| Lab Name |
Properties of waves, using experiment allowing the visualization of AM and FM wave signals.
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| Subject Area |
Science
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| Grade |
7
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| Topic |
Evolution of Technology (Waves)
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| Experiment Title |
Visualization of AM and FM wave signals from a microphone showing the frequency and amplitude
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| Hardware |
Linux machines (ex laptop, raspberry pi) and 2 Software Defined Radios (ADALM Pluto).
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| Software |
GNU Radio, COSMOS toolkit framework.
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| Number of Sessions to teach the topic |
1 session.
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| Educational standards to be addressed |
- MS-PS4-1
Develop a model and use mathematical representations to describe waves that include frequency, wavelength, and how the amplitude of a wave is related to the energy in a wave.
- MS-PS4-2
Develop and use a model to describe that waves are reflected, absorbed, or transmitted through various materials.
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| COSMOS concepts to be used for the lab |
Wireless signals, visualization of AM and FM wave signals on the computer screen, signal strength, relationship between signal strength and amplitude.
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| K12 Educational Goals (How the educational goals are achieved through teaching using the experiment, how the topic is connected to the COSMOS concepts used) |
Teaching the properties of waves by visualizing AM and FM wave signals on the computer screen and observing the relationship between different signals (clap, whistle, etc.) and comparing their strength and amplitude. |
| Short Description and Walk-through of the experiment |
- Teacher demonstrates pitch for students (through a video about bats & echolocation, cats reacting to high pitch, or the Human Benchmark test showing the link between age and ability to hear high-pitched sounds.
- Students use classroom computers and the COSMOS node to play sounds of different pitches and observe their frequencies.
- Students will see that higher pitch correlates with higher frequency.
- Students will also observe that AM or FM (i.e. the type of modulation) has no effect on the frequency.
- Students will speculate about whether AM or FM modulation is better for transmitting pitch.
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| Testbed mapping of the experiment |
- We can configure a particular node to represent a signal from a microphone as an AM signal and another to represent a signal from a microphone as an FM signal and display the information showing the waveform and spectrogram. So, we perform the experiment using nodes on the testbed and we can visualize the wave signals on the computer screen. From this visualization we can observe the relationship between signal, frequency, amplitude, signal strength etc.
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© 2019 COSMOS Project. Created by Anne Williard, Mott Hall 2.