Digital Communication Test Questions - Set 4

1)   ASK modulated signal has the bandwidth

a. Same as the bandwidth of baseband signal
b. Half the bandwidth of baseband signal
c. Double the bandwidth of baseband signal
d. None of the above
Answer  Explanation 

ANSWER: Same as the bandwidth of baseband signal

Explanation:
No explanation is available for this question!


2)   Coherent detection of binary ASK signal requires

a. Phase synchronization
b. Timing synchronization
c. Amplitude synchronization
d. Both a and b
Answer  Explanation 

ANSWER: Both a and b

Explanation:
No explanation is available for this question!


3)   The probability of error of DPSK is ______________ than that of BPSK.

a. Higher
b. Lower
c. Same
d. Not predictable
Answer  Explanation 

ANSWER: Higher

Explanation:
No explanation is available for this question!


4)   In Binary Phase Shift Keying system, the binary symbols 1 and 0 are represented by carrier with phase shift of

a. Π/2
b. Π
c.
d. 0
Answer  Explanation 

ANSWER: Π

Explanation:
No explanation is available for this question!


5)   BPSK system modulates at the rate of

a. 1 bit/ symbol
b. 2 bit/ symbol
c. 4 bit/ symbol
d. None of the above
Answer  Explanation 

ANSWER: 1 bit/ symbol

Explanation:
No explanation is available for this question!


6)   The BPSK signal has +V volts and -V volts respectively to represent

a. 1 and 0 logic levels
b. 11 and 00 logic levels
c. 10 and 01 logic levels
d. 00 and 11 logic levels
Answer  Explanation 

ANSWER: 1 and 0 logic levels

Explanation:
No explanation is available for this question!


7)   The binary waveform used to generate BPSK signal is encoded in

a. Bipolar NRZ format
b. Manchester coding
c. Differential coding
d. None of the above
Answer  Explanation 

ANSWER: Bipolar NRZ format

Explanation:
No explanation is available for this question!


8)   The bandwidth of BFSK is ______________ than BPSK.

a. Lower
b. Same
c. Higher
d. Not predictable
Answer  Explanation 

ANSWER: Higher

Explanation:
No explanation is available for this question!


9)   In Binary FSK, mark and space respectively represent

a. 1 and 0
b. 0 and 1
c. 11 and 00
d. 00 and 11
Answer  Explanation 

ANSWER: 1 and 0

Explanation:
No explanation is available for this question!


10)   The frequency shifts in the BFSK usually lies in the range

a. 50 to 1000 Hz
b. 100 to 2000 Hz
c. 200 to 500 Hz
d. 500 to 10 Hz
Answer  Explanation 

ANSWER: 50 to 1000 Hz

Explanation:
No explanation is available for this question!


11)   The spectrum of BFSK may be viewed as the sum of

a. Two ASK spectra
b. Two PSK spectra
c. Two FSK spectra
d. None of the above
Answer  Explanation 

ANSWER: Two ASK spectra

Explanation:
No explanation is available for this question!


12)   The maximum bandwidth is occupied by

a. ASK
b. BPSK
c. FSK
d. None of the above
Answer  Explanation 

ANSWER: FSK

Explanation:
No explanation is available for this question!


13)   QPSK is a modulation scheme where each symbol consists of

a. 4 bits
b. 2 bits
c. 1 bits
d. M number of bits, depending upon the requirement
Answer  Explanation 

ANSWER: 2 bits

Explanation:
No explanation is available for this question!


14)   The data rate of QPSK is ___________ of BPSK.

a. Thrice
b. Four times
c. Twice
d. Same
Answer  Explanation 

ANSWER: Twice

Explanation:
No explanation is available for this question!


15)   QPSK system uses a phase shift of

a. Π
b. Π/2
c. Π/4
d.
Answer  Explanation 

ANSWER: Π/2

Explanation:
No explanation is available for this question!


16)   Minimum shift keying is similar to

a. Continuous phase frequency shift keying
b. Binary phase shift keying
c. Binary frequency shift keying
d. QPSK
Answer  Explanation 

ANSWER: Continuous phase frequency shift keying

Explanation:
No explanation is available for this question!


17)   In MSK, the difference between the higher and lower frequency is

a. Same as the bit rate
b. Half of the bit rate
c. Twice of the bit rate
d. Four time the bit rate
Answer  Explanation 

ANSWER: Half of the bit rate

Explanation:
No explanation is available for this question!


18)   The technique that may be used to reduce the side band power is

a. MSK
b. BPSK
c. Gaussian minimum shift keying
d. BFSK
Answer  Explanation 

ANSWER: Gaussian minimum shift keying

Explanation:
No explanation is available for this question!


19)   In DPSK technique, the technique used to encode bits is

a. AMI
b. Differential code
c. Uni polar RZ format
d. Manchester format
Answer  Explanation 

ANSWER: Differential code

Explanation:
No explanation is available for this question!


20)   Synchronization of signals is done using

a. Pilot clock
b. Extracting timing information from the received signal
c. Transmitter and receiver connected to master timing source
d. All of the above
Answer  Explanation 

ANSWER: All of the above

Explanation:
No explanation is available for this question!