1
GATE ECE 2007
MCQ (Single Correct Answer)
+2
-0.6
An input to a 6-level quantizer has the probability density function f(X) as shown in the figure. Decision boundaries of the quantizer are chosen so as to maximize the entropy of the quantizer output. It is given that 3 consecutive decision boundaries are ‘-1’, ‘0’ and ‘1’. GATE ECE 2007 Communications - Noise In Digital Communication Question 25 English

The values of a and b are

A
a = 1/6 and b = 1/12
B
a = 1/5 and b = 3/40
C
a = 1/4 and b = 1/16
D
a = 1/3 and b = 1/24
2
GATE ECE 2007
MCQ (Single Correct Answer)
+2
-0.6
During transmission over a certain binary communication channel, bit errors occurs independently with probability p. The probability of at most one bit in error in a block of n bits is given by
A
$${p^n}$$
B
$$1 - {p^n}$$
C
$$np{\left( {1 - p} \right)^{n - 1}} + {\left( {1 - p} \right)^n}$$
D
$$1 - {\left( {1 - p} \right)^n}$$
3
GATE ECE 2007
MCQ (Single Correct Answer)
+2
-0.6
In a Direct sequence CDMA system the chip rate is $$1.2288\,\, \times \,\,{10^6}$$ chips per second. If the processing gain is desired to be at least 100. The data rate
A
must be less than or equal to $$12.288\,\, \times \,\,{10^3}$$ bits per sec.
B
must be greater than $$12.288\,\, \times \,\,{10^3}$$ bits per sec.
C
must be exactly equal to $$12.288\,\, \times \,\,{10^3}$$ bits per sec.
D
can take any value less than $$12.288\,\, \times \,\,{10^3}$$ bits per sec.
4
GATE ECE 2007
MCQ (Single Correct Answer)
+2
-0.6
Two 4-ray signal constellations are shown. It is given that $${\phi _1}$$ and $${\phi _2}$$ constitute an orthonormal basis for the two constellations. Assume that the four symbols in both the constellations are equiprobable. Let $${{{N_0}} \over 2}$$ denote the power spectral density of white Gaussian noise. GATE ECE 2007 Communications - Noise In Digital Communication Question 22 English

If these constellations are used for digital communications over an AWGN channel, then which of the following statements is true?

A
Probability of symbol error for Constellation 1 is lower
B
Probability of symbol error for Constellation 1 is higher
C
Probability of symbol error is equal for both the constellations
D
The value of N0 will determine which of the two constellations has a lower probability of symbol error.