Return-path: Received: from mail30g.wh2.ocn.ne.jp ([220.111.41.239]:35165 "HELO mail30g.wh2.ocn.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1758021AbYDCBz4 convert rfc822-to-8bit (ORCPT ); Wed, 2 Apr 2008 21:55:56 -0400 From: bruno randolf To: "Luis R. Rodriguez" Subject: Re: [PATCH] mac80211: use hardware flags for signal/noise units Date: Thu, 3 Apr 2008 10:55:43 +0900 Cc: jt@hpl.hp.com, ath5k-devel@lists.ath5k.org, jirislaby@gmail.com, mickflemm@gmail.com, linux-wireless@vger.kernel.org, linville@tuxdriver.com, johannes@sipsolutions.net, flamingice@sourmilk.net, jbenc@suse.cz, "Ivan Seskar" , "Haris Kremo" , "Kishore Ramachandran" , "Sanjit Kaul" References: <20080326123042.11233.80949.stgit@localhost> <20080327001909.GA17555@bougret.hpl.hp.com> <43e72e890804021619k4e8fea71i152c5dafe010ddfc@mail.gmail.com> In-Reply-To: <43e72e890804021619k4e8fea71i152c5dafe010ddfc@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Message-Id: <200804031055.43707.bruno@thinktube.com> (sfid-20080403_025601_410090_AAB27F58) Sender: linux-wireless-owner@vger.kernel.org List-ID: On Thursday 03 April 2008 08:19:07 Luis R. Rodriguez wrote: > > > Jean, if range->max_qual.level is set to -110 does this mean sig= nal > > > level can be set only from -110 up to 0 ? Is max_qual.level supp= osed > > > to be the weakest signal possibly detected? > > > > Yes. This is what make most sense. > > How so? I think I must still be seriously misunderstanding something > then. If the weakest signal possibly detected is -110 dbm it does not > imply the strongest signal will be 0 dbm. On the contrary, I expect t= o > be able to receive frames with positive dbm values. For example, if I > hook up a card's antenna which is transmitting at 20dbm to another > card's antenna directly with cables with 10 dbm attenuator in the > middle I expect to see 10 dbm on the reception side. Therefore > shouldn't the max be close the max allowed, or at least expected, > EIRP? from a paper, from Joshua Bardwell, also available at: http://madwifi.org/attachment/wiki/UserDocs/RSSI/you_believe_D100201.pd= f "Bear in mind that, realistically, stations will nearly always receive = signals=20 below 1 mW, unless they are very close (within a few feet) of the acces= s=20 point. Therefore, the power levels below 1 mW are critical to the opera= tion=20 of an 802.11 chipset." =2E.. "Realistically, 1 mW is about the maximum power that a station is likel= y to=20 receive, and the station would have to be within inches of a powerful A= P to=20 receive even that much! (That might surprise you, but remember that 802= =2E11=20 NICs can receive signals down to about 10-7 to 10-9 mW, so a =E2=80=9Cw= eak=E2=80=9D 1 mW=20 signal is actually millions of times stronger than the weakest signal t= he=20 card could discern.)" =2E.. "Consequently, the RSSI ranges used by the 802.11 chipset manufacturers= don=E2=80=99t=20 measure at all above 1 mW. The maximum RSSI value for all 802.11 chipse= ts and=20 NICs represents a power level that is less than 1 mW. Everything betwee= n 1 mW=20 and 100 mW is simply considered =E2=80=9C100 %=E2=80=9D RSSI." bruno -- To unsubscribe from this list: send the line "unsubscribe linux-wireles= s" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html