problem 1: A message signal of frequency 10 kHz and peak voltage of 10 volts is employed to modulate a carrier of frequency 1 MHz and peak voltage of 20 volts. Find out:

a) Modulation index.
b) The side bands produced.

problem 2: A carrier wave of peak voltage 12V is employed to transmit a message signal. What must be the peak voltage of the modulating signal in order to have a modulation index of 75%?

problem 3: Define the word modulation. Describe the requirement of modulation. Name three different kinds of modulation used for a message signal by using a sinusoidal continuous carrier wave. Describe the meaning of any one of them.

problem 4: What does the term LOS communication signify? Name the types of waves which are used for this communication. Give typical illustrations, with the help of appropriate figure of communication: It signifies ‘Line of sight communication’.

problem 5: What do you mean by the term space wave propagation? Which two communication techniques make use of this mode of propagation? If the sum of the heights of transmitting and receiving antennas in line of sight of communication is fixed at h, show that the range is maximum when the two antennas have a height h/2 each.