[time-nuts] DDS, OCXO and ADEV

d0ct0r time at patoka.org
Sun May 3 10:44:19 EDT 2015



The counter is in TIME MODE. And simple calculation could transform it 
to frequency as necessary. For example:

1/(350.50824*10^-9)
2852999.97512184021693755330

OR

1/0.0000003505082409000000
2852999.96779619226350692058

Which is pretty close to my DDS VFO freq. value [2853000]

I switch counter to TIME MODE, because ADEV1 utility using times, not 
frequency:

Here is from documentation:

"Adev1 works on everything from pendulum clocks to hydrogen masers. The 
only restrictions are that the data must be phase (time interval) rather 
than frequency; the data must be sequential (no gaps); and the data 
should be free from glitches or outliers."

I am using 10 second intervals for the measurement. DDS VFO clocked by 
Trimble TB and its using AD9852 chip.


Regards,

V.P.

On 2015-05-03 10:01, Bob Camp wrote:
> Hi
> 
> Either the output data is with the counter set to time mode (and
> it’s in 100’s of ns) or you have it
> set to frequency mode and have a very stable system.
> 
> Bob
> 
>> On May 2, 2015, at 9:53 PM, d0ct0r <time at patoka.org> wrote:
>> 
>> 
>> Hello,
>> 
>> 
>> I would like to create some charts for ADEV for following setup:
>> 
>> HP5386A counter connected to External REF. (OCXO). The input of 
>> counter connected to my DDS VFO. The frequency on VFO is 2853000 Hz.
>> 
>> Here is what I got from counter via GPIB:
>> 
>> S +3.505082408E-7
>> S +3.505082408E-7
>> S +3.505082408E-7
>> S +3.505082408E-7
>> S +3.505082408E-7
>> S +3.505082408E-7
>> S +3.505082408E-7
>> S +3.505082409E-7
>> S +3.505082408E-7
>> S +3.505082409E-7
>> S +3.505082408E-7
>> S +3.505082408E-7
>> S +3.505082408E-7
>> 
>> I converted it to following form:
>> 
>> 0.0000003505082409000000
>> 0.0000003505082409000000
>> 0.0000003505082409000000
>> 0.0000003505082408000000
>> 0.0000003505082409000000
>> 0.0000003505082409000000
>> 0.0000003505082409000000
>> 0.0000003505082409000000
>> 0.0000003505082409000000
>> 0.0000003505082409000000
>> 0.0000003505082409000000
>> 0.0000003505082409000000
>> 0.0000003505082409000000
>> 0.0000003505082409000000
>> 0.0000003505082409000000
>> 
>> Then I tried to use ADEV by tvb (long life to Tom!). See attached file 
>> 1b.bmp
>> 
>> And I tried to create the charts for the collected data. See attached 
>> file 1a.bmp.
>> 
>> But it seems I am doing something wrong. Any advises will be greatly 
>> appreciated. Thanks !
>> 
>> 
>> --
>> WBW,
>> 
>> V.P.<1a.png><1b.png>_______________________________________________
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-- 
WBW,

V.P.


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