This set of Digital Communications Multiple Choice Questions & Answers (MCQs) focuses on “Link Budget Analysis and Error Control”.
1. Field of view is ______ to antenna gain.
a) Proportional
b) Inversely proportional
c) Half the
d) Double
View Answer
Explanation: The antenna field of view is the measure of a solid angle in which most of the field power is concentrated. It is inversely related to antenna gain.
2. Antenna gain ______ as effective area increases.
a) Increases
b) Decreases
c) Remains same
d) None of the mentioned
View Answer
Explanation: Antenna gain increases with a decrease in wavelength increase in frequency and increase in effective area.
3. The beam-width becomes narrower on
a) Increasing frequency
b) Increasing antenna size
c) Increasing frequency & antenna size
d) None of the mentioned
View Answer
Explanation: Increasing either the signal frequency or antenna size results in narrower beam-width.
4. Path loss Ls is dependent on
a) Signal power
b) Effective area
c) Wavelength
d) Antenna size
View Answer
Explanation: The path loss is wavelength(frequency) dependent.
5. Thermal noise is generated due to
a) Lossy coupling
b) Lossless coupling
c) Lossy & Lossless coupling
d) None of the mentioned
View Answer
Explanation: Thermal noise occurs due to the thermal motion of electrons in all conductors. It occurs due to lossy coupling between an antenna and the receiver.
6. In analog receivers, noise bandwidth is _________ signal bandwidth.
a) Lesser than
b) Greater than
c) Equal to
d) Not related
View Answer
Explanation: With analog receivers, noise bandwidth seen by the demodulator is usually greater than the signal bandwidth.
7. The link availability measures the percentage of time the link can be ______
a) Open
b) Closed
c) Used
d) None of the mentioned
View Answer
Explanation: Link availability is the measure of long term link utility stated on an average annual basis for a given geographical location, the link availability measures the percentage of time the link can be closed.
8. Visibility is ________ to required availability.
a) Proportional
b) Inversely proportional
c) Equal
d) Not related
View Answer
Explanation: For a fixed link margin, visibility is inversely proportional to the required availability, and for a fixed availability visibility increases monotonically with margin.
9. The stop and wait ARQ needs _______ connection.
a) Half duplex
b) Full duplex
c) Simplex
d) None of the mentioned
View Answer
Explanation: The stop and wait ARQ needs half duplex system since the transmitter needs ACK for each transmission.
10. In continuous ARQ will pullback uses _____ system.
a) Half duplex
b) Full duplex
c) Simplex
d) None of the mentioned
View Answer
Explanation: The ARQ procedure called continuous ARQ with pullback requires full duplex connection.
11. Which method requires less redundancy?
a) Error detection
b) Error correction
c) Error detection & correction
d) None of the mentioned
View Answer
Explanation: Error detection requires much simpler decoding equipment and much less redundancy than error correction.
12. Hybrid automatic repeat request is a combination of
a) ARQ and error correction code
b) ARQ and error detection code
c) Error detection and correction codes
d) One of the mentioned
View Answer
Explanation: An alternate approach for error control is a hybrid automatic repeat request method which is a combination of ARQ and error correction code.
13. Automatic repeat request is also called as
a) Forward error correction
b) Backward error correction
c) Forward & Backward error correction
d) None of the mentioned
View Answer
Explanation: Automatic repeat request is also referred to as backward error correction method.
14. Error detection is realized using
a) Hash function
b) Check sum
c) Hash function & Check sum
d) None of the mentioned
View Answer
Explanation: Error detection is commonly realized using a suitable hash function or check-sum algorithm.
15. Check-sum scheme has
a) Check bits
b) Parity bits
c) Longitudinal redundancy bits
d) All of the mentioned
View Answer
Explanation: Check-sum scheme includes parity bits, longitudinal redundancy bits and check bits.
16. Example of block code is
a) Hamming code
b) Reed-solomon code
c) Repetition code
d) All of the mentioned
View Answer
Explanation: Some examples of block codes are repetition codes, hamming codes, parity check bit codes, reed-solomon codes, turbo codes etc.
Sanfoundry Global Education & Learning Series – Digital Communications.
To practice all areas of Digital Communications, here is complete set of 1000+ Multiple Choice Questions and Answers.
