Fourier experiment (T212)

Subject Elec Eng

Welcome to the Fourier activity in the OpenEngineering Laboratory. This equipment contains a rotating disc, photodiodes and red LEDs.

In this activity, you will experiment with sampling and the associated Fourier spectrums of signals created by passing infrared light through arc-shaped slots in a disc. This creates a square wave, since light is sensed for a short period of time (causing the signal to rise to 3.3 V), then no light is sensed for another short period of time (causing the signal to fall to 0.0 V). Because the disc is spinning at a constant speed, this creates rectangular waves.

You will first determine whether the rotational speed of the disc is indeed constant. Then you will experiment with the time­⁠–⁠voltage signal data transformed from the time domain into the frequency domain. In particular, you will try to identify the relevant harmonic frequencies for a square wave and reconstruct a time-domain signal from these frequency-domain data. Thus the challenge is to identify the harmonic frequencies associated with the signals, and to reconstruct the signals from these harmonics.

The link to the booking system is below.

Please note that the equipment is now in its long-term availability configuration. This means that there are fewer peices of equipment available at any one time, but they can be used for 22 hours in a day. You also should be aware that we may need to take equipment off-line with little or no notice for operational reasons. We apologise for any inconvenience if this is the case.

Please be aware that all bookings are in UK local time.

If you wish to check that the experiment will run at the location you intend to access it from then please visit this link using the computer, browser, and network you will use.

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