1

GATE ECE 2010

MCQ (Single Correct Answer)

+2

-0.6

Consider a base band binary PAM receiver shown below. The additive channel noise
$$n(t)$$ is white with power spectral density $${S_N}\left( f \right) = {N_0}/2 = {10^{ - 20}}$$ $$W/Hz$$. The low-pass filter
is ideal with unity gain and cut -off frequency $$1MHz$$. Let $${Y_k}$$ represent the random variable $$y\left( {{t_k}} \right)$$.

$${Y_k} = {N_k}$$ if transmitted bit $${b_k} = 0$$

$${Y_k} = a + {N_k}$$ if transmitted bit $${b_k} = 1$$

Where $${b_k} = 0$$ represents the noise sample value. The noise sample has a probability density function, $${P_{{N_k}}}\left( n \right)\,\,\,\,\,\,\, = 0.5\alpha {e^{ - \alpha \left| n \right|}}$$ (This has mean zero and variance $$2/{\alpha ^2}$$). Assume transmitted bits to be equiprobable and threshold $$z$$ is set to $$a/2 = {10^{ - 6}}V$$.

$${Y_k} = {N_k}$$ if transmitted bit $${b_k} = 0$$

$${Y_k} = a + {N_k}$$ if transmitted bit $${b_k} = 1$$

Where $${b_k} = 0$$ represents the noise sample value. The noise sample has a probability density function, $${P_{{N_k}}}\left( n \right)\,\,\,\,\,\,\, = 0.5\alpha {e^{ - \alpha \left| n \right|}}$$ (This has mean zero and variance $$2/{\alpha ^2}$$). Assume transmitted bits to be equiprobable and threshold $$z$$ is set to $$a/2 = {10^{ - 6}}V$$.

The probability of bit error is

2

GATE ECE 2009

MCQ (Single Correct Answer)

+2

-0.6

The amplitude of random signal is uniformly distributed between $$-$$5V and 5V

If the signal to quantization noise ratio required in uniformly quantizing the signals is 43.5 dB, the step size of the quantization is approximately

3

GATE ECE 2009

MCQ (Single Correct Answer)

+2

-0.6

The amplitude of random signal is uniformly distributed between $$-$$5V and 5V

If the positive values of the signal are uniformly quantized with a step size of 0.05 V, and the negative values are uniformly quantized with a step size of 0.1V, the resulting signal to quantization noise ratio is approximately

4

GATE ECE 2008

MCQ (Single Correct Answer)

+2

-0.6

Consider a Binary Symmetric Channel (BSC) with probability of error being 'p'. To transit a bit, say 1, we transmit a sequence of three 1s. The receiver will interpret the received sequence to represent 1 if at least two bits are 1. The probability that the transmitted bit will be received in error is

Questions Asked from Noise In Digital Communication (Marks 2)

Number in Brackets after Paper Indicates No. of Questions

GATE ECE 2016 Set 1 (2)
GATE ECE 2015 Set 2 (1)
GATE ECE 2015 Set 1 (2)
GATE ECE 2014 Set 4 (2)
GATE ECE 2014 Set 2 (1)
GATE ECE 2013 (1)
GATE ECE 2012 (2)
GATE ECE 2011 (2)
GATE ECE 2010 (2)
GATE ECE 2009 (2)
GATE ECE 2008 (1)
GATE ECE 2007 (5)
GATE ECE 2006 (2)
GATE ECE 2005 (3)
GATE ECE 2004 (1)
GATE ECE 2003 (2)
GATE ECE 2001 (1)
GATE ECE 1999 (2)
GATE ECE 1988 (2)
GATE ECE 1987 (1)

GATE ECE Subjects

Signals and Systems

Representation of Continuous Time Signal Fourier Series
Discrete Time Signal Fourier Series Fourier Transform
Discrete Time Signal Z Transform
Continuous Time Linear Invariant System
Transmission of Signal Through Continuous Time LTI Systems
Discrete Time Linear Time Invariant Systems
Sampling
Continuous Time Signal Laplace Transform
Discrete Fourier Transform and Fast Fourier Transform
Transmission of Signal Through Discrete Time Lti Systems
Miscellaneous
Fourier Transform

Network Theory

Control Systems

Digital Circuits

General Aptitude

Electronic Devices and VLSI

Analog Circuits

Engineering Mathematics

Microprocessors

Communications

Electromagnetics