06-28-2020, 12:39 AM
in case you need more encouragement to add basic camera support (brightness):
cameras can see IR. many wattmeters today emit an IR pulse every 1 Wh or so (1 kWh / ~1000..10000 Pulses). to read that, you just need to press the phone's camera right on top of that LED, sum/average the whole picture to get a brightness reading, plot over time, do some simple thresholding, and calculate (1 kWh / pulse count / time difference) to get current power. since camera data has poor time resolution (1/30 sec usually), this is a good way to show what lowpass filtering can achieve.
if you're driving on a road with "Leitpfosten" (retroreflectors every 50 meters), you can pick those up too, and calculate traveled distance and speed. just point the phone out the window, zoom in, and turn on its flashlight to make use of the retroreflectors.
another simple measurement would be taking one scanline (horizontal or vertical) out of the picture. you can plot that over time like a waterfall diagram. you can also find the maximum and plot that.
cameras can see IR. many wattmeters today emit an IR pulse every 1 Wh or so (1 kWh / ~1000..10000 Pulses). to read that, you just need to press the phone's camera right on top of that LED, sum/average the whole picture to get a brightness reading, plot over time, do some simple thresholding, and calculate (1 kWh / pulse count / time difference) to get current power. since camera data has poor time resolution (1/30 sec usually), this is a good way to show what lowpass filtering can achieve.
if you're driving on a road with "Leitpfosten" (retroreflectors every 50 meters), you can pick those up too, and calculate traveled distance and speed. just point the phone out the window, zoom in, and turn on its flashlight to make use of the retroreflectors.
another simple measurement would be taking one scanline (horizontal or vertical) out of the picture. you can plot that over time like a waterfall diagram. you can also find the maximum and plot that.