[time-nuts] Most accurate small crystal

Thu May 27 18:50:58 UTC 2010

Jim,
Getting back to the original question, I'd suggest that the Epson-Toyocom FC-12M would be an appropriate device. See http://ndap3-net.ebz.epson.co.jp/w/www/PDFS/epdoc_qd.nsf/WE_khz_unit/737394E88F20BFBA4925736B002B4C07?OpenDocument. It is a surface mount device, very small, 2 x 1.2 x 0.6mm, and is a true tuning fork, but manufactured using QMEMs (Quartz micro-electro-mechanical, photolithographic techniques). The repeatability achieved by this manufacturing method gives a tightly specified parabolic frequency response (typical of tuning forks) with 25°C turnover temperature.

As others have mentioned, there are plenty of strategies around for managing the temperature control of the reference, most achieved by operating the crystal slightly high, and running a pulse swallower driven by a table or other algorithm. Clearly (as is done in the Dallas device) the closer you can associate the temperature sensor with the crystal, the lower the hysteresis and the better the accuracy. Of course a pulse swallower isn't something you'd use for frequency control, but is quite appropriate for time keeping over days and weeks.

I have tested the FC-12M in a low power oscillator (I used the Texas LVC1404 oscillator chip and an LM94022 silicon temperature sensor), and it gave very nice results, no dips or jumps over temperature, and reasonable phase noise (although this isn't an issue with RTCs). I modelled the temperature response in EXCEL and it closely followed the 2nd order model.

Regards,
Murray Greenman

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Subject: time-nuts Digest, Vol 70, Issue 75

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Today's Topics:

   1. Re: For your museum only Loran-C monitor (paul swed)
   2. Re: IRIG B (jimlux)
   3. Re: Digital tight PLL method (Steve Rooke)
   4. Re: Digital tight PLL method (J. L. Trantham)
   5. Re: Digital tight PLL method (Bob Camp)
   6. Re: IRIG B (Robert Atkinson)
   7. Most accurate small crystal (Jim Palfreyman)
   8. Re: Most accurate small crystal (Brooke Clarke)

----------------------------------------------------------------------

Message: 1
Date: Wed, 26 May 2010 08:44:16 -0400
From: paul swed <paulswedb at gmail.com>
Subject: Re: [time-nuts] For your museum only Loran-C monitor
To: Discussion of precise time and frequency measurement
	<time-nuts at febo.com>
Message-ID:
	<AANLkTimW7V-LPhnXADNrj__nYuXAHB1AoBS-v4rEk0Up at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

Great  ?
Have to respond later

On Wed, May 26, 2010 at 1:27 AM, Hal Murray <hmurray at megapathdsl.net> wrote:

>
> paulswedb at gmail.com said:
> > Thats why I designed the loran c simulator. It works well. All I need to
> do
> > is hook it to an antenna and away you go. Maybe a small power amp would
> be
> > handy. Say 100KW? Antennas the real killer. I think its a zoning problem.
>
> What's going to happen to that chunk of spectrum?
>
> How much power/antenna would it take to make a signal that was useful out
> to
> 1 mile?  100 miles?
>
> What are the chances the FCC would let amateurs run timing and/or location
> services on that band?  1/2 :), but there might be something interesting in
> there.
>
>
>
> --
> These are my opinions, not necessarily my employer's.  I hate spam.
>
>
>
>
> _______________________________________________
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------------------------------

Message: 2
Date: Wed, 26 May 2010 06:16:49 -0700
From: jimlux <jimlux at earthlink.net>
Subject: Re: [time-nuts] IRIG B
To: Discussion of precise time and frequency measurement
	<time-nuts at febo.com>
Message-ID: <4BFD1F41.2050900 at earthlink.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Bob Camp wrote:
> Hi
> 
> Strange as it seems, *stocking* the R's and C's can be an issue. There's also placement cost. Based on some of the numbers you see, the cross over point (IC to odd value R's and C's) is amazingly low. I'm not saying any of that's right, just that it's the way a lot of companies roll up the costs. 
> 
> Bob
> 
>
Not surprising.. the cost to stock, pick, place, solder is probably the 
same for a small IC and a R or C.  So, the only possible saving would be 
  if the IC is a LOT more expensive than a single or two Rs or Cs.

There might be a power dissipation difference, or a temperature range 
difference that would push you one way or another.

------------------------------

Message: 3
Date: Thu, 27 May 2010 02:50:42 +1200
From: Steve Rooke <sar10538 at gmail.com>
Subject: Re: [time-nuts] Digital tight PLL method
To: Discussion of precise time and frequency measurement
	<time-nuts at febo.com>
Message-ID:
	<AANLkTin0L2YbApgu0h5FcxxwjV-_67xd6AsFvY3c8xzm at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

On 25 May 2010 04:48, WarrenS <warrensjmail-one at yahoo.com> wrote:
>

> Can't beat a simple analog version of ?NIST's "Tight Phase-Lock Loop Method
> of measuring Freq stability".
> http://tf.nist.gov/phase/Properties/one.htm#oneone ? ?Fig 1.7"

I can't seem to access that link, can anyone else?

