Several customers have asked about this recently. They have some specific application in mind and only want their app to react to the beacon at very close range. So then they want to know how LOW they can set the TX power of the beacon.

While this sorta works, it’s actually the wrong way to achieve this goal. What you instead need to do is to set the minimum level for the RSSI reading within the app that you will create.

When an app “sees” a beacon, it measures the strength of the broadcast signal from the beacon. The numbers are negative numbers, which are lower and lower as the beacon is farther and farther way. You just need to set a minimum RSSI reading for the app to activate (i.e. do whatever it is supposed to do when close enough to a target beacon).

So your app will “see” the beacon, maybe even from quite far away, but the RSSI strength of the beacon’s signal will be too low, so the app will know to ignore the beacon. Once the beacon gets close enough so that the RSSI signal measured by the app is ABOVE the minimum level set within the app specs, the app will then activate and do what it is programmed to do.