Returning to the OP "A TimeSync certification program will appear later this year, but semiconductor firms will have to create new Wi-Fi chips including the feature." so this "new thing" will be hardware of some TBD form. https://www.wi-fi.org/discover-wi-fi/wi-fi-timesync But more interesting to time-nuts, I think, is how do you do it without the new hardware. http://www.cse.msu.edu/~glxing/docs/WizSync.pdf says, in part: 802.11 requires all APs to broadcast periodic beacon frames that carry important management information (e.g., supported rates and security settings). The default beacon period is 102.4 ms, which is rarely changed on production APs. ...However, as defined in 802.11, whether a beacon frame is delayed or not, the subsequent beacon frame shall always be scheduled at the undelayed nominal beacon interval. so this is the "use a 1pps, but throw out outliers" kind of strategy... And there would need to be some sort of measurement of the AP's timing error - they make the assumption that the timing of the beacons is driven by a clock with max 25ppm error (as required by the 802.11 std), although they've measured <5ppm normally Ultimately, they got on the order of 0.1 0.2 ms. That's a few orders of magnitude worse than "microsecond", but it's also an interesting read. an older presentation (2006) might be useful http://www.ieee802.org/1/files/public/docs2006/avb-stanton-wifi-timesync-intro-060613.pdf discusses 802.11v there's been a lot of stuff on time sync/distribution over 802.11 links for the last decade.. maybe this CES announcement is more about "we at WiFi alliance are ready to market it". Has anyone gone through the 802.11 standards list recently? It might well be that the standard is already there. 802.11aa says "Amendment 2: MAC Enhancements for Robust Audio Video Streaming" in the description... although that might just be things like QoS and access control-digital rights management

Here is a ti app note with timestamping hardware wl8 but ordinary ap's with no special protocol just timestamping the beacon frame. http://www.ti.com/lit/an/swaa162a/swaa162a.pdf On Sun, Jan 15, 2017 at 10:06 AM jimlux <jimlux@earthlink.net> wrote: > Returning to the OP > > "A TimeSync certification program will appear later this year, but > > semiconductor firms will have to create new Wi-Fi chips including the > > feature." > > > > so this "new thing" will be hardware of some TBD form. > > https://www.wi-fi.org/discover-wi-fi/wi-fi-timesync > > > > > > > > But more interesting to time-nuts, I think, is how do you do it without > > the new hardware. > > > > http://www.cse.msu.edu/~glxing/docs/WizSync.pdf > > says, in part: > > > > 802.11 requires all APs to broadcast periodic beacon frames that > > carry important management information (e.g., supported rates and > > security settings). The default beacon period is 102.4 ms, which is > > rarely changed on production APs. ...However, as defined in 802.11, > > whether a beacon frame is delayed or not, the subsequent beacon > > frame shall always be scheduled at the undelayed nominal beacon interval. > > > > so this is the "use a 1pps, but throw out outliers" kind of strategy... > > > > And there would need to be some sort of measurement of the AP's timing > > error - they make the assumption that the timing of the beacons is > > driven by a clock with max 25ppm error (as required by the 802.11 std), > > although they've measured <5ppm normally > > > > Ultimately, they got on the order of 0.1 0.2 ms. > > > > > > That's a few orders of magnitude worse than "microsecond", but it's also > > an interesting read. > > > > > > > > an older presentation (2006) might be useful > > > http://www.ieee802.org/1/files/public/docs2006/avb-stanton-wifi-timesync-intro-060613.pdf > > > > discusses 802.11v > > > > there's been a lot of stuff on time sync/distribution over 802.11 links > > for the last decade.. maybe this CES announcement is more about "we at > > WiFi alliance are ready to market it". Has anyone gone through the > > 802.11 standards list recently? It might well be that the standard is > > already there. > > > > 802.11aa says "Amendment 2: MAC Enhancements for Robust Audio Video > > Streaming" in the description... although that might just be things > > like QoS and access control-digital rights management > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > >

