Frequencies in the UHF range normally propagate by means of:

A speech signal of 3kHz is used to modulate a carrier signal of frequency 1MHz, using amplitude modulation.The frequencies of the sidebands will be

Identify the mathematical expression for amplitude modulated wave:

Audio sine waves of 3kHz frequency are used to amplitude modulate a carrier signal of 1.5 MHz. Which of the following statements are true?

Out of the following, which is not an essential element of a communication system?

What are the limitations of amplitude modulation?

What is a transducer? Give two examples.

Why cannot the
(i) ground waves
(ii) space waves and
(iii) sky waves be sustained for long distance communication system beyond 10 MH to 20 MHz.

Differentiate between (i) PAM and (ii) PPM

A 100 MHz carrier is modulated by a 12 kHz sine wave so as to cause a frequency swing of +50kHz. Find the modulation index

Explain why T.V. transmission towers are usually made high.

A T.V tower has a height 100 m. What is the population density around the T.V tower if the total population covered is 50 lakh? Radius of earth \( =6.4\times{ 10 }^{ 6 }m\)

Explain that microwaves are better carriers of signals than radio waves?

Define the critical frequency in relation to sky wave propagation of electromagnetic waves.On a particular day, the maximum frequency reflected from the ionosphere is 10 MHz.On another day, it was found to decrease to 8 MHz.Calculate the ratio of the maximum electron densities of the ionosphere on the two days.

An audio signal of amplitude 0.1 V is used in amplitude modulation of a carrier wave of amplitude 0.2V.Calculate the modulation index.

Arnab was talking on his mobile to his friend for a long time. After his conversation was over, his sister Anita advised him that if his conversation was of such a long duration, it would be better to talk through a land line.
Answer the following questions :
(a) Why is it considered harmful to use a mobile phone for a long duration?
(b) Which values are reflected in the advice of his sister Anita?
(c) A message signal of frequency 10 kHz is superposed to modulate a carrier wave of frequency 1 MHz. Determine the sidebands produced.

(a) Distinguish between sinusoidal and pulseshaped signals.
(b) Explain, showing graphically, how a sinusoidal carrier wave is superimposed on a modulating signal to obtain the resultant amplitude modulated (AM) wave.

A TV transmitting antenna is tall. How much service area this transmitting antenna cover, if the receiving antenna is at the ground level? Radius of earth = 6400 km.

By what percentage will the transmission range of a T.V. tower be affected when the height of the tower is increased by 21%?