1
GATE ECE 2014 Set 1
Numerical
+2
-0
Let $$Q\left( {\sqrt y } \right)$$ be the BER of a BPSK system over an AWGN channel with two - sided noise power spectral density N0/2. The parameter 𝛾 is a function of bit energy and noise power spectral density. A system with two independent and identical AWGN channels with noise power spectral density N0/2 is shown in the figure. The BPSK demodulator receives the sum of outputs of both the channels

If the BER of this system is $$Q\left( {b\sqrt y } \right),$$ then the value of b is -----------.

2
GATE ECE 2013
+2
-0.6
Bits 1 and 0 are transmitted with equal probability. At the receiver, the pdf of the respective received signals for both bits are as shown below.

If the detection threshold is 1, the BER will be

A
$${1 \over 2}$$
B
$${1 \over 4}$$
C
$${1 \over 8}$$
D
$${1 \over 16}$$
3
GATE ECE 2013
+2
-0.6
Bits 1 and 0 are transmitted with equal probability. At the receiver, the pdf of the respective received signals for both bits are as shown below.

The optimum threshold to achieve minimum bit error rate (BER) is

A
$${1 \over 2}$$
B
$${4 \over 5}$$
C
1
D
$${3 \over 2}$$
4
GATE ECE 2011
+2
-0.6
X(t) is a stationary random process with autocorrelation function Rx$$\left( \tau \right)$$= exp$$\left( { - \pi {\tau ^2}} \right)$$. This process is passed through the system shown below. The power spectral density of the output process Y(t) is
A
$$\left( {4\,{\pi ^2}{f^2} + 1} \right)\,\exp \left( { - \pi {f^2}} \right)$$
B
$$\left( {4\,{\pi ^2}{f^2} - 1} \right)\,\exp \left( { - \pi {f^2}} \right)$$
C
$$\left( {4\,{\pi ^2}{f^2} + 1} \right)\,\exp \left( { - \pi f} \right)$$
D
$$\left( {4\,{\pi ^2}{f^2} - 1} \right)\,\exp \left( { - \pi f} \right)$$
GATE ECE Subjects
Signals and Systems
Network Theory
Control Systems
Digital Circuits
General Aptitude
Electronic Devices and VLSI
Analog Circuits
Engineering Mathematics
Microprocessors
Communications
Electromagnetics
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