Date: Wed, 1 Aug 2012 11:13:22 +0800 From: "Wright, Brett" <Brett.Wright@cooperindustries.com> To: <freebsd-wireless@freebsd.org> Subject: Atheros DFS radar detection Message-ID: <475A4E02EFF4724A9E58F55A56AC1316063B3323@APEVS1.ap.ci.root>
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Hi All, I've been trying to get DFS radar detection working with Atheros ar5212 (and later). As for matching the ETSI/FCC radar patterns that is OK - I can make the open source DFS code comply. The problem is that it is too sensitive (i.e. too many false detects). What I have found is that using ar5213 I get LOTS of radar phy errors just for normal crc error free data transfer. Even just an iperf test on the bench will give me approx 1 radar phy error for every 5 or so tx/rx frame. This means that any "real" data of sufficient data rate for these false pulses to match the radar patterns will trigger false detection of radar and a channel change... (usually iperfing for a couple of minutes is enough!) One approach I've been looking at is some "smarts" that look at how much real data is being received and try to decide what "pulses" are not real and discard them. However this risks having a radio that does not always detect real radar co-incident with when the radio is very busy. I also can't help but feel there is some other way to detect and weed out these "false" phy radar errors. (for example FreeBSD defines HAL_PHYERR_FALSE_RADAR_EXT - I'm not even sure what this is/does). Any clues/info anyone can provide about how to determine what phy radar errors are potentially false would be a huge help... Thanks again Brett Wright
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