This set of Radar Multiple Choice Questions & Answers (MCQs) focuses on “Limitations to Tracking Accuracy”.
1. Which of the following does not show the phenomenon of glint?
a) Sphere
b) Aircraft
c) Ship
d) Automobile
View Answer
Explanation: A single point scatterer, such as a sphere, does not show the phenomenon of glint. Complex targets with multiple scattering centers, such as aircraft, can cause glint and degrade tracking. The echo from a single scatterer generally arrives as the radar antenna with a uniform planar waveform that has a tilt which depends on the angle of arrival.
2. The noise at the input of a radar receiver affects the detection capability of radar as well as __________
a) power
b) accuracy
c) speed
d) frequency
View Answer
Explanation: The noise at the input of a radar receiver affects the detection capability of radar as well as the accuracy. Receiver noise can limit the overall result of a radar’s output. This usually happens when other circuits including amplifiers add some noises to a signal due to which the SNR compared to input gets higher at the output.
3. Why does fluctuation occur when the amplitude of the radar echo from a complex target with multiple scattering centers?
a) Higher thresholding
b) Larger signal to noise ratio
c) Change of aspect of target
d) Low clutter
View Answer
Explanation: The amplitude of the radar echo from a complex target with multiple scattering centers will fluctuate as the aspect of the target changes with respect to the radar. Changes in aspect may be due to the motion of the target in yaw, roll, or pitch. Aspect changes also occur even if the target moves in a straight line.
4. Surveillance radars estimate the target direction as the antenna pointing angle where the echo signal is ____________
a) balanced
b) nullified
c) minimum
d) maximum
View Answer
Explanation: In addition to tracking radars, glint also occurs with scanning surveillance radars. They estimate the target direction as the antenna pointing angle where the echo signal is maximum. The estimate of angle in scanning surveillance radars is often made by beam splitting or something equivalent.
5. Amplitude fluctuations from aircraft targets are/is ___________
a) low frequency or high frequency
b) only low frequency
c) only high frequency
d) no frequency
View Answer
Explanation: Amplitude fluctuations from aircraft targets are classified as either low frequency or high frequency. The low frequency amplitude fluctuation is due to variations in the target cross section and high frequency amplitude fluctuation can be caused by reflections from propellers and jet engines.
6. If the amplitude fluctuation noise power were large at the conical-scan or lobing frequency, it could not be readily eliminated by AGC or _____________
a) synthesis
b) filtering
c) cluttering
d) decomposition
View Answer
Explanation: If the amplitude fluctuation noise power were large at the conical-scan or lobing frequency, it could not be readily eliminated by AGC or filtering. A typical conical scan frequency, for example, might be 30Hz. Generally, the higher the scan frequency, the less the noise due to amplitude fluctuation.
7. Which of the following is the hunting action of the tracking servomechanism?
a) Target noise
b) Receiver noise
c) Servo noise
d) Clutter noise
View Answer
Explanation: Servo noise is the hunting action of the tracking servomechanism which is observed due to backlash. The objective of a servomechanism is to level and maintain the system’s output at a specific point or a desired value whenever there are any chances of disturbances.
8. The angle error due to glint does not depend on the radar frequency.
a) True
b) False
View Answer
Explanation: The angle error due to glint depends on the radar frequency since the relative phase α in the simple two scatterer model depends on frequency. A change in the relative phase α can change the glint error, it can be smaller or it can be larger.
9. Detection of moving targets in clutter using MTI pulse Doppler methods is not compatible with a pulse to pulse frequency agility.
a) True
b) False
View Answer
Explanation: It is true since to employ Doppler processing, the frequency must remain constant for a significant number of pulses. Frequency diversity is possible by transmitting either simultaneously or in sequence a number of constant-frequency pulses at each of several frequencies that are separated.
10. How does polarization agility effects glint error?
a) Increases
b) Reduces
c) Nullifies
d) Equates
View Answer
Explanation: Polarization agility can reduce the glint error based on the expectation that the scattering centers will be different with different polarizations. However, it might not be expected that polarization can decorrelate the glint errors as well as can frequency agility.
Sanfoundry Global Education & Learning Series – Radar.
To practice all areas of Radar, here is complete set of Multiple Choice Questions and Answers.
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