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!
