Re: [time-nuts] Excel logarithmic function (was Thermal impact on OCXO)

[Bob Camp]

Hi

In a conventional fit situation, you have < 30 days worth of data and the “time 
constant”
is > 30 days. Put another way bt <= 1 in the normal case. It is only when you 
go out to years
that bt gets large.

Bob

> On Nov 18, 2016, at 9:58 PM, Scott Stobbe  wrote:
> 
> Hi Lars,
> 
> I agree with you, that if there is data out there, it isn't easy to find,
> many thanks for sharing!
> 
> Fitting to the full model had limited improvements, the b coefficient was
> quite large making it essentially equal to the ln(x) function you fitted in
> excel. It is attached as "Lars_FitToMil55310.png".
> 
> So on further thought, the B term can't model a device aging even faster
> than it should shortly after infancy. In the two extreme cases either B is
> large and (Bt)>>1 so the be B term ends up just being an additive bias, or
> B is small, and ln(x) is linearized (or slowed down) during the first bit
> of time.
> 
> You can approximated the MIL 55310 between two points in time as
> 
> f(t2) - f(t1) = Aln(t2/t1)
> 
> A = ( f(t2) - f(t1) )/ln(t2/t1)
> 
> Looking at some of your plots it looks like between the end of year 1 and
> year 10 you age from 20 ppb to 65 ppb,
> 
> A ~ 20
> 
> The next plot "Lars_ForceAcoef", is a fit with the A coefficient forced to
> be 2 and 20. The 20 doesn't end-up fitting well on this time scale.
> 
> Looking at the data a little more, I wondered if the first 10 day are going
> through some behavior that isn't representative of long-term aging, like
> warm-up, retrace (I'm sure bob could name half a dozen more examples). So
> the next two plots are fits of the 4 data points after day10, and seem to
> fit well, "Lars_FitAfterDay10.png", "Lars_1Year.png".
> 
> If you are willing to share the next month, we can add that to the fit.
> 
> Cheers,
> 
> On Fri, Nov 18, 2016 at 1:26 PM, Lars Walenius 
> wrote:
>> 
>> Hopefully someone can find the correct a and b for a*ln(bt+1) with
> stable32 or matlab for this data set:
>> Days ppb
>> 2   2
>> 4   3.5
>> 7   4.65
>> 8   5.05
>> 9   5.22
>> 12 6.11
>> 13 6.19
>> 25 7.26
>> 32 7.92
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Thermal impact on OCXO

[Azelio Boriani]

Are Oscilloquartz's Star-4 commands described somewhere? I can't find
them in the wild...

On Sat, Nov 19, 2016 at 4:34 AM, Mark Sims  wrote:
> Several years ago I replaced the OCXOs in some Tektronix DC5010 counters with 
> surplus Oscilloquartz 8663 DOCXOs.   The darn things have freaky good aging 
> characteristics.   They have been on 24/7 (except for a few brief 
> power-outages) for over 3 years.   After a month I set their freq against a 
> cesium oscillator.   They still show 10 MHz out to 8 or 9 decimal places.
>
> I just got in an Oscilloquartz Star-4 ATDC (automatic temperature / drift 
> compensation) that uses the same DOCXO.   They take 24 hours from a cold 
> start before the ATDC learning kicks in (you can fake it out by power cycling 
> during that interval and it thinks it was a brief outage and reports a 1 hour 
> learning delay).   After an unspecified time (at least several days) the 
> device learns the compensation characteristics and the holdover performance 
> status switches from POOR to IN-SPEC.   I have not yet gotten it past the 
> learning stage...
>
> Oh,  and Lady Heather now speaks Star-4 management interface commands which 
> are also used on a NEC GPSDO that shows up on Ebay... I have one of those on 
> order.
>
> ---
>
>> OSA8663: per year, 3.0E-8, in 10 years < 30.0E-8
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

[time-nuts] Oscilloquartz Star-4 GPSDO (was: Thermal impact on OCXO)

[Mark Sims]

There was a copy uploaded to EEVBLOG.   I uploaded it  and another one that 
Atilla found to ko4bb.com  I don't know if they are out of quarantine yet.

The device does not provide any PPS/OSC info to plot (only a 0.03C res 
temperature reading).   You can set the PLL time constant,  satellite elevation 
mask,  enter manual holdover.It does track SBAS satellites.  It also sees 
sat PRN 4,  which is not-active.

The BG7TBL Star-4 GPSDO does not make the management interface available on the 
RS-232 connector.  I wired an external RS-232 converter to the management port 
(he breaks out the 26-pin Star-4 connector to pads).  I will probably re-wire 
his RS-232 signals (which are tapped off an internal Ublox serial interface) to 
the management port and get rid of my kludge.  His output normally sends out 
NMEA data, but once you talk to the management port, it switches to Ublox 
binary data.  Sending commands to the Ublox does not appear to do anything.  
The BG7TBL device uses the ATDC version of the Star-4 which is the highest 
spec'd version.

I may also bring out the Star-4 TOD (time of day) signal (which is a 4800 BPS 
NMEA port) to the connector so NTP has something to get time messages from.

---

> Are Oscilloquartz's Star-4 commands described somewhere? I can't find
them in the wild...
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] A (slightly) different apu2 question

[Jay Grizzard]

> 1 This board has got exposed test pads for lots of 1PPS / frequency in /
> out pins tied to timestamping hardware making it very easy to tap into
> them. This is a great opportunity which begs to be exploited.

I was actually unaware that you could discipline these ports like this!
This is actually the first system I'm getting to play with PTP on (to any
serious degree), so I'm afraid I'm missing a lot of desirable background.

