Several results of Doppler experiments are shown in Figure
13. The first images, labeled (a) and (b), are results of a
popular, easy to find scene in the local urban area. Each of
these plots show velocity versus time for an observation of
traffic, where the stop-and-go action of vehicles can be seen
distinctly. There is an interesting phenomenon seen in image
(a), as cars drive under an overpass. This experiment provides
what appears as extremely fast acceleration which is actually
the overpass blocking the returns from the vehicles. The image
labeled (c) is a unique image of a swinging pendulum which
accelerates and decelerates through its periodic motion as
time progresses, creating a repeating Doppler pattern. The last
image, labeled (d), is a Doppler signature of a glass elevator
as it moves between floors and stops to load and unload.
a. b.
c. d.
Fig. 13. Doppler results; moving traffic (a and b), pendulum (c), and glass
elevator (d).
These images represent a small sample of the often interesting
and inventive DTI experiments that the students in the course
designed and carried out