SNS COLLEGE OF ENGINEERING
DEPARTMENT OF ECE
DIGITAL COMMUINCATION
MCQ
1. Error control for data integrity may be exercised by means of a) Forward error correction b) error detection c) Error correction d) reverse error correction
ANS: a) Forward error correction
2.The dimensionless ratio r = k/n is called the rate. a) bit b)code c)system d) error
ANS: b) code
3.The encoder for a convolutional code operates on the incoming message sequence, using a
a)hamming window b)blackman window
c) hanning window d)sliding window
ANS: d) sliding window
4. Abbreviate FEC a) forward error correction b)front error correction c)first error correction d)final error correction
ANS: a)forward error correction
5.In coding and modulation block diagram noise is given to which channel? a) encoder b) source c)waveform channel d) user
ANS: c) waveform channel

1.------------- has a discrete memory less channel. a)cyclic codes b)channel codes c)convolutional codes ans:b
2.The rate of channel coding ranges from -----------
a)R=C
b)R≤C
c)R≥C ans:b
3.In channel coding --------- probability is within the tolerate limits
a)state
b)error
c)cycle ans:b
4.----------- statement says if R>C, every message will be error
a)positive
b)negative
c)neutral ans:b
5.what is the channel capacity in the channel coding theorem?
a)minimum
b)maximum
c)constant ans:b

1.LBC means a) Linear bit code b) Linear block code c)Linear block check d)Linear binary code
Answer: Linear block code
2. The generator matrix G is used in the encoding operation at a) Receiver b) Transmitter c) Encoder d) Decoder
Answer: transmitter
3. The syndrome depends only a) Transmitted code word b) Error pattern c) Receive code word d) Parity pattern
Answer: Error pattern
4. Minimum distance of the LBC is defined as a) Smallest distance b) Longest distance c) Medium distance
Answer: Smallest
5. Error detection a)dmin≤s+1 b)dmin≥s+1 c)dmax≥s+1 ans:b
• The combination of the modulator the waveform channel and the detector acts as
_______________
• Discrete memoryless channel
• Memoryless channel
•
Discrete channel
• None of the above
Ans: a) discrete memoryless channel
•
Demodulate output is indicated by the symbol _______
•
I

•
J
•
K
• L
Ans: b) j
• Abbreviate BSC
• Binary symmetric channel
• Bit symmetric channel
•
Binary schematic channel
•
Binary symmetric code
Ans: a) Binary symmetric channel
•
Channel coding theorem is ______ in nature
•
Constructive
•
Non-constructive
•
Consecutive
•
Non-consecutive
Ans: b) Non-constructive
•
Channel coding theorem only asserts the existence of _____
•
Good codes
•
Moderate codes
•
Parity bits
•
Code word

Ans: a) good codes
1) IN VITERBI DECODING HOW MANY ERROR SHOULD WANT TO BE OCCURRED
•
1
•
5
• 4
•
2
ANS : 1
•
THE VITERBI ALGORITM IS A _____________DECODE
•
MAXIMUM –LIKEHOOD
• MINIMUM –LIKEHOOD
•
NONE OF THESE
ANS:1
3) THE VITERBI ALGORITHM WAS EQUIVALENT TO TECHNIQUE KNOWN
HAS_______________
• PROGRAM
•
DYNAMIC
•
DYNAMIC PROGRM
•
ALL THE ABOVE
ANS: C
5) THE PATHS THAT ARE RETAINED BY THE ALGORITHM ARE______
1. SURVIVORS
2. LENGTH
3. HEIGHT
4. NONE OF THE ABOVE
ANS:1

4) IN ________YEAR VITERBI PROPOSED A DECODING ALGORITHM FOR
CONVOLUCTION CODES
•
1947
• 1996
• 1945
•
1967
ANS:4
1. . For hamming distance dmin and number of errors D, the condition for receiving invalid codeword is a) D <= dmin + 1 b) D <= dmin-1 c) D <= 1- dmin d) D <= dmin
ANSWER: b) D <= dmin-1
2. Q2. For hamming distance dmin and t errors in the received word, the condition to be able to correct the errors is a) 2t + 1 <= dmin b) 2t + 2 <= dmin c) Both a) and b) d) 2t + 1<= 2dmin
ANSWER: c) Both a) and b)
3.consider X=1010101 Y=1101111
Find the hamming distance

a)5 b)1 c)2 d)4
ANSWER:d) 4
4.what is the hamming weight?
For X= 1011101 a)4 b)5 c)1 d)7
Answer:(b)5
5.find the dmin of the code vectors
X1=1010101
X2=110001
X3=111011 a)1 b)2 c)6 d)3 ans:d)3