This set of Digital Communication Problems focuses on “Spread Spectrum “.
1. Spread spectrum is a ______ technique.
a) Encoding
b) Decoding
c) Encoding & Decoding
d) None of the mentioned
View Answer
Explanation: Spread spectrum is an important encoding technique for a wireless communication system.
2. Spread spectrum can be used to transmit
a) Analog data
b) Digital data
c) Analog & Digital data
d) None of the mentioned
View Answer
Explanation: Spread spectrum is used to transmit analog data and digital data using analog signal.
3. Spread spectrum makes ______ difficult.
a) Jamming
b) Interception
c) Jamming & Interception
d) None of the mentioned
View Answer
Explanation: Spread spectrum makes jamming and interception difficult and provides improved reception.
4. Spread spectrum has immunity from
a) Noise
b) Multi-path distortion
c) Noise & Multi-path distortion
d) None of the mentioned
View Answer
Explanation: Spread spectrum has immunity to noise and multi-path distortion.
5. The width of each channel in frequency hopping spread spectrum corresponds to
a) Bandwidth of input signal
b) Pseudorandom sequence used
c) Carrier frequency
d) None of the mentioned
View Answer
Explanation: The width of the channel in frequency hopping spread spectrum corresponds to bandwidth of the input signal.
6. The transmitter of frequency hopping system is fed with encoding scheme such as
a) Frequency shift keying
b) Binary phase shift keying
c) Frequency & Binary phase shift keying
d) None of the mentioned
View Answer
Explanation: For transmission, the binary data is fed into modulator using modulation scheme such as frequency shift keying or binary phase shift keying.
7. Which filter is used to get the final FHSS signal?
a) Low pass filter
b) High pass filter
c) Band pass filter
d) Band stop filter
View Answer
Explanation: Band pass filter is used to block difference frequency and allow the sum frequency to yield final FHSS signal.
8. In CDMA the incoming signal is _____ with the spreading code.
a) Added
b) Multiplied
c) XOR-ed
d) None of the mentioned
View Answer
Explanation: In CDMA, the incoming signal is multiplied with the spreading code.
9. The original bandwidth of the unspread signal in spread spectrum is ____ to data rate.
a) Proportional
b) Inversely proportional
c) Not related
d) None of the mentioned
View Answer
Explanation: In spread spectrum, the original bandwidth of the unspread signal is proportional to the data rate.
10. In DSSS the signal is recovered using
a) Low pass filter
b) High pass filter
c) Band pass filter
d) Band stop filter
View Answer
Explanation: In direct sequence spread spectrum, band pass signal at the demodulator can be used to recover the original signal.
Sanfoundry Global Education & Learning Series – Digital Communications.
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