A cellular unit shows a small LTE indicator with four bars along the bottom of its screen, on every view. It is there so the question “does this spot have coverage?” can be answered at the wall, rather than discovered days later from readings that never arrived.
- Green means the unit has reported in recently. Red means it has not, and someone should look.
- The bars show the signal measured the last time it connected, with the number beside them.
- Green does not mean the radio is on right now. A cellular unit keeps its radio off between reports on purpose — that is what keeps data costs down — so it is normally green and idle at the same time.
When a unit is first powered on it shows CONNECTING, then CONNECTED with the signal it found. Two bars or better is a good mounting position. One bar will usually still work, because a unit buffers its readings and sends them when it can, but it is worth trying another spot before you mount it permanently.
The same signal (and the unit's supply voltage) appears on the unit's page in the dashboard, refreshed automatically every couple of minutes from the cellular network's own measurements — so you can check whether a mounted unit is in a good spot without standing in front of it.