[time-nuts] Method for comparing oscillators

Bruce Griffiths bruce.griffiths at xtra.co.nz
Wed Aug 5 00:35:12 UTC 2009


Lux, Jim (337C) wrote:
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>> Behalf Of Bruce Griffiths
>> Sent: Tuesday, August 04, 2009 5:06 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] Method for comparing oscillators
>>
>>     
>>> http://www.uspto.gov/
>>>
>>> patent search
>>> quick
>>> symmetricom in "Assignee Name"
>>>
>>>
>>>       
>> Actually Timing Solutions corp would be better choice of assignee as
>> they developed the concept until swallowed/absorbed by Symmetricom
>>
>> Bruce
>>
>>     
> 1 	7,436,166 	Full-Text 	Direct digital synthesizer producing a signal representing an amplitude of a sine wave
> 2 	7,227,346 	Full-Text 	Two channel digital phase detector
> 3 	5,315,566 	Full-Text 	Time scale computation system
> 4 	5,155,695 	Full-Text 	Time scale computation system including complete and weighted ensemble definition
>
> The second one, to Wayne Solbrig, looks interesting.
>
> The present invention is directed to a digital phase detector that is capable of being used in a phase measurement system to make very low phase noise measurements and, in one embodiment, as low as about 180 dB/Hz below the carrier frequency
>
>
> It would appear that some folks from Cal Tech and JPL, have used a similar technique in 7,511,469, for measuring small changes in laser frequencies.
>
>
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>   
The first 2 are the relevant patents.

You may also find it useful to download the 5125A manual.
This instrument uses subNyquist sampling together with a bank of
switched antialiasing bandpass filters to compare 2 sources over the
1-400MHz frequency range.
There may be additional patents pending for this.

Bruce





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