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As there is no internet deployed back-end, the devices needed to be USB connected, which limited the testing range.
Human error in distance measurement +/- 2cm
Only Android and two types of device used
The phones remained flat, although it is known that tilting the phone changes the outputs
Method
Built and installed APK via USB to both phones
Over 45 minutes (with a tape measure) moving the two devices running the app around at distances between 0 and 320cm (changing distance every two minutes)
Extracted the readings from the phone databases manually (method)
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