On Thu, Aug 8, 2019 at 7:01 PM Tim Lister <[email protected]> wrote:
> On Thu, Aug 8, 2019 at 8:07 AM Adam Kumiszcza <[email protected]> > wrote: > > > > Hi everybody! My first post here, I hope the subject is adequate for this > > mailing list. > > > > I'm using a tiny layer 1 NTP server consisting of Raspberry Pi 3B+ with > > Ublox MAX-M8Q expansion board providing GNSS (currently GPS, Galileo and > > Glonass, sometimes I switch to Beidou, too) reference with PPS + a simple > > patch antenna hanging near the window. Offset, jitter and rms are most > > often smaller than 1 µs. The server is included in NTP pool. > > > > I'm using several Windows 10 machines on the same LAN, all using NTP > client > > software from Meinberg. The typical offset and jitter in those are about > > 100-500 µs. I would like to make it lower. I've heard that one of the > > latest versions of Windows 10 provides support for PTP protocol (IEEE > > 1588v2). Hence my questions: > > > > 1. Did anybody try using it on Windows 10 already? From what I can tell > > right now, there's only a demonstration web site showing it works when > > using Ubuntu Linux as a virtual machine [1]. Or should I wait a bit for > > more robust implementation? > > EndRun Technologies > (https://endruntechnologies.com/products/grandmaster-clocks/ptp-slaves) > make mention of a Windows PTP slave - not sure if it's the same > version you have found. It does also make mention of the fact that > precision is limited on Windows depending on version although from > what I gather from the satsignal.eu that precious on Windows improved > with 7 or later. > It's additional software here. As far as I understand, recent Windows 10 versions introduced under-the-hood internal implementation of PTPv2, with kernel support for it. > > 2. Do I guess correctly that current implementation of PTP works only on > > Ethernet? Some of the computers are on wlan. > > For deterministic timing I think it has to be Ethernet and as outlined > in their white paper (https://endruntechnologies.com/pdf/PTP-1588.pdf) > it works best if you have hardware timestamping in the NICs at each > end and IEEE1588 compatible network switches (and even when the claim > to support it, apparently they don't always do it properly: > > https://www.linkedin.com/pulse/ptp-support-high-end-ethernet-switches-heiko-gerstung > ). > You may be able to do some Pi-to-Windows PTP experiments with a > crossover cable. Not sure if the Pi has the hardware timestamping, > seems unlikely given the low cost of the Pi's as in the 3B+ (and below > I believe) the Ethernet is provided by a combined Ethernet/USB2 hub > and limited by the speed of the USB2. > Pi 3B+ has only software timestamping, and even this is not completely clear (I had to patch the kernel). Pi-to-Windows direct crossover testing is a great idea! Best regards, Adam _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
