# 2010 Rajasthan Technical University B.Tech 4 Semester Computer science & engineering "Analog & digital communication" question paper

Question Paper Details:

University: Rajasthan Technical University
Course: B.Tech Computer science & engineering
Subject: Analog & Digital Communication

Exam Year:   June 2010
Year or Semester: Second year/ Fourth Semester
Paper Code: 4E2920

Unit-I

a)      Derive the equation of amplitude modulation (AM) also power relation and frequency spectrum of AM. [Marks 10]
b)      Explain the working of envelop (Diode) detector circuit for AM detection. [Marks 6]
OR

a)      Explain the different methods of generation of SSB signal. [Marks 10]
b)      Determine the power content of the carrier and each of side band for AM signal having % modulation of 80% and total power of 2500 watt. [Marks 6]
Unit-II

a)      Explain the principle of FM detection. Also explain any one method of FM demodulator in brief. [Marks 8]
b)      Compare AM, FM, PM. [Marks 8]
Unit-III

a)      Explain the working of pulse code modulation (PCM). Define the signal to quantization noise ration in PCM. [Marks 10]
b)      In binary PCM, the O/P signal to quantization ratio is to be held to minimum of 40 dB. Determine number of level required. [Marks 6]
OR
a)      Compare PCM, DPCM, DM and ADM. [Marks 10]
b)      Determine error probability in PCM system. [Marks 6]
Unit-IV

a)      Explain the types of line coding in brief. [marks 10]
b)      The data rate in T1 carries system is 1.544 Mb/sec and band width is 50 KHz. What SNR is needed to put T1 carries on 50 KHz channel? [marks 6]
OR
Explain pulse analog (PAM, PWM, PPM) modulation & demodulation in brief. [Marks 16]
Unit-V
Write the short notes on following:
i)                    ASK (Amplitude shift keying)
ii)                   BFSK
iii)                 QPSK
iv)                 PSK
OR
a)      Calculate error probability performance of ASK, BPSK and QPSK. [Marks 10]
b)      A binary receiver system receive a bit rate of 1 Mb/s. the wave form amplitude in 5 mV and the nose power spectral density is 0.5×10^11 WHz. Calculate bit error probability if modulation scheme are