JNTU
JNTU B.Tech II Year DATA COMMUNICATION Previous Question Paper (July/August - 2021 - R13)
Answer any Five Questions. All Questions Carry Equal Marks.
Main
Distinguish between serial and parallel data transmissions.
Answer
In parallel transmission, multiple bits are sent simultaneously over separate physical wires or channels. This method is fast and suitable for short-distance communication, such as data transfer between a CPU and memory or a printer, but it is expensive due to the need for multiple wires and suffers from skew issues over long distances.
In serial transmission, bits are sent one after another over a single channel. While slower than parallel transmission, it is cost-effective, requires only one communication path, and is ideal for long-distance data transmission. Serial transmission is further categorized into asynchronous, synchronous, and isochronous modes.
Determine the minimum bandwidth, baud and bandwidth efficiency for a bit rate of 9600 bps with 8-PSK and 16-PSK.
Answer
For M-PSK modulation, the baud rate (symbol rate) is calculated as
For 8-PSK (M=8):
- Bits per symbol: log2(8) = 3 bits/symbol
- Baud rate: 9600 / 3 = 3200 baud
- Minimum bandwidth: 3200 Hz
- Bandwidth efficiency: 3 bits/Hz
For 16-PSK (M=16):
- Bits per symbol: log2(16) = 4 bits/symbol
- Baud rate: 9600 / 4 = 2400 baud
- Minimum bandwidth: 2400 Hz
- Bandwidth efficiency: 4 bits/Hz
What is digital line encoding? What are factors that must be considered while selecting a line encoding format?
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Describe the operation of electronic telephones with necessary block diagram.
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What are the transmission parameters of a private line circuit? Describe them in detail.
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Determine BCS for the data polynomial
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What is modem? Draw its block diagram and explain each block in detail.
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What is the use of scrambler and descrambler circuits? Explain.
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Explain the principle of QPSK with necessary waveform and constellation diagram.
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Describe various methods of maintaining frame synchronization in TDM.
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What are types of voice frequency circuit arrangements? Describe the four wire configurations in detail.
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Describe the basic principles of paging systems.
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