How to calculate the percentage of signal strength level from dBm

[Chih-Chieh Chou]

Hi All,

  Here's a question that I have been searching the Internet but
couldn't get an solution to it. I wanted to know all the wireless
hotspots around me and their signal strengths. I used "wpa_cli scan;
wpa_cli scan_results" to list the hotspots around me with signal
level, which were -75 and -83 in my case. I guess the unit here is
dBm. My question is how to convert dBm to percentage of signal
strength. I'm using ath9k driver. I saw a document on the internet
saying that I can use the following formula to convert dBm to
percentage:

    RSSI - 95 = dBm
    RSSI_MAX for Atheros chips is 60. So, -35 dBm is equivalent to
100%, and -95 dBm to 0%


  It doesn't look right to me because I put an access point very close
to me but got -79 dBm via wpa_cli. Please can anyone help?

Thanks and Best Regards,
CC