Kumar Mittal Solutions for Exercise 2: For DIFFERENT COMPETITIVE EXAMINATIONS

In an amplitude modular circuit, the carrier wave is given by, $C\left(t\right)=4 \sin \left(20000 \mathrm{\pi t}\right)$ while modulating signal is given by, $m\left(t\right)=2 \sin \left(2000 \mathrm{\pi t}\right)$. The values of modulation index and lower side band frequency are:

A signal $A\cos \omega t$ is transmitted using $v_{°}\sin {\omega }_{°}t$ as carrier wave. The correct amplitude modulated (AM) signal is:

A $100 V$ carrier wave is made to vary between $160 V$ and $40 V$ by a modulating signal. What is the modulation index?

The physical sizes of the transmitter and receiver antenna in a communication system are:

An amplitude modulated signal is given by $V\left(t\right)=10\left[1+0.3 \cos \left(2.2\times {10}^{4}t\right)\right]\sin \left(5.5\times {10}^{5}t\right)$. Here $t$ is in seconds. The side-band frequencies (in $\mathrm{kHz}$) are: (Given $\mathrm{\pi }=22/7$).

In a communication system operating at wavelength $800 \mathrm{nm}$, only one percent of source frequency is available as signal bandwidth. The number of channels accommodated  for transmitting TV signals of bandwidth $6 \mathrm{MHz}$ are: (Take velocity of light $c=3\times {10}^8 \mathrm{m}/\mathrm{s}, h=6.6\times {10}^{-34} \mathrm{J}-\mathrm{s}$)

A TV transmission tower has a height of $140 \mathrm{m}$ and the height of the receiving antenna is $40 \mathrm{m}$. What is the maximum distance up to which signals can be broadcasted from this tower is LOS (Line of Sight) mode? (Given: radius of earth$=6.4\times {10}^6 \mathrm{m}$).

The wavelength of the carrier waves in a modern optical fibre communication network is close to: