Monday 31 August 2015

CDMA Multiple Choice Questions And Answers

11. In general, Spread Spectrum communications is distinguished by which of these elements?
A. The signal occupies a bandwidth much greater than that which is necessary to send the information
B. The bandwidth is spread by means of a code which is independent of the data
C. The receiver synchronizes to the code to recover the data
D. All of the above
Ans: D

12. Which of this is the way to spread the bandwidth of the signal
A. Frequency hopping
B. Time hopping
C. Direct sequence
D. All of the above
Ans: D

13. The digital data is directly coded at a much higher frequency. The code is generated pseudo-randomly, the receiver knows how to generate the same code, and correlates the received signal with that code to extract the data. Which type of spread spectrum is this?
A. Frequency hopping
B. Time hopping
C. Direct sequence
D. None of the above
Ans: C

14. The signal is transmitted in short bursts pseudo-randomly, and the receiver knows before hand when to expect the burst.Which type of spread spectrum is this?
A. Frequency hopping
B. Time hopping
C. Direct Sequence
D. None of the above
Ans: B

15. What is the data rate for Adaptive Differential Pulse Code Modulation (ADPCM)
A. 8 kBits/sec
B. 16 kBits/sec
C. 32 kBits/sec
D. 64 kBits/sec
Ans: C

16. What is the data rate for Low Delay Code Excited Linear Prediction (LD-CELP)?
A. 8 kBits/sec
B. 16 kBits/sec
C. 32 kBits/sec
D. 64 kBits/sec
Ans: B

17. The subscriber unit correctly generates its own matching code and uses it to extract the appropriate signals. Each subscriber uses
A. singal independant channels.
B. several independant channels.
C. singal dependant channels.
D. several dependant channels.
Ans: B

18. In CDMA, the pseudo-random code must have the following property
A. It must be deterministic
B. It must appear random to a listener without prior knowledge of the code
C. The code must have a long period
D. All of the above
Ans: D

19. What will be the correlation of two codes ,if the two codes are identical ?
A. 0
B. 0.5
C. 1
D. infinite
Ans: C

20. The bit rate of the PN code is called
A. Chipping Frequency (fc)
B. Information rate (fi)
C. Chip
D. Epoch
Ans: A

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