Re: [time-nuts] Low noise quartz crystal oscillator by Bruce Griffiths

[Bob Camp]

Hi

They do it pretty much the same way everybody else makes the same
sort of oscillators. Design, build,  tune / select, test, re-tune/ select, 
re-test.
The amount of test / tune depends enormously on what level of oscillator 
is being made. > 80% of the volume shipped gets relatively less effort than 
the other 20%.

Bob

> On Oct 28, 2015, at 6:24 PM, Alexander Pummer  wrote:
> 
> Hi Rick,
> any info on how Wenzel makes that low noise oscillators?
> 73
> KJ6UHN
> Alex
> 
> On 10/28/2015 3:04 PM, Richard (Rick) Karlquist wrote:
>> Do you have a specific URL for "hacking oscillators"?  I can't
>> find it on Rubiola's web site.
>> 
>> Rick
>> 
>> On 10/28/2015 1:32 PM, Gerhard Hoffmann wrote:
>>> Am 28.10.2015 um 19:22 schrieb KA2WEU--- via time-nuts:
 This oscillator seems to have been more a frequency standard then a noise
 standard. Today's 10 MHz oscillators are different/better, such a
 crystal is
 no  longer available/made.
>>> Yes. Rubiola gives it the credit of being able to be mass-produced, and
>>> it _was_
>>> one successful product. There is a section in "hacking oscillators" on it;
>>> my copy of the book is 200 miles away right now.
>>> 
>>> regards,
>>> 
>>> Gerhard, DK4XP
>>> 
>>> 
>>> (see www.rubiola.org)
>>> ___
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Re: [time-nuts] The Pendulum Paradigm by Martin Beech, 2014

[Jim Lux]

On 10/28/15 7:48 PM, Jim Lux wrote:

On 10/28/15 7:23 AM, Peter Reilley wrote:

I have been pondering pendulum clocks.   I was wondering what the ADEV
of a
pendulum would show.   I assume that you could see the errors in the
gear train.
You should see the period of each gear.   You should see the spring wind
down
and being rewound.

Further, would you be able to see the phase of the moon and the tides?
This
is using the pendulum as a gravimeter.   Would it be sensitive enough
for that?



yes.. it's in the sub-ppm range, as I recall.

Period goes as sqrt(L/g)


from wikipedia
lunar tidal acceleration at the Earth's surface along the Moon-Earth
axis is about 1.1 × 10−7 g, while the solar tidal acceleration at the
Earth's surface along the Sun-Earth axis is about 0.52 × 10−7 g


So sqrt(1/(1+1E-7))... about 0.05 ppm



so you'd need an ADEV <1E-9 at a tau of 12 hours



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Re: [time-nuts] Low noise quartz crystal oscillator by Bruce Griffiths

[Jim Lux]

On 10/28/15 4:29 PM, Adrian wrote:

That's chapter 6 of his book.
http://rubiola.org/indexx-oscillator-noise.html
Just scroll down for the phase noise plots.
The left hand column of plots contains the essentials.

Adrian





what would be nice is some similar simple analysis for lower performing 
oscillators.. (like the oscillator in a PC, or run of the mill 1-10 ppm 
TCXOs)



tvb has some on his website.

I guess there's stuff around, but it's not all gathered together.


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Re: [time-nuts] Leap seconds coming up for debate, yet again

[Tony Finch]

Mark Sims  wrote:

> http://www.theregister.co.uk/2015/10/29/leap_second_international_comms_conf/

> Interesting take-away... 2012 leap second caused lots of snafus...
> 2015 leap second barely noticed.  The computer world seems to have
> finally payed the leap second the respect that it deserves and now has
> it under control.

Most Cisco routers had to be disconnected from NTP to avoid a
leapsecond-related crash.

Large cloud providers are doing leap smear not leap seconds.

Hundreds of servers in the NTP pool got it wrong.

It's still a collosal mess.

Tony.
-- 
f.anthony.n.finch    http://dotat.at/
Bailey: South 7 to severe gale 9. High or very high. Rain or showers. Good,
occasionally poor.
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Re: [time-nuts] The Pendulum Paradigm by Martin Beech, 2014

[Azelio Boriani]

Yes, but first you need a very stable pendulum clock as pointed out by
TVB, a stability better than 0.05ppm for a mechanical clock is a real
challenge.



On Thu, Oct 29, 2015 at 12:56 PM, Jim Lux  wrote:
> On 10/28/15 7:48 PM, Jim Lux wrote:
>>
>> On 10/28/15 7:23 AM, Peter Reilley wrote:
>>>
>>> I have been pondering pendulum clocks.   I was wondering what the ADEV
>>> of a
>>> pendulum would show.   I assume that you could see the errors in the
>>> gear train.
>>> You should see the period of each gear.   You should see the spring wind
>>> down
>>> and being rewound.
>>>
>>> Further, would you be able to see the phase of the moon and the tides?
>>> This
>>> is using the pendulum as a gravimeter.   Would it be sensitive enough
>>> for that?
>>>
>>
>> yes.. it's in the sub-ppm range, as I recall.
>>
>> Period goes as sqrt(L/g)
>>
>>
>> from wikipedia
>> lunar tidal acceleration at the Earth's surface along the Moon-Earth
>> axis is about 1.1 × 10−7 g, while the solar tidal acceleration at the
>> Earth's surface along the Sun-Earth axis is about 0.52 × 10−7 g
>>
>>
>> So sqrt(1/(1+1E-7))... about 0.05 ppm
>>
>
> so you'd need an ADEV <1E-9 at a tau of 12 hours
>
>
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>
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[time-nuts] Looking for Datum/Symmetricom MONITOR.EXE software

