An AP signal strength of .0000001 milliwatts is equivalent to -80 dBm. The dBm scale is logarithmic, with every 10 dBm representing a tenfold increase or decrease in power. A signal strength of 1 milliwatt (mW) is 0 dBm, so a signal strength of .0000001 mW is 80 decibels less than 1 mW, which is -80 dBm.