Atheros and how to convert RSSI to dBm

[Rui Paulo]

On 26 May 2010, at 23:25, Miroslav Chlastak wrote:

> Hello,
> 
>  is there a way how to convert RSSI from output of "ifconfig ath0 list sta" to dBm?:
> 
> [snip]
> 
> ADDR               AID CHAN RATE RSSI IDLE  TXSEQ  RXSEQ CAPS FLAG
> 00:4f:62:1d:d8:5d   14    9  11M 18.5    0  15932  22400 ES   A
> 
> [snip]
> 
> I my test enviroment I use this function:
> noise floor + RSSI*2 = signal of client in dBm
> 
> Then i get the same value as from "tcpdump -n -i ath0 -p -y IEEE802_11_RADIO":
> 
> [snip]
> 
> 10:41:04.746395 86402611933us tsft short preamble 58.5 Mb/s -61dB signal -98dB noise antenna 1 [0x00000012] IP 10.0.0.1.2049 > 192.168.100.2.123: NTPv3, Client, length 48
> 
> [snip]
> 
> 
> Right? Or is this conversion "stupid"? Some better idea?
> 
> Is there a way how to get noise floor via "ifconfig"? I get it from output of "athstats" :(

No, there's no way right now.

Check this: http://lists.freebsd.org/pipermail/freebsd-stable/2006-September/028895.html

Regards,
--
Rui Paulo