Analog Communication Systems · Communications · GATE ECE
Marks 1
An amplitude modulator has output (in Volts)
$$s(t) = A \cos(400 \pi t) + B \cos(360 \pi t) + B \cos(440 \pi t)$$.
The carrier power normalized to $1\Omega$ resistance is 50 Watts. The ratio of the total sideband power to the total power is 1/9. The value of $B$ (in Volts, rounded off to two decimal places) is _______.
Marks 2
Let a frequency modulated (FM) signal $$x(t) = A\cos ({\omega _c}t + {k_f}\int_{ - \infty }^t {m(\lambda )d\lambda )} $$, where $$m(t)$$ is a message signal of bandwidth W. It is passed through a non-linear system with output $$y(t) = 2x(t) + 5{(x(t))^2}$$. Let $${B^T}$$ denote the FM bandwidth. The minimum value of $${\omega _c}$$ required to recover $$x(t)$$ from $$y(t)$$ is
Let x$$_1$$(t) and x$$_2$$(t) be two band-limited signals having bandwidth $$B=4\pi\times10^3$$ rad/s each. In the figure below, the Nyquist sampling frequency, in rad/s, required to sample y(t), is
Consider an FM broadcast that employs the pre-emphasis filter with frequency response
$${H_{pe}}(\omega ) = 1 + {{j\omega } \over {{\omega _0}}}$$,
where $$\omega$$0 = 104 rad/sec.For the network shown in the figure to act as a corresponding de-emphasis filter, the appropriate pairs of (R, C) values is/are ____________.


The ratio kp/kf (in rad/Hz) for the same maximum phase deviation is
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 $$\frac{Total\;sideband\;power}{Carrier\;power}$$ is
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 $$\cos\left[2\mathrm\pi\left(1008\times10^3\right)t\right]$$ in the FM signal (in terms of the Bessel coefficients) is