From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon Barber Subject: TSFT Date: Fri, 16 Nov 2012 22:26:31 -0800 Message-ID: <50A72E17.6070207@superduper.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Sender: radiotap-owner-sUITvd46vNxg9hUCZPvPmw@public.gmane.org To: "radiotap-sUITvd46vNxg9hUCZPvPmw@public.gmane.org" Cc: thomas-W/OLz77bvjtBDgjK7y7TUQ@public.gmane.org List-Id: radiotap@radiotap.org This is the current definition of TSFT: "Value in microseconds of the MAC's 64-bit 802.11 Time Synchronization Function timer when the first bit of the MPDU arrived at the MAC. For received frames only." My experience with TSFT is with Atheros cards, which record the timestamp at the end of the frame, not the start. Do you know the behaivour of any particular capture systems re: TSFT - where do they timestamp the frame? Furthermore for DSSS/CCK the definition above is reasonable, but for OFDM and HT (802.11n) the SIGNAL field (part of the PLCP header, not part of the MPDU) is part of the first data symbol. It would be much clearer to change the definition to state that the timestamp is at the start of this first SIGNAL/data symbol. Any objections to doing this, or preference to change the reference point to a different part of the frame? In my wireshark patch I've added options to interpret TSFT as the start of end of the frame. Simon