Preview Test-2 Analog Communications

Which of the following schemes suffer(s) from the threshold effect ?

A 4 GHz carrier is DSB-SC modulated by a lowpass message signal with maximum frequency of 2 MHz. The resultant signal is to be ideally sampled. The minimum frequency of the sampling impulse train should be

Which of the following demodulator(s) can be used for demodulating the signal x (t) = 5(1 + 2 cos 200 \pi t) cos 20000 \pit

A superheterodyne radio receiver with an intermediate frequency of 455 kHz is tuned to a station operating at 1200 kHz. The associated image frequency is _____kHz.

A 10 MHz carrier is frequency modulation by a sinusoidal signal of 500 Hz, the maximum frequency deviation being 50 kHz. The bandwidth required, as given by the Carson’s rule is _______.

A PLL can be used to demodulate

The image channel rejection in a superheterodyne receiver comes from

The image channel selectivity of superheterodyne receiver depended upon

A message m(t) bandlimited to the frequency f_m has a power of P_m. The power of the output signal in the figure is

The Hilbert transform of  cos \omega _{1}t+ sin \omega _{2}t  is

Consider the amplitude modulation (AM) signal A_{c}\; cos\omega _{c}t+2\; cos \omega _{m}t \; cos \omega _{c}t  . For demodulating the signal using envelope detector, the minimum value of A_c should be

Consider the frequency modulation signal 10cos(2 \pi \times 1500t)+7.5sin(2 \pi \times 1500t) with carrier frequency of 10^5  Hz. The modulation index is

A massage signal given by m(t)=\left(\frac12\right)\cos\omega_1t\left(\frac12\right)\sin\omega_2t is amplitude modulation with a carrier of frequency \omega_c  to generated

s(t) =[1 + m(t)]cos \omega_c t What is the power efficiency achieved by this modulation scheme?

Consider an angle modulation signal x(t)=6cos[2 \pi  \times 10^6t + 2sin(8000 \pi t)+4cos(8000 \pi t)]V. The average power of x(t)is

Consider sinusoidal modulation in an AM system. Assuming no overmodulation, the modulation index ( \mu ) when the maximum and minimum values of the envelope, respectively. are 3 V and 1 V, is _______.