This set of Radar Multiple Choice Questions & Answers (MCQs) focuses on “Tracking Radar”.
1. Single target tracker is designed to continuously track a single target at a relatively rapid _________
a) data rate
b) frequency
c) time interval
d) oscillation
View Answer
Explanation: Single target tracker is designed to continuously track a single target at a relatively rapid data rate. The antenna beam of a single target tracker follows the target by obtaining an angle error signal and employing a closed loop servo system to keep the error signal small.
2. What does ADT stands for?
a) Autonomous detection and tracking
b) Automatic detection and track
c) Asynchronous detection while tracking
d) Ambiguous detection and track
View Answer
Explanation: ADT stands for Automatic detection and track. Its major use is in air surveillance. These types of radars are found in military and air traffic control since by using these, the digital processing increases and a decrease occurs in hardware size and cost.
3. The method in which information concerning the angular location of a target is obtained by comparison of signals received in two or more simultaneous beams is called as _________
a) sequential lobbing
b) conical scanning
c) monopulse tracking
d) hybrid scanning
View Answer
Explanation: The method is called as monopulse tracking. As the name suggests, a single pulse is used in order to measure angle that’s why it’s called as monopulse. This configuration is easy to use but increasing the number of pulses also increases the accuracy of the detection probability.
4. Which of the following is not present in the block diagram of amplitude-comparison monopulse?
a) Amplitude detector
b) Mixer
c) IF amplifier
d) IR amplifier
View Answer
Explanation: IR amplifier is not a part of amplitude-comparison monopulse. Amplitude-comparison monopulse is first described for the measurement of only one angle coordinate. Two overlapping antenna patterns with their main beams pointed in slightly different directions are used.
5. In amplitude-comparison monopulse, it is important that the sum and difference channels have amplitude characteristics and ________
a) same phase
b) different phase
c) constant phase
d) null phase
View Answer
Explanation: In amplitude-comparison monopulse, it is important that the sum and difference channels have amplitude characteristics and same phase. For this reason, a single local oscillator is shared by the two channels. The outputs of the sum and difference channels are the inputs to the phase sensitive detector, which is a nonlinear device that compares two signals of the same frequency.
6. Which of the following is a four port device that provides at its two output ports the sum and difference of the signals that are at its two input ports?
a) Phase sensitive detector
b) Hybrid junction
c) Amplitude detector
d) Local oscillator
View Answer
Explanation: The hybrid junction is a four port device that provides at its two output ports the sum and difference of the signals that are at its two input ports. For monopulse radar, they are usually constructed from waveguide, but they can also be in coax or stripline. The hybrid junction is known as the magic-T consists of an E-plane T-junction and an H-plane T-junction.
7. Which of the following is a compact form of hybrid junction that can also be used to obtain the sum and difference signals for monopulse?
a) 5-dB directional coupler
b) 1-dB directional coupler
c) 3-dB directional coupler
d) 7-dB directional coupler
View Answer
Explanation: The 3-dB directional coupler is a relatively compact form of the hybrid junction. One method of obtaining a 3-dB directional coupler is to align two rectangular waveguides with their narrow walls touching. Microwave energy is coupled by means of appropriate holes or slots between the two waveguides.
8. What does AGC stands for?
a) Angle growing capacity
b) Angle gain capacity
c) Automated growing control
d) Automatic gain control
View Answer
Explanation: AGC stands for Automatic gain control. It is required in the receiving system in order to maintain a stable closed-loop servo system for angle tracking and to ensure that the angle-error signal is not affected by changes in the received signal amplitude.
9. The greater the squint angle, the lower will be the slope of the angle-error at boresight.
a) True
b) False
View Answer
Explanation: The greater the squint angle, the greater will be the slope of the angle-error at boresight and also the better will be the accuracy of the angle measurement. As the squint angle increases, however, the on axis gain of the sum pattern decreases. Thus there will be optimum value of the squint angle.
10. Angle information can be extracted in a phase-comparison monopulse by employing sum and difference patterns and processing the signals similar to that described for the amplitude-comparison method.
a) True
b) False
View Answer
Explanation: It is true since the full aperture area can then be utilized, which is an advantage over the phase-measurement method. An analysis of the sum and difference patterns for phase-comparison monopulse shows that a 90° phase shift has to be introduced in the difference signal so that the output of the phase-sensitive detector is an error signal.
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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