WBUT question of Analog communication 2007

2007
ANALOG COMMUNICATION
GROUP-B
2 (A) Define amplitude modulation and modulation index. Use a sketch of sinusoidally modulated AM waveform to help to explain the definition.
(b) Derive the expression between the output power of an AM transmitter and the depth of modulation.
3. What is angle modulation ? Justify that frequency modulation is an angle modulation.
4. drive the expression of single to noise ratio of DSB-SC system.
5.(A)What do you mean by FDM? when it is used?
(b) What is Carson's rile?
6. The equation for an FM wave is
S(t)=10sin(5.7×108t + 5sin12×103t)
Calculate:
(a) carrier frequency
(b) modulating frquency
(c) frequency deviation
(d) modulation index
(e) power dissipated in 100 ohm
GROUP-C
7.(a) What is the concept behind NBFM ? Drive its equation.
(b) Explain how FM can be generated using VCO.
(c) Discuss about the roles of pre-emphasis and de-emphasis circuit in FM
broadcasting.
8.(a) Draw the block diagram for generation and detection of PCM system.
(b) What is quantization? Find signal to quantization noise ratio for PCM system.
(c) A signal is sampled at Nyquist rate of 8 kHz and is quantized using 8 bit uniform quantizer. Assuming SNRq for a sinusoidal signal, calculate bit rate, SNRq and BW.
9 (a) State and prove parseval's power theorem.
(b) Describe with a block diagram the principle of operation of a square low modulator generating DSB-SC.
(c) Explain the advantages and disadvantages of modulation.
10 (a) Draw the block diagram of a superheterodyne receiver and explain its working principle .
(b) Explain the operation of balanced modulator.
11 Write short notes on any three of the following :
(a) Entropy and its properties
(b) QCM
(c) termal noise
(d) power spectral density function
(e) pulse coded modulation