Question

AM is used for broadcasting because (A) it is more noise immune than other modulation system (B) it requires less transmitting power compared with other system (C) it avoids receiver complexity (D) No other modulation system can provide the necessary band width faithful transmission

Short answer

The correct answer is (C) "it avoids receiver complexity." AM is used for broadcasting because it results in simpler and more affordable receivers compared to other modulation systems.

Step-by-step solution

Analyzing choice (A)

Let's analyze option (A): "it is more noise immune than other modulation systems." In reality, AM is not more noise immune compared to modern modulation systems such as Frequency Modulation (FM) and digital modulation schemes. In fact, AM is more susceptible to noise than these other systems. So, this option is incorrect.

Analyzing choice (B)

Now let's analyze option (B): "it requires less transmitting power compared with other systems." Option (B) is true, as AM does require less transmitting power compared to other systems like FM or digital modulation systems. However, this reason alone is not sufficient to justify the use of AM in broadcasting, as other factors need to be considered.

Analyzing choice (C)

Next, let's analyze option (C): "it avoids receiver complexity." This statement is true. AM receivers are relatively simple and inexpensive compared to other modulation systems. This is one of the main reasons why AM is used in broadcasting, especially in areas where receiver cost is a significant factor.

Analyzing choice (D)

Finally, let's analyze option (D): "No other modulation system can provide the necessary bandwidth faithful transmission." This statement is false. Modern digital modulation systems can provide high-fidelity transmissions with limited bandwidth. So, this option is incorrect.

Conclusion

Based on the analysis of each option, the correct answer is (C) "it avoids receiver complexity." This is because AM receivers are simpler and more affordable compared to those needed for other modulation systems.

Key concepts

Noise Immunity in Communication Systems

Noise immunity refers to a system's ability to resist disturbances in the signal caused by external noise. Amplitude Modulation (AM) is relatively susceptible to noise compared to other modern modulation systems, like Frequency Modulation (FM) and digital techniques.
Noise typically enters an AM signal through its amplitude, directly affecting the audio quality. Unlike AM, FM modulates the frequency of the carrier wave, making it more resistant to amplitude noise variations.
Enhancing noise immunity is crucial because it improves signal quality and clarity. Modern systems often utilize digital modulation, which offers robustness against noise due to its binary signal representation, allowing for error checking and correction features. This is why other modulation systems are preferred over AM when noise resistance is crucial.

Transmitting Power in Broadcasting

Transmitting power in broadcasting refers to the amount of energy used to send radio signals. Amplitude Modulation requires relatively lower transmitting power compared to Frequency Modulation and some digital systems for equivalent coverage.
This efficiency in AM comes from its use of lower frequency bands, which naturally propagate further distances with lower power requirements.
However, even though AM might use less power, this is not the sole factor in choosing a modulation system for broadcasting. Efficiency in power needs to be balanced with other considerations like signal clarity and listener experience.

Receiver Complexity

Receiver complexity refers to how intricate and costly the technology and methods are required to decode transmitted signals. AM systems are renowned for their simple and inexpensive receivers.
An AM receiver only needs to demodulate the variation in signal amplitude, which can be done with basic diode and capacitor arrangements. This simplicity makes AM ideal in cost-sensitive and technologically limited environments.
In contrast, FM and digital modulation require more complex decoding processes due to their advanced techniques for noise suppression and clarity improvement, impacting production costs and technological requirements.

Bandwidth in Modulation Systems

Bandwidth in modulation systems is the range of frequencies required to transmit a signal effectively. AM typically requires more bandwidth compared to FM for the same range of audio frequencies. This is because AM transmits both sidebands along with the carrier frequency.
Modern digital modulation systems have the advantage of using their bandwidth more efficiently, transmitting more data over less bandwidth. This capability allows for clearer transmission and the bundling of multiple signals within a limited frequency range.
In today's digital age, bandwidth efficiency is a key aspect in the choice of modulation systems, influencing the decision away from AM to more advanced digital systems for wideband communications.