STUPIDSID
Solve any one question from Q1 and Q2
1 (a)
Explain with the help of block diagram formatting and transmission of baseband signal.
8 M
1 (b)
Define mean, correlation, standard deviation of a random process.
6 M
1 (c)
Draw the block diagram of DM transmitter and explain its working. Comment on the drawbacks of DM.
6 M
2 (a)
Define the terms related to digital communication
i) Messages
ii) Characters
iii) Symbols
i) Messages
ii) Characters
iii) Symbols
6 M
2 (b)
Explain digital signal hierarchy using TI carrier system.
6 M
2 (c)
The output of an oscillator is described by x(t)=A cos(π Ft+θ) where the amplitude A is constant and F and φ are independent random
variables. The probability density function of θ is defined by [ f_\phi( heta) = \left{egin{matrix}
\frac {1}{2 \pi}, & 0 \le \theta \le 2\pi \0
& \text{otherwise}
\end{matrix}
ight. ] Find the power spectral density of x(t) in terms of the probability density function of the frequency F.
8 M
Solve any one question from Q3 and Q4
3 (a)
Consider the signal S(t) shown in fig. Determine the impulse response of a filter matched to this signal and sketch it as a function of time, plot the matched filter output as a function of time.
8 M
3 (b)
Derive the expression of SNR for optimum filter.
8 M
Write a short note on:
4 (a) (i)
MAP
4 M
4 (a) (ii)
LRT
4 M
Draw & explain signal space representation of following signal.
4 (b) (i)
BPSK
4 M
4 (b) (ii)
8 Array PSK
4 M
Solve any one question from Q5 and Q6
5 (a)
Explain block diagrams for generation and reception of M-ary PSK signals. With suitable mathematical expressions, signal space representation Bandwidth and PSD.
10 M
5 (b)
Binary data is transmitted using PSK at a rate 3M bps over RF link having bandwidth 10MHz. Find signal power required at receiver input so that error probability is less than or equal to 10-4 Assume noise PSD
to be 10-10 watt/Hz. [Q (3.71) = 10-4 ]
8 M
6 (a)
Explain with block diagram QPSK receives Write an expression for its
error probability
8 M
6 (b)
find error probability of coherent FSK when amplitude of I/P at coherent optimal receiver is 10mv and frequency 1MHz, the signal corrupted with
white noise of PSD 10-9 W/Hz. the data rate is 100kbps. [erfc (1.01) = 0.1531, erfc (1.11) = 0.1164, erfc (1.22) = 0.0844 & erfc (1.33 = 0.0599)].
10 M
Solve any one question from Q7 and Q8
7 (a)
Draw and explain 4bit P.N. sequence generator and find maximum length sequence.
8 M
7 (b)
The signal has the following parameter number of bits per MFSK symbol K = 2 number of MFSK tone M = 2k = 4 length of PN sequence per hop K = 3 total No. frequency hops 2k = 8 sketch the o/p transmits freq of fast FH/MFSK signals.
8 M
8 (a)
Write a short note on personal communication system (PCS).
8 M
8 (b)
Compare DSSS with FHSS system.
8 M
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