raw to dBm conversion

[Valerio, Danilo]

Hi everybody,
I searched in the mailing list archive for information about the 
conversion from the raw value of Signal and Noise to a dBm value but i 
didn't find anything really considerable...
I'm sniffing via TCPdump, and i need to convert that raw values of the 
prismII header (or AVS header) to dBm values...
After having a look into the driver code and making some measurement, i 
realized that a correct formula seems to be:

((raw_value) - dBmAdjust) * (100/255) - 100

With this conversion, the signal strength can be between -90dBm and -40dBm.
Is this correct? I'm really getting crazy with this stuff :-)
Please, let me know if you have additional information about it...

This is my configuration:

wifi0: NIC: id=0x800c v1.0.0
wifi0: PRI: id=0x15 v1.1.1
wifi0: STA: id=0x1f v1.7.4


Thanks a lot,
Danilo