Communication Systems

A carrier wave of peak voltage 14 V is used for transmitting a message signal. The peak voltage of modulating signal given to achieve a modulation index of 80% will be :

The number of amplitude modulted broadcast stations that can be accomodated in a $$300$$ $$kHz$$ band width for the highest modulating frequency $$15$$ $$kHz$$ will be :

A speech signal given by 11 sin(2200 $$\pi$$t) V is used for amplitude modulation with a carrier signal given by 44 sin(6600 $$\pi$$t) V. The minimum amplitude of modulated wave will be :

In AM modulation, a signal is modulated on a carrier wave such that maximum and minimum amplitudes are found to be 6 V and 2 V respectively. The modulation index is :

A radio can tune to any station in $$6 \,\mathrm{MHz}$$ to $$10 \,\mathrm{MHz}$$ band. The value of corresponding wavelength bandwidth will be :

The maximum and minimum voltage of an amplitude modulated signal are $$60 \mathrm{~V}$$ and $$20 \mathrm{~V}$$ respectively. The percentage modulation index will be :

In the case of amplitude modulation to avoid distortion the modulation index $$(\mu)$$ should be :

A FM Broadcast transmitter, using modulating signal of frequency 20 kHz has a deviation ratio of 10. The Bandwidth required for transmission is :

Consider telecommunication through optical fibres. Which of the following statements is not true?

This question has Statement - $$1$$ and Statement - $$2$$. Of the four choices given after the statements, choose the one that best describes the two statements. Statement -$$1$$ : Sky wave signals are used for long distance radio communication. These signals are in general, less stable then ground wave signals. Statement -$$2$$ : The state of ionosphere varies from hour to hour, day to day and season to season.

A radar has a power of $$1kW$$ and is operating at a frequency of $$10$$ $$GHz.$$ It is located on a mountain top of height $$500$$ $$m.$$ The maximum distance upto which it can detect object located on the surface of the earth (Radius of earth $$= 6.4 \times {10^6}m$$) is :

A signal is to be transmitted through a wave of wavelength $$\lambda$$, using a linear antenna. The length l of the antenna and effective power radiated P_eff will be given respectively as : (K is a constant of proportionality)

A telephonic communication service is working at carrier frequency of 10 GHz. Only 10% of it is utilized for transmission. How many telephonic channels can be transmitted simultaneously if each channel requires a bandwidth of 5 kHz ?

In a communication system operating at wavelength 800 nm, only one percent of source frequency is available as signal bandwith. The number of channels accomodated for transmitting TV signals of band width 6 MHz are (Take velocity of light c = 3 $$\times$$ 10⁸m/s, h = 6.6 $$\times$$ 10^$$-$$34 J-s)

A TV transmission tower has a height of 140 m and the height of the receiving antenna is 40 m. What is the maximum distance upto which signals can be broadcasted from this tower is LOS (Line of Sight) mode ? (Given : radius of earth = 6.4 × 10⁶ m).

To double the covering range of a TV transmittion tower, its height should be multiplied by :

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

In a line of sight radio communication, a distance of about 50 km is kept between the transmitting and receiving antennas. If the height of the receiving antenna is 70m, then the minimum height of the transmitting antenna should be : (Radius of the Earth = 6.4 × 10⁶ m).

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