Digital Communications Questions and Answers – Link Budget Analysis and Error Control

This set of Digital Communication quiz 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

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

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

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

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

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.
Note: Join free Sanfoundry classes at Telegram or Youtube

6. In analog receivers, noise bandwidth is _________ signal bandwidth.
a) Lesser than
b) Greater than
c) Equal to
d) Not related

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

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

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

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

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

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

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

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

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

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

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 Communication for quizzes, here is complete set of 1000+ Multiple Choice Questions and Answers.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]