Gain insights into the true nature of carrier signals and the components involved in their modulation. Understand the correct modulation techniques used to produce carrier signals, dispelling misconceptions about frequency bandwidth as a modulated component.
Table of Contents
Question
Which of the following statements about carriers is false?
A. A carrier is an electromagnetic wave that is modulated to transmit a signal, and its waveform is typically a sine wave.
B. Carrier signals can be produced by modulating the three components (frequency bandwidth, frequency, and phase) of electromagnetic waves.
C. Carriers are the physical basis and bearer tool for transmitting voice and data information.
D. The receiver end needs to parse carrier signals to obtain data.
Answer
B. Carrier signals can be produced by modulating the three components (frequency bandwidth, frequency, and phase) of electromagnetic waves.
Explanation
The statement “Carrier signals can be produced by modulating the three components (frequency bandwidth, frequency, and phase) of electromagnetic waves” is false.
Carrier signals are typically produced by modulating only two components of an electromagnetic wave: amplitude and phase. Frequency bandwidth is not a modulated component of a carrier signal.
The correct statement should be:
Carrier signals can be produced by modulating the amplitude and/or phase of electromagnetic waves.
A carrier is an electromagnetic wave that serves as the basis for transmitting information in a communication system. The process of modulation involves varying or modulating certain characteristics of the carrier wave to encode the information (data or voice) onto the carrier signal.
The two primary modulation techniques are:
- Amplitude Modulation (AM): In this technique, the amplitude (or strength) of the carrier wave is varied according to the information signal.
- Phase Modulation (PM): In this technique, the phase of the carrier wave is varied according to the information signal.
Frequency Modulation (FM) is another technique where the frequency of the carrier wave is varied based on the information signal. However, FM is a form of phase modulation, as a change in frequency also results in a change in phase.
Frequency bandwidth refers to the range of frequencies occupied by a modulated signal or the amount of spectrum required for transmitting the signal. It is not a component that is directly modulated to produce the carrier signal.
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