Communication systems practice · Mixed difficulty

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

Through which mode of propagation, the radio waves can be sent from one place to another

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

In a radio receiver, the short wave and medium wave stations are tuned by using the same capacitor but coils of different inductance ${L_s}$ and ${L_m}$ respectively then

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?

In earth's atmosphere, for ${\mathrm{F}_2}$-layer, the virtual height and critical frequency in night time are

The waves relevant to telecommunications are

Two electrons are moving in opposite direction with speeds 0.8 c and 0.4 c, where c the speed of light in vacuum. Then the relative speed is about

A transmitting antenna of height h and the receiving antenna of height 45 m are separated by a distance of 40 km for satisfactory communication in line of sight mode. Then the value of h is

Identify the incorrect statement from the following

An oscillator is producing FM waves of frequency 2 kHz with a variation of 10 kHz. What is the modulating index?

A radio station has two channels. One is AM at 1020 kHz and the other FM at 89.5 Mhz. For good results you will use

A laser device produces amplification in the

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 in LOS (Line of Sight) mode? (Take, radius of earth $= 6.4 \times {10^6}m)$

In satellite communication, the communication satellite;

zone layer above earth's atmosphere will not