Electronics World articles Popular Electronics articles QST articles Radio & TV News articles Radio-Craft articles Radio-Electronics articles Short Wave Craft articles Wireless World articles Google Search of RF Cafe website Sitemap Electronics Equations Mathematics Equations Equations physics Manufacturers & distributors Engineer Jobs LinkedIn Crosswords Engineering Humor Kirt's Cogitations RF Engineering Quizzes Notable Quotes App Notes Calculators Education Engineering magazine articles Engineering software Engineering smorgasbord RF Cafe Archives RF Cascade Workbook 2018 RF Stencils for Visio RF & EE Shapes for Word Advertising RF Cafe Homepage Thank you for visiting RF Cafe!
Exodus Advanced Communications

The Micro-Doppler Effect in Radar
Answers to RF Cafe Quiz #42

RF Engineering Quizzes - RF CafeAll RF Cafe Quizzes make great 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.

Click here for the complete list of RF Cafe Quizzes.

Note: Some material based on books have quoted passages.

Return to RF Cafe Quiz #42

This quiz is based on the information presented in  Note: Some of these books are available as prizes in the monthly RF Cafe Giveaway.

The Micro-Doppler Effect in Radar - RF Cafe Quiz #42This 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)  Christian Doppler - RF Cafe
"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)  The Micro-Doppler Effect in Radar, Helicopter Blade Doppler Signature - RF Cafe Quiz #42
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)
RF Cascade Workbook 2018 by RF Cafe ConductRF Precision RF Test Cables - RF Cafe
LadyBug Technologies LB479A RF Power Sensor - RF Cafe Res-Net Microwave - RF Cafe
About RF Cafe
Kirt Blattenberger - RF Cafe Webmaster
Copyright: 1996 - 2024
    Kirt Blattenberger,

RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while typing up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

My Hobby Website:  AirplanesAndRockets.com


Please Support RF Cafe by purchasing my  ridiculously low−priced products, all of which I created.

These Are Available for Free