How is Strips Comfort reporting ambient light?
For Strips Comfort – the discreet temperature & LUX sensor, Sensative developed an algorithm for ambient light reporting system that reports in regards to relevance. Instead of having a certain reporting interval, which is the norm, we have decided to bring down the total number of reportings without losing accuracy & speed when light change happens.
Over the course of a whole day or a whole night, there are long periods of time where there are no significant changes in the light conditions; therefore the device reports the same Lux level over and over again. For a sensor that reports every 5 minutes it means that 288 reports are sent during a 24 hour period. This can result in battery lifetime shortage. For Strips during a normal day with sunlight 20 to 30 reports are sent during a 24 hour period.
What Strips Comfort does is it reads the Lux sensor once per minute and makes a decision if it should send a report or not dependent on the difference in reading since last sent report.
A new report is sent when the Lux value I doubled or is half of previous sent value, or if 24 hours have passed since last report.
The human eye sensitivity is logarithmic in the same way as the ear is for sound levels, reacting to a relative change of energy rather than absolute levels. A change with a factor of 2 in light energy (Lux) is a clearly noticeable change for the human eye.
There is also a filtering function to avoid that temporary changes as headlights passing by or if some one is passing by and blocking the sensor to trigger a reporting. The filtering levels dependent if normal or frequent mode is set. Normal reporting provides more filtering and frequent reporting have a lighter filtering allowing changes to more quickly pass through.
There also exist possibility to set an absolute lux value when reporting is to be sent, for instance if a certain scenario is to be set in the controller. There is on for transition from dark to lighter and on for transition from light to darker.