[time-nuts] Expected 10 MHz offset from a GPSDO?

Bryan _ bpl521 at outlook.com
Sat Aug 20 05:43:31 EDT 2016


Bob:
With a GPSDO as a general rule is there much variation of the 0.005 to 0.02 ppb range. Would there me much if only 2 satellites were visible but the unit was no in holdover vs say 6 satellites. I assume there is probably a lot of variables such as quality of GPSDO and OCXO, multi path interference, antenna location, etc, but worse case what would a user expect assuming the unit isn't in holdover.

-=Bryan=-

> From: kb8tq at n1k.org
> Date: Fri, 19 Aug 2016 20:03:59 -0400
> To: time-nuts at febo.com
> Subject: Re: [time-nuts] Expected 10 MHz offset from a GPSDO?
> 
> Hi
> 
> Ok let's toss some numbers into the mix.
> 
> The counter time base one day after calibration is in the 0.5 to 1.5 ppb range.
> 
> The LPRO ten years after it left the factory is in the 0.5 to 1.5 ppb range.
> 
> The GPSDO when running properly should be in the 0.005 to 0.02 ppb range at one second.
> 
> One ppb at 10 MHz is 0.01 Hz. It also is a the resolution limit on a 5335 at 1 second.
> 
> Bob
> 
> 
> 
> > On Aug 19, 2016, at 5:29 PM, Mark Sims <holrum at hotmail.com> wrote:
> > 
> > Try driving your counter frequency reference input with the LPRO or comparing the LPRO with the GPSDO.  The LPRO is (most likely) much more accurate the counters' internal timebase.
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