Thanks for the tip Magnus!
One comment on the 1938 discussion: I recently fired-up my E1938
disciplined by our Fury GPSDO. It took 3+ days for the retrace (aging) to slow
down
significantly. Now it's working really well.
Said
In a message dated 4/11/2009 13:53:41 Pacific Daylight Time,
Mike Monett wrote:
> > Chris
>
> > The biggest problem with the OCXO is probably that it has a square
> > wave output.
>
> > With careful design it is possible to achieve a jitter of a few
> > tens of femtosec for a logic level output from a limiter, but the
> > OCXO designers are u
> Chris
> The biggest problem with the OCXO is probably that it has a square
> wave output.
> With careful design it is possible to achieve a jitter of a few
> tens of femtosec for a logic level output from a limiter, but the
> OCXO designers are unlikely to have used such a limit
Thanks for the info.
My plan is to develop a stable GPS disciplined reference suitable for use as
a reference for Microwave work in the 10 GHz range that can be used in
portable locations with relatively quick start up.
Perhaps the 1938 would be better in the shop where it could be left on for
w
If nobody has already mentioned it, Fluke.1 has the Rockwell
Tu00-D205 high performance 12-channel GPS receiver OEM modules for
$9.99 ea with free shipping worldwide, item number: 290306684157
These appear to have the 10KHz output described at
http://www.jrmiller.demon.co.uk/p
J. L. Trantham wrote:
> I, too, snagged one of these since it has the reputation of being the
> ultimate achievement of crystal oscillator technology with the goal of
Thanks, we thought it was pretty good :-)
>
> Toward that end, since it takes a few minutes for the 1938 to 'lock', is
> there
Must be coupling in via the EFC, then. The phase shift does correlate
precisely with the 1Hz LED. The EFC is just connected to the center tap
of a 1meg pot, which is connected to +VREF and EFC shield.
But, this is just for testing so I could trim the 1938 to my reference
to check drift, of which
I, too, snagged one of these since it has the reputation of being the
ultimate achievement of crystal oscillator technology with the goal of
building a GPS controlled reference using a Brooks Shera controller card and
a GPS receiver.
Toward that end, since it takes a few minutes for the 1938 to 'l
2009/4/13 Magnus Danielson :
>>> Dead time is when the counter looses track of time in between two
>>> consecutive measurements. A zero dead-time counter uses the stop of one
>>> measure as the start of the next measure.
>>
>> This becomes very important when the data to be measured has a degree
>>
Bruce,
2009/4/12 Bruce Griffiths :
> Steve
>
> Steve Rooke wrote:
>> If I take two sequential phase readings from an input source and place
>> this into one data set and aniother two readings from the same source
>> but spaced by one cycle and put this in a second data set. From the
>> first data
wje wrote:
> Fluke.l (China) was selling a number of 1938's on Ebay. I snagged one
> just to have a piece of HP history.
> It works just fine, but I've noticed something a little strange.
>
> Comparing the 1938 to both my cesium and GPS standards, there's a
> distinct periodic 1ns phase shift ev
Hi Mark,
2009/4/13 Mark Sims :
>
> Hello Steve,
>
> Try this... take Tom's sample data set, run the numbers. Then, using a
> good random number generator, make another data set by randomly throwing out
> half (or more) of the samples (to simulate a non ZDT counter). Run the
> numbers agai
Fluke.l (China) was selling a number of 1938's on Ebay. I snagged one
just to have a piece of HP history.
It works just fine, but I've noticed something a little strange.
Comparing the 1938 to both my cesium and GPS standards, there's a
distinct periodic 1ns phase shift every second. Seems to sm
Hello Steve,
Try this... take Tom's sample data set, run the numbers. Then, using a good
random number generator, make another data set by randomly throwing out half
(or more) of the samples (to simulate a non ZDT counter). Run the numbers
again. See how they change. This should give y
Hej Magnus
Magnus Danielson wrote:
> Bruce Griffiths skrev:
>
>> Rex wrote:
>>
>>> Bruce Griffiths wrote:
>>>
>>>
...
Brice
>>> An impostor? An alias? :-)
>>>
>>>
>>>
>>>
>> And I thought I was alluding to aliasing of
Bruce Griffiths skrev:
> Rex wrote:
>> Bruce Griffiths wrote:
>>
>>> ...
>>>
>>> Brice
>>>
>>>
>>>
>> An impostor? An alias? :-)
>>
>>
>>
> And I thought I was alluding to aliasing of the phase noise spectrum not
> the characters of the alphabet.
So it is not a case of shot noise of
Steve Rooke skrev:
> 2009/4/11 Magnus Danielson :
>> Tom Van Baak skrev:
Nevertheless leaving every second sample out is NOT exactly the same as
continous data with Tau0 = 2 s. Instead it is data with Tau0 = 1 s and a
DEAD TIME of 1s. There are dead time correction schemes available
Rex wrote:
> Bruce Griffiths wrote:
>
>> ...
>>
>> Brice
>>
>>
>>
>
> An impostor? An alias? :-)
>
>
>
And I thought I was alluding to aliasing of the phase noise spectrum not
the characters of the alphabet.
Bruce
> ___
> time-nuts mailing
Bruce Griffiths wrote:
> ...
>
> Brice
>
>
An impostor? An alias? :-)
___
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Steve
Steve Rooke wrote:
> If I take two sequential phase readings from an input source and place
> this into one data set and aniother two readings from the same source
> but spaced by one cycle and put this in a second data set. From the
> first data set I can calculate ADEV for tau = 1s and can
Steve
Steve Rooke wrote:
> 2009/4/11 Magnus Danielson :
>
>> Tom Van Baak skrev:
>>
Nevertheless leaving every second sample out is NOT exactly the same as
continous data with Tau0 = 2 s. Instead it is data with Tau0 = 1 s and a
DEAD TIME of 1s. There are dead time correctio
If I take two sequential phase readings from an input source and place
this into one data set and aniother two readings from the same source
but spaced by one cycle and put this in a second data set. From the
first data set I can calculate ADEV for tau = 1s and can calculate
ADEV for tau = 2 sec fr
2009/4/11 Magnus Danielson :
> Tom Van Baak skrev:
>>> Nevertheless leaving every second sample out is NOT exactly the same as
>>> continous data with Tau0 = 2 s. Instead it is data with Tau0 = 1 s and a
>>> DEAD TIME of 1s. There are dead time correction schemes available in the
>>> literature.
>>
Tom,
2009/4/11 Tom Van Baak :
>> Nevertheless leaving every second sample out is NOT exactly the same as
>> continous data with Tau0 = 2 s. Instead it is data with Tau0 = 1 s and a
>> DEAD TIME of 1s. There are dead time correction schemes available in the
>> literature.
>
> Ulrich, and Steve,
>
>
Ulrich,
2009/4/11 Ulrich Bangert :
>> So why would my counter show any significant differences
>> between a 1 sec or 2 sec gate time?
>
> suppose your source has a 0.5 Hz frequency modulation. Would you see it with
> 2 s gate time or a integer multiple of it? Would you notice it with 1 s gate
> ti
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