[time-nuts] new member with questions NTP, PRS, GPS, ocxo

Jim Lux jimlux at earthlink.net
Sat Aug 18 12:25:43 UTC 2012

On 8/17/12 10:41 PM, Mark Spencer wrote:
> Regarding the NTP server another option is to buy a stand alone NTP server that can accept a 1pps and or 10 Mhz input, and feed it the GPS or other reference of your chosing.  I picked up a Datum unit from ebay which is currently fed 1pps from a Jackson Labs Fury.  It also accepts 10 Mhz as well which it will use in lieu of it's built in VCXO.
> I agree with the comments about the Fury being a nice plug and play GPSDO solution.   I thought long and hard about going the ebay route and acquring a used HP GPSDO to supplement my Thunderbolt and ended up buying the Fury.   That being said the price differnce between the Fury and a typical used Thunderbolt is signficant.
> I would steer clear of the typical combined NTP, GPS units with TCXO's or VCXO's if you are interested in a using them as a source of a highly accurate 10 Mhz reference signal.   The VCXO in my datum NTP server is orders of magnitude less stable than a typical OCXO.

Depends on the options..  The Symmetricom/TrueTime XL-DC had a low phase 
noise option that's pretty good, for instance, so if you found one that 
had the NTP option too, you're in good shape.

> Installing a GPS antenna in a location with a clear view of the sky is also helpfull.

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