Guru Gobind Singh Indraprastha Vishwavidyalaya 2005 B.Tech Communication Systems and circuits - Question Paper
Wednesday, 29 May 2013 12:55Web
End-Term exam
Fourth Semester [B.Tech] - May 2005
Paper Code : ETEC – 208 Subject : Communication Systems and Circuits
Time : three Hours
Maximum Marks : 75
Note : Attempt any five ques. in all.
Q1 ( a ) provide the time-domain and frequency domain representation of the subsequent signals:
(i) AM-DSB/FC (ii) AM-DSB/SC
(iii) AM-SSB/FC (iv) AM-SSB/SC
provide graphical representation wherever necessary.
( b ) In a certain SSB generator of phase shift type, the phase shift for modulating signal is deviated by 20 from its ideal value of 900. obtain the ratio of undesired sideband amplitude to desired sideband amplitude.
Q2 ( a ) discuss the indirect method for generation of FM signals.
( b ) List the difference ranging from NBFM and WBFM signals. 3
( c ) Am FM signal is provided by
V(t) = 20 cos(108t + 20cos(3000t))
obtain the different parameters associated with this signal.
Q3 ( a ) State and discuss sampling theorem for and limited signals.
( b ) compute Nyquist rate of sampling for the subsequent signal:
V(t) = 20 cos(2000pt) . cos(1000pt) + sin2(3000pt) 3
( c ) discuss the principle of different pulse modulated signals using necessary waveforms.
Q4 ( a ) discuss the difference ranging from PCM and DM systems. How the slope overload is minimized using ADM systems.
( b ) A modulator transmits 1000 symbols /sec. every symbol has 32 various possible states. Find:
(i) bit rate (ii) baud rate 3
( c ) A signal of 1V amplitude and one KHz frequencies transmitted by DM system. obtain minimum step size so that slope overloading is avoided if the sampling frequency = 40 samples /sec. 4
Q5 ( a ) discuss the principles of PSK and DPSK systems. How will you modulate and demodulate such signals?
( b ) Why are the different line coding formats required? Encode the bit stream 11010101 using:(i) RZ (ii) NRZ
(iii) AMI (iv) Manchester
Q6 ( a ) A matched filter is to be designed for PCM systems. The PCM pulse has amplitude A for 0
H(w) and h(t) of the matched filter.
Maximum SNR at the output.
Minimum probability of fault.
( b ) discuss the principle of companding.
Q7 ( a ) discuss Shannon Hartley theorem of channel capacity.
( b ) Find:
(i) Shannon Fano's codes (ii) Huffman's codes
for the subsequent digits with specified probabilities:i A B C D E F
P (i) 0.30 0.24 0.21 0.13 0.07 0.05
compute efficiency of transmission before and after coding using Shannon Fano's codes.
( a ) A random variable has probability density function:
p(x) = a e-bx ; x>0
= 0 ; x<0
obtain the total probability that the random variable lies ranging from one and 2.
( b ) obtain he mean and variance of sum of 2 random variables provided by
Z = x + y
( c ) describe (i) stationary and random processes
(ii) ergodic random process
| Earning: Approval pending. |
