Helping Spirits

Imagine coming home on a cold winter's day; it's already cosily warm, the lights are switched on automatically, and a favorite song is playing through the speakers. Everyday users can already implement this scenario without great difficulty. Software tools such as the open source Home Assistant [1] offer various components for determining the presence of home residents. GPS location capabilities, combined with automation rules, result in some interesting applications for heating and lighting control.

In most cases, however, GPS is not a suitable solution for automating light switches for the rooms within a house. The signal quality of GPS inside buildings is often too poor to allow fast detection, and it is not precise enough to allow location down to the room level.

A few commercial systems offer in-home positioning services. These systems usually rely on a series of sensors that receive signals from portable radio beacons. They then calculate their position based on the signal strength or the time difference of the received signals. However, most systems are proprietary and not intended for private users. One promising tool within this category is the DecaWave DWM1000 [2], which claims to have a detection accuracy of up to 10 centimeters indoors. Unfortunately, I couldn't find any manufacturer-independent information on its suitability for everyday use.

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