Advertisements
Advertisements
Question
Which of the following frequencies will be suitable for beyond-the-horizon communication using sky waves?
(a) 10 kHz
(b) 10 MHz
(c) 1 GHz
(d) 1000 GHz
Solution
(b) Answer:
10 MHz
For beyond-the-horizon communication, it is necessary for the signal waves to travel a large distance. 10 KHz signals cannot be radiated efficiently because of the antenna size. The high energy signal waves (1GHz − 1000 GHz) penetrate the ionosphere. 10 MHz frequencies get reflected easily from the ionosphere. Hence, signal waves of such frequencies are suitable for beyond-the-horizon communication.
APPEARS IN
RELATED QUESTIONS
Frequencies in the UHF range normally propagate by means of:
(a) Ground waves.
(b) Sky waves.
(c) Surface waves.
(d) Space waves.
Digital signals
(i) Do not provide a continuous set of values,
(ii) Represent values as discrete steps,
(iii) Can utilize binary system, and
(iv) Can utilize decimal as well as binary systems.
Which of the above statements are true?
(a) (i) and (ii) only
(b) (ii) and (iii) only
(c) (i), (ii) and (iii) but not (iv)
(d) All of (i), (ii), (iii) and (iv).
Answer the following question :
Define 'bandwidth' and describe briefly its importance in communicating signals ?
Block diagram of a receiver is shown in the figure:
(a) Identify ‘X’ and ‘Y’.
(b) Write their functions.
Distinguish between ‘Analog and Digital signals’.
Write any two factors which justify the need for modulating a signal ?
Draw a diagram showing an amplitude modulated wave by superposing a modulating signal over a sinusoidal carrier wave.
Write briefly any two factors which demonstrate the need for modulating a signal. Draw a suitable diagram to show amplitude modulation using a sinusoidal signal as the modulating signal.
What do you mean by bandwidth of a signal? Give its importance.
Differentiate between Analog and Digital communication.
The area of the region covered by the TV broadcast by a TV tower of 100 m height is (Radius of the earth = 6.4 × 106 m):
Long distance short-wave radio broadcasting uses
Broadcasting antennas are generally
Broadcast band in which FM lies is ______.
