Q#1: Digital transmission refers to:
(A) Sending digital data over digital signals
(B) Sending analog data over digital signals
(C) Sending data without encoding
(D) None of the above
Answer: (A) Sending digital data over digital signals
Q#2: Unipolar signaling uses:
(A) Positive and negative voltages
(B) Only positive voltage and zero
(C) Three levels: +V, 0, -V
(D) Frequency changes
Answer: (B) Only positive voltage and zero
Q#3: Polar signaling uses:
(A) Only positive voltage
(B) Positive and negative voltages
(C) Three levels
(D) Phase shifts
Answer: (B) Positive and negative voltages
Q#4: Bipolar signaling uses:
(A) Two levels only
(B) Three levels: +V, 0, -V
(C) Frequency modulation
(D) Phase modulation
Answer: (B) Three levels: +V, 0, -V
Q#5: NRZ-L (Non-Return to Zero-Level) encoding uses:
(A) Voltage level represents bits
(B) Voltage transition represents bits
(C) Frequency change
(D) Phase change
Answer: (A) Voltage level represents bits
Q#6: NRZ-I (Non-Return to Zero-Inverted) encoding uses:
(A) Level for bit 1 or 0
(B) Transition indicates bit 1
(C) Frequency shift
(D) Phase shift
Answer: (B) Transition indicates bit 1
Q#7: Manchester encoding combines:
(A) Clock and data into one signal
(B) Frequency and amplitude
(C) Phase and amplitude
(D) None
Answer: (A) Clock and data into one signal
Q#8: Differential Manchester encoding indicates bit by:
(A) Transition at start
(B) Transition in middle
(C) Frequency change
(D) Amplitude level
Answer: (A) Transition at start
Q#9: Digital signal advantages include:
(A) Less noise effect
(B) Easy error detection
(C) Can be regenerated
(D) All of the above
Answer: (D) All of the above
Q#10: Digital signal disadvantage is:
(A) Requires more bandwidth
(B) Cannot detect errors
(C) Less secure
(D) Cannot be transmitted
Answer: (A) Requires more bandwidth
Q#11: Bit rate is defined as:
(A) Number of bits per second
(B) Number of bytes per second
(C) Number of packets per second
(D) Signal amplitude
Answer: (A) Number of bits per second
Q#12: Baud rate is defined as:
(A) Number of bits per second
(B) Number of signal changes per second
(C) Data rate
(D) Packet size
Answer: (B) Number of signal changes per second
Q#13: In digital transmission, bandwidth refers to:
(A) Frequency range needed
(B) Signal amplitude
(C) Bit duration
(D) Noise level
Answer: (A) Frequency range needed
Q#14: Unipolar NRZ has:
(A) Zero average voltage
(B) Non-zero average voltage
(C) Positive and negative equal
(D) Only negative
Answer: (B) Non-zero average voltage
Q#15: Polar NRZ has:
(A) Zero average voltage
(B) Non-zero average voltage
(C) Only positive
(D) Only negative
Answer: (A) Zero average voltage
Q#16: Bipolar encoding has:
(A) Zero DC component
(B) Non-zero DC component
(C) Only positive voltages
(D) Only negative voltages
Answer: (A) Zero DC component
Q#17: Return-to-Zero (RZ) encoding:
(A) Voltage returns to zero in middle of bit
(B) Voltage stays constant
(C) Only positive voltage
(D) Only negative voltage
Answer: (A) Voltage returns to zero in middle of bit
Q#18: NRZ encoding:
(A) Does not return to zero
(B) Returns to zero
(C) Uses three levels
(D) Uses frequency shift
Answer: (A) Does not return to zero
Q#19: Digital-to-digital conversion includes:
(A) Line coding
(B) Block coding
(C) Both A and B
(D) Modulation only
Answer: (C) Both A and B
Q#20: Line coding purpose is:
(A) Representing digital data for transmission
(B) Error detection
(C) Compression
(D) Modulation
Answer: (A) Representing digital data for transmission
Q#21: Block coding purpose is:
(A) Add redundancy for error detection
(B) Modulation
(C) Data compression
(D) Convert analog to digital
Answer: (A) Add redundancy for error detection
Q#22: 4B/5B coding is an example of:
(A) Block coding
(B) Line coding
(C) Analog encoding
(D) Frequency modulation
Answer: (A) Block coding
Q#23: AMI (Alternate Mark Inversion) is a type of:
(A) Polar line coding
(B) Unipolar line coding
(C) Frequency modulation
(D) Phase modulation
Answer: (A) Polar line coding
Q#24: Pseudoternary encoding represents:
(A) 0 by alternating voltages
(B) 1 by alternating voltages
