[ntp:questions] ESR looking for good GPS clocks

Terje Mathisen "terje.mathisen at tmsw.no" at ntp.org
Fri Mar 9 06:57:33 UTC 2012


Bruce Lilly wrote:
> On Mon, 05 Mar 2012 20:18:31 +0000, unruh wrote:
>
>> The problem is that parallel ports are far rarer than serial ports these
>> days, and even rarer than usb ports. And you would then have to get the
>> output of that counter into the computer. A bit more than $100 for the
>> whole thing I suspect.
>
> Here's an outline of how this can be easily done for far less than $100
> of hardware: any parallel output for which a suitable driver exists can

The more I look at this, the more I settle down on using Ethernet as the 
communication channel!

Something like the Soekris board reduced to the size of a pack of cards, 
with a (timing) gps chip on a daughter card, and an Ethernet port for 
communication. Preferably using a cheap TCXO or more expensive OCXO for 
local holdover and stability. The TCXO could be synthesized by moving 
one of the regular temperature monitoring channels to the crystal. (We 
have seen experiments doing this with the normal cpu & hard disk temp 
monitors, they seemed to give an order of magnitude reduction in 
temperature-induced excursions.)

I.e. the recently posted link to an ntp black box server embedded in an 
outdoor-proof antenna enclosure, but a couple of orders of magnitude 
cheaper. :-)

Terje
-- 
- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"



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