Test
IT - Theory Part
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Preguntas del test (79)
1... is a measure of uncertainty
- AEncoding
- BEntropy
- CInformation
- DRedundancy
2{1,2,3,4,5,6} is the sample space of ...
- Aone coin toss
- Bone dice roll
- Csum of two dice
- Dremoving a card from the standard deck
3A redundancy of a code S = ...
- A1 - Iavr/Imax
- BIavr/Imax
- C1 + Iavr/Imax
- DImax/Iavr
4An average length of codewords qavr = ...
- A∑ (pi * qi)
- B∑ (pi / qi)
- C∑ pi
- D∑ qi
5An efficiency of a code E = ...
- AIavr/Imax
- BImax/Iavr
- CIavr/100
- DImax - Iavr
6ASCII code is a
- AVariable length code
- BFixed length code
- CError-correction code
- DNone of the given
7By the Bayes' rule for conditional entropy H(Y|X) \= ...
- AH(X|Y) - H(X) + H(Y)
- B[P(B|A)][P(A)] /P(B)
- CH(X|Y) - H(X)
- DH(X|Y)+ H(Y)
8By the Bayes' theorem ...
- AP(B|A) = P(A and B)/P(A)
- BP(A|B) = [P(B|A)][P(A)] /P(B)
- CP(B|A) = P(A and B)*P(A)
- DP(A|B) = [P(B|A)][P(A)] * P(B)
921. By the Chain rule H(X,Y) \= H(Y|X) + ...
- AH(X)
- BH(Y)
- CH(Y|X)
- DH(X|Y)
10By the Hartley's formula the amount of information I = ...
- AI = n*log m
- BI = m*n
- CI = log (m/n)
- DI = log (m*n)
11By the Hartley's formula the entropy H = ...
- AH \= - ∑(pi * log pi)
- BH \= - ∑ (log pi)
- CH \= log m
- DH \= - ∑ (pi / log pi)
12By the property of joint entropy H(X,Y) <= ...
- AH(X)
- BH(Y)
- CH(X) + H(Y)
- DNone of the given
13By the property of joint entropy H(X,Y) ...
- AH(X,Y) >= H(X) and H(X,Y) <= H(Y)
- BH(X,Y) <= H(X) and H(X,Y) >= H(Y)
- CH(X,Y) >= H(X) and H(X,Y) >= H(Y)
- DH(X,Y) >= H(X) + H(Y)
14By the Shannon's formula the amount of information I = ...
- AH \= - n * ∑( pi * log pi)
- BH \= - n * ∑ (log pi)
- CH \= - n * ∑ pi
- DH \= - n * ∑ (pi / log pi)
15By the Shannon's formula the entropy H = ...
- AH \= - ∑( pi * log pi)
- BH \= - ∑ (log pi)
- CH \= - ∑ pi
- DH \= - ∑ (pi / log pi)
16Calculate the code rate for Hamming (15,11) code
- A1
- B0,733
- C0,571
- D0,839
17Calculate the code rate for Hamming (31,26) code
- A1
- B0,839
- C0,733
- D0,571
18Choose the formula to determine the number N of possible messages with length n if the message source alphabet consists of m characters, each of which can be an element of the message
- AN = mn
- BN = nm
- CN = m*n
- DN = log m
19Code is optimal when ...
- Aqavr = H
- Bqavr ≠H
- Cqavr <H
- Dqavr >H
20Code rate R (k information bits and n total bits) is defined as
- Ak = n/R
- BR = k * n
- Cn = R * k
- DR = k/n
21Conditional entropy H(Y|X) lies between
- A- H(Y) and 0
- B0 and H(Y)
- C- H(Y) and H(Y)
- D0 and 1
22Conditional probability P(B|A) = ...
- AP(A and B)/P(A)
- B[P(B|A)][P(A)] /P(B)
- CP(A and B)*P(A)
- D[P(B|A)][P(A)] * P(B)
23Find the information amount of a symbol from the language with total number of symbols n = 18.
- AI = log218
- BI = log182
- CI = 18 * log218
- DI = 18 * log182
24For a Hamming (15, 11) code, 15 is the total number of bits and 11 is the number of ...
- Aredundant bits
- Bdata bits
- Cparity bits
- Dnone of the given
25Which of the following symbols will get the shortest codeword after Shannon-Fano coding if probabilities are p(a) = 0.05, p(b) = 0.6, p(c) = 0.2 and p(d) = 0.15?
