Question

Modulation is used to (A) reduce the band width used (B) separate the transmission of different areas (C) ensure that information may be transmitted to long distance (D) allow the use of practical antennas

Short answer

The short answer to the question is: (C) ensure that information may be transmitted to long distance. Modulation primarily helps in effective transmission over long distances by reducing the frequency of the information signal, which in turn helps to decrease signal attenuation.

Step-by-step solution

Define Modulation

Modulation is the process of varying one or more properties of a carrier wave, such as its amplitude, frequency, or phase, in accordance with the information signal. This is done to transmit the information in the form of a modulated signal.

Identify the Importance of Modulation

There are several reasons why modulation is used in communication systems: 1. To reduce the frequency of the signal so that it can be easily transmitted over long distances and to allow the use of practical antennas. 2. To allow multiple users to coexist in the same communication system and send their information signals simultaneously without interference. 3. To improve the signal-to-noise ratio and the overall quality of the communication.

Analyze Each Option

(A) Modulation does not directly reduce the bandwidth used; instead, modulation techniques can be chosen according to requirements on bandwidth and other factors. (B) Modulation indeed helps in separating the transmission of different information signals by assigning them different frequencies or other distinct properties. However, this is not an exclusive purpose of modulation. (C) One key purpose of modulation is to ensure effective transmission over long distances by reducing the frequency of the information signal, which in turn helps to decrease signal attenuation. (D) Modulating the signal allows for the use of practical antennas, as the wavelength of a low-frequency signal can be immense, making antenna design for such frequencies impractical.

Choose the Correct Option

Based on the explanation above, the correct option is (C) ensure that information may be transmitted to long distance. Modulation helps improving the ability to transmit information over long distances, and it does influence antenna design, but option (D) is not its main purpose.

Key concepts

Signal Transmission

In communication systems, signal transmission is the process of sending information from one point to another using a medium. Whether it's a wired connection like cables or a wireless medium like radio waves, the main goal is to deliver the message clearly and accurately.
Signal transmission involves converting information, such as speech, video, or data, into an electrical signal that can be easily transmitted. This is typically achieved using modulation, which enhances the signal's ability to travel longer distances and penetrate barriers. This ensures that by the time the signal reaches the receiver, it retains as much of the original information as possible. Effective signal transmission requires a clear channel and the minimization of noise and interferences that can distort the signal.

Frequency Modulation

Frequency Modulation (FM) is a type of modulation where the frequency of the carrier wave is varied in accordance with the information signal. This is commonly used in radio broadcasting.
FM's main advantage is its resistance to signal degradation over long distances. By varying the frequency, rather than the amplitude, FM reduces susceptibility to noise and interference, leading to better sound quality compared to Amplitude Modulation (AM). It allows for high-fidelity sound transmission, making it great for music and voice broadcasts.

• FM is resilient to changes in amplitude, which means it remains stable even when faced with physical interferences.
• This form of modulation is widely used in various applications, not only radio, but also television and telemetry systems.

Communication Antennas

Communication antennas are crucial for transmitting and receiving radio waves. They act as a bridge between electrical and radio signals.
An antenna receives the modulated signal and transmits it into the space as radio waves, or vice versa. The size of the antenna is closely related to the wavelength of the transmission signal. This is why modulation, like frequency modulation, allows practical antenna sizes. Using a modulated signal, antennas can be designed in manageable sizes, effectively enabling efficient transmission and reception.

• For low-frequency signals, antennas would need to be excessively large without modulation.
• By increasing the signal frequency through modulation, antenna sizes are reduced to practical levels.

Antenna design is tailored to specific transmission frequencies to maximize efficiency.

Bandwidth Management

Bandwidth management in communication systems ensures the optimal use of available bandwidth to send the maximum amount of data efficiently. Bandwidth is the range of frequencies within a given band that can be used for transmitting a signal.
Without proper management, too many signals can overcrowd the bandwidth, leading to interference and data loss. Modulation techniques help in organizing different users' signals within the same bandwidth, ensuring each user gets a clear channel without overlap.

• Effective bandwidth management involves assigning frequencies correctly to avoid overlap.
• Diverse modulation schemes are used according to bandwidth requirements.

A well-managed bandwidth is crucial for modern communication, allowing for simultaneous transmission of multiple signals, enhancing the overall efficiency of the communication system.