On Tue, May 12, 2015 at 7:11 PM, Mark Spencer <m...@alignedsolutions.com> wrote: > Hi sorry for a possibly OT post. > Has anyone had practical experience with small commercially available time > servers / ntp servers suitable for mobile use in a vehicle.
I don't know about any commercially-available products, but it sounds like it'd be pretty straightforward to do with a Raspberry Pi or something similar if you don't mind a little bit of DIY. What constraints do you have on budget, size, power requirements, and cooling? > The use case is I am in need of an accurate (ie. within 100 ms) time source > for several pc's in moving vehicle. Being able to run directly off a 13.8 > or 28 VDC source would be a major plus but AC power is also available. The Pi runs on 5V DC. DC-DC buck converters that can convert 7-35V to 5V DC are cheap, efficient, and widely available. Shouldn't be a problem. > Hold over if there are gaps in GPS coverage is also a major plus. How long would you need holdover? Seconds or minutes (e.g. driving through a tunnel)? Hours? Days? Would the computers in the vehicle be subject to large temperature shifts? A Pi should be able to handle +/- 100ms of holdover in the minutes-to-hours range using NTP. > We already have a GPS with a 1 pps output, but an integrated box with it's > own GPS would be best. A tiny integrated module like the Adafruit Ultimate GPS breakout[1] is cheap, handy, and emits a 1PPS signal. It's also extremely small and can be purchased in "hat" form[2] that mounts directly to the Pi. Cheers! -Pete [1] https://www.adafruit.com/products/746 [2] https://www.adafruit.com/products/2324 -- Pete Stephenson On Tue, May 12, 2015 at 7:11 PM, Mark Spencer <m...@alignedsolutions.com> wrote: > Hi sorry for a possibly OT post. > Has anyone had practical experience with small commercially available time > servers / ntp servers suitable for mobile use in a vehicle. > > The use case is I am in need of an accurate (ie. within 100 ms) time source > for several pc's in moving vehicle. Being able to run directly off a 13.8 > or 28 VDC source would be a major plus but AC power is also available. > > Hold over if there are gaps in GPS coverage is also a major plus. > > We already have a GPS with a 1 pps output, but an integrated box with it's > own GPS would be best. > > Yes I am aware I could feed a 1 pps signal into a laptop and use that as a > time server and I may end up going that route. > > There is a small Ethernet LAN in the vehicle. The pc's currently get their > time via a wireless connection to various NTP servers. I need to be able to > ensure accurate time on the PC's if there is no wireless coverage. > > > This is for a one off project so piecing together various parts is an option > but a single box COTS solution would be nice. I've found a few candidates > via web searches but would welcome any feed back. > > Thanks in advance > > Mark Spencer > _______________________________________________ > 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. -- Pete Stephenson _______________________________________________ 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.