RESEARCH TIME!

I got this apu2 specifically to hack the hardware of... I'll report back
once I play with this.

-j
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Inside of FT1200-100

[Christopher Hoover]

tl;dr: I've made some progress and have the1200  oscillator core out of the
dewar:

https://goo.gl/photos/SDHtvgFmftQq6vYJA



I got some 5 thou brass stock and worked it between the rubber sheet and
the dewar.

That seemed to help but it was insufficient free things up -- I busted off
the unused solder lug trying to pull the core out with it.

Having not a lot to lose, I took a chance that the screws going into the
TO-23 went into threaded holes (rather than being clearance holes with nuts
inside).  This was indeed the case.

With two 6-32 threaded rods into the TO-23 threaded holes and and an
appropriately machined piece of mild steel bar stock suspended across the
case , I was able to easily get
the oscillator core out of the dewar by evenly tightening the the nuts on
the bar.Really easily -- I might have been able to pull it out by just
pulling on the bar stock.  I don't know if the shim stock shenanigans were
even needed.

Despite running out the three sloted screws on the "top" around the
circumference,  I'm not into the inside yet.   I don't have the  right
thin-walled socket to remove the nuts at the opposite end.

I found an epoxy covered hole on the top.   It is/was under the green blob
midway between 1 and 2 o'clock in this picture here
..  There was something blue and
at this point crumbly underneath it.   Not sure yet what, if anything, is
beyond all of that.  I'm hoping for a trimmer cap.  :-)

-- Christopher.
73 de AI6KG




On Mon, Sep 26, 2016 at 9:24 PM, Chuck Harris  wrote:

> Back when I was going to work on mine, I was thinking of
> prying the rubber away from the aluminum oven with something
> like a feeler gauge, but also using some naptha (lighter fluid)
> to help release any adhesive...  I didn't get around to doing
> it, but that was the way I was going to progress.
>
> -Chuck Harris
>
> Ed Palmer wrote:
> >
> >
> > On 2016-09-26 10:00 AM, Christopher Hoover  wrote:
> >>> >
> >>> >You might be able to slide something like a feeler guage down between
> the
> >>> >oven and the rubber blanket to break the oscillator free.  The oven
> on mine
> >>> >is a plain metal cylinder.  This way, the rubber sheet should protect
> the
> >>> >Dewar from your feeler guage.  On mine, the mounting bolts for the
> 2N3792
> >>> >transistor both have ground lugs.  I think I see them on yours.  You
> could
> >>> >hook something through the ground lugs and use that to pull the
> oscillator
> >>> >out of the rubber sheet and then remove the sheet later.
> >>> >
> >> Thanks Ed,
> >>
> >> I think the rubber sheet on mine is against metal.  I haven't yet seen
> the
> >> glass dewar.
> >>
> >> The adhesion is huge.
> >>
> >> Do you know if the holes opposite the 2N3792 are threaded?   If they
> are, I
> >> might try running the screws out and using those holes with longer
> screws
> >> as my pull points.I can't pull on the lugs hard enough -- I've
> tried.
> >>
> >> -christopher.
> >> 73 de AI6KG
> >
> > Yes, you have seen the Dewar.  The silvery ring that's outside the
> rubber is the top
> > of the Dewar.  What you have to do is unstick and unfold the rubber
> starting from the
> > open area in the center.  Work your way outward.  The rubber is only 2
> or 3 mm
> > thick.  Once you completely clear the rubber out of the way, you'll see
> the edge of
> > the oven.  The TO-3 transistor is mounted on top of the oven assembly.
> Once you can
> > see the edge, you have to slide something like a long feeler gauge down
> along the
> > edge of the oven to break it free from the rubber.  Work your way all
> around the
> > oven.  It's about 85 mm long.  It'll still be stuck on the bottom, but
> you might be
> > able to pull it free.
> >
> > When I took mine apart, I ended up tearing off all the rubber at the top
> and then
> > cutting out that ring of hard foam to get at the Dewar so I could smash
> it more.  I'm
> > guessing you'd rather not do that! :)  But sacrificing the rubber on the
> top might be
> > okay, if you have to.
> >
> > Sorry, but I don't know if the mounting holes for the transistor are
> threaded or
> > not.  In any case, since the oven and Dewar are bonded to the rubber,
> you're pulling
> > on the Dewar when you pull on the oven.  Not a good plan until you break
> the oven
> > free from the rubber.  Those Dewars are built in a rather fragile
> manner.  Your
> > typical home Thermos is much more robust.
> >
> > Ed
> >
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>
___
time

[time-nuts] Need for a document comparing time interval counters

[Dr. David Kirkby]

If anyone has the time & inclination, a document comparing different time 
interval counters would be useful to budding time nuts. There are quite a few 
different models at prices that are affordable to many.

I have had a HP 5370B and a Stanford Research  SR620, but have neither now. I 
regretted selling the HP, but then after buying the SR620, I swapped that and a 
4.2 GHz HP signal generator for an HP 4291B 1.8 GHz impedance and material 
analyzer. 

I was looking for something cheap,  but see a used Keysight 53230A on eBay for 
considerably more than a new one from Keysight. It had a "make offer" so I 
could not resist pointing out a new one is much less, and making a redicously 
low offer of $1000. I doubt it will be accepted,  but one never knows.  I once 
got a current Ketsight product for 2% of the current price,  so anything is 
possible.  

But a  comparison of TI counters,  and a discussion of the important 
specifications would be njce. 


.Dave. 
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.