The Rssid Coverage control displays those areas where the signal strength received from any of the selected access points falls below the selected threshold value. Signal strength has a significant impact on the quality of communications. Signal strength is measured in dBm, and ranges from 0 dBm (stronger) to -100 dBm (weaker).
Acceptable values range from 0 to -75 dBm. Proper communication cannot be guaranteed with lower signal strength values.