AM & SSM Modulation MCQ Questions And Answers Quiz

Demodulation is the process of extracting the original information signal from a modulated carrier signal. Modulation is the process of modifying a carrier signal with the information signal. Therefore, the opposite of modulation is demodulation, as it involves reversing the process and extracting the original signal from the modulated carrier. Reverse modulation, downward modulation, and unmodulation are not commonly used terms and do not accurately describe the opposite of modulation.

A modulator is a circuit used to produce modulation. Modulation is the process of varying a carrier signal in order to transmit information. The modulator takes an input signal, called the modulating signal, and combines it with a carrier signal to produce a modulated signal. This modulated signal can then be transmitted over a communication channel. Therefore, a modulator is the correct answer as it is specifically designed for the purpose of producing modulation.

Modulation is the correct answer because it refers to the process of changing some characteristic of a carrier signal, such as its amplitude, frequency, or phase, in order to encode information onto it. This allows the carrier signal to carry the information over a communication channel. Multiplexing is the process of combining multiple signals into one, while duplexing refers to the simultaneous transmission of signals in both directions. Linear mixing is not a commonly used term in this context.

The modulation index is the correct answer because it refers to the ratio of the peak modulation signal voltage to the peak carrier voltage. This index is used to measure the extent of modulation in a communication system. It determines the level of variation in the carrier signal due to the modulation signal. By calculating this ratio, we can understand the degree of modulation and the quality of the transmitted signal.

A modulator circuit performs the mathematical operation of multiplication on its two inputs. This means that it takes the two input signals and multiplies them together to produce an output signal. Multiplication is a fundamental mathematical operation that is used in many different applications, including signal processing and communication systems. By multiplying the input signals, a modulator circuit can combine or modulate the information contained in the signals to create a new output signal with desired characteristics.

Modulation is the process of superimposing information onto a carrier signal, resulting in the generation of new signals known as sidebands. These sidebands contain the actual information being transmitted and are located on either side of the carrier frequency. Spurious emissions refer to unwanted signals that are unintentionally generated during the modulation process. Harmonics are multiples of the carrier frequency that can be produced as a result of modulation. Intermodulation products are unwanted signals generated when two or more frequencies interact with each other. Therefore, the correct answer is sidebands.

The correct answer is "Envelope". In modulation, the outline of the peaks of a carrier signal takes the shape of the modulating signal. This outline, which represents the varying amplitude of the carrier, is known as the envelope. The envelope carries the information of the modulating signal and is used to retrieve the original signal at the receiving end.

When m is greater than 1, it means that the modulation index is greater than 1. This indicates that the amplitude of the information signal is larger than the carrier signal. As a result, the information signal becomes distorted as it is unable to be accurately represented by the carrier signal. This distortion can lead to a loss of fidelity and clarity in the transmitted signal.

For ideal AM (Amplitude Modulation), the modulation index (m) represents the ratio of the peak amplitude of the modulating signal to the peak amplitude of the carrier signal. In this case, the correct answer states that m=1, which means that the peak amplitude of the modulating signal is equal to the peak amplitude of the carrier signal. This indicates that the amplitude of the carrier signal is being completely modulated by the modulating signal, resulting in a full modulation.

The typical audio modulating frequency range used in radio and telephone communications is 300 Hz to 3 KHz. This range is chosen because it encompasses the frequencies of human speech, which typically fall within this range. By limiting the frequency range to 300 Hz to 3 KHz, the communication system can effectively transmit and reproduce speech signals without unnecessary bandwidth usage.

In an AM (Amplitude Modulation) signal, the carrier wave is the main component that carries the information. The carrier wave is a high-frequency signal that is modulated by the modulating signal, which contains the actual information. The carrier wave itself does not contain any information but is necessary to transmit the modulating signal. Therefore, most of the power in an AM signal is dedicated to the carrier wave.

One sideband is the minimum AM signal needed to transmit information. In amplitude modulation (AM), the carrier wave is modulated by the audio signal to create sidebands. The sidebands contain the information being transmitted. By transmitting only one sideband, the bandwidth required for transmission is reduced, making it more efficient. The carrier wave is not necessary for transmitting the information, as it does not contain any useful data. Therefore, transmitting only one sideband is sufficient for transmitting information in an AM signal.

