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Mastering Internet of Things by Peter Waher

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Illustrating measurement results

Following image shows how our measured quantity behaves. The light sensor is placed in broad daylight on a sunny day, so it's saturated. Things move in front of the sensor, creating short dips. The thin blue line is a scaled version of our raw input A0. Since this value is event based, it is being reported more often than once a second. Our red curve is our measured, and corrected, ambient light value, in percent. The dots correspond to our second values. Notice that the first two spikes are removed and don't affect the measurement, which remains close to 100%. Only the larger dips affect the measurement. Also, notice the small delay inherent in our algorithm. It is most noticeable if there are abrupt changes: ...

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