Hello, I am trying to sync the system clocks of two desktop/laptop computers within sub millisecond accuracy.
The goal is to have a setup for measuring One Way Delay of UDP packets between two moving nodes, over a long-range wireless network. My plan is to set up the two machines as Stratum-1 NTP servers using 1PPS GPS output over RS-232 and NTP. Specifically, I want to: - Use an external GPS receiver with 1 PPS output and interface it via RS-232/USB port to the desktop/laptop - Use LinuxPPS or some other Kernel-level PPS interfacing library to receive the pulses from the Serial port. - Compile ntpd to use the PPS source for sync. - Patch the Linux kernel if needed (RT_PREEMPT and PPS related stuff) The main problem I am facing is how to choose a GPS receiver that will give the required acuracy and fit my budget (< EUR 150 a piece). From the foll. resources, it seems that GPS-based disciplining for NTP is possible in both Windows and Linux: http://www.satsignal.eu/ntp/NTP-on-Windows-serial-port.html http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm Ideally I would prefer to use a receiver that provides an accurate 1PPS pulse over USB that can enable absolute accuracy of the computer system clock under 1ms. Any suggestions/comments on my approach are much appreciated. Thanks, Sandip _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
