This set of Radar Multiple Choice Questions & Answers (MCQs) focuses on “Radar Equation”.
1. Which of the following is the best possible way to determine whether a target is present at the receiver or not?
a) Setting a threshold at the receiver output
b) Increasing the effective aperture of the receiver
c) Increasing the resolution of the display
d) Operate at long wavelength
View Answer
Explanation: The detection of radar signal is based on creating a threshold at the output of the receiver. So, a target is said to be present if the output received at the receiver end exceeds the threshold.
2. The unit of minimum detectable signal in radar range equation is kilowatts.
a) True
b) False
View Answer
Explanation: Minimum detectable signal in radar range equation is represented in watts. Minimum receivable power Prmin is another specific value of minimum detectable signal, and as it is known that the echo power of antenna always gives output of IF amplifier, so the power is always represented in watts.
3. Which of the following best describes the term which is used when a signal is detected falsely even though it’s not present?
a) Uncalled echo
b) Minimum detectable signal
c) False alarm
d) Unambiguous signal
View Answer
Explanation: A false alarm is said to be detected if the threshold of the receiver is set too low and because of this noise might exceed the threshold and be mistaken for a target.
4. What is the name of the condition in which the target echo is not recognized even if it is present?
a) False indication
b) Threshold detection
c) False alarm
d) Missed detection
View Answer
Explanation: Missed detection occurs when the threshold is set too high due to which the weak target echoes fail to cross the threshold level, and because of this the weak echoes from targets are not recognized even if they are present and along with noise components.
5. In order to obtain the radar receiver output, which filter is used to maximize the output signal-to-noise ratio?
a) Doppler filter
b) Matched filter
c) High pass filter
d) Band reject filter
View Answer
Explanation: In order to increase the output SNR ratio, matched filter is the perfect choice which operates in the presence of additive stochastic noise. To put it simply, it maximizes the ratio of output peak power to mean noise power in frequency response.
6. The signals which manages to cross the threshold level at the radar receiver output always consist of target echo signal only.
a) True
b) False
View Answer
Explanation: It is not necessary that all the signals which are exceeding the threshold level only consist of the target echo since majority of the signals which are able to cross the threshold are said to be combination of both target echo and noise.
7. The video output of a radar receiver plotted between amplitude versus time is displayed on ______
a) A-scope
b) E-scope
c) PPI
d) F-scope
View Answer
Explanation: A-scope display is used in order to plot the output of radar receiver between amplitude versus time. This display is used only to display the range and the relative strength instead of position of the target echo and is highly preferred in weapon control radar systems.
8. What is the reason behind the detection of weak echo signal when noise is added to it?
a) Noise reduces fluctuations caused by target echo
b) Noise is easier to detect compared to echo signal
c) Just like echo signal, noise occupies the same frequency spectrum
d) Echo signal gets more stable when noise is added to it
View Answer
Explanation: It’s not necessary that the received target echo is always strong enough to pass through the threshold level. So, the noise which is added midway in the target echo occupies the same frequency spectrum which helps in increasing the strength of the signal.
9. In the maximum radar range equation, minimum detectable signal is represented by __________
a) σ
b) Dmin
c) Mmin
d) Smin
View Answer
Explanation: Minimum detectable signal in radar range equation can be represented by Smin. It is the weakest signal that can be detected by a radar receiver since most of the weak signals occupies the same frequency spectrum as noise.
10. Which out of the following targets representing signal plus noise can be categorized as valid detection?
a) A & B
b) B & C
c) C & A
d) Only A
View Answer
Explanation: A and C are the only target signals which are able to exceed or touch the threshold level, this indicates that they consist of target echo signal with some additional components of noise.
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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