- Ac
- Ba
- Cd
- Db
26Which of the following is not a correct statement about a probability.
- AIt must have a value between 0 and 1
- BIt is the collection of several experiments
- CA value near 0 means that the event is not likely to occur/happens
- DIt can be reported as a decimal or a fraction
27Which of the following is a part the channel coding?
- AHuffman code
- BHamming code
- CShannon-Fano code
- DRLE code
28For a Hamming (31, 26) code, 31 is the total number of bits and 26 is the number of ...
- Aredundant bits
- Bdata bits
- Cparity bits
- Dnone of the given
29For Hamming distance d<sub>min</sub> and s errors in the received word, the condition to be able to correct the errors is
- Admin>= s+1
- Bdmin>= 2s+1
- Cdmin>= 2s+2
- Ddmin>= s+2
30Hamming distance can easily be found with ...
- AXNOR operation
- BXOR operation
- COR operation
- DAND operation
31In a throw of coin what is the probability of getting head.
- A1
- B1/2
- C2
- D0
32Specify the formula to calculate numbers of k and n bits to create the Hamming code
- A(n, k) = (2r - 1, 2r - 1 - r)
- B(n, k) = (2r, 2r - 1 - r)
- C(n, k) = (2r - 1, 2r - r)
- D(n, k) = (2r - 1, 2r - 1 + r)
33In a throw of coin what is the probability of getting tails.
- A1
- B1/2
- C2
- D0
34Specify the formula to find the amount of information if events have different probabilities.
- AHartley's formula
- BShannon's formula
- CFano's formula
- DBayes' formula
35Specify the formula to find the amount of information if events have the same probabilities.
- AShannon's formula
- BHartley's formula
- CFano's formula
- DBayes' formula
36Specify the most effective type of code when an alphabet consists of 2 symbols with probabilities p(x1) = 0,05 and p(x2) = 0,95.
- AASCII code
- BShannon-Fano's code
- CShannon-Fano's code by blocks
- DHartley's code
37In digital communication system, smaller the code rate, ... are the redundant bits.
- Aa. less
- Bb. equal
- Cc. more
- Dd. unpredictable
38Specify the right formula if dmin is Hamming distance, s - number of correctable errors and r - number of detectable errors.
- Admin>= s+r+1
- Bdmin>= 2s+r+1
- Cdmin>= s+2r+1
- Ddmin>= s+r+2
39Specify two types of error control algorithms
- Ablock and linear
- Blinear and nonlinear
- Cblock and convolution
- Dnone of the given
40Noise affects ...
- Ainformation source
- Breceiver
- Cchannel
- Dtransmitter
41The basic idea behind Shannon-Fano coding is to
- Acompress data by using more bits to encode more frequently occuring characters
- Bcompress data by using fewer bits to encode more frequently occuring characters
- Ccompress data by using fewer bits to encode fewer frequently occuring characters
- Dexpand data by using fewer bits to encode more frequently occuring characters
42Probability of occurrence of an event lies between
- A-1 and 0
- B0 and 1
- C-1 and 1
- Dexactly 1
43The Hamming distance between "client" and "server" is
- A0
- B1
- C6
- Dimpossible to detect
44The Hamming distance between "make" and "made" is
- A4
- B3
- C1
- Dimpossible to detect
45The Hamming distance between "push" and "pull" is
- A0
- B4
- C2
- Dimpossible to detect
46Probability of second event in situation if first event has been occurred is classified as
- Aconditional probability
- Bjoint entropy
- Cconditional entropy
- Dnone of the given
47The Hamming distance between "starting" and "finishing" is
- A4
- B3
- Cimpossible to detect
- D5
48The Hamming distance between 001111 and 010011 is
- A1
- B2
- C3
- D4
49Shannon-Fano and Huffman codes are an encoding algorithms used for
- Alossy data compression
- Blossless data compression
- Cerror correction
- Derror detection
50The Hamming distance between 010111 and 010011 is
- A2
- B3
- C1
- D4
51The Hamming distance between 011111 and 010011 is
- A1
- B3
- C2
- D4
52Specify parts of the receiver side
- ASource encoder, channel encoder, digital modulator
- BSource decoder, channel decoder, digital demodulator
- CSource decoder, channel encoder, digital modulator
- DSource encoder, channel decoder, digital modulator
53The Hamming distance between 101001 and 010011 is
- A1
- B2
- C4
- D3
54The Hamming distance between two strings with equal length is ...
