Date: Tue, 30 Aug 2005 13:40:13 -0500 From: Sam Pierson <samuel.pierson@gmail.com> To: Sam Leffler <sam@errno.com> Cc: FreeBSD Hackers <freebsd-hackers@freebsd.org> Subject: Re: Atheros driver and radiotap reliability Message-ID: <d9204e4c05083011405830aae4@mail.gmail.com> In-Reply-To: <4314A65C.4070802@errno.com> References: <d9204e4c050829120713734e3d@mail.gmail.com> <4313A2EC.5070300@errno.com> <d9204e4c05083010171fa6cfc9@mail.gmail.com> <4314A65C.4070802@errno.com>
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On 8/30/05, Sam Leffler <sam@errno.com> wrote: > David appears to be talking about how netbsd works. Understand that > David does not work on FreeBSD; I'm not even sure he uses it. ... > tcpdump and ethereal get the same data. If they display it differently > given identical data then one is wrong. If you have an example of where > things are wrong please present it. I tried and it looks like everything is being displayed correctly and that tcpdump and ethereal are displaying the same values. The only reason I said they looked different is that in the morning when I examined a few hundred frames with ethereal, the values were consistently 10dB=20 lower than what I had observed through tcpdump. I'm very glad that they are displaying the same values now though. > > *it*, referring to the rssi value above? >=20 > "it" =3D ds->ds_rxstat.rs_rssi which is the value returned by the hardwar= e. Alright, it makes much more sense now. You said earlier that we can use the RSSI value and correspond each unit to ~.5dBm above the noise floor. I didn't see anything being passed through the hardware which records the noise on that same per packet basis, but I can get ahold of the average noise floor for the environment. Will this affect the=20 accuracy of the measurements to the point where they will be=20 significantly skewed? =20 (Thanks for the help, again, it seems like there isn't a lot of information out there regarding these topics) -Sam
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