Harlan, Why? The GPS NTP Server is Stratum-1. If it fails computer clocks will freewheel for hours or days before losing significant time, during which period you can simply order a replacement unit. If that isn’t fast enough, buy two $300 boxes. The “consensus” issue is moot, since a GPS server gets a consensus of clock time from the GPS satellite constellation.
The “enough NTP peers” you speak of are simply not necessary. -mel via cell > On May 1, 2019, at 6:49 PM, Harlan Stenn <st...@nwtime.org> wrote: > > > >> On 5/1/19 4:53 PM, Mel Beckman wrote: >> Ask, >> >> But with a small compact server like the DC-powered TimeMachines Inc unit, >> which costs something like $300, you simply put the server where the >> visibility is and connect back to the nearest Ethernet port in your network, >> up to 300’ away, or virtually any distance with fiber transceivers. We’ve >> installed these in Cantex boxes on a windy, rainy tenth-story rooftop in >> upstate NY and it runs flawlessly, warmed by its own internal heat at >> sub-zero temps, and perfectly happy at ambient temps of 110F. >> >> It’s hard to consider messing with signal converters and pricey >> remotely-powered active antennas when you can solve the problem for $300. :) > > I sure hope you have ntpd set up to peer or get time with enough other > servers. > > H > -- >> -mel >> >>> On May 1, 2019, at 4:44 PM, Ask Bjørn Hansen <a...@develooper.com> wrote: >>> >>> >>> >>>> On May 1, 2019, at 12:22, Mehmet Akcin <meh...@akcin.net> wrote: >>>> >>>> I am trying to buy a GPS based NTP server like this one >>>> >>>> https://timemachinescorp.com/product/gps-time-server-tm1000a/ >>>> >>>> but I will be placing this inside a data center, do these need an actual >>>> view of a sky to be able to get signal or will they work fine inside a >>>> data center building? if you have any other hardware requirements to be >>>> able to provide stable time service for hundreds of customers, please let >>>> me know. >>> >>> [ with my hobby-hat on … ] >>> >>> tl;dr: if any of the below is too much work, just run reasonably well >>> monitored NTP server syncing from other NTP servers. If you want more than >>> that, you need to see the sky. Don’t do the CDMA thing. >>> >>> Depending on your requirements having the antenna in the window may or may >>> not be satisfactory. If it’s fine you probably could just have done a >>> regular NTP server in the first place. For long swaths of the day you >>> might not see too many satellites which will add to the uncertainty of the >>> signal. >>> >>> Meinberg’s GPS antenna has a bit more smarts which helps it work on up to >>> 300 meters on RG58 or 700 meters on RG213. (They also have products that >>> use regular L1 antennas with the limitations Bryan mentioned). >>> >>> https://www.meinbergglobal.com/english/products/gps-antenna-converter.htm >>> >>> They also have a multi-mode fiber box to have the antenna be up to 2km from >>> the box or 20km with their single mode fiber box, if you have fiber to >>> somewhere else where you can see the sky and place an antenna. >>> >>> It will be more than the one you linked to, but their systems are very >>> reasonably priced, too. For “hundreds of customers” whatever is the >>> smallest/cheapest box they have will work fine. Even their smallest models >>> have decent oscillators (for keeping the ticks accurate between GPS >>> signals). >>> >>> The Meinberg time server products (I am guessing all of them, but I’m not >>> sure) also have a mode where they poll an upstream NTP server aggressively >>> and then steer the oscillator after it. I haven’t used it in production, >>> but it worked a lot better than it sounded like it would. (In other words, >>> even without GPS it’s a better time server than most systems). >>> >>> >>> Ask > > -- > Harlan Stenn <st...@nwtime.org> > http://networktimefoundation.org - be a member!
