[time-nuts] Most accurate small crystal

Don Latham djl at montana.com
Fri May 28 05:46:24 UTC 2010


As usual, no prices. If you have to ask, you can't afford one :-)
Don

----- Original Message ----- 
From: <Luke.Hoffmann at l-3com.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Thursday, May 27, 2010 8:33 PM
Subject: Re: [time-nuts] Most accurate small crystal


> Hi Jim,
>
> If you are looking for low power (< 80 mW @ 24 degrees C), stable
> (better that 1ppb per day) & accurate (within 5ppb of 1Hz from factory)
> then have a look at these devices.
>
> They also have an input pin that takes a GPS 1pps ref used to discipline
> them. (Used by the device to recalibrate itself.)
>
> www.l-3com.com/nautronix/products/hptr.html
> www.l-3com.com/nautronix/pdfs/HPTR_Rev_2.1.pdf
>
> Regards
> Luke Hoffmann
>
>
>
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Jim Palfreyman
> Sent: Thursday, 27 May 2010 12:22 PM
> To: Discussion of precise time and frequency measurement
> Subject: [time-nuts] Most accurate small crystal
>
> Hi All,
>
> I have a RSA SecurID device which I use to log in to my work's VPN. For
> those of you not familiar with these, they show you a 6 digit number
> that
> you use (combined with a PIN) to log in. This number changes every
> minute.
> The changing of this number lines up with the servers at the other end
> and,
> as I understand it, they do take into account gradual drift. These
> devices
> have a limited programmed lifetime of three years as well. So the
> internal
> clock on one of these needs to be decent.
>
> I have timed the accuracy of this internal clock and have found it to be
> pretty good so far. 17 days ago it was ticking over at 21.8 sec past the
> minute and a quick visual inspection today and it was still *very* close
> to
> that. I will confirm it properly tonight.
>
> Now this device travels around with me, like a wristwatch, but is not on
> my
> person. It is usually in my laptop bag. So it is subject to quite
> varying
> temperatures.
>
> So it's been nearly 3 weeks and this device has barely changed 0.1 to
> 0.2
> secs tops. Now that's not bad compared to digital watches.
>
> I presume it has a quartz crystal in it, obviously no oven, but my
> question
> is:
>
> What is the best crystal you can get on the market today that would work
> in
> a watch type device with very little power available? What's the best
> accuracy that can be expected?
>
> I know straight out of the factory they can be pretty spot on (as my
> Casio G
> Shock was) but it has aged markedly and now gains a couple of seconds a
> week. So what is the best we can expect long term too?
>
> Regards,
>
> Jim Palfreyman
> _______________________________________________
> 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.
>
> _______________________________________________
> 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. 




More information about the time-nuts mailing list