Received Signal Strength Indicator (RSSI) is the measure of RF signal strength between the Remote Station modem and a base station, expressed in dBm. The signal strength should be no less than -100 dBm (considered weak coverage), -50 dBm is considered full signal strength.
A site survey can be performed prior to installation, to determine the signal strength on site. This can be done using a cellular device.
For GSM modems, a general indication of the signal strength can be determined from the number of LEDs that light up on the modem:
- 0-1 LEDs (-101 dBm or less) = unacceptable coverage
- 1-2 LEDs (-100 dBm to -91 dBm) = weak coverage
- 2-3 LEDs (-90 dBm to -81 dBm) = moderate coverage
- 4 LEDs (-80 dBm or greater) = good coverage
Signal strength can be increased by adding an optional antenna, or by simply relocating the Remote Station to an area with maximum signal strength on site.