The statement provides a correct and fundamental definition of modulation. Modulation is the process of varying one or more properties (such as amplitude, frequency, or phase) of a periodic, high-frequency waveform, known as the carrier signal, in accordance with an information-bearing signal (the modulating signal). This process "adds" or impresses the information onto the carrier, shifting the information signal's frequency spectrum to a higher band that is more suitable for transmission over a specific communication channel (e.g., free space, optical fiber). This makes transmission more efficient, allows for the use of practical antenna sizes, and enables multiple signals to be transmitted simultaneously over the same channel through multiplexing.

This is a "TRUE OR FALSE" question; therefore, there is no incorrect option to analyze. The provided statement is factually correct.

1. Huawei HCIA-Transmission V2.0 Training Material. The official courseware for the H31-341 exam defines modulation as a core concept for transmitting signals over a medium. It explains that baseband signals are often unsuitable for direct transmission and must be modulated onto a carrier wave to match the characteristics of the transmission channel. (Reference: HCIA-Transmission V2.0 Training Material

Chapter on WDM Principles).

2. Lathi

B. P.

& Ding

Z. (2009). Modern Digital and Analog Communication Systems (4th ed.). Oxford University Press. In Chapter 4

"Modulation

" the text states

"Modulation is the process by which some characteristic of a carrier is varied in accordance with a modulating signal... The purpose of a communication system is to transmit information signals... through a communication channel. The information-bearing signals... are often called baseband signals. Modulation is the process of shifting the frequency spectrum of a signal to a different frequency region." (pp. 179-180). This source confirms that modulation processes a signal and adds it to a carrier to make it suitable for channel transmission.

3. Proakis

J. G.

& Salehi

M. (2008). Digital Communications (5th ed.). McGraw-Hill. Chapter 4

"Basic Bandpass Modulation and Demodulation

" describes modulation as the process of converting a digital or analog information signal into a waveform that is suitable for transmission over a communication channel. It explicitly states that this involves varying the amplitude

phase

or frequency of a high-frequency carrier signal. This aligns with the statement that "a carrier changes with a signal." (Section 4.1

Introduction).