Hi, All of the chips do a hardware RX timestamp of some sort.
The default timestamp is the TSF timestamp. It's based on the TSF, which gets nudged by the AP. The AR9287 is the first chip with a second TSF counter, designed to be free-running and not be locked into the AP broadcast TSF. Ie, if you wanted to be an AP and a STA, you'd have one TSF for the AP and one TSF for the STA association. But I don't know how it all works in too much depth and I'm not sure how the relevant TSF gets stamped to which RX frame. There's also the Azimuth mode timestamp that is in a debug mode somewhere; I don't know (yet!) much about how that works. -a On 18 February 2014 06:45, Diego Bernardes <di3go.bernar...@gmail.com> wrote: > Hi, > > I have one question about hardware timestamp in Atheros chipsets. > From a post in Wireshark community, the chipset AR9287 can do hardware > timestamp. > > The question is, how accurated this timestamp is? The precision is in > nanoseconds, but what accuracy i can expect? > > My main need is the implement a good precision TDOA algorithm. > > I don't know jack about driver development, but is something that interests > me. If the accuracy is low, can i improve it in driver or firmware? > If its possible, i can even trade reception packet speed for a better > accuracy in timestamp. > > The other question is, what is the difference between the ath9k_htc and > carl9170 drivers? Both support the AR9287 (from the debian wiki). > > Thanks for all > > Links: > > Wireshark community: > http://ask.wireshark.org/questions/28683/recommended-wireless-adapter-usb-with-linux-wireshark-that-reports-mactime-in-radiotap-header > > Debian Wiki ath9k_htc: https://wiki.debian.org/ath9k_htc > > Debian Wiki carl9170: https://wiki.debian.org/carl9170 > > _______________________________________________ > ath9k-devel mailing list > ath9k-devel@lists.ath9k.org > https://lists.ath9k.org/mailman/listinfo/ath9k-devel > _______________________________________________ ath9k-devel mailing list ath9k-devel@lists.ath9k.org https://lists.ath9k.org/mailman/listinfo/ath9k-devel
