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

Scott Stobbe scott.j.stobbe at gmail.com
Fri Jan 13 18:27:49 UTC 2017


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 <kb8tq at n1k.org> wrote:

> 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 <scott.j.stobbe at gmail.com>
> wrote:
> >
> > 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 <kb8tq at n1k.org> wrote:
> >
> >> 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 find these things in the first place. My
> >> guess is that
> >> it’s the only spec they have to call the device good or bad in this case
> >> …They don’t seem
> >> to have Hadamard in their list of variances. If I was going after
> >> systematics with a deviation,
> >> that’s the one I’d use. Of course I probably would not use a
> something-dev
> >> in the first place.
> >>
> >> Bob
> >>
> >>
> >>> On Jan 13, 2017, at 1:52 AM, Ole Petter Ronningen <
> opronningen at gmail.com>
> >> wrote:
> >>>
> >>> Hi, all
> >>>
> >>> The question of phase shifts in cables pops up every now and then on
> this
> >>> list - I stumbled across a good table of measured phase shifts with
> >>> temperature in different cable types in this paper:
> >>> http://www.ira.inaf.it/eratec/gothenburg/presentations/ERATEC_2014_
> >> PresentationWSchaefer.pdf
> >>> that I though would be of interest to others.
> >>>
> >>> A quick summary given below, see pdf for full details. Lots of other
> >>> interesting stuff in there also.
> >>>
> >>> Values in ppm/K, for 10 Mhz except when otherwise stated. (The paper
> >> gives
> >>> values for 5, 10 and 100Mhz)
> >>>
> >>> Huber-Suhner Multiflex 141: -6
> >>> RG-223: -131.9
> >>> Semiflex Cable: -11.5
> >>> Huber-Suhner: -8.6
> >>> Times Microwave LMR-240: -3.4
> >>> Times Microwave SFT-205: 7.7
> >>> Meggitt 2T693 SiO2: 30.6
> >>> Andrew FSJ-1 (@5Mhz): 25
> >>> Andrew FSJ-4 (@5Mhz): 10
> >>> Andrew LDF-1P-50-42: 2.8
> >>> Andrew LDF4-50A: 4.7
> >>> Times Microwave TF4FLEX (@100Mhz):6.4
> >>> Phasetrack PT210 (@100Mhz): 2
> >>>
> >>> Ole
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