Date: Thu, 27 May 2010 09:23:54 +0100 From: Rui Paulo <rpaulo@FreeBSD.org> To: Miroslav Chlastak <mira@chlastak.cz> Cc: freebsd-mobile@freebsd.org Subject: Re: Atheros and how to convert RSSI to dBm Message-ID: <D7D115EF-3485-49F7-81A5-18CB4A082801@FreeBSD.org> In-Reply-To: <4BFE260D.1090701@chlastak.cz> References: <4BFD9FE4.3090309@chlastak.cz> <BFBFCF99-8D2E-43BB-98DA-2B681C99514D@FreeBSD.org> <4BFE260D.1090701@chlastak.cz>
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On 27 May 2010, at 08:58, Miroslav Chlastak wrote: > On 27.5.2010 02:16, Rui Paulo wrote: >> On 26 May 2010, at 23:25, Miroslav Chlastak wrote: >>=20 >> =20 >>> 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" :( >>> =20 >> No, there's no way right now. >>=20 >> Check this: = http://lists.freebsd.org/pipermail/freebsd-stable/2006-September/028895.ht= ml >>=20 >> Regards, >> -- >> Rui Paulo >>=20 >>=20 >> =20 >=20 > But this mail was sent on September 2006 - it's still impossible? :( >=20 > And how to do it tcpdump? >=20 > 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 > Signal -61dB is right signal of my connected wireless client. Tcpdump = this signal "know", but system (via ifconfig) doesn't? Yes, that's right. The changes were not done yet to support displaying = this data in ifconfig. It's not hard to change ifconfig, what's hard is = changing every driver to provide useful info. ath passes this = information to radiotap the same way it provides this information to = athstats. Regards, -- Rui Paulo
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