(C) Bits by phase
(D) Bits by frequency
Answer: (A) 0 by alternating voltages
Q#25: Error detection in line coding is possible using:
(A) Bipolar violation
(B) DC component
(C) Frequency
(D) Phase
Answer: (A) Bipolar violation
Q#26: Digital transmission can be affected by:
(A) Noise
(B) Attenuation
(C) Distortion
(D) All of the above
Answer: (D) All of the above
Q#27: Attenuation refers to:
(A) Loss of signal strength
(B) Phase shift
(C) Frequency change
(D) Bandwidth increase
Answer: (A) Loss of signal strength
Q#28: Noise causes:
(A) Unwanted signal interference
(B) Loss of bandwidth
(C) DC component
(D) Clock loss
Answer: (A) Unwanted signal interference
Q#29: Inter-symbol interference (ISI) is caused by:
(A) Pulse spreading
(B) DC voltage
(C) Frequency shift
(D) Phase shift
Answer: (A) Pulse spreading
Q#30: Regeneration in digital transmission:
(A) Restores original signal
(B) Converts analog to digital
(C) Modulates signals
(D) Multiplexes signals
Answer: (A) Restores original signal
Q#31: Digital signal advantage over analog:
(A) Less noise effect
(B) Easy regeneration
(C) Error detection possible
(D) All of the above
Answer: (D) All of the above
Q#32: Digital signal disadvantage:
(A) Requires more bandwidth
(B) Cannot detect errors
(C) Cannot be regenerated
(D) Less reliable
Answer: (A) Requires more bandwidth
Q#33: Line coding also helps:
(A) Synchronization
(B) Multiplexing
(C) Encryption
(D) Compression
Answer: (A) Synchronization
Q#34: NRZ-L maps:
(A) Bit 1 = high voltage, 0 = low voltage
(B) Bit 1 = low voltage, 0 = high voltage
(C) Bit 1 = transition, 0 = no transition
(D) Bit 1 = frequency change
Answer: (A) Bit 1 = high voltage, 0 = low voltage
Q#35: NRZ-I maps:
(A) Bit 1 = transition, 0 = no transition
(B) Bit 1 = high, 0 = low
(C) Bit 1 = low, 0 = high
(D) Bit 1 = frequency shift
Answer: (A) Bit 1 = transition, 0 = no transition
Q#36: Manchester encoding ensures:
(A) Clock synchronization
(B) DC component
(C) Low bandwidth only
(D) Frequency shift
Answer: (A) Clock synchronization
Q#37: Differential Manchester avoids:
(A) Ambiguity due to polarity inversion
(B) Bandwidth usage
(C) Noise
(D) Error detection
Answer: (A) Ambiguity due to polarity inversion
Q#38: Spectral efficiency refers to:
(A) Bits per Hz
(B) Bits per second
(C) Signal amplitude
(D) Bandwidth
Answer: (A) Bits per Hz
Q#39: Power efficiency measures:
(A) Energy required per bit
(B) Bandwidth
(C) Frequency
(D) Signal amplitude
Answer: (A) Energy required per bit
Q#40: Digital modulation types include:
(A) ASK, FSK, PSK
(B) AM, FM, PM
(C) Both A and B
(D) None
Answer: (A) ASK, FSK, PSK
Q#41: ASK uses:
(A) Amplitude changes to represent bits
(B) Frequency changes
(C) Phase changes
(D) Time interval changes
Answer: (A) Amplitude changes to represent bits
Q#42: FSK uses:
(A) Frequency change
(B) Amplitude change
(C) Phase change
(D) None
Answer: (A) Frequency change
Q#43: PSK uses:
(A) Phase change
(B) Amplitude change
(C) Frequency change
(D) Bandwidth
Answer: (A) Phase change
Q#44: Bandwidth required increases with:
(A) Higher bit rate
(B) Lower bit rate
(C) Constant bit rate
(D) None
Answer: (A) Higher bit rate
Q#45: Attenuation compensation uses:
(A) Repeaters or amplifiers
(B) Modulation
(C) Multiplexing
(D) Encoding
Answer: (A) Repeaters or amplifiers
Q#46: Distortion is:
(A) Alteration of signal waveform
(B) Noise
(C) Attenuation
(D) Amplification
Answer: (A) Alteration of signal waveform
Q#47: Noise margin ensures:
(A) Signal can be detected correctly despite noise
(B) Higher bit rate
(C) Lower bandwidth
(D) Zero error
Answer: (A) Signal can be detected correctly despite noise
Q#48: Digital signals can be regenerated using:
(A) Repeaters
(B) Amplifiers only
(C) Modems
(D) Multiplexers
Answer: (A) Repeaters
Q#49: Digital transmission systems include:
(A) Baseband transmission
(B) Broadband transmission
(C) Both A and B
(D) None
Answer: (C) Both A and B
Q#50: Baseband transmission uses:
(A) Directly sending digital signals
(B) Modulation to higher frequency
(C) Frequency division
(D) Phase division
Answer: (A) Directly sending digital signals