Friend As on your Asking Here I m Providing Sample Question Which Asked in BSNL Telecom Technical Assistants Recruitment Exam :

1) Wave guides are generally made of

(a) Cast iron or steel

(b) White metal or gun metal

(c) bronze or aluminium

(d) plastic or bakelite

2) The cut off frequency of a wave guide means

(a) lower frequencies will not be propagated

(b) it determines the dimensions of the wave guide

(c) frequency at which zero transmission takes place

(d) None of above

3) In case of matched load

(a) Transmission is zero

(b) reflection is zero

(c) reflection is unity

(d) transmission is equivalent to reflection

4) In an AM wave with 100% modulation, the carrier is suppressed. The percentage of power saving will be

(a) 100%

(b) 50%

(c) 25%

(d) 66.7%

5) The function of AM detector circuit is

(a) to rectify the input signal

(b) to discard the carrier

(c) to provide the audio signal
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(d) All of the above

6) In FM, the noise can be further decreased by

(a) decreasing deviation

(b) increasuig deviation

(c) keeping deviation constant

(d) none of these

7) In PPM, message resides in

(a) Pulses

(b) time location of pulse edges

(c) none of these

8) Which of the following pulse systems is preferred for communication in presence of noise?

(a) PAM

(b) PDM

(c) PPM

(d) none of above

9) Which of the following pulse systems requires higher bandwidth

(a) PAM

(b)PDM

(c)PPM

(d)none of these

10) The audio frequency range lies between

(a) 20 to 20,000 Hz

(b) 20 to 20,000 KHz

(c) 400 to 8,000Hz

(d) 500 to 5,000 Hz

11) Maximum undistorted power output of a transmitter is obtained when its modulation is:

(a) more than 100%

(b) 100%

(c) less than 100%

(d) 50%

12) The AGC voltage in a radio receiver is proportional to

(a) the amount of modulation

(b) the amplitude of audio signal

(c) the amplitude of IF carrier

(d) none of these


The Most Common Modulation System Used for telegraphy is
FSK
PSK
PCM
Single tone Modulation
Two Tone Modulation

VSB is an Abbreviation if vestigial Sideband, is derived by Filtering
DSB
AM
Either (a) or (b)
PM

The Hartely Law State that
The Maximum Rate of Information transmission depends on the Depth of Modulation
The Maximum Rate of Information Depends on the channel Bandwith
Only Binary Codes may be used
Redundancy is Essential

The FM Signal with a Modulation index mf is passed through a Frequency Tripler. The Wave is the Out Put of the Tripler will have a modulation Index of
Mf 9
Mf 3
Mf
3 Mf
9 Mf

In high power AM transmission, Modulation is done at
Buffer Stage
Oscillator Stage
RF Stage
IF Stage

Vacuum Tube Eventually Fall at Microwave Frequencies Because of their
Inter Electrode Capacitance
Small Series inductance
Large Shunt Capacitance
Short Transit Time
Increase Noise Figure

The Biggest Disadvantage the IMP ATT Diode has is its
Low Efficiency
High Noise
Low BW
Inutility to provide Pulse Operation
Low Power handling Ability

In AM transmission the Frequency, Which is not transmitted is
Carrier Frequency
Audio Frequency
Upper Side Frequency
Lower Side Frequency

FM Broadcast band lies in
VHF
UHF
SHF
HF

The Modulation System inherently is most Noise Resistant in
SSB Suppressed carrier
FM
PPM
PCM