Date: Thu, 30 Oct 2014 06:57:12 +0000 From: "Graf Monika" <grafmon@student.ethz.ch> To: Adrian Chadd <adrian@freebsd.org>, Sergey Ryazanov <ryazanov.s.a@gmail.com> Cc: "freebsd-wireless@freebsd.org" <freebsd-wireless@freebsd.org> Subject: AW: Time-of-flight positioning - Atheros Message-ID: <2CCC302EA38F004C899D788D1F3438D51FA025CA@MBX22.d.ethz.ch> In-Reply-To: <CAJ-Vmok1FKVetcKVRC-BA_j1hQiZ0WfP=hZ2yS4RuN2aQmbRTA@mail.gmail.com> References: <1E0B1592-5212-4D65-8F08-344EC215EA47@student.ethz.ch> <CAHNKnsTo5Pt4tvxnL4MJKsUsjGc-fYQMXdi3%2BDzBvvJZNxwYrg@mail.gmail.com>, <CAJ-Vmok1FKVetcKVRC-BA_j1hQiZ0WfP=hZ2yS4RuN2aQmbRTA@mail.gmail.com>
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thanks for your answers!:)=0A= =0A= Adrian, could you specify a little bit more, how that I get out the PHY tim= estamp?=0A= =0A= Thank you!=0A= =0A= Monika=0A= ________________________________________=0A= Von: adrian.chadd@gmail.com [adrian.chadd@gmail.com]" im Auftrag von &= quot;Adrian Chadd [adrian@freebsd.org]=0A= Gesendet: Mittwoch, 29. Oktober 2014 19:34=0A= An: Sergey Ryazanov=0A= Cc: Graf Monika; freebsd-wireless@freebsd.org=0A= Betreff: Re: Time-of-flight positioning - Atheros=0A= =0A= Oh, I asked him to. I don't mind which list he's asking for hardware help o= n.=0A= =0A= =0A= On 29 October 2014 02:33, Sergey Ryazanov <ryazanov.s.a@gmail.com> wrote:= =0A= > Hi Monika,=0A= >=0A= > 2014-10-29 11:44 GMT+03:00 Graf Monika <grafmon@student.ethz.ch>:=0A= >> Hello Everyone=0A= >>=0A= >> I am currently at a project where I am using Atheros Chipsets AR9590 wit= h the ath9k driver.=0A= >>=0A= > It's a bit strange to ask questions about linux driver in=0A= > freebsd-wireless mailing list. Just in case, there are two mailing=0A= > lists for ath9k: ath9k-devel and linux-wireless.=0A= >=0A= >> I am wondering how the time-of-flight information can be retrieved per p= acket in most recent Atheros chipsets. Is it required a proprietary HAL ver= sion ?=0A= >>=0A= > If you need a round-trip-time: take a tx timestamp from tx-complete=0A= > descriptor of data frame, then take a timestamp from received ACK=0A= > frame and then compute the time. To get received ACK frames from NIC=0A= > you should enable control frames receiving in Rx filter. If you need=0A= > more details about descriptor format or time of timestamp capture,=0A= > then may be Adrian could help.=0A= =0A= The RX timestamp is from the MAC, not the PHY. So it's an OK estimate,=0A= but for metre and sub-metre accuracy you still need to get the=0A= original PHY timestamp. IIRC the timestamps are microsecond accurate,=0A= which limits your actual distance calculation.=0A= =0A= Now, the AR9380 and later chips do have some stuff to pull out the PHY=0A= timestamp and some information about the leading edge of the received=0A= frame.=0A= =0A= > BTW, a month ago or so, Lorenzo Bianconi added a dynamic ACK timeout=0A= > estimation to the ath9k, based exactly on round-trip-time computation.=0A= =0A= That was pretty cute.=0A= =0A= =0A= -adrian=0A=
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