Re: [time-nuts] Thermal effects on cables --> ADEV

May I suggest to turn the 24 hours reset period into a parameter? On Fri, Jan 13, 2017 at 8:45 PM, Tom Van Baak wrote: > Mark, Ole, > > Yes, averaging can both enhance precision but also destroy information. In > many cases too much data is a bad thing. The solution is to

Re: [time-nuts] Thermal effects on cables --> ADEV

I think their advice was to limit the ADEV calculation for some tau to 300 bins. The standard error on estimating the standard deviation is ~ +- 5% for 200 samples. So loosely speaking in the neighborhood of 100-300 bins the resulting adev will have an rms uncertainty of roughly 5%. So limiting

Re: [time-nuts] Thermal effects on cables --> ADEV

Mark, Ole, Yes, averaging can both enhance precision but also destroy information. In many cases too much data is a bad thing. The solution is to add another dimension to the plot. Stable32 does this with DAVAR (dynamic Allan variance). TimeLab has a multi- "trace" feature. Both of these break

Re: [time-nuts] Thermal effects on cables --> ADEV

Hi That’s the way I read what they are saying. More or less: Keep the number of samples above 100, but below 300. Bob > On Jan 13, 2017, at 12:30 PM, Ole Petter Rønningen > wrote: > > That IS interesting.. It reads to me that the advice is to keep a "moving 300 > pt

Re: [time-nuts] Thermal effects on cables --> ADEV

That IS interesting.. It reads to me that the advice is to keep a "moving 300 pt ADEV" when continously monitoring a (pair of) frequency source in e.g a VLBI site - the reason for limiting it to 300 pts being that much more than that is likely to average out potential issues.. Does that make

Re: [time-nuts] Thermal effects on cables --> ADEV

You are certainly justified to be cautious of only using an xDEV for state of health. I don't know what GPS does for example to mark SV's as healthy or not healthy. On Fri, Jan 13, 2017 at 1:11 PM, Bob Camp wrote: > Hi > > I do agree with their point that systematics will get

Re: [time-nuts] Thermal effects on cables --> ADEV

Hi I do agree with their point that systematics will get buried in giant data blocks. What I’m not quite as sure of is the utility of even 300 sample blocks to spot systematic issues. Bob > On Jan 13, 2017, at 1:08 PM, Scott Stobbe wrote: > > I think you might be

Re: [time-nuts] Thermal effects on cables --> ADEV

I think you might be overthinking their point, that if you plan to use an xDEV as a measure for state of health, don't use years worth of data. Otherwise it could be days before the xDEV visually changes. On Fri, Jan 13, 2017 at 11:04 AM, Bob Camp wrote: > Hi > > There’s an

Re: [time-nuts] Thermal effects on cables --> ADEV

Hi There’s an interesting comment buried down in that paper about limiting ADEV to < 300 samples per point. Their objective is apparently to better highlight “systematic errors”. I certainly agree that big datasets will swamp this sort of thing. I’m not quite sure that I’d recommend ADEV to