[time-nuts] OT: NTP server questions

Wed Dec 1 01:12:23 UTC 2010

Er, rather, add 7 hours.  You get the idea.

On Tue, Nov 30, 2010 at 6:10 PM, Robert Darlington <rdarlington at gmail.com>wrote:

> Hi Greg (and everyone!)
>
> The environment will be dusty and hot and cold and hot and cold...   There
> will be air conditioning but probably not much in the way of filtering.
> Diesel and gas generators run out of fuel, UPS's are probably not going to
> be going along with our stuff since they're too heavy.  I'm actually pretty
> concerned about the heat issue getting out of control and we were kidding at
> work about spontaneous fusion reactions due to the power density.  Our #1
> problem with this project has been time synchronization.  Most of the big
> issues were worked out but sometimes still crop up.  The really big issue we
> see over and over is when people timestamp data and send that data into our
> server, the timestamp doesn't meet our spec.  We require time in "UNIX time"
> in whole numbers of seconds and assume UTC.  You'd be surprised at how many
> months have passed since we first realized people were sending us time in
> miliseconds so all dates looked like they were 40,000 years in the future.
> Our computers are good but we don't have anywhere near that kind of
> predictive capability.  The next big issue was when a sensor or some other
> device sends the data to an intermediary that sends the data to us.  More
> times than not there is a timezone correction done twice.  The sensor will
> send in UTC and somebody will subtract 7 hours to put it into UTC again.
> They're still doing this from time to time.  I recommended we modify our
> message protocol to include a timezone offset to force people to think about
> it but that opens a whole other can of worms.  Do you do it in seconds or
> minutes or hours and introduce a whole other potential where people send in
> the wrong format?
>
> Guys, I think I have everything I need now -at least when it comes to
> mobile time serving.  I really appreciate the responses.   Thank you.
>
> -Bob
>
>
> On Tue, Nov 30, 2010 at 5:35 PM, Greg Dowd <GDowd at symmetricom.com> wrote:
>
>> Rob, you wound me :-)  Actually, the Meinberg unit is a great box.  The
>> commercial devices pretty much all fit the need that you describe.  One
>> caution I would make about them is the note about the environmentals.
>> From experience I can tell you that a HV is a very harsh environment for
>> shock and vib that could, and probably does, sometimes exceed the spec
>> on these boxes.  For a box that has to survive repeated power cycles,
>> dusty conditions with limited airflow and unmanned operation, the
>> commercial boxes are optimal but can still have issues.  For OP, Rb in
>> these devices is primarily targeted at holdover, providing extended
>> periods of NTP service when the input time source (e.g. GPS) is lost.
>> It doesn't sound like this is a requirement for your application.
>>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>> Behalf Of Rob Kimberley
>> Sent: Tuesday, November 30, 2010 7:55 AM
>> To: 'Discussion of precise time and frequency measurement'
>> Subject: Re: [time-nuts] OT: NTP server questions
>>
>> FWIW, you can't go wrong with Meinberg.
>>
>> Several  versions to choose from, reliable, and priced well.
>>
>> Rob Kimberley
>>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>> Behalf Of Robert Darlington
>> Sent: 30 November 2010 2:47 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] OT: NTP server questions
>>
>> Basically I need something to provide time within one second.  I can't
>> roll
>> my own in this case.  At home I have a Soekris box with a custom built
>> gps
>> board for my normal level of time-nuttery but this is not for home.  I'm
>> looking for commercially made rack mount servers that will not have
>> Internet
>> access for reference and will need to rely on gps.   The system will
>> need to
>> serve time to less than 100 systems but it will live in a nasty
>> environment
>> in the back of a humvee (or something like an S-250 electronics
>> enclosure)
>> with no air conditioning of any sort.  I'm currently looking at
>> Symmetricom,
>> Trimble NetRS, EndRun, and Meinberg.
>>
>> Also, I apologize if I'm breaching protocol with this thread.  This is
>> just
>> about the first post I ever saw on this list that didn't get a steady
>> stream
>> of replies.  I was actually questioning if this even made it into the
>> list
>> till I saw this reply.  Yes this is for work and I could really use some
>> opinions on this stuff since dropping $4-6k isn't in my nature to do at
>> home
>> for a network clock so I never gave this thought before.
>>
>> Thanks again,
>> Bob
>>
>>
>> On Mon, Nov 29, 2010 at 11:39 PM, Chris Albertson
>> <albertson.chris at gmail.com
>> > wrote:
>>
>> > What do you need to do?  What precision is required and how many
>> > clients will
>> > you be serving.   For most "normal" uses you don't need a special
>> purpose
>> > server system.  A $600 notebook PC and any GPS unit with a serial
>> > connection and a copy of Linux or BSD.
>> >
>> > On Mon, Nov 29, 2010 at 11:36 AM, Robert Darlington
>> > <rdarlington at gmail.com> wrote:
>> > > Hi guys,
>> > >
>> > > I'm looking to buy an NTP server for a field deployable server
>> > > system.  I currently have a Symmetricom SyncServer S250 which does
>> more
>> than I need.
>> >  I
>> > > am considering buying an S200 (same as the S250 but without the
>> > > ability
>> > to
>> > > connect to an external frequency standard).  My gut feeling is I
>> > > don't
>> > need
>> > > a rubidium oscillator or even an OCXO internally since we'd be going
>>
>> > > from
>> > a
>> > > power on to being used state in under an hour, outside of any kind
>> > > of temperature controlled environment.  Are there any manufacturers
>> > > out
>> > there
>> > > besides Symmetricom that I should be looking at for something like
>> this?
>> > > The unit we're considering buying is about $4k new and is inside of
>> > > our budget.
>> > >
>> > > Thanks,
>> > > Bob
>> > > _______________________________________________
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>> > >
>> >
>> >
>> >
>> > --
>> > =====
>> > Chris Albertson
>> > Redondo Beach, California
>> >
>> > _______________________________________________
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