[time-nuts] Symmetricom CSAC is Cs acting like a Rb unit

[Bob Camp]

Hi

Using this directly at microwave - not a real good idea. Using it to drive a 100 MHz phase locked low noise VCXO through a very narrow loop and then taking that on up to microwave - should work pretty well. The only gotcha would be if they are into PSK-32 at 24 GHz and don't like to tune around. Then indeed the GPSDO might do a bit better. 

The degree of advantage will depend on just how much power they are already hauling along. If the rest of the gear runs a hundred watts, then there's no significant savings over the alternatives. If they have everything else down to under ten watts, then indeed there will be a real advantage to the low power / small size. 

Bob


On Jan 18, 2011, at 7:43 PM, Tom Holmes wrote:

> OK, so aside from the price of this toy, are there any performance reasons
> why this itty bitty gizmo wouldn't be quite useful to my ham friends who do
> portable/mobile microwave operation, as opposed to dragging along a GPSDO or
> OCXO? Think in terms of frequency error at 10 GHz, 24 GHz or even higher.
> 
> Tom Holmes, N8ZM
> Tipp City, OH
> EM79
> 
> 
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>> Behalf Of Bob Camp
>> Sent: Tuesday, January 18, 2011 5:55 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] Symmetricom CSAC is Cs acting like a Rb unit
>> 
>> Hi
>> 
>> In this case, it's an itty bitty gizmo that has some significant
> compromises in
>> performance compared to it's bigger cousins.
>> 
>> Bob
>> 
>> 
>> On Jan 18, 2011, at 5:47 PM, William H. Fite wrote:
>> 
>>> Oh gosh, it would never, EVER do to find a li'l bitty product that
> performs
>>> as well as our big ole spare rooms full of costly, bulky, heavy, mostly
>>> antiquated equipment.  [?]
>>> 
>>> 
>>> 
>>> On Tue, Jan 18, 2011 at 5:10 PM, Bob Camp <lists at rtty.us> wrote:
>>> 
>>>> Hi
>>>> 
>>>> Simply having cesium in it does not make it a primary standard. Since
> it's
>>>> more like a rubidium than anything else, it's a lot easier to think of
> it
>>>> as
>>>> a "really small low power rubidium". One other advantage it may have is
>>>> that
>>>> the LED may have a longer life than a normal "light bulb" source. I
> suspect
>>>> it's a little early to forecast 20 year (or not) life on these yet.
>>>> 
>>>> Bob
>>>> 
>>>> -----Original Message-----
>>>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>>>> Behalf Of WB6BNQ
>>>> Sent: Tuesday, January 18, 2011 5:03 PM
>>>> To: Discussion of precise time and frequency measurement
>>>> Subject: [time-nuts] Symmetricom CSAC is Cs acting like a Rb unit
>>>> 
>>>> To the list,
>>>> 
>>>> If you listen carefully to the Symmetricom slide show, particularly
> page 3,
>>>> it will tell you all you need to
>>>> know:
>>>> 
>>>> 
>>>> 
>> http://www.brainshark.com/Steve_FatSymmetricom/vu?pi=691826191&dm=5&pau
>> se=1&
>>>> 
>> appKey=77<http://www.brainshark.com/Steve_FatSymmetricom/vu?pi=691826191
>> &dm=5&pause=1&%0AappKey=77>
>>>> 
>>>> You will discover that that it is indeed a Cesium operated device.
> HOWEVER
>>>> !  It is operated in the same manner
>>>> as a Rubidium device.  Doing such does NOT make it a primary standard.
>>>> 
>>>> In a Cesium Primary standard, a beam of Cesium atoms are energized to a
>>>> higher state whose decay give off a
>>>> photon of light such that being on frequecy produces more light to the
>>>> detector.  In the Rb system, the Rb cell
>>>> acts simply as a light filter such that when on frequency the light
> level
>>>> is
>>>> reduced as seen by the detector.
>>>> 
>>>> This Symmetricom CSAC device uses the same process as the Rb method
>> above.
>>>> It uses a laser to push light through
>>>> a chamber of Cesium gas.  This Cesium gas is acting as a simple light
>>>> filter.  So in its current state it will
>>>> not rival it superior cousins except in size and power comsumption and
>>>> possibly price for performance in some
>>>> applications.
>>>> 
>>>> Bill....WB6BNQ
>>>> 
>>>> 
>>>> 
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