Hello, How or when will the ublox refclock be added to ntpsec?
Kind regards, Udo from ntp.hackers: Begin forwarded message: Date: Fri, 10 Aug 2018 13:03:19 +0200 From: Lukas Senger <lu...@fridolin.com> To: hack...@lists.ntp.org Subject: [ntp:hackers] u-blox reference clock driver Hi, I've been writing a reference driver for u-blox GPS receivers as part of my master's thesis and thought ntp hackers might be interested in it. Additionally to normal PPS operation this driver can make use of the u-blox's "Timemark" functionality. It does this by enabling the PPSAPI echo, which generates an echo pulse right after receiving a PPS pulse. This echo is connected to EXTINT0 on the u-blox, where it is timestamped. So now I have the PPS timestamp as a local time and the timemark as the receiver time to calculate an offset. The cool thing about this is, that the offset does not include the local interrupt latency anymore, which leads to less jitter. Here's the driver: https://gitlab.cs.fau.de/luksen/ntp-ubx/blob/ubx/ntpd/refclock_ubx.c The echo/timemark feature requires kernel patches on Linux (with gpio pins) and FreeBSD (parallel port). It's probably easiest to test on a Raspberry Pi with the Linux patch and via GPIO pins. Linux patch: https://gitlab.cs.fau.de/snippets/28 FreeBSD patch: https://gitlab.cs.fau.de/snippets/29 I originally tried to send this message some time ago but it seems like there were some problems with the mailing list. By now the thesis is finished and you can find it here: https://wwwcip.informatik.uni-erlangen.de/~in18otin/thesis.pdf --Lukas _______________________________________________ hackers mailing list hack...@lists.ntp.org http://lists.ntp.org/listinfo/hackers _______________________________________________ devel mailing list devel@ntpsec.org http://lists.ntpsec.org/mailman/listinfo/devel
