[ntp:questions] Re: Looking for time sync hardware supported under Linux for under $400?

Tim Keck timkeck at gmpexpress.net
Wed Jan 18 10:23:23 UTC 2006


Richard B. Gilbert wrote:

> You can get an "FS Oncore" GPS Timing receiver from Synergy Systems 
> <http://www.synergy-gps.com/>
> 
> You should plan to purchase one with the "evaluation kit" unless you are 
> equipped to design and produce your own circuit board.  I bought one 
> about fourteen months ago when they were still manufactured by Motorola 
> and paid about $200 US for it.   It comes with a power supply (wall 
> wart) and an antenna.  I've been using it with a Sun Ultra 10 running 
> Solaris 8.   It generally synchronizes within a millisecond or less.
> sunblok_$ ntpq -p
>     remote           refid      st t when poll reach   delay   offset  
> jitter
> ============================================================================== 
> 
> *GPS_ONCORE(0)   .GPS.            0 l    4   16  377    0.000    0.001   
> 0.001
> 
> There are other GPS receivers that will work quite nicely; one sells for 
> around $85 US.   Be certain to get one with a serial (RS-232) interface 
> (the USB interface does not work well in timing applications).  Also be 
> certain to get a receiver designed for timing applications.  Many GPS 
> receivers are designed for navigation and it is generally not possible 
> for a receiver to do both timing and navigation well.
> 

Maybe I'm confused, but aren't the delay, offset, and jitter in 
milliseconds, indicating (here) 1 microsecond offset and jitter?
Tim Keck




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