Very Short Question Answers

Q1. What are the basic blocks of a communication system?

Ans.

A communication system has 3 basic blocks. 

1) Transmitter. 2) channel 3) Receiver

---

Q2. What is “world wide web (www)” ?

Ans.

It is an encyclopedia of knowledge accessible to everyone round the clock though out the year.

---

Q3. Mention the frequency range of speech waves.

Ans.

Frequency range of speech waves is from 300HZ to 3100 HZ

 

---

Q4.  What is sky wave propagation?

Ans.

Long distance communication can be achieved by   ionosphere reflection of radio wavesback towards earth.  This mode of propagation is called sky wave propagation. Frequency range: few MHz up to 30 to 40 MHz, 

---

Q5.  Mention the various parts of the ionosphere.

Ans.

1) D part of stratosphere

2) E part of stratosphere

3) F₁ part of mesosphere

4) F₂ part of thermosphere   

---

Q6. Define modulation. Why is it necessary?

Ans.

Modulation: The process of combing audio frequency signal with high frequency signal is called modulation.

Necessity:

1) to reduce size of antenna.

2) to increase effective radiated power by the antenna.

---

Q7. Mention the basic methods of modulation.

Ans.

1)Amplitude modulation    

 2)Frequency modulation    

 3) Phase modulation 

---

Q8. Which type of communication is employed in mobile phones?

Ans.

Space wave communication.

---