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INDIAN RAILWAY QUESTION BANK

 SIGNAL & TELECOMMUNICATION

TELECOMMUNICATION - PART I

 

1) What is the advantage of DTL MUX over conventional ITI MUX?

2) According to the CCITT recommendations, how the basic group is onstructed? Explain with diagram?

3) In DTL MUX, what are the steps involved to translate a low frequency voice channel to high frequency of band 60 to 552 KHz ?

4) Write short
notes on
any two of the following:

a) Channel modem b) VFT card c) Base band combiner Board.

5) What are the basic requirements of PCM system? Explain about sampling?

What is a frame and multi-frame? Explain about multi-frame?

6) List out the factors to be considered for selecting a site for a microwave station.

7) What do you understand by the terms non-fade level, fade margin and threshold level. Briefly explain each of them.

8) What are the merits and de-merits of frequency diversity system over space diversity system?

9) Explain working of SPC exchange with a functional block diagram

10) Draw the basic block diagram of an ELECTRONIC TELEPHONE and explain its working.

11) List out the features of any electronic exchange and explain any five features

12) What are the different types of modulation techniques and explain balance modulator?

13) Expalin about positive and negative feed back? Explain advantages of negative feedback in amplifiers

14) Write short notes on any Three

i) Phase lock loop
ii) Automatic gain control (AGC)
iii) Varactor Diode
iv) Step Recovery diode
v) Mixer in Receiver

15) What do you understand by hybrid circuit? Describe the audio range bybrid function in full detail with diaram

16) What are the precautions to be taken while loading the RE main telecom
cable
drums? How cable is laid on culverts and bridges?



17) What are the different types of RE cable joints? Explain the function of loading coil joint and condenser joint?



18) What are the periodical tests to be carried out on underground
cables
and give the accepted value?
19) Write the quad allocation for 6-quad cable and give its electrical characteristics?

20) What are the periodical tests to be conducted on RE cable circuits and explain the procedure for each? Write about emergency control in RE area

21) Explain the working of Section Control in RE area with the help of a
Schematic diagram
?

22) Draw the simplified
circuit diagram
of 2W control telephone and explain its working?

23) Descibe the basic differences between AM and FM receivers

24) What is the purpose of limiter in FM receiver?

25) List out different antenna used in railway communication.

26) Draw the block diagram of a 7GHz Digital Radio and explain briefly?

27) What are the differences between Analog and Digital MW systems?

28) Draw the block diagram QPSK modulator and explain briefly?

29) Write short notes on any THREE of the following:

a) TXDPU b) SWO & SWO Central Card
c) RXDPU d) Measurements on Digital Radio

30) Draw the block diagram of 7D15 Radio equipment, and explain the type of switching employed in 100% standby mode briefly?

31) Write the advantages of Harris Radio equipment over 7D15. Write the significance of OSCMOD and Harmonic Mixer in the transmitter section of HARRIS Radio equipment?

32) State the salient features of 7D20 radio equipment. Describe the function of DEV 34 MODULATOR unit in 7D20 Transmitter?

33) Write short notes on:

1) Receive local oscillator of 7D20.
2) Injection lock
amplifier
(ILA).
3) PLL circuit of Harris Transmitter.
4) Fresenal zone
5) K Factor
6) Polarisation

34) Explain the call processing in CDOT 128 P RAX?

35) Draw the block diagram of CDOT 128P RAX and briefly explain each block?

36) Explain briefly about the difference circuit cards used in CDOT 128P PBX?

37) Explain briefly about SLICA, SLICEE, LSLIC in OKI exchange?



38) What is the use of Attendant
Console
used in OKI exchange? List out features of attendant console?



39) Write short notes:
i) Two frequency plan ii) fresnel zone. Iii) folded dipole antenna

iv) K-factor.

40) Define any two of the following:

i) Beamwidth ii) Antenna gain iii) Isotropic iv) skip distance.


