**T.E. (E & TC)DIGITAL COMMUNICATION(2015 Pattern) (Semester – I)**

**Time : 2Â½ HourMax. Marks : 70Instructions to the candidates:1) Answer Q.1 or Q.2, Q.3 or Q.4, Q.5 or Q.6, Q.7 or Q.8.2) Assume suitable data if necessary.3) Figures to the right side indicate full marks.**

Q.1 a) What is narrowband noise? Show the generation of narrowband noise from its in phase and quadrature components.** [6M]**

b) A binary channel with 32kbps bit rate is available for PCM voice transmission. Find **[6M]**

i) No. of quantization levels

ii) No. of bits per sample

iii) sampling frequency

The voice signal is band limited to3.4KHz.

c) What is bit synchronization? Explain Early-Late bit synchronizer in detail.**[8M]**

**OR**

Q2) a) List properties of Line Codes (Data Formats). Draw the following line codes for bit stream 10110010** [8M]**

i) Polar RZ

ii) Polar NRZ

iii) Manchester

iv) AMI

v) Polar Quaternary

vi) Unipolar RZ

b) What is White noise? Explain. **[6M]**

c) With the help of neat block diagram, explain Pulse Code Modulation.**[6M]**

Q3) a) Explain likelihood function.** [6M]**

b) Derive an expression for probability of error of matched filter. **[8M]**

c) State properties of Match filter. **[2M]**

**OR**

Q4) a) Derive an expression for signal to noise ratio of integrator and dump filter.** [6M]**

b) Find impulse response of matched filter whose input is given by **[6M]**

g(t) = A sin(2Ï€t/T) ; 0 < t < T

= 0; Otherwise

c) Draw block diagram and explain in detail correlation receiver. **[4M]**

Q5) a) Draw block diagram of BPSK and explain it. **[4M]**

b) With the help of block diagram and waveforms, explain generation of coherent BFSK. **[6M]**

Binary data is transmitted using PSK at a rate 5Mbps over RF link having bandwidth 10 MHz. Find signal power required at receiver input so that error probability is less than or equal to 10â€“4 watt/Hz. Q(3.71) = 10â€“4, No/2 = 10â€“10. **[6M]**

**OR**

Q6) a) Compare BPSK, BFSK, QPSK w.r.t.** [6M]**

i) BW

ii) Probability of Error

iii) Bit Rate

b) Draw block diagram and Explain generation of QPSK with waveforms.**[6M]**

c) Explain M-ary QAM transmitter and receiver. **[4M]**

Q7) a) Define **[4M]**

i) Processing Gain

ii) Jamming Margin

b) The DSSS communication system has message bit duration (Tb) = 4.095ms and chip duration(Tc) = 1 Î¼s. Calculate the processing gain and jamming margin if (Eb/No) = 10 and the average probability of error Pe = 0.5 Ã— 10â€“5 **[6M]**

c) Draw the block diagram of DSSS system and explain various blocks. **[8M]**

**OR**

Q8) Write short note on** [18M]**

i) FHSS

ii) Properties of PN sequence

iii) Fast and slow frequency hoping

Login

Accessing this course requires a login. Please enter your credentials below!