[time-nuts] ok, newbie questions

W2HX w2hx at w2hx.com
Sat Nov 27 17:11:37 UTC 2010


Aah. This is a very good point about antenna location and extra satellites!
In fact, it is quite possible that the location my antenna will be (outdoors
but not above roof line) may have limited sight.  That's very much

73 Eugene W2HX


-----Original Message-----
From: jimlux [mailto:jimlux at earthlink.net] 
Sent: Friday, November 26, 2010 6:48 PM
To: Eugene Hertz; Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] ok, newbie questions

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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