AM/FM Modulation

Author: Panagiotis Skrimponis, New York University: ps3857[at]nyu.edu

Last updated: September 22, 2020

Description

Teaching the properties of waves by visualizing amplitude modulated (AM) and frequency modulated (FM) wave signals in time and frequency domain.

Educational Standards

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.

Experiment Execution

First you need to complete all the steps described in the ​tutorial. Then, you need open the web interface of either one of the nodes. Let's open ​http://localhost:8081. If you did all the steps correctly you should be able to see the following,

Press on the 'Science' radio button to the open the science lesson plan webpage, where you need to select 'Grade 8'.

Observe that some of the lessons in the top right corner have an indication that they can be executed on COSMOS website. While in the 'COSMOS Education Toolkit' we have more than 100+ lesson plans and labs, we currently support only few for remote experimentation. We will keep updating the website and the experiments until all of them can be executed both locally and remotely.

Then, you need to select 'AM/FM Modulation'.In the new webpage we can see a detailed description of the experiment, the educational standards that we focus on, and a detailed description of the experiment execution. In the experiment execution you can expand the 'Remote Experiment' section.

The students first need to observe the AM signal first. So they should press START either on node #1 or node #2. In this tutorial we consider sdr2-s1-lg1 as node #1 and sdr2-md1 as node #2. The students need to use different information wave signals (square and sine), and different carrier frequency. The students should observe the effect of these two parameters between the original information and the AM signal. The students should take notes on their observations for both time and frequency domain plots. When the students are done they should press the appropriate STOP to complete the AM experiment. Then, the students should press START either on node #1 or node #2 to start the FM experiment, and repeat the above process to collect measurements and observations. In the end the students will compare their observations for the AM signal and FM signal and state their interpretations. After all students complete their handouts there will be a share out with observations and comments.

(a) Amplitude modulation of a signal	(b) Frequency modulation of a signal