The given answer states that the carrier frequency changes, which means that it is not true about AM. In amplitude modulation (AM), the carrier amplitude varies, meaning that the amplitude of the carrier wave is modified according to the information signal. However, the carrier frequency remains constant, meaning that it does not change. Therefore, the statement "The carrier frequency changes" is not true about AM.

When the modulating signal is distorted, it introduces harmonics into the signal. These harmonics result in an increase in signal bandwidth. Therefore, the correct answer is bandwidth.

The power in one sideband of an AM transmitter can be calculated using the formula:

Power in one sideband = (Percentage of modulation/100) * (Carrier power/2)

Given that the percentage of modulation is 88 and the carrier power is 440W, the calculation would be:

Power in one sideband = (88/100) * (440/2) = 0.88 * 220 = 193.6W

However, since the question asks for the power in one sideband, we need to divide this value by 2:

Power in one sideband = 193.6/2 = 96.8W

Therefore, the closest option to the calculated value is 85W.

For 100 percent modulation, the power is equally distributed between the upper and lower sidebands. Since there are two sidebands in total, each sideband carries 50 percent of the power. However, since the question asks for the percentage of power in each sideband, we divide the power equally between the two sidebands, resulting in 25 percent of power in each sideband.

Frequency translation is carried out by a circuit called a Converter. A converter is a device that can change the frequency of a signal from one frequency to another. It can be used to convert a signal from a higher frequency to a lower frequency or vice versa. This is commonly done in communication systems to shift the frequency of a signal to a different band for transmission or processing. The converter circuit can be implemented using various techniques such as mixing, heterodyning, or modulation to achieve the desired frequency translation.

SSB (Single Sideband) offers the advantage of using less spectrum space compared to standard AM (Amplitude Modulation) or DSB (Double Sideband) techniques. In SSB, only one sideband is transmitted, along with the carrier frequency, while the other sideband is suppressed. This results in a more efficient use of the available frequency spectrum. SSB also requires simpler equipment compared to AM or DSB, as it eliminates the need for a complex demodulation process to recover the original signal. Additionally, SSB consumes less power as it transmits only a single sideband, reducing the overall power requirements.

Frequency conversion refers to the process of translating a signal, with or without modulation, to a higher or lower frequency for processing. This can be done for various reasons, such as to match the frequency range of different devices or to enable signal processing at a specific frequency range. It involves changing the frequency of the signal while preserving its essential characteristics.

A signal without the carrier is called a Double Sideband (DSB) signal. In DSB, both the upper and lower sidebands are transmitted, while the carrier is suppressed. This type of modulation is commonly used in AM (Amplitude Modulation) systems, where the information is encoded in the amplitude variations of the carrier signal. By removing the carrier, the DSB signal can be demodulated to retrieve the original information.

In an AM signal, the transmitted information is contained within the sidebands. Sidebands are the frequency components that are created by the modulation process and are located on either side of the carrier frequency. These sidebands carry the actual information that is being transmitted, such as audio or data signals. The carrier itself does not contain any useful information, and the modulating signal is used to modulate the amplitude of the carrier, resulting in the creation of the sidebands. Therefore, the sidebands are where the transmitted information is encoded in an AM signal.

The output power of an SSB transmitter is usually expressed in terms of peak envelope power. This is because peak envelope power represents the maximum power level that the transmitter can deliver during the peaks of the modulated signal. It takes into account the amplitude variations of the signal, which is important in single sideband modulation where the carrier and one sideband are suppressed. Average power, RMS power, and peak to peak power do not accurately represent the maximum power output of the transmitter during modulation peaks, making peak envelope power the most appropriate measure.

The best sideband to use in SSB (Single Sideband) depends on the specific use or application. It is not determined by a fixed rule or standard. The choice of upper or lower sideband will depend on factors such as the frequency spectrum, available bandwidth, modulation technique, and receiver design. Therefore, it cannot be concluded that either the upper or lower sideband is universally the best to use in SSB.

A display of signal amplitude versus frequency is referred to as the frequency domain because it represents the signal in terms of its frequency components. In the frequency domain, the signal is analyzed and displayed based on the different frequencies present in it, allowing for a better understanding of the signal's spectral content. This representation is useful in various fields such as audio processing, telecommunications, and signal analysis.