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Cont…..2
Code No: 07A5EC09 :2: Set No.3
II Fill in the blanks:
11) A signal extending over-4V to +4Vis quantized in to 8e maximum possible quantization
error obtainable is-------------
12) Probability of error of PSK scheme is-----------------------
13) PSK and FSK have a constant--------------
14) Granular noise occurs when step size is--------------
15) Converting discrete time continuous signal into discrete amplitude discrete time signal is
called-----------------.
16) The minimum symbol rate of a PCM system transmitting an analog signal band limited to
2 KHz, the number of Q-levels 64 is ------------------
17) In DM granular noise occurs if when step size is -------------
18) The combination of compressor and expander is called---------------------
19) Data word length in DM is ---------------
20) Band width of PCM signals is -----------
-oOo-
Code No: 07A5EC09 Set No. 4
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
III B.Tech. I Sem., I Mid-Term Examinations, September – 2010
DIGITAL COMMUNICATIONS
Objective Exam
Name: ______________________________ Hall Ticket No.
Answer All Questions. All Questions Carry Equal Marks.Time: 20 Min. Marks: 20.
I Choose the correct alternative:
1) Which of the following requires more band width [ ]
A) ASK B)PSK C)FSK D)DPSK
2) Companding results in [ ]
A) More S/N ratio at higher amplitudes B) More S/N ratio at lower amplitudes
C) Uniform S/N ratio throughout the signal D) Better S/N ratio at lower frequencies
3) Mean square quantization noise in the PCM system with step size of 2V is [ ]
A)1/3 B)1/12 C)3/2 D)2
4) Word length in Delta modulation in Delta modulation is [ ]
A)3 bits B)2 bits C)1 bit D)2 n bits
5) Which of the following gives minimum probability of error [ ]
A)FSK B)ASK C)DPSK D)PSK
6) QPSK is an example of M-ary data transmission with M= [ ]
A)2 B)8 C)6 D)4
7) The quantization error in PCM when Δ is the step size [ ]
A) Δ 2 /12 B) Δ 2 /2 C) Δ 2 /4 D) Δ 2 /3
8) Quantization noise occurs in [ ]
A) TDM B)FDM C) PCM D)PWM
9) Non Uniform quantization is used to make [ ]
A) (S/N) q
is uniform B) (S/N) q
is non-uniform
C) (S/N) q
is high D) (S/N) q
is low
10) Slope Overload distortion in DM can be reduced by [ ]
A) Increasing step size B)Decreasing step size
C) Uniform step size D)Zero step size