[Skip Withrow]

Hello Time-Nuts,

Looks like the TLI interface on my PRS-50 has died (I just can't get
anything through either serial port - 9600,8,N,1), and I need to switch the
auxiliary output from its current 5MHz to 10MHz.  When I remove the TLI
interface I can see status over the rear RS-232 connector at 2400,7,O,2, so
it looks like it is working.  Trouble is, it looks like I need the old
Datum DOS monitor.exe program to be able to talk to the PRS-50 now.  Google
doesn't seem to have been my friend, if anyone has it squirreled away I
would very much appreciate a copy.  My guess is that this software was used
with the PRS-45 also.

There is also a Windows program called Instrument Monitor that works with
the 2400,7,O,2 interface, but doesn't seem to be able to change the
auxiliary port or if it can, let me know how).  The Monitor2, Monitor3, and
Hyperterminal can only be used with the TL1 command language.  I have
copies of all of them (but are now useless).

Thanks in advance for any help.

Regards,
Skip Withrow
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Re: [time-nuts] Looking for Datum/Symmetricom MONITOR.EXE software

[Bob Stewart]

Hi Skip,

You might try contacting Symmetricom directly.  That's how I got my copy of 
monitor3.exe for my PRS-45A.  You can change the baudrate etc on monitor3.exe.

Bob

  From: Skip Withrow 
 To: time-nuts  
 Sent: Thursday, October 29, 2015 9:18 AM
 Subject: [time-nuts] Looking for Datum/Symmetricom MONITOR.EXE software
   
Hello Time-Nuts,

Looks like the TLI interface on my PRS-50 has died (I just can't get
anything through either serial port - 9600,8,N,1), and I need to switch the
auxiliary output from its current 5MHz to 10MHz.  When I remove the TLI
interface I can see status over the rear RS-232 connector at 2400,7,O,2, so
it looks like it is working.  Trouble is, it looks like I need the old
Datum DOS monitor.exe program to be able to talk to the PRS-50 now.  Google
doesn't seem to have been my friend, if anyone has it squirreled away I
would very much appreciate a copy.  My guess is that this software was used
with the PRS-45 also.

There is also a Windows program called Instrument Monitor that works with
the 2400,7,O,2 interface, but doesn't seem to be able to change the
auxiliary port or if it can, let me know how).  The Monitor2, Monitor3, and
Hyperterminal can only be used with the TL1 command language.  I have
copies of all of them (but are now useless).

Thanks in advance for any help.

Regards,
Skip Withrow
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[time-nuts] Wildwood eLoran on air schedule

[paul swed]

The Wildwood eLoran Transmitter will be on air for testing purposes from
0900 (EST) on 03 November until 1200 (EST) on 06 November and then again
from 0900 (EST) on 09 November until  1500 (EST) on 13 November. Wildwood
will be broadcasting as 8970 Master and Secondary.
Regards
Paul
WB8TSL
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Re: [time-nuts] Datum TS2100 10MHz frequency drift

[Esa Heikkinen]

Philip Zahariev via time-nuts kirjoitti:


Unfortunately I'm not happy with results because 10 MHz output signal
after GPS lock (both leds on front "Locked" and "tracking" are "ON")
has frequency drift (phase shift) with period around one second plus
minus ~18 deg (+-5 ns) compared to other 10 MHz. I measure this by 2
channel scope on 10 nS sweep, first channel connected to TS2100 10


Yes it works like that and it seems to update the DAC value once per 
second. Frequency wobbling is perfectly in sync with PPS output, which 
is kind of logical.


If you look TS2100 manual it says "stand alone time server" which means 
it's designed to serve as time standard - not as frequency standard. If 
you need stable frequency then you should try with Rubidium oscillator 
or with some other GPS unit. For example Thunderbolt has much more 
stable frequency output than TS2100, but it's also a timing receiver, 
not frequency standard.


However with OCXO and GPS upgrades you will get more than 10 times 
better timing than original TS2100. Without upgrades the TS2100 PPS is 
just below 1 microsecond, with MTI OCXO and Heol Design N024 GPS board 
it's about +-50 ns. So it's relatively good for every day timing 
purposes.. :)


Of course you could try could be to play with timing constant settings 
but I don't think it would help anything if the DAC is still written 
once per second. But if you find better values please let us know!


Best regards,

--
73s!
Esa
OH4KJU
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Re: [time-nuts] Historical frequency data of UK grid

[Daniel Mendes]

Very nice... thank you!

Daniel

Em 28/10/2015 19:53, Dr. David Kirkby (Kirkby Microwave Ltd) escreveu:

Unlike the USA, the UK has just one grid. Someone pointed this out to me,
which looks an interesting visual display

http://www.gridwatch.templar.co.uk/

but there are links to the raw historical data, which includes frequency. I
have not looked into how much data is available, but it might interest
some, especially if you have made your own frequency measurements.



Dave
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[time-nuts] Leap seconds coming up for debate, yet again

[Mark Sims]

http://www.theregister.co.uk/2015/10/29/leap_second_international_comms_conf/
Interesting take-away... 2012 leap second caused lots of snafus...  2015 leap 
second barely noticed.   The  computer world seems to have finally payed the 
leap second the respect that it deserves and now has it under control.

  
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