From owner-freebsd-stable@FreeBSD.ORG Thu Sep 28 15:53:17 2006 Return-Path: X-Original-To: stable@freebsd.org Delivered-To: freebsd-stable@FreeBSD.ORG Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 2EE3916A403 for ; Thu, 28 Sep 2006 15:53:17 +0000 (UTC) (envelope-from sam@errno.com) Received: from ebb.errno.com (ebb.errno.com [69.12.149.25]) by mx1.FreeBSD.org (Postfix) with ESMTP id DF70143D8C for ; Thu, 28 Sep 2006 15:52:56 +0000 (GMT) (envelope-from sam@errno.com) Received: from [10.0.0.199] ([10.0.0.199]) (authenticated bits=0) by ebb.errno.com (8.13.6/8.12.6) with ESMTP id k8SFqHWg089781 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 28 Sep 2006 08:52:17 -0700 (PDT) (envelope-from sam@errno.com) Message-ID: <451BEFAC.4040502@errno.com> Date: Thu, 28 Sep 2006 08:52:12 -0700 From: Sam Leffler Organization: Errno Consulting User-Agent: Thunderbird 1.5.0.7 (Macintosh/20060909) MIME-Version: 1.0 To: Eduardo Meyer References: <451AECA0.7000103@errno.com> In-Reply-To: X-Enigmail-Version: 0.94.0.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: stable@freebsd.org Subject: Re: 802.11 RSSI value displayed from ifconfig(8) X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 28 Sep 2006 15:53:17 -0000 Eduardo Meyer wrote: > Thank you Mr Leffler for this explanation. Honestly I did not know > about those tools. Very interesting, useful and some curious (say, > number of associations denied by wlan acl) information, which I > believe I will be able to produce some logs of it with audit support. > > But I did not find any "signal" information nor any value which looks > like dBm > > # athstats -i ath0 > 4 watchdog timeouts > 549821 tx management frames > 7 tx frames discarded prior to association > 1744404 tx stopped 'cuz no xmit buffer > 15 tx linearized to cluster > 97625 tx failed 'cuz too many retries > 9069518 long on-chip tx retries > 422577 tx frames with no ack marked > 62850632 tx frames with short preamble > 1700110 tx frames with an alternate rate > 24280171 rx failed 'cuz of bad CRC > 1 rx failed 'cuz frame too large > 62560031 rx failed 'cuz of PHY err > 4211566 OFDM timing > 101667 OFDM restart > 58199442 CCK timing > 47356 CCK restart > 31931664 beacons transmitted > 109058 periodic calibrations > rssi of last ack: 24 > 417831 switched default/rx antenna > Antenna profile: > [1] tx 31753038 rx 33886147 > [2] tx 31594701 rx 33711543 > > # wlanstats -i ath0 > 1509703 rx discard 'cuz dup > 335650 rx frame ssid mismatch > 2314 rx deauthentication > 377 rx disassociation > 4959 rx discard 'cuz acl policy > 1068 tx failed for no node > 3 active scans started > 142 nodes timed out inactivity > > Note that I am acting in hostap mode. Looks like you're not running HEAD or RELENG_6 or your system is not update recently. Sam > > On 9/27/06, Sam Leffler wrote: >> Eduardo Meyer wrote: >> > Hello, I would like to convert RSSI to dBm (in fact I would love if >> > ifconfig cound display SNR in dBM), so I would like to know if this >> > formula is any right: >> > >> > /* Calculate the RSSI Value */ >> > V_RSSI = 3.0 * (RSSI_VAL/1024); >> > RSSI_dBM = (int8_t) ((-50.0 * V_RSSI) - 45.5); >> > >> > And if there are any other tools which can help me finding out signal >> > stenght, when I am acting as an access point. >> >> ifconfig reports rssi as whatever the driver provided. The intent is >> that it be a signed value relative to the current noise floor (both in >> dBm). If you look at the output of wlanstats >> (tools/tools/net80211/wlanstats) or, for ath devices, athstats >> (tools/tools/ath/athstats) you will see the default displays show >> "signal" which is rssi+noise-floor in dBm. The main issue(s) right now >> are that the net80211-driver api does not pass noise floor up so it can >> be reported to user apps and drivers reports rssi+nf in varying units. >> athstats doesn't have that issue since it queries the driver directly >> (hence it's display has a reasonable noise floor). >> >> It's on my todo list to push signal-related data up properly and fix >> ifconfig so it displays a proper signal strength in the normal status >> display. The issue of units is more difficult as converting data for >> some devices to dBm can be tricky. >> >> Sam >> > >