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151.

A sinusoidal signal with peak-to-peak amplitude of 1.536 V is quantized into 128 levels using a mid-rise uniform quantizer. The quantization noise power is [2 marks]
(a) 0.768 V
(b) 48 × 10^-6V²
(c) 12 × 10^-6V²
(d) 3.072 V

asked in Electronics and Communication Engineering, 2003

A superheterodyne receiver is to operate in the frequency range 550 kHz – 1650 kHz, with the intermediate frequency of 450 kHz. Let R =C_max/C_min denote the required capacitance ratio of the local oscillator and I denote the image frequency (in kHz) of the incoming signal. If the receiver is tuned to 700 kHz, then [2 marks]
(a) R = 4.41, I = 1600
(b) R = 2.10, I = 1150
(c) R = 3.0, I = 1600
(d) R = 9.0, I = 1150

asked in Electronics and Communication Engineering, 2003

Choose the correct one from among the alternatives A, B, C, D after matching an item in Group 1 with the most appropriate item in Group 2.

Group 1 Group 2

P. Ring modulator 1. Clock recovery

Q. VCO 2. Demodulation of FM

R. Foster-Seely discriminator 3. Frequency conversion

S. Mixer 4. Summing the two inputs

5. Generation of FM

6. Generation of DSB-Sc

[2 marks]
(a) P – 1, Q – 3, R – 2, S – 4
(b) P – 6, Q – 5, R – 2, S – 3
(c) P – 6, Q – 1, R – 3, S – 2
(d) P – 5, Q – 6, R – 1, S – 3

asked in Electronics and Communication Engineering, 2003

Let m(t ) = cos[(4π×10³)t] be the message signal and c(t)=5cos[(2π×10⁶)t] be the carrier.

[1]	c(t) and m(t) are used to generate an AM signal. The modulation index of the generated AM signal is 0.5. Then the quantity (Total sideband power)/(Carrier power) is : [2 marks] (a) 1/3 (b) 1/4 (c) 1/2 (d) 1/8

[2]

c(t) and m(t) are used to generate an FM signal. If the peak frequency deviation of the generated FM signal is three times the transmission bandwidth of the AM singal, then the coefficient of the term cos[2π(1008×10³t)] in the FM signal (in terms of the Bessel coefficients) is
[2 marks]
(a) 5j₄(3)
(b) 5j₈(3)/2
(c) 5j₈(4)/2
(d) 5j₄(6)

asked in Electronics and Communication Engineering, 2003

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155.

A DSB-SC signal is to be generated with a carrier frequency f_c = 1MHz using a nonlinear device with the input-output characteristic
v_o = a_ov_i + a₁(v_i)³
where a₀ and a₁ are constants. The output of the nonlinear device can be filtered by an appropriate band-pass filter.
Let v_i = A'_ccos(2πf'_ct) + m(t) where m(t) is the message signal. Then the value of f'_c (in MHz) is [2 marks]
(a) 1.0
(b) 0.333
(c) 0.5
(d) 3.0

asked in Electronics and Communication Engineering, 2003

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156.

The zero-input response of a system given by the state-space equation

[2 marks]

asked in Electronics and Communication Engineering, 2003

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