Exam Details
| Subject | Digital Communication | |
| Paper | ||
| Exam / Course | Diploma In Electronics And Communication Engineering (DECVI)/ Advanced Level Certificate Course In Electronics And Communication Engineering (ACEVI)/ | |
| Department | School of Engineering & Technology (SOET) | |
| Organization | indira gandhi national open university | |
| Position | ||
| Exam Date | June, 2015 | |
| City, State | new delhi, |
Question Paper
1. Choose the correct answer:
Spread spectrum modulation technique utilizes
direct sequence modulation
pseudorandom sequence modulation
double modulation
wideband modulation
The maximum possible time interval between two successive samples of a 2 kHz signal is
0·25 ms
0·125 ms
0·5 ms
1 ms
Nyquist rate is the minimum sampling rate to avoid
amplitude distortion
foldover distortion
frequency distortion
phase distortion
In PCM, the quantization noise mainly depends on
sampling rate
signal power
number of quantization levels
number of bits per sample
Flat top sampling leads to
aliasing error
aperture effect
signal level attenuation
quantization error
Which encoding method uses alternative positive and negative values for
NRZ-1
RZ
(iii Manchester
AMI
How many different symbols are possible at the output of a 16-QAM modulator?
8
16
64
256
Define Entropy. Define different properties of entropy.
For a source transmitting two independent messages M1 and M2 having probability of P and respectively, prove that the entropy is maximum when both the messages are equally likely.
The output signal to quantizing noise ratio (SNR)o in a PCM system is defined as the ratio of average signal power to average quantizing noise power. For full scale sinusoidal modulating signal with amplitude prove that
(SNR)o
where L is the number of quantizing levels.
Discuss the need of companding in PCM system.
4. What are the different types of digital modulation techniques Explain any two
techniques.
Define line coding. The binary data 101100110101 is transmitted over a base band channel. Draw the waveform for the transmitted data using the following formats:
UNIPOLAR-RZ
BIPOLAR-RZ
SPLIT PHASE MANCHESTER
What is the difference between bit rate and baud rate? Define ADPCM briefly.
Distinguish between FSK and MSK. What is the advantage of MSK
What is the need of multiplexing Compare FDM and TDM.
7. What is spread spectrum communication? Name various commonly used spread spectrum techniques and also write the advantages of spread sprectrum communication.
8. Write short notes on any four of the following:
Run Property
Channel Coding
PN-Sequence
Processing Gain
PAM
Companding
Spread spectrum modulation technique utilizes
direct sequence modulation
pseudorandom sequence modulation
double modulation
wideband modulation
The maximum possible time interval between two successive samples of a 2 kHz signal is
0·25 ms
0·125 ms
0·5 ms
1 ms
Nyquist rate is the minimum sampling rate to avoid
amplitude distortion
foldover distortion
frequency distortion
phase distortion
In PCM, the quantization noise mainly depends on
sampling rate
signal power
number of quantization levels
number of bits per sample
Flat top sampling leads to
aliasing error
aperture effect
signal level attenuation
quantization error
Which encoding method uses alternative positive and negative values for
NRZ-1
RZ
(iii Manchester
AMI
How many different symbols are possible at the output of a 16-QAM modulator?
8
16
64
256
Define Entropy. Define different properties of entropy.
For a source transmitting two independent messages M1 and M2 having probability of P and respectively, prove that the entropy is maximum when both the messages are equally likely.
The output signal to quantizing noise ratio (SNR)o in a PCM system is defined as the ratio of average signal power to average quantizing noise power. For full scale sinusoidal modulating signal with amplitude prove that
(SNR)o
where L is the number of quantizing levels.
Discuss the need of companding in PCM system.
4. What are the different types of digital modulation techniques Explain any two
techniques.
Define line coding. The binary data 101100110101 is transmitted over a base band channel. Draw the waveform for the transmitted data using the following formats:
UNIPOLAR-RZ
BIPOLAR-RZ
SPLIT PHASE MANCHESTER
What is the difference between bit rate and baud rate? Define ADPCM briefly.
Distinguish between FSK and MSK. What is the advantage of MSK
What is the need of multiplexing Compare FDM and TDM.
7. What is spread spectrum communication? Name various commonly used spread spectrum techniques and also write the advantages of spread sprectrum communication.
8. Write short notes on any four of the following:
Run Property
Channel Coding
PN-Sequence
Processing Gain
PAM
Companding
Other Question Papers
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