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The Micro-Doppler Effect in RadarAnswers to RF Cafe Quiz #42 | ||||||
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| 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | | 42 | 43 | 44 | 45 | 46 | 47 | 48 | All RF Cafe quizzes would make perfect fodder for employment interviews for technicians or engineers - particularly those who are fresh out of school or are relatively new to the work world. Come to think of it, they would make equally excellent study material for the same persons who are going to be interviewed for a job. Some of these books used in quizzes are available as prizes in the monthly RF Cafe Giveaway. Note: Many answers contain passages quoted from the text. This quiz is based on the information presented in Note: Some of these books are available as prizes in the monthly RF Cafe Giveaway.  This quiz is based on the information presented in "The Micro-Doppler Effect in Radar," by Victor C. Chen .1. What is the micro-Doppler effect? a) An oscillatory motion in addition to a bulk motion If the object or any structural component of the object has an oscillatory motion in addition to the bulk motion of the object, the oscillation will induce additional frequency modulation on the returned signal and generates its side bands about the Doppler shift frequency of the transmitted signal due to the bulk motion. (see page 1) 2. Which of these is an image of Christian Doppler? c)  "a" is mathematician Charles Babbage, "b" is telephone inventor Alexander Graham Bell, and "d" is spread spectrum inventor Hedy Lamar. (see page 3) 3. What is an Euler angle? b) Angles of counterclockwise rotation about the x, y, and z axes. The rotation angles (φ, θ, ψ) are called Euler angles, where φ is defined as the counterclockwise rotation about the z-axis, θ is defined as the counterclockwise rotation about the y-axis, and ψ is defined as the counterclockwise rotation about the axis. (see page 37) 4. Which of the following are mechanisms for producing micro-Doppler shift? In addition to those, there are the bistatic, multistatic micro-Doppler effect d) All the above (see pages 60, 63, 66, 71, and 77) 5. In the case of a rotating helicopter blade on a stationary aircraft, which Doppler frequency graph would be correct? a)  Because the advancing blade has a higher velocity toward the observer than does the receding blade, its Doppler frequency is higher than that of the receding blade. The stronger amplitude signature from the receding blade is due to the RCS difference. (see page 107) 6. In figure "a" from question 5, why is a plateau over a range of Doppler frequencies formed in the blade signature rather than a single frequency? b) Blade speed varies along the span, increasing toward the tips Although the rotational velocity is the same along the span, the linear velocity toward the observer increases when progressing from the hub to the tip, per v = ωr. (see page 108) 7. What is the Denavit-Hartenberg (D-H convention)? d) A kinematic representation of human body links and joints The D-H convention states that each link has its own coordinate system with its z-axis in the direction of the joint axis, the x-axis aligned with the outgoing link, and the y-axis orthogonal to the x- and z-axes. (see page 162) 8. When analyzing articulated locomotion (animal walking, bird wing flapping, etc.), what is commonly assumed to describe the style of sinusoidal motion? c) Harmonic oscillations Harmonic oscillations are the basis of analyzing complicated motion because any motion can be decomposed into a summation of a series of harmonic components with different amplitudes and frequencies by using the Fourier series. (see page 195) 9. What is the difference between bipedal and quadrupedal locomotion? a) Two additional feet biped: "animal with two feet," 1640s, from L. bipedem (nom. bipes) "two-footed," from bi- "two" + pedem (nom. pes) "foot" quadruped: from L. quadrupes (gen. quadrupedis) "four-footed, a four-footed animal," from quadri- "four" (see quadri-) + pes "foot" (see foot). (see page 202) 10. Which parameters can be extracted from micro-Doppler signatures of targets? d) All the above Feature extraction and target information based on micro-Doppler signatures is the primary use of the technique. (see page 273) | ||||||
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