From owner-freebsd-hackers@FreeBSD.ORG Tue Aug 30 18:41:13 2005 Return-Path: X-Original-To: freebsd-hackers@freebsd.org Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 8B55C16A41F for ; Tue, 30 Aug 2005 18:41:13 +0000 (GMT) (envelope-from samuel.pierson@gmail.com) Received: from wproxy.gmail.com (wproxy.gmail.com [64.233.184.204]) by mx1.FreeBSD.org (Postfix) with ESMTP id 5293B43D77 for ; Tue, 30 Aug 2005 18:40:14 +0000 (GMT) (envelope-from samuel.pierson@gmail.com) Received: by wproxy.gmail.com with SMTP id i21so781113wra for ; Tue, 30 Aug 2005 11:40:13 -0700 (PDT) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=iHNEtDjNhmOufEU9TeFeT3mLCOKcHOSoZP2v34NDtjVWdtBt2vLJ64jUsBo5flpqDGCvxH8uxnGAWHt+zbPaDr9Ih4Xc2szPbPC7rqykXqht106iTKwakuIitPRm86tbFheOOw02vEy7n6krxECR9IYhsFThZkuS+3nKZKCEnf4= Received: by 10.54.13.65 with SMTP id 65mr737161wrm; Tue, 30 Aug 2005 11:40:13 -0700 (PDT) Received: by 10.54.144.1 with HTTP; Tue, 30 Aug 2005 11:40:13 -0700 (PDT) Message-ID: Date: Tue, 30 Aug 2005 13:40:13 -0500 From: Sam Pierson To: Sam Leffler In-Reply-To: <4314A65C.4070802@errno.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline References: <4313A2EC.5070300@errno.com> <4314A65C.4070802@errno.com> Cc: FreeBSD Hackers Subject: Re: Atheros driver and radiotap reliability X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 30 Aug 2005 18:41:13 -0000 On 8/30/05, Sam Leffler 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