[time-nuts] ok, newbie questions

jimlux jimlux at earthlink.net
Fri Nov 26 23:48:06 UTC 2010


W2HX wrote:
> Ahh. Very interesting explanation. So is it somewhat correct to assume (yes,
> I know) that for a stationary (non-mobile) environment, these extra sats
> don’t make much difference? This seems to be what the explanation is saying.

Depends on your antenna location and type.  The extra satellites help 
reduce the effect of multipath.  And, the overall variance of the 
nav/timing solution is reduced when you put more signals into the 
solution (e.g. a sqrt(N) sort of thing)


> 
> Ok. So let me see. For a frequency standard for use in lab equipment, it
> appears that short term, phase noise and other sources of noise are the
> things to be concerned with  to get better results. These seem to really be
> accomplished with a good oxco.  However, if I want a very accurate
> time-of-day clock for long periods of time, then I need long term stability
> which is where the GPS comes in.  Do I have this right?

Yes.

> 
> So if I want a really souped-up freq standard for my lab, then I should
> concentrate on finding the best oxco I can (which may be disciplined by the
> GPS or manually occasionally calibrated to GPS), and use the best power
> supply I can find.  These seem to be what I should concentrate on rather
> than more channels. 
> 

Yes.




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