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Name: Sharan Multani
Name:
Conceptual Questions
1.)
An ultrasonic motion sensor sends very short pulses of ultrasound to measure the
distance to an object. The sensor cannot send another pulse until the echo from the
previous is detected. What is the maximum possible number of individual
measurements per second (i.e., the maximum sampling rate) if the distance turns
out to be 1.50m? The velocity of ultrasound waves is equal to 344m/s. Show your
calculations.
Ans1.) Given Date:
Velocity: 344m/s
Distance: 1.50m
Total Distance: 1.5 x 2 = 3m
We know that:
=
=
v distancetime dt
Therefore,
=
=
t dv 3344
= 0.0087209 seconds
Therefore, 1 pulse takes 0.0087209 seconds
to propagate and echo back.
Pulse
Time
1.
0.0087209 seconds
X
1 second
Therefore,
X = 1/0.0087209 seconds
X = 114.667 Pulses
Therefore the maximum possible number of individual measurements per second (i.e., the
maximum sampling rate) is:
114 Pulses/second.
2) Consider two types of measuring devices. The first device has good accuracy, but poor
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This note was uploaded on 02/14/2011 for the course PHYS 220 taught by Professor Chang during the Fall '09 term at Purdue University.
 Fall '09
 CHANG

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