correct Answer: False

Explanation:


Introduction / Context:
A carrier wave is a high-frequency sinusoidal signal used in communication systems. It acts as a vehicle for information by being modulated in amplitude, frequency, or phase. This question checks whether learners understand the role of a carrier before modulation.


Given Data / Assumptions:

  • Carrier wave is defined as Acos(2πfct + φ), with fixed amplitude, frequency, and phase.
  • No modulation is applied in the base case.


Concept / Approach:
A pure unmodulated carrier is deterministic and contains no message or information. Only after modulation (AM, FM, PM, etc.) does the carrier convey useful information. Therefore, the correct answer is 'False.'


Step-by-Step Solution:

Consider Acos(2πfct). Without modulation, it has constant amplitude and frequency.Information requires variation corresponding to a message signal.Thus, an unmodulated carrier contains no message information.


Verification / Alternative check:
Communication system references emphasize that the carrier is a 'blank canvas' for modulation. Spectrum analysis of a pure carrier shows a single frequency spike with no sidebands, confirming no information content.


Why Other Options Are Wrong:

'True': incorrect, as an unmodulated carrier has no information.'Only in digital systems' / 'Only in wireless transmission': irrelevant distinctions; same concept applies everywhere.'Depends on amplitude': amplitude alone without modulation does not encode information.


Common Pitfalls:

Confusing a carrier's ability to carry information with the statement that it already contains information.


Final Answer:

False
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