JNTU B.Tech II Semester Examinations,Telecommunication Switching Systems And Networks
, Apr/May 2008
( Common to Electronics & Communication Engineering and Electronics &
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
1. (a) Explain the principle and advantages of touch tone dialing scheme?
(b) What is the importance of a steady current flowing through a carbon microphone? Is the harmonic distortion affected by a change in the energizing current? [8+8]
2. (a) Define each of the following terms: program, procedure, processor, process,
user, task, job and subroutine.
(b) Find the blocking probability of a three stage network for M=N=2048,p=q=16
and ? = 0.1 for S= 16, 24 and 32. [8+8]
3. (a) What are the functions performed by subscriber line interface? Explain.
(b) A national network uses 4 wire and 2 wire circuits with impedances of 500ohms and 750 ohms. The phase velocity of 3.2×107 m/S. The longest circuit length is 500km. Find the echo time and return loss. Is it necessary to employ an echo suppressor. [8+8]
4. (a) Explain outband signaling scheme with E and M control with the help of neat
(b) 10,000 subscribers are connected to an exchange. If the exchange is designed to achieve a call completion rate of 0.8 when the busy hour calling rate is 4.8, What is the BHCA that can be supported by the exchange? What should be the call processing time for this exchange? [8+8]
5. (a) Explain the operation of Multipoint data communications circuit.
(b) What is a protocol? Distinguish between connection less and connection oriented protocols [8+8]
6. (a) Explain in detail Mesh, Ring, Star and Bus network topologies in detail .
What are its merits and demerits. 
7. (a) Describe functional groupings and reference points of ISDN.
(b) Discuss numbering and addressing formats of ISDN. [10+6]
8. (a) How does ADSL divide the band width of a twisted pair cable ?
(b) How does ADSL Modulate a Signal?.
(c) What is FTTC and who uses it. [5+5+6]