[time-nuts] Small time server for mobile use.

[Chris Albertson]

The quickest no-cost way to get decent hold over if all you need is
about 100 ms is to configure all you NTP users to be part of an
"orphan" network.  When the outside NTP server is lost the island will
look at the set of local NTP systems that agree with each other.   So
you in effect use the most stable internal clocks for hold over.   It
is just a matter if setting up all the ntp.conf files on all the
computers to do this.

On Tue, May 12, 2015 at 3:03 PM, Bob Darlington <rdarlington at gmail.com> wrote:
> What's your budget?  I've done this with 1U sized NTP servers from
> Symmetricom (S300 and S350 systems) for mobile military use.  These are a
> few thousand bucks a pop.  They're rugged, and held up just fine in places
> the military goes.Compared to the rest of the system I was working on, this
> was quite small in comparison and we used more than one at each location.
> My personal one died recently so I'm working on developing a cape for the
> BeagleBone Black.  The prototype is working just fine so far so I'm moving
> forward with a board layout and eventual sale to the list members if there
> is any interest (I'm not asking for interest yet).
>
> -Bob
>
> On Tue, May 12, 2015 at 11:11 AM, Mark Spencer <mark at 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
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-- 

Chris Albertson
Redondo Beach, California