8/8/2019 ADC test1_2010

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Compiled by: L. Krishnananda, Asst Professor Page 1

REVA INSTITUTE OF TECHNOLOGY & MANAGEMENT, BANGALORE

Class: M. Tech (CNE) Sub: Advanced Digital Communication

MODEL QUESTION PAPER

Max. Marks:50

No Questions Marks

1. Briefly discuss the necessity of Image compression. Comment on the properties, bit rate and type of

compression needed in the following examples:

a) cartoon program b) A music video c) A documentary

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2. Give examples of Stream oriented and Block oriented digital information. A scanner has a resolution of

600 x 600 pixels/sq inch. How many bits are produced by an 8-inch x 10-inch image if scanning uses 8

bits/pixel? 24 bits/pixel.

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3. Explain the difference between facsimile, GIF and JPEG coding. Give an example of an image that is

appropriate to each.

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4.What are the bit rates generated for digitizing a voice signal, a CD quality audio signal and a HDTV

signal. How many PCM voice calls and high quality audio channels can be supported using an HDTVchannel?

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5. Suppose a storage device has 4 GB capacity. How many 2-minute songs can be stored using

conventional CD format? MP3 format?

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6. a) An audio digitizing utility in a PC samples an input signal at a rate of 44 KHz and 16 bits per sample.

What is the file size required to record the audio for 30 seconds.6

7. Compare the features of analog and digital transmission techniques. Why digitization of analog signal is

necessary?

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8. Explain the operation of analog and digital transmission system with neat diagrams, 6

9. Define the following: a) bandwidth of the channel b) bandwidth of the signal c) Nyquist rate d)

Signal-to-noise ratio e) low-pass channel f) band-pass channel

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10. a) Consider a 20 KHz baseband channel. Pulses are sent at Nyquist rate. Compute the bit rate of the

system if pulses take 16 levels? 64 levels?

b) Suppose that a link between two telephone offices has 50 repeaters. Suppose the probability that a

repeater fails during year is 0.01. a) What is the probability that any link does not fail at all? b) If only

10 repeaters are present, what is the probability of failure?

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11. Discuss the effect of SNR on the maximum rate at which data can be through a channel with a graph.

Comment on the importance of Shannons channel capacity theorem.

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12. a) Consider an analog repeater in which signal power is x2 and noise power is n2. At each repeater,

the noise gets accumulated. Find the SNR after n repeater links.

b) Suppose that a signal has twice the power of a noise added. Find the SNR is decibels. Repeat is signalpower is (i) 10 times (ii)2n times and (iii) 10n times the noise

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13. a) A low-pass communication channel has 2 MHz bandwidth. What bit rate is achieved using 16-level

pulses? What is the Shannon capacity of this channel if SNR is (i) 30 dB (ii) 40 dB.

b)What SNR is needed to put a T1 carrier on a 100 KHz line.

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