Signal Modulation Module
(Grades 9-12)
What are the essential questions for this module?
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What is signal modulation?
How is speech converted into an electrical signal?
What is meant by “over the air” waves?
What is superposition?
What is amplitude and frequency modulation?
What is pulse code modulation?
What central concepts are discussed?
The conversion of sound to an electrical signal, superposition principle, amplitude modulation,
frequency modulation, pulse code modulation electromagnetic spectrum.
What National Science Education Standards are addressed?
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Science as Inquiry. Content Standard A.
Abilities necessary to do Scientific Inquiry
Physical Science. Content Standard B.
Interactions of Energy and Matter
Science and Technology. Content Standard E.
Abilities of Technological Design
Understanding about Science and Technology
What do students need to know to work with this module?
Understandings
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Electromagnetic spectrum
Radio waves
Bandwidth
Frequency
Amplitude
Wavelength
Speed of light
Modulation
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Wireless
Signal
Carrier
Hertz
Period
Constructive and destructive interference
Superposition
Digitization
Signal Modulation Module (Grades 9-12)
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Skills
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Calculate frequency, wavelength, velocity
and amplitude.
Gather data and develop a relationship
between two variables.
Use SI prefixes (nano, milli, kilo, mega etc)
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Sketch the superposition of two or more
waves
Predict the wave pattern that will result
during amplitude and frequency modulation
Use binary code to form a simple picture.
Signal Modulation Module (Grades 9-12)
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WHAT WILL STUDENTS
UNDERSTAND AS A
RESULT OF THEIR WORK
WITH THIS MODULE?
HOW WILL STUDENTS
COME TO THIS
UNDERSTANDING?
They will
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Information (sound or image) must be
turned into and electrical signal to be
transmitted.
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Signals can be transmitted “over the
air” (radio waves) or over cable
(copper, coaxial, optical fiber).
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Signals (waves) will interfere with each
other when transmitted. This
interference can be constructive or
destructive.
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AM and FM refer to amplitude and
frequency modulation of a radio
broadcasting system. Carrier waves are
used to transmit the signal.
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Pulse code modulation is a form of
digital communication. Wave
(analogue) signals are converted to a
series of on/off pulses and transmitted
as light or electrical pulses.
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HOW WILL STUDENTS
DEMONSTRATE THIS
UNDERSTANDING?
They will
Explore using a simulation the
effect of changing the amplitude
and frequency of a sound wave
(model of a microphone) on the
electrical signal it produces.
Read and analyze information.
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Use simulation of a microphone.
Develop a relationship between
the input (sound intensity and
pitch) with the output (electrical
signal)
Explore using a simulation of the
electromagnetic spectrum the
effect a change in frequency has
on data wavelength.
Read and analyze information
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Develop a mathematical relation
between frequency and
wavelength by collecting and
graphing data and writing an
equation for the graph.
Inquire using a simulation what
final wave form will result from
superposition of two waves.
Read and analyze information.
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Predict the final waveform of two
or more waves that will be
superimposed on each other.
Investigate the difference between
AM and FM by using a simulation
that allows a signal to be placed on
a carrier wave.
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Use signal carrier waves to sketch
a final wave form of an AM or
FM wave.
Answer conceptual questions
Read and investigate new
information.
Explore suing a graphing activity
how code is used to form images.
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Form an image by graphing
digital code into a grid system to
obtain a video image.
Amplitude modulated waves are used to
transmit information long distances. FM
waves are used in shorter distances such
as emergency services. PCM is used
with optical fibers technology to
transmit clean noise free images
Signal Modulation Module (Grades 9-12)
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