Spread Spectrum Communications Mid - I, September - 2014

1.The spread spectrum systems may be ___________________
  • Averaging type
  • Avoidance type
  • Both a and b
  • None
Answer: C
2.Which of the following is known as time-shared early late tracking loop which uses only correlator branch?
  • Non-coherent delay lock
  • Tau-Dither
  • Delay-lock
  • Double-Dither
Answer: B
3.For a slow hopping system, the frequency spacing between the signal alternatives must be a multiple of _____________ to allow for non-coherent detection.
  • 1/Ts
  • Ts
  • 2Ts
  • Ts/2
Answer: A
4.____________is used to refer to the output of the binary shift register generator.
  • Gold code
  • Spreading code
  • Black code
  • Hamming code
Answer: B
5.Which of the following is the most popular quasi-orthogonal CDMA codes
  • Black codes
  • Gold codes
  • Spreading codes
  • Walsh codes.
Answer: B
6.In ______________ systems, channels are defined not by time or frequency but by code.
  • TDMA
  • FDMA
  • CDMA
  • MAI
Answer: C
7.The source of interference in CDMA system is________________
  • Multiple access Interference
  • Multipath Interference
  • Both a and b
  • None
Answer: C
8.The decision static for _____________ modulation can be written as the output of the correlator version of the matched filter.
  • PSK
  • QPSK
  • BPSK
  • MPSK
Answer: C
9.The ________________ tracking loop is used to solve the gain-imbalance problem of delay-lock loops.
  • Non-coherent delay lock
  • Tau-dither
  • Delay lock
  • Double dither
Answer: D
10.A set of gold sequences of period N=2n-1, consists of _____________ sequences for which we have excellent cross-correlation properties.
  • N/2
  • N
  • N+2
  • N-2
Answer: C
11.A spread spectrum format where a narrow-band signal is multiplied by a high rate pseudo noise code prior to transmission is known as _______________
Answer: Direct sequence
12.In __________________systems the interference is reduced by averaging it over the long period.
Answer: Averaging
13.The number of 1’s is always one more than the number of zeros in each period of a maximum length sequence is called_________________
Answer: Balance property
14.The early-late tracking loop can be also called as_________________
Answer: Delay-locked loop
15.The non-coherent tracking loops are relatively insensitive to___________________
Answer: Data modulation
16.__________________is essential to the delivery of information over spread spectrum systems.
Answer: Code time synchronization
17.CDMA stands for ____________________
Answer: Code division multiple access
18.The __________________spreads the signals randomly over the wide frequency band.
Answer: Pseudo noise sequence
19.When the pseudo-noise sequence generated by linear feedback shift register has the length of 2m-1 is called____________________
Answer: Maximum length sequence
20.Pseudo-noise sequence will have a period of ________________bits.
Answer: 2m-1