Communication systems practice · Medium

The diameter of an optical fibre is

Sinusoidal carrier voltage of frequency 1.5 MHz and amplitude 50 V is amplitude modulated by sinusoidal voltage of frequency 10 kHz producing 50% modulation. The lower and upper side-band frequencies in kHz are

In pulse modulation of analog signals, common pulse system employed are

The diameter of an optical fiber is

Intensity of electric field obtained at receiver antenna for a space wave propagation is

In satellite communication, the uplink frequency band used is:

The number of telephonic message which are carried by a fiber at an instant with much less intensity loss are

Modulation is the phenomenon of

Audio signal cannot be transmitted because

Given the electric field of a complete amplitude modulated wave as $\vec{E}=\hat{i} E_c\left(1+\frac{E_m}{E_c} \cos \omega_m t\right) \cos \omega_c t.$ Where the subscript $c$ stands for the carrier wave and ${m}$ for the modulating signal. The frequencies present in the modulated wave are

Television signals reach us only through the ground waves. The range $R$ related with the transmitter height $h$ is in Proportional to

Consider telecommunication through optical fibres. Which of the following statements is no true?

The height of transmitting antenna is $180 \, \mathrm{m}$ and the height of the receiving antenna is $245 \, \mathrm{m}$. The maximum distance between them for satisfactory communication in line of sight will be:

(given $R=6400 \, \mathrm{km}$ )

A carrier is simultaneously modulated by two sine waves having modulation indices of 0.3 and 0.4. The total modulation index will be

Basically, a communication system is a

Which mode of communication is/are employed for the transmission of TV signals?

A TV tower has a height 150 m. What is the total population covered by the TV tower, if the population density around the TV tower is ${10^3}\mathrm{\;k}{\mathrm{m}^{ - 2}}?$ Radius of the earth is $6.4 \times {10^6}\;\mathrm{m}.$

A radar sends an electromagnetic signal of electric field $\left( {{E_0}} \right) = 2.25\,\,V/m$ and magnetic field $\left( {{B_0}} \right) = 1.5\, \times {10^{ - 8}}T$ which strikes a target on line of sight at a distance of 3 km in a medium. After that, a part of signal (echo) reflects back towards the radar with same velocity and by same path. If the signal was transmitted at time $t = 0$ from radar, then after how much time echo will reach to the radar?

What is the reason behind the disturbing of incoming and reflected signals when a low flying aircraft passes overhead, which results in slight shaking of the picture on our TV screen?

The characteristic impedance of a coaxial cable is of the order of

The space wave propagation is utilized in

The velocity factor of a transmission line is x. If dielectric constant of the medium is 2.6, the value of x is

What should be the height of transmitting antenna and the population covered, if the television telecast is to cover a radius of 150 km? The average population density around the tower is $2000/k{m^2}$ and the value of ${R_e} = 6.5 \times {10^6}\,m$.

Antenna is

A FM Broad cast transmitter, using modulating signal of frequency $20 \mathrm{kHz}$ has a deviation ratio of 10. The Bandwidth required for transmission is

Frequencies in the UHF range normally propagate by means of

A signal $A\cos \omega t$ is transmitted using ${v_0}\sin {\omega _0}t$ as carrier wave. The correct amplitude modulated (AM) signal is

An AM wave has 1800 watt of total power content, for $100 \%$ modulation the carrier should have power content equal to

A communication between a fixed base station and several mobile units, located on ships or aircraft utilising two way radio communication in the VHF and UHF is of frequency band

Which of the following is not the frequency of frequency modulated (FM) signal?