Virtual Labs

DSB-SC, SSB-SC Modulator & Detector

1. How is the carrier signal used in the demodulation of a DSB-SC signal?

a: The carrier signal is needed at the receiver to recover the original message signal. Explanation

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b: The carrier signal is not needed for demodulation; only the modulated signal is required. Explanation

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c: The carrier signal is used to filter out the sidebands. Explanation

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d: The carrier signal is used to amplify the modulated signal. Explanation

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2. In Single Sideband Suppressed Carrier (SSB-SC) modulation, how is the message signal typically reconstructed?

a: By mixing the received signal with a local oscillator that has the same frequency as the carrier used in modulation. Explanation

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b: By filtering out the unwanted sideband from the received signal. Explanation

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c: By using an envelope detector to extract the message signal. Explanation

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d: By direct demodulation without any further processing. Explanation

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3. Which of the following best describes the phase relationship between the message signal and carrier in DSB-SC modulation?

a: The message signal and carrier are in phase. Explanation

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b: The message signal and carrier are out of phase by 90 degrees. Explanation

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c: The phase relationship is irrelevant in DSB-SC modulation. Explanation

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d: The message signal and carrier are out of phase by 180 degrees. Explanation

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4. Which filter type is typically used to extract the original message signal from an SSB-SC signal?

a: Band-pass filter Explanation

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b: Low-pass filter Explanation

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c: High-pass filter Explanation

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d: Band-stop filter Explanation

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5. In DSB-SC modulation, how is the amplitude of the carrier signal affected by the modulation process?

a: The amplitude of the carrier signal is suppressed or removed. Explanation

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b: The amplitude of the carrier signal increases proportionally with the message signal. Explanation

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c: The amplitude of the carrier signal remains unchanged. Explanation

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d: The amplitude of the carrier signal is modulated in a manner similar to amplitude modulation. Explanation

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6. What is the key difference between DSB-SC and SSB-SC in terms of bandwidth usage?

a: DSB-SC uses twice the bandwidth of SSB-SC. Explanation

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b: SSB-SC uses twice the bandwidth of DSB-SC. Explanation

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c: DSB-SC and SSB-SC use the same bandwidth. Explanation

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d: Bandwidth usage depends on the modulation index of the signal. Explanation

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7. In an SSB-SC signal, what happens to the carrier frequency?

a: The carrier frequency is completely removed from the signal. Explanation

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b: The carrier frequency is present but at a reduced amplitude. Explanation

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c: The carrier frequency is modulated along with the message signal. Explanation

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d: The carrier frequency is used for phase modulation of the message signal. Explanation

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8. In a DSB-SC system, how is the demodulated signal obtained?

a: By multiplying the received signal with a locally generated carrier signal. Explanation

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b: By directly filtering the received signal with a low-pass filter. Explanation

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c: By using an envelope detector on the received signal. Explanation

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d: By applying a frequency demodulator to the received signal. Explanation

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9. Which property of SSB-SC modulation makes it preferable for long-distance communication compared to DSB-SC?

a: Higher bandwidth efficiency. Explanation

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b: Lower power consumption. Explanation

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c: Greater resistance to interference. Explanation

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d: Simpler demodulation process. Explanation

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10. In evaluating the efficiency of various amplitude modulation schemes, which key limitation makes DSB-SC less bandwidth-efficient than its alternatives, particularly SSB-SC?

a: DSB-SC transmits both sidebands without utilizing the carrier, effectively doubling the required bandwidth compared to SSB-SC. Explanation

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b: DSB-SC experiences higher power losses due to redundant sideband transmission. Explanation

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c: DSB-SC is highly susceptible to phase distortion during demodulation. Explanation

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d: DSB-SC necessitates precise synchronization due to its suppressed carrier, complicating implementation. Explanation

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