Hi Ok, that’s a pretty good paper. At least it shows data and digs into the details. It also would lead one to believe that a “Time Nuts” grade sync system might be a hackable sort of thing …… hmmm…..Given how highly integrated these WiFi chip sets have become, that probably is a fantasy. Bob > On Jan 15, 2017, at 11:10 AM, Scott Stobbe <scott.j.stobbe@gmail.com> wrote: > > Here is a ti app note with timestamping hardware wl8 but ordinary ap's with > no special protocol just timestamping the beacon frame. > > http://www.ti.com/lit/an/swaa162a/swaa162a.pdf > > On Sun, Jan 15, 2017 at 10:06 AM jimlux <jimlux@earthlink.net> wrote: > >> Returning to the OP >> >> "A TimeSync certification program will appear later this year, but >> >> semiconductor firms will have to create new Wi-Fi chips including the >> >> feature." >> >> >> >> so this "new thing" will be hardware of some TBD form. >> >> https://www.wi-fi.org/discover-wi-fi/wi-fi-timesync >> >> >> >> >> >> >> >> But more interesting to time-nuts, I think, is how do you do it without >> >> the new hardware. >> >> >> >> http://www.cse.msu.edu/~glxing/docs/WizSync.pdf >> >> says, in part: >> >> >> >> 802.11 requires all APs to broadcast periodic beacon frames that >> >> carry important management information (e.g., supported rates and >> >> security settings). The default beacon period is 102.4 ms, which is >> >> rarely changed on production APs. ...However, as defined in 802.11, >> >> whether a beacon frame is delayed or not, the subsequent beacon >> >> frame shall always be scheduled at the undelayed nominal beacon interval. >> >> >> >> so this is the "use a 1pps, but throw out outliers" kind of strategy... >> >> >> >> And there would need to be some sort of measurement of the AP's timing >> >> error - they make the assumption that the timing of the beacons is >> >> driven by a clock with max 25ppm error (as required by the 802.11 std), >> >> although they've measured <5ppm normally >> >> >> >> Ultimately, they got on the order of 0.1 0.2 ms. >> >> >> >> >> >> That's a few orders of magnitude worse than "microsecond", but it's also >> >> an interesting read. >> >> >> >> >> >> >> >> an older presentation (2006) might be useful >> >> >> http://www.ieee802.org/1/files/public/docs2006/avb-stanton-wifi-timesync-intro-060613.pdf >> >> >> >> discusses 802.11v >> >> >> >> there's been a lot of stuff on time sync/distribution over 802.11 links >> >> for the last decade.. maybe this CES announcement is more about "we at >> >> WiFi alliance are ready to market it". Has anyone gone through the >> >> 802.11 standards list recently? It might well be that the standard is >> >> already there. >> >> >> >> 802.11aa says "Amendment 2: MAC Enhancements for Robust Audio Video >> >> Streaming" in the description... although that might just be things >> >> like QoS and access control-digital rights management >> >> >> >> _______________________________________________ >> >> time-nuts mailing list -- time-nuts@febo.com >> >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> >> and follow the instructions there. >> >> > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there.

On 1/15/17 8:26 AM, Bob Camp wrote: > Hi > > Ok, that’s a pretty good paper. At least it shows data and digs into the details. > It also would lead one to believe that a “Time Nuts” grade sync system might > be a hackable sort of thing …… hmmm…..Given how highly integrated these > WiFi chip sets have become, that probably is a fantasy. > maybe, maybe not.. They might have implemented the time stamping feature (like in that WiFi Arduino thing) but the details are poorly documented, and of course, everyone is different. But it's a start. and 802.11v appears to be the "standard" for how to do it in a "standards compliant" way.

Just wanted to inform you that the linux-gpib maintainer Dave Penkler. Has fixed the problem with the Agilent 82357B GPIB USB adapter, that have been present since the switch to kernel 4.x.x. *** Snip *** Turned out to be non dma compatible buffers. SVN R1654 fixes it. Please let me know if it works for you. thanks, -Dave *** Sip *** Also: We're building a RasPi based logging platform for VoltNuts for now @ http://www.eevblog.com/forum/metrology/raspberry-pi23-logging-platform-for-voltnuts/ CFO

Pretty much every wifi transceiver is adc sampled so the frames are "timestamped", but the adc sample time may not get pushed up. The rtt/tof for the large umbrella of localization applications, I would imagine will be impented even farther back in the rx chain. On Sun, Jan 15, 2017 at 11:42 AM jimlux <jimlux@earthlink.net> wrote: > On 1/15/17 8:26 AM, Bob Camp wrote: > > > Hi > > > > > > Ok, that’s a pretty good paper. At least it shows data and digs into the > details. > > > It also would lead one to believe that a “Time Nuts” grade sync system > might > > > be a hackable sort of thing …… hmmm…..Given how highly integrated these > > > WiFi chip sets have become, that probably is a fantasy. > > > > > > > maybe, maybe not.. > > > > They might have implemented the time stamping feature (like in that WiFi > > Arduino thing) but the details are poorly documented, and of course, > > everyone is different. > > > > But it's a start. > > > > and 802.11v appears to be the "standard" for how to do it in a > > "standards compliant" way. > > > > > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > >