Communication Systems : Revision Test

One mark questions

1. What is the meant by the term attenuation ?


2. Why ground wave transmission is restricted to 1500 kHz?


3. Define critical frequency in sky wave propagation.


4. What type of modulation is required in TV transmission?


5. Why AM radio reception is affected by electrical disturbances while FM radio reception is not?


6. What should be the length of a dipole antenna for a carrier wave of frequency 3 x 10⁸ Hz


7. Draw a block diagram showing the basic communication system.


8. What is the range of frequencies used for FM radio transmission?

Two marks Questions

1. Distinguish analog and digital transmission


2. Write the functions of transducer and repeater in Communication systems.


3. Distinguish amplitude modulation and frequency modulation.


4. Draw a block diagram showing a simple amplitude modulator


5. Explain how a message signal is extracted from Amplitude Modulated signal.


6. Distinguish Sky wave propagation and Space wave propagation.


7. Name the different layers of earth’s atmosphere.


8. Mention two ways in which the range of transmission can be increased.


9. Explain the term modulation index and describe its significance.


10. List four devices used for communication each of which differ from other in the mode of communication.

Three marks questions

1. Explain the need for modulation


2. Derive an expression for the range of transmission from an antenna of height h.


3. Describe the demodulation of AM wave using waveforms and circuit diagrams.