JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II ANALOG COMMUNICATIONS Previous Question Paper (February -2024 - R16)
Note: i) Question paper consists of Part A, Part B. ii) Part A is compulsory, which carries 25 marks. In Part A, answer all questions. iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
Part A
What is the primary purpose of modulation in communication systems? Explain briefly.
Answer
The primary purpose of modulation is to shift the frequency spectrum of a baseband signal to a higher frequency range suitable for efficient transmission over a physical medium. This process enables the use of smaller, practical antenna sizes, facilitates frequency division multiplexing to allow multiple signals to share the same channel without interference, and improves signal-to-noise ratio by reducing the impact of low-frequency noise.
Define Frequency Division Multiplexing (FDM) and explain its significance in communication.
Answer
Frequency Division Multiplexing (FDM) is a technique where the total available bandwidth of a communication channel is divided into a series of non-overlapping frequency sub-bands, each used to carry a separate signal. Multiple baseband signals are modulated onto different carrier frequencies and then combined into a single composite signal for transmission over a shared medium.
The significance of FDM lies in its ability to increase the efficiency of a communication system by allowing multiple users or services to share a single physical link simultaneously without interference. It is fundamental to analog communication systems, such as radio broadcasting, television transmission, and traditional telephone networks, as it enables the concurrent transmission of multiple information streams over a single wideband channel.
Explain the generation of Double Side Band Suppressed Carrier (DSB-SC) waves.
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Differentiate between DSB-SC and VSB.
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Describe the time domain characteristics of single tone modulation in Frequency Modulation (FM).
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Discuss the power relations in FM waves and their importance in communication.
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Define and explain the concept of Effective Noise Temperature.
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Discuss the properties of narrow-band noise and its relevance in communication systems.
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What are the different types of radio receivers? Briefly explain the characteristics of a Superheterodyne receiver.
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Compare PAM and PWM.
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Part B
Analyze the advantages and disadvantages of square law modulation. Propose a scenario where square law modulation is preferable.
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Create a flowchart illustrating the generation of AM waves. Annotate the key components and processes involved.
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Describe the demodulation of AM using envelop detector.
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Evaluate the demodulation techniques for DSB-SC waves, emphasizing the advantages and limitations of each.
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Devise a mathematical representation for Vestigial Side Band (VSB) modulation and discuss its practical applications.
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Design a comparison chart highlighting the key differences between various AM techniques, including DSB-SC, SSB, and VSB.
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Assess the time domain characteristics of AM SSB modulation, considering both frequency and phase discrimination methods.
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Formulate a scenario where VSB modulation is the most suitable, providing technical justifications.
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Investigate the spectrum analysis of Sinusoidal Frequency Modulation (FM) waves. Provide insights into narrow-band and wide-band FM.
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Develop a comprehensive comparison between Direct FM and Indirect FM in terms of generation and practical applications.
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Utilize the concept of Balanced Frequency Discriminator to explain the detection of FM waves. Discuss the advantages of using a Phase-Locked Loop (PLL) in FM demodulation.
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Evaluate the transmission bandwidth of FM waves and its implications in communication system design.
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Analyze the impact of noise in DSB and SSB systems. Propose strategies to mitigate noise effects in analog communication systems.
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Create a flowchart illustrating the threshold effect in Angle Modulation systems. Annotate the key parameters and conditions involved.
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Compare resistive noise sources and arbitrary noise sources in terms of their impact on communication systems.
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Evaluate the significance of pre-emphasis and de-emphasis in noise reduction for communication systems.
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Formulate a case study comparing the performance of Tuned Radio Frequency (TRF) receivers and Superheterodyne receivers.
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Develop a schematic diagram illustrating the amplitude limiting process in an FM receiver. Provide a step-by-step explanation.
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Assess the advantages and disadvantages of Pulse Amplitude Modulation (PAM). Propose a real-world application where PAM is most suitable.
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Design an experiment to demonstrate the generation and demodulation of Pulse Position Modulation (PPM).
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