- Athe number of positions at which the corresponding symbols are different
- Bthe number of positions at which the corresponding symbols are equal
- Cthe number of identical symbols in the first string
- Dthe number of identical symbols in the second string
55Specify parts of the transmitter side
- ASource decoder, channel decoder, digital demodulator
- BSource encoder, channel encoder, digital modulator
- CSource decoder, channel encoder, digital modulator
- DSource encoder, channel decoder, digital modulator
56The number of digits by which any two binary sequences differ is called the ...
- AHamming weight
- BHamming distance
- CHamming code
- DHamming length
57Specify the case when entropy is maximum
- Ap1=0,5 and p2=0,5
- Bp1=1 and p2=0
- Cp1=0 and p2=1
- Dp1=0,9 and p2=0,1
58The prefix code is also known as ...
- Ablock code
- Buniquely decodable code
- Cconvolutional code
- Dparity bit
59In a throw of dice what is the probability of getting number greater than 5.
- Aa. 1/3
- Bb. 1/6
- Cc. 1/5
- Dd. 1
60The string was encoded with Hamming (15,11) code using the transformation matrix. Specify numbers of positions of the parity bits.
- A12,13,14,15
- B1,2,3,4
- C1,2,4,8
- D2,3,4,5
6178. For a Hamming (31, 26) code, 31 is the total number of bits and 26 is the number of ...
- Aa. redundant bits
- Bb. data bits
- Cc. parity bits
- Dd. none of the given
62The string was encoded with Hamming (31,26) code using the transformation matrix. Specify numbers of positions of the parity bits.
- A27,28,29,30,31
- B1,2,3,4,5
- C1,2,4,8,16
- D2,3,4,5,6
6379. For a Hamming (7, 4) code, 7 is the total number of bits and 4 is the number of ...
- Aa. redundant bits
- Bb. data bits
- Cc. parity bits
- Dd. none of the given
64When data is compressed, the goal is to reduce
- Anoise
- Bredundancy
- Cchannel capacity
- Dnone of the given
65When the base of the logarithm is 10, then the unit of measure of information is
- Abytes
- Bdits
- Cnits
- Dbits
6643. Code has dmin = 3. How many errors can be detected by this code?
- A1
- B3
- C2
- D4
67When the base of the logarithm is 2, then the unit of measure of information is
- Abytes
- Bbits
- Cnits
- Ddits
68When the base of the logarithm is e, then the unit of measure of information is
- Abytes
- Bnits
- Cdits
- Dbits
69Which block or device does the data compression?
- AChannel encoder
- BSource encoder
- CModulator
- DNone of the given
70Which letter will get the shortest codeword after Huffman coding of the word "abracadabra"?
- Ac
- Br
- Cd
- Da
71Which of the following codes has the highest code rate?
- Acode rate is constant for all of the Hamming codes
- BHamming (31,26)
- CHamming (15,11)
- DHamming (7,4)
72Which of the following codes has the highest redundancy?
- Aredundancy is constant for all of the Hamming codes
- BHamming (7,4)
- CHamming (15,11)
- DHamming (31,26)
73Which of the following codes is non-uniform?
- AShannon-Fano
- BASCII
- CHamming
- DNone of the given
74Which of the following codes is prefix?
- A0, 111, 11
- B0, 111, 10
- C0, 101, 10
- D00, 10, 101
75Which of the following codes is prefix?
- A0, 01, 11
- B0, 10, 11
- C0, 10, 1
- D0, 01, 001
76Which of the following codes is uniform?
- AASCII
- BShannon-Fano
- CHuffman
- DNone of the given
77Which of the following codes is uniform?
- A10,011,11,001,010
- B0,10,110,1110,1111
- C10,01,0001,100,1010
- D100,110,001,000,010
78Which of the following indicate(s) an error in a received combination?
- AParity bits
- BError syndrome
- CData bits
- DNone of the given
79The string was encoded with Hamming (7,4) code using the transformation matrix. Specify numbers of positions of the parity bits.
- Aa. 5,6,7
- Ba. 1,2,3
- Ca. 1,2,4
- Da. 2,3,4
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