[time-nuts] chip scale atomic clock
Bob Camp
lists at cq.nu
Sat Dec 26 18:09:06 UTC 2009
Hi
Thanks, that's one I hadn't seen yet. I did not get Besancon this year.
I guess my main point is that *if* the physics package is capable of ~2x10^-11 with good electronics, then what ever you get past that is simply mission related. A different system requirement could take the performance closer to that "ideal".
Good to see that the RbXO is coming back to life (again). It would have been nice to get it into production back at EG&G.
Bob
On Dec 26, 2009, at 12:30 PM, Robert Lutwak wrote:
> Notwithstanding the performance of one physics package, I think it's safe to say that no-one is holding their breath waiting for a 1e-11 CSAC.
>
> That figure (5B) shows the Allan deviation of 10 physics packages (measured with optimal laboratory electronics) and you are correct that the best of the bunch is down around 2-3e-11 at 1-second. At that time, with low-power CSAC electronics, the performance of that same physics package was up around 1e-10 and most were in the 2-3e-10 range (see Figure 6), which would have led to a spec somewhere north of there, perhaps 3-4e-10.
>
> For your amusement, I just added a more recent paper (from the 2009 FCS/EFTF) to my WWW site. Figure 3 in that paper shows some more recent results with (newer, better, and lower power) electronics but similar physics package architecture. These days, typical CSAC instability is in the range of 8-10e-11 @ 1second, which might lead to a spec in the 1-3e-10 range.
>
> -RL
>
>
> At 11:41 AM 12/26/2009, you wrote:
>> Hi
>>
>> I *knew* I'd seen a chart somewhere that was getting close to 1x10-11 at 1 second for the best of the group.
>>
>> It's figure B on page 7 of your FSM 2008 paper.
>>
>> Bob
>>
>>
>> On Dec 26, 2009, at 10:36 AM, Robert Lutwak wrote:
>>
>> > I pay pretty close attention to what people in this field are saying, and I've never heard anyone say "we'll get to 1e-11 short term stability at 1 second real soon now."
>> >
>> > 1e-11 at 1 second is the XPRO spec (and 2X better than LPRO or PRS10). There are good (physics) reasons why those units all draw 100X more power than a CSAC.
>> >
>> > CSAC is intended for portable battery-powered operation. Surely your basement has the space and wallplug power to support an LPRO. (p.s. don't cool the damn thing, heat it).
>> >
>> > The cats were much happier during the CsIII development (see http://home.comcast.net/~rlutwak). It was bigger and warmer. Any Cat-Nuts out there who can help me find one with significantly lower SWAP?
>> >
>> > -RL
>> >
>> > At 10:08 AM 12/26/2009, you wrote:
>> >> Hi
>> >>
>> >> 1x10-11 at 1 second, going down by tau^0.5.
>> >>
>> >> That makes them candidates for the basement system ....
>> >>
>> >> Bob
>> >>
>> >> On Dec 26, 2009, at 9:33 AM, Robert Lutwak wrote:
>> >>
>> >> > How "good" do you want?
>> >> >
>> >> >
>> >> > At 09:13 AM 12/26/2009, you wrote:
>> >> >> Hi
>> >> >>
>> >> >> They still seem to be at the stage of "we'll get to good short term stability at 1 second real soon now".
>> >> >>
>> >> >> Bob
>> >> >>
>> >> >>
>> >> >> On Dec 26, 2009, at 8:23 AM, Ronald Held wrote:
>> >> >>
>> >> >> > I read about this a while ago. Has anyone seen anything recent about
>> >> >> > it, notably desktop or even portable units?
>> >> >> > Ronald
>> >> >> >
>> >> >> > _______________________________________________
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>> >> >>
>> >> >>
>> >> >> _______________________________________________
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>> >> >
>> >> >
>> >> > -RL
>> >> >
>> >> > -----------------------
>> >> > Robert Lutwak
>> >> > Symmetricom - Technology Realization Center
>> >> > <mhtml:mid://00000000/mailto:RLutwak@Symmetricom.com>RLutwak at Symmetricom.com (Business)
>> >> > <mhtml:mid://00000000/mailto:Lutwak@Alum.mit.edu>Lutwak at Alum.mit.edu (Personal)
>> >> > (978) 232-1461 (Desk)
>> >> > (339) 927-7896 (Mobile)
>> >> > (978) 927-4099 (Facsimile)
>> >> >
>> >> >
>> >> >
>> >> > -RL
>> >> >
>> >> > -----------------------
>> >> > Robert Lutwak
>> >> > Symmetricom - Technology Realization Center
>> >> > <mhtml:mid://00000000/mailto:RLutwak@Symmetricom.com>RLutwak at Symmetricom.com (Business)
>> >> > <mhtml:mid://00000000/mailto:Lutwak@Alum.mit.edu>Lutwak at Alum.mit.edu (Personal)
>> >> > (978) 232-1461 (Desk)
>> >> > (339) 927-7896 (Mobile)
>> >> > (978) 927-4099 (Facsimile)
>> >> > _______________________________________________
>> >> > time-nuts mailing list -- time-nuts at febo.com
>> >> > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> >> > and follow the instructions there.
>> >> >
>> >>
>> >>
>> >> _______________________________________________
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>> >
>> >
>> >
>> > -RL
>> >
>> > -----------------------
>> > Robert Lutwak
>> > Symmetricom - Technology Realization Center
>> > <mhtml:mid://00000000/mailto:RLutwak@Symmetricom.com>RLutwak at Symmetricom.com (Business)
>> > <mhtml:mid://00000000/mailto:Lutwak@Alum.mit.edu>Lutwak at Alum.mit.edu (Personal)
>> > (978) 232-1461 (Desk)
>> > (339) 927-7896 (Mobile)
>> > (978) 927-4099 (Facsimile)
>> >
>> >
>> >
>> > -RL
>> >
>> > -----------------------
>> > Robert Lutwak
>> > Symmetricom - Technology Realization Center
>> > <mhtml:mid://00000000/mailto:RLutwak@Symmetricom.com>RLutwak at Symmetricom.com (Business)
>> > <mhtml:mid://00000000/mailto:Lutwak@Alum.mit.edu>Lutwak at Alum.mit.edu (Personal)
>> > (978) 232-1461 (Desk)
>> > (339) 927-7896 (Mobile)
>> > (978) 927-4099 (Facsimile)
>> > _______________________________________________
>> > time-nuts mailing list -- time-nuts at febo.com
>> > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> > and follow the instructions there.
>> >
>>
>>
>> _______________________________________________
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>> and follow the instructions there.
>
>
>
> -RL
>
> -----------------------
> Robert Lutwak
> Symmetricom - Technology Realization Center
> <mhtml:mid://00000000/mailto:RLutwak@Symmetricom.com>RLutwak at Symmetricom.com (Business)
> <mhtml:mid://00000000/mailto:Lutwak@Alum.mit.edu>Lutwak at Alum.mit.edu (Personal)
> (978) 232-1461 (Desk)
> (339) 927-7896 (Mobile)
> (978) 927-4099 (Facsimile)
>
>
>
> -RL
>
> -----------------------
> Robert Lutwak
> Symmetricom - Technology Realization Center
> <mhtml:mid://00000000/mailto:RLutwak@Symmetricom.com>RLutwak at Symmetricom.com (Business)
> <mhtml:mid://00000000/mailto:Lutwak@Alum.mit.edu>Lutwak at Alum.mit.edu (Personal)
> (978) 232-1461 (Desk)
> (339) 927-7896 (Mobile)
> (978) 927-4099 (Facsimile)
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
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