41) Draw the functional block diagram of SPC exchange and mention the working of Each block.



42) Explain call processing in any telephone exchange.



43) Draw the block diagram of push button telephone and explain each block.



44) List out the special features of electronic exchange.



45) List out the wave guide devices used in
microwave communication
with their usages



46) What are the periodical tests to be carried out for U/G RE cable?



47) What are the different types of cable joints used for RE cable? Explain what is loading section.



48) How Telecom cable is protected on culverts and bridges?



49) What are the precautions to be taken while cable laying?



50) What daily maintenance you will carry out for diesel engine?



51) Describe the power supply arrangement provided in MW station with block diagram?



52) Write five advantages of SMPs over conventional power supply?



53) Explain the function of anyone of the microphone with necessary diagram and also explain its characteristics?



54) What are the requirements needed to install a PA system for platform announcement?



55) Briefly explain the PA system arrangements for conference hall.



56) Give the list of materials that are kept in ARTs ?



57) Give the periodicity of testing BD SPLs by different staff ?



58) What are the arrangements made at accident spot when the accident occurs in underground cable area?



59) What is the essential difference between ISDN and normal telephone system?

Explain briefly BRI, PRI and NT.



60) What are the advantages of ISDN?



61) What are the faults in PRS system and what are the different types of tests to be conducted to isolate the faults?



62) Explain IVRS system with a simple block diagram?

Write short notes on:

a) Statistical Multiplexer.

b) Modem

c) LDR

d) Router.



63) Explain briefly about SLICA, SLICEE, LSLIC in OKI exchange. List out any 12 cards used in CME rack.



64) What is the use of Attendant Console used inOKI exchange? List out features of attendant console?



65) Explain how a CO call is connected to a local extension in OKI exchange?



66) Explain principle and operation of a dynamic microphone with a neat diagram.



67) What is the need for matching in PA system. Explain voltage matching method with necessary diagram.



68) Explain platform announcement system for a 4 Nos of platforms of 1 KM each.



69) What is meant by UPS? Name the three types of UPS and explain any one of them with block diagram? Give it uses?



70) What are the advantages of SMPS over linear power supply? Explain briefly working of SMPS with block diagram.



71) Write short notes on:

a) Power supply arrangement at MW station.

b) Difference between three types of UPS

c) Voltage regulator

d) VRLA battery

e) Initial charging of
lead acid battery



72) What are the advantages and disadvantages of SMPS over conventional power plants?

73) What are the maintenance requirement for conventional lead acid batteries ?

74) Write the different types of battery charging and where they are used?

75) What are the precautions to be taken for battery room?

76) Write the procedure of initial charging of a lead acid battery and write the precautions to be taken during charging?

77) Write the maintenance to be carried out for lead acid battery? Explain how you will attend a sulphated lead acid cell?

78) Write what precautions you will take to avoid defects in lead acid battery? Draw the simple type of battery charger block diagram and explain function of each stage?



79) Explain with a neat sketch how the tapping for a way station is done in a 4- wire DTMF Control communication system.

80) Explain with a block diagram the working of DTMF decoder used in way station.

81) Explain the working of an auto dialling system and how it is used in control working?

82) What are the different types of main telecom cable joints used in RE area? Explain the function of each joint.

83) What are the periodical tests to be conducted in RE main telecom cable?

84) What are the precautions to be taken for cable jointing?

85) Draw and explain the functional block diagram of SPC Exchange.

86) What do you know about electronic exchanges and different circuits used in any electronic telephone exchange? Briefly explain.

87) Explain what do you understand by Conference facility in an exchange.

88) What are the functions of MDF?

89) What are the protection arrangements done in an exchange?

90) What would be the role of a railway servant in the case of train accident, when he/she is traveling in the same train?

91) What would be the role of the testroom during an accident of passenger train?

92) Why earth is required ? Give five points in support of your explanation.

93) Explain with schematic diagram the principle of SMPS based power plants
.