dc

B) (Power required)/( Minimum Band width)
C) (Transmission Bit rate)/ (Minimum Band width)
D) (Power Saved during transmission)/(Minimum Band width)
9. The Auto-correlation function of White Noise is [ ]
A) Impulse function B) Constant C) Sampling function D) Step function
10. The minimum band width required for a BPSK signal is equal to [ ]
A) one fourth of bit rate B) twice the bit rate C) half of the bit rate D) bit rate
Cont……2
A
Code No: 56026 :2: Set No. 3
II Fill in the blanks
11. The advantage of DPCM over Delta Modulation is _________________________
12. The phases in a QPSK system can be expressed as ______________________
13. The Synchronization is defined as _______________________
14. The sampling rate in Delta Modulation is _______________than PCM.
15. The bit error Probability of BPSK system is __________________that of QPSK.
16. Non-coherent detection of FSK signal results in ____________________
17. _____________ is used as a Predictor in a DPCM transmitter.
18. The Nyquist's rate of sampling of an analog signal S(t) for alias free reconstruction is
5000samples/sec. For a signal x(t) = [S(t)]2 ,the corresponding sampling rate in
samples/sec is __________________
19. A Matched filter is used to __________________________
20. A signal extending over -4v to +4v is quantized into 8 levels. The maximum possible
quantization error obtainable is _____________V.
-oOo-
Code No: 56026 Set No. 4
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
III B.Tech. II Sem., I Mid-Term Examinations, February – 2012
DIGITAL COMMUNICATIONS
Objective Exam
Name: ______________________________ Hall Ticket No.
Answer All Questions. All Questions Carry Equal Marks.Time: 20 Min. Marks: 10.
I Choose the correct alternative:
1. In Non-Coherent demodulation, the receiver [ ]
A) relies on carrier phase B) relies on the carrier amplitude
C) makes an error with less probability D) uses a carrier recovery circuit
2. The advantage of Manchester encoding is [ ]
A) less band width requirement B) less bit energy required for transmission
C) less probability of error D) less bit duration
3. Granular Noise in Delta Modulation system can be reduced by
A) using a square law device B) increasing the step size
C) decreasing the step size D) adjusting the rate of rise of the base band signal
4. The minimum band width required to multiplex 12 different message signals each of band
width 10KHz is [ ]
A) 60KHz B) 120KHz C) 180KHz D) 160KHz
5. In 8-PSK system, adjacent phasors differ by an angle given by ( in degrees) [ ]
A) n/4 B) n/8 C) n/6 D) n/2
6. Band Width efficiency of a Digital Modulation Method is [ ]