Questiom of TELECOMMUNICATION SYSTEMS (sem-5) -2009

                               TELECOMMUNICATON SYSTEM
                             CS/B.tech(ECE)SEM-5/EC-501/209-10
1. Choose the correct Alternative.
 (1) In modem uploading data rates always less then downloading data rates because
   (i) SNR (20db)is very low in communication channel.
   (ii) quantisation noise limits the channel data rates
   (iii) during uploading extra control bits are added with the data
   (iv) none of these.
 (2) the voice signal BW is 4 KHz and the Nyquist sampling rate is 8 KHz and time multiplexed space swiching 30 channel is to be multiplexed. the TS is
   (i) 4.16 micro sec (ii) 8.33 micro sec. (iii)125 micro sec (iv) none of these
 (3) MTTR means
   (i) Mean time to repair (ii) Maximum time to repair
   (ii) Most time to repair (iv) mean time to represent.
 (4) Blocking probability is
    (i) call congestion (ii) time congestion (iii) both (i) and (ii). (iv)none of these
 (5) GOS in india is
   (i)0.002 (ii) 0.02 (iii) 0.2 (iv) 2.
  (6) ISDN B-channel carries data and service at
    (i) 16 kbps (ii) 32 kbps (iii) 64 kbps (iv) 1.544 Mbps
 (7) Loudspeaker is an end instrument of
   (i)transmitter side (ii) receiver side (iii) both (iv) none of these
 (8) CHILL is a
    (i) CCITT language (ii) IEEE language (iii) IEE language (iv) ANSI language.
 (9) Attenuation can be reduced in subscriber loop by using
   (i) higher diameter in copper wire (ii) series of inductance in line
   (iii) lower diameter in copper wire (iv) serise of capacitance in line.
 (10) SDL stands for
    (i) software description language (ii) specification derived language
    (iii) specification description language (iv) sofeware derive language.
(11) A subscriber makes 3 calls of 3 mints , 4 mints, and 2 mints duaration in one hour period Calculate the subscriber traffic in Erlangs.
   (i)0.15 E (ii) 0.2E (iii)0.5E (iv) 0.7 E
 (12) In a  Strowger system the high value of CCI indicates
   (i) good design (ii) poor design (iii) no impact on design (d) none of these
                       GROUP - B
 Answer any three
 2 (a) What do you mean by point to point communication ?
   (b) Explain the disadvantages of this system
   (c) If the number of node in point to point communication is 770 , find out the total number of links required for total connevtivity.
3. (a) Show the GOS =  p b  , explain the meaning of the symbol.
   (b) Over a 20 minute observation interval, 40 subscribers initiate calls. Total duration of the calls is 4800 sec . calculate the load offered to the network by the sescribers and the average subscriber traffic.
4. What is call completion rate (CCR) ? 10000 subscribers are connected to an exchange , if the exchange is designed to achieve a CCR of 0.8 when the busy hour calling rate is 4.8 , calculate BHCA of the exchange.
5. What is BORSCHT function ? Why is this important in electronics exchange.
6. How many type of transmission medi are used in telecommunication ? What are the advantages of twisted pair cable over parallel wire cable ? what is step index fiber and graded index fiber?
                    GROUP -C
Answer any there
7 (a) assuming simultaneously forward and backward wave propagation in a transmission line. Derive the follwing general equation for the line,
    V=V1cos hrd +I1Z0sinhrd,
    I= I1coshrd+I1/Z0 sinhrd,
   Where V and I are the voltage and current respectively at a distance from a load end of the transmission line having characteristic independence Z0 and propagation constant r. the load end voltage and current V1 and I1respectively.
 (b) A loseless line has a characteristics impedance of 75 ohm and is terminated in a load of 300 ohms . find out the reflection cofficient and VSWR in the line.
  (c) explain the principle of DTMF dialing.
8. (a) what ia ISDN? Explain the transmission channel in ISDN?
   (b) what are the drawbacks of ISDN? how does B-ISDN overcome from this?
  (C) Write function grouping and reference point in ISDN.
9. (a) Explain centralized SPC and different modes of it.
(b) Explain distributed SPC and explain the different types of leve processing in it.
 (c) In the load sharing configuration of centralised SPC MTBF =2000 hours and MTTR =4 hours calculate the unavailability for single and dual processor system.
(d) Explain time division space switching.
10. What is DTE and DCE? Explain how data communication takes place between DTE and DCE using RS @#@C serial interface. why is conventional telephone modem down stream data rate 56 kbps? A telephone line has a bandwidth of 3000 Hz and SNR is 34 Db calculate the data rate of this line.
11. Write short notes on any three of the following.
(A) Packet switching
(b) ISDN systems interface.
 (c) Difference between circiut switch , packet swith and message swith
(d) Modems and standards
(e) facsimile transmission.