[ntp:questions] Windows time question.

David Lord snews at lordynet.org
Tue May 3 11:58:01 UTC 2011


DaveB wrote:
> In article <iou44b$q9o$1 at dont-email.me>, david-
> taylor at blueyonder.co.uk.invalid says...
>> "Rob" <nomail at example.com> wrote in message 
>> news:slrnir54hp.hnj.nomail at xs8.xs4all.nl...
>> []
>>> The initial question:
>>> | Due to my wandering use of a laptop for, "work" (cough!)   Often away
>>> | from the office, and our server, but with local internet access (Hotel
>>> | WiFi etc).
>>> |
>>> | What UK based "RELIABLE" (cant emphasize that enough) UK time 
>>> server(s)
>>> | would the group recomend I point Windows time sync' to?
>>>
>>> and the subsequent discussion about the NTP pool and its reliability,
>>> and how many servers from the pool one would resonably use to get good
>>> results without overloading a voluntarily provided service, is a good
>>> and valid discussion on its own.
>>>
>>> There is no need to pollute that discussion by talking about GPS 
>>> receivers
>>> yet again.  It is not a solution for the original poster, and it does
>>> not contribute to the discussion about either of the topics brought up.
>>>
>>> You may be exited about your new GPS receiver toy, but there is no need
>>> to recommend that hammer as the only tool one will ever need.  It isn't.
>> .. and why shouldn't someone consider taking a GPS 18x LVC as a portable 
>> time reference?
>>
> 
> As the OP who started this (long and sometimes ammusing) thread...
> 
> I do carry a GPS receiver with me, but sadly not PPS capable, I use it 
> for location determination/tracking/navigating etc.   Maybe I should 
> include a GPS18 or 16 in the already bulging Laptop bag I lug arround.
> 
> In any case, with most hotel's now, you can't open the windows (the ones 
> in the outside wall of the room, not the OS!) enough, to get anything 
> sensible outside to get a decent view of the sky.   Many do not open at 
> all, many are also now using "K Glass" that has a coating on it for 
> thermal reasons, that appears to seriously attenuate GPS signals.
> 
> I have also encountered problems many times with GPS RX's used for 
> "normal satnav" purposes in the vicinity of some hotels, due I suspect 
> to the *Huge* ammount of EM crap that seems to radiate from such 
> establishments these days, in many, you cant even listen to FM radio in 
> your room, let alone AM (or Shortwave for WWV etc!)  So much for EMC 
> regs eh?
> 
> Even mobile phone signals are heavily attenuated (or spoiled?) "in 
> room", leaving only the expensive hotel wifi network (if it's working) 
> as a comm's route out...   Not that mobile internet is any good for 
> timekeeping!  I think from the latencies I sometime see, they use 
> moonbounce to get back to base....
> 
> I have in one instance, had to use one of the "long range" BlueTooth 
> adapters, to bt to a phone in the car, from a room (that luckily) 
> overlooked the car park, to get any 'net conectivity.  Naff latency, but 
> I got my work done!   I've also done the same trick, hoisting the phone 
> some 50' up a mast in a plastic bag on a halyard (it was raining!) to 
> get a signal on a remote customer site with no landline, then bt in 
> remote sim mode to use the phone from the car!  And that was just for a 
> voice call! 
> 
> As earlier, the problem was a clash of interests between XP's own 
> W32Time, and the National Instruments time discoverer/server, foisted on 
> me by an update to other software (from our principle) that blindly and 
> stupidly updates ALL of the NI installed tools and utilities, causing 
> other problems too, not just the lockups.
> 
> Now I've id'd the problem, I can work arround it.   But as earlier, the 
> info about the pool servers and (perhaps) not needing the location tags 
> was good to know, though from what else I read, it's debatable if it 
> will work reliably and predicably in practice for a traveling laptop.

Sometimes I use a notebook from a pub and am limited to using
mobile broadband dongle via usb port. Latency can be as high
as 10 seconds if ntp is used normally so I use 'burst' with a
couple of server lines in my ntp.conf which gets me within a
few milliseconds.  The particular servers I abuse are my own.

I also have a GPS 18x-LVC but would have to use a serial2usb
adaptor which doesn't give me the few microsecond offset vs
PPS via real serial or parallel port and also it's difficult
to find a location that has good GPS reception so I don't
carry it with me. My larger notebooks have both serial and
parallel ports and are within a few microseconds when GPS is
usable.


David

> 
> Thanks for the info and insight peeps.
> 
> Regards.
> 
> DaveB
> 




More information about the questions mailing list