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From: Rui Paulo <rpaulo@FreeBSD.org>
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Date: Thu, 27 May 2010 01:16:55 +0100
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To: Miroslav Chlastak <mira@chlastak.cz>
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Subject: Re: Atheros and how to convert RSSI to dBm
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On 26 May 2010, at 23:25, Miroslav Chlastak wrote:

> Hello,
>=20
>  is there a way how to convert RSSI from output of "ifconfig ath0 list =
sta" to dBm?:
>=20
> [snip]
>=20
> 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
>=20
> [snip]
>=20
> I my test enviroment I use this function:
> noise floor + RSSI*2 =3D signal of client in dBm
>=20
> Then i get the same value as from "tcpdump -n -i ath0 -p -y =
IEEE802_11_RADIO":
>=20
> [snip]
>=20
> 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
>=20
> [snip]
>=20
>=20
> Right? Or is this conversion "stupid"? Some better idea?
>=20
> 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.ht=
ml

Regards,
--
Rui Paulo