Code: DE20                                                   Subject: ELECTRONIC SWITCHING SYSTEMS

Flowchart: Alternate Process: DECEMBER 2008Time: 3 Hours                                                                                                     Max. Marks: 100

 

NOTE: There are 9 Questions in all.

·      Question 1 is compulsory and carries 20 marks. Answer to Q. 1. must be written in the space provided for it in the answer book supplied and nowhere else.

·      Out of the remaining EIGHT Questions answer any FIVE Questions. Each question carries 16 marks.

·      Any required data not explicitly given, may be suitably assumed and stated.

 

 

Q.1 A    Choose the correct or the best alternative in the following:                                   (2x10)

       

a.       Telex is a

 

                   (A)  Telephone Service between various subscribers

                                                                              (B)  Teleprinter Service between various subscribers

                                                                              (C)  Television Service between various subscribers       

                    (D)  Telegraph Service between various subscribers

       

b.      The bandwidth requirement of a telephone channel is

 

                   (A)  3 KHz                                          (B)  15 KHz

(C)    5 KHz                                         (D)  25 KHz

            

             c.   Distortion caused on telephone line by an adjacent one is called

                                      

(A)    Cross Fire                                    (B) Inductive Disturbance

(C)  Cross Talk                                   (D) None of these

 

             d.   Erlang is used to

 

(A)    Measure busy period                   (B)  Give total busy period in minutes

(C)  Measure average call rate            (D)  Indicate total call period

 

             e.   The grade of service is measured in

                                      

(A)     Percentage                                   (B)  Number

(C)  Fractional Number                       (D)  Logarithmic Number

                  

             f.    Network with point-to-point link is known as

 

(A)   Fully Connected Network            (B)  Half Connected Network

(C)  Duplex Connected Network         (D)  None of these

 

             g.    SPC is used for

 

(A)  Carrying Exchange Control Functions

(B)  Carrying Subscriber Control Functions

(C)  Exchange Hardware                    

(D)  Signalling Purpose

 

 

             h.    Trunks are the lines that run between

 

(A)  subscribers and exchange             (B)  switching system and power plant

(C)  Local Area Network                    (D)  switching systems

 

             i.    Example of circuit switching and S&F (Stored and Forward) switching is

 

(A)    Telephone and Post of Telegraph 

(B)    Video Signal Post or Telegraph

(C)  Digital Signal Post or Telegraph   

(D)  None of above

       

             j.    Network Layer is used for

 

(A)  Breaking up the data in frames for transmission          

(B)  Deal with Error correction

(C)  Automatic Recovery of Procedure     

(D)  Physical Architecture

 

 

 

Answer any FIVE Questions out of EIGHT Questions.

Each question carries 16 marks.

 

 

 

  Q.2     a.   Explain crossbar exchange, with all call processing steps and diagrams.               (8)

       

             b.   Calculate the blocking probably Pb in 100 line strowger switching system where 10 calls are in progress and 11th one arrives, probably that there is a call in a given decade = 1/10 and probably that another call is destined to same decade but not to same number = 9/98.                                   (8)

 

  Q.3     a.   Explain simple telephone communication system with circuit and equation of current flow in microphone?                                                                (8)

            

             b.   Find the total number of link L having five entities?  Explain differences between folded and non-folded network.                                              (8)                                                             

 

  Q.4     a.   List all seven layer of OSI model and describe function of application layer.                        (8)

 

             b.   Explain difference of Inchannel and Common channel signalling.  Draw routing diagram of non-associated signalling.                                             (8)

      

  Q.5     a.   Explain topology method used in LAN technology in detail.                                 (8)

                

 

             b.   A CSMA/CD bus spans a distance of 1.5 Km.  If data is 5 Mbps. What is minimum frame size where propagation speed in LAN cable is .                                                  (8)

 

  Q.6     a.   What is Traffic Engineering?  Define the term busy hour, traffic intensity and grade of service.                                                                     (8)

 

             b.   Distinguish between single stage and multistage networks.                                   (8)          

  Q.7     a.   Name the switching schemes used in a digital exchange. Explain, how call processing takes place.                                                              (8)

 

             b.   Explain SPC. Also discuss different modes of centralized SPC.                          (8)

 

  Q.8           Write short notes on any TWO:-                                                                      (16)

 

(i)         Transmission plan

(ii)       DTMF signalling

(iii)      Non-blocking Networks

 

  Q.9     a.   Discuss briefly subscriber loop system. Give some technical specification for subscriber lines.                                                                     (8)

 

             b.   Discuss different Routing plan adopted in a Telephone network.                          (8)