Steve
-- 
Steve Rooke - ZL3TUV & G8KVD
A man with one clock knows what time it is;
A man with two clocks is never quite sure.

------------------------------

Message: 4
Date: Wed, 26 May 2010 10:06:57 -0500
From: "J. L. Trantham" <jltran at att.net>
Subject: Re: [time-nuts] Digital tight PLL method
To: "'Discussion of precise time and frequency measurement'"
	<time-nuts at febo.com>
Message-ID: <00c701cafce5$16fc8a40$44f59ec0$@net>
Content-Type: text/plain;	charset="iso-8859-1"

Worked fine for me and very informative.

Joe

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Steve Rooke
Sent: Wednesday, May 26, 2010 9:51 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Digital tight PLL method

On 25 May 2010 04:48, WarrenS <warrensjmail-one at yahoo.com> wrote:
>

> Can't beat a simple analog version of ?NIST's "Tight Phase-Lock Loop
Method
> of measuring Freq stability".
> http://tf.nist.gov/phase/Properties/one.htm#oneone ? ?Fig 1.7"

I can't seem to access that link, can anyone else?

Steve
-- 
Steve Rooke - ZL3TUV & G8KVD
A man with one clock knows what time it is;
A man with two clocks is never quite sure.

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Message: 5
Date: Wed, 26 May 2010 11:58:03 -0400
From: "Bob Camp" <lists at rtty.us>
Subject: Re: [time-nuts] Digital tight PLL method
To: "'Discussion of precise time and frequency measurement'"
	<time-nuts at febo.com>
Message-ID: <069FBEBD95394AA4971B3D08B59EDE1F at vectron.com>
Content-Type: text/plain;	charset="iso-8859-1"

Hi

Works from here. It's a very brief description of pretty much every way in
the world to measure frequency.

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Steve Rooke
Sent: Wednesday, May 26, 2010 10:51 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Digital tight PLL method

On 25 May 2010 04:48, WarrenS <warrensjmail-one at yahoo.com> wrote:
>

> Can't beat a simple analog version of ?NIST's "Tight Phase-Lock Loop
Method
> of measuring Freq stability".
> http://tf.nist.gov/phase/Properties/one.htm#oneone ? ?Fig 1.7"

I can't seem to access that link, can anyone else?

Steve
-- 
Steve Rooke - ZL3TUV & G8KVD
A man with one clock knows what time it is;
A man with two clocks is never quite sure.

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Message: 6
Date: Wed, 26 May 2010 20:17:02 +0000 (GMT)
From: Robert Atkinson <robert8rpi at yahoo.co.uk>
Subject: Re: [time-nuts] IRIG B
To: Discussion of precise time and frequency measurement
	<time-nuts at febo.com>
Message-ID: <424356.9169.qm at web27103.mail.ukl.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1

A good example is the good old 555 timer. A cmos 55 is 41 cents and needs a timing cap and resistor. A pic10f200 is 31 cents and needs no support components. You can also do fancy timing with the pic. I hate to say it but there is really no contest once you have the tools (free complier and a programmer for <$50). Just a shame it's killing analog skills.
?
Robert G8RPI.?

--- On Wed, 26/5/10, jimlux <jimlux at earthlink.net> wrote:

From: jimlux <jimlux at earthlink.net>
Subject: Re: [time-nuts] IRIG B
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Date: Wednesday, 26 May, 2010, 14:16

Bob Camp wrote:
> Hi
> 
> Strange as it seems, *stocking* the R's and C's can be an issue. There's also placement cost. Based on some of the numbers you see, the cross over point (IC to odd value R's and C's) is amazingly low. I'm not saying any of that's right, just that it's the way a lot of companies roll up the costs. 
> Bob
> 
> 
Not surprising.. the cost to stock, pick, place, solder is probably the same for a small IC and a R or C.? So, the only possible saving would be? if the IC is a LOT more expensive than a single or two Rs or Cs.

There might be a power dissipation difference, or a temperature range difference that would push you one way or another.

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time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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------------------------------

Message: 7
Date: Thu, 27 May 2010 14:22:18 +1000
From: Jim Palfreyman <jim77742 at gmail.com>
Subject: [time-nuts] Most accurate small crystal
To: Discussion of precise time and frequency measurement
	<time-nuts at febo.com>
Message-ID:
	<AANLkTimNBz5wwBJ8dR0_eNZrFPxcKWlklxFCa7cx6yV9 at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

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

------------------------------

Message: 8
Date: Wed, 26 May 2010 22:30:36 -0700
From: Brooke Clarke <brooke at pacific.net>
Subject: Re: [time-nuts] Most accurate small crystal
To: Discussion of precise time and frequency measurement
	<time-nuts at febo.com>
Message-ID: <4BFE037C.7060301 at pacific.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Hi Jim:

The last time I looked into this it was the DS3231 (now part of Maxim).  
See the live demo:
http://www.maxim-ic.com/products/timers/DS3231_demo/

Have Fun,

Brooke Clarke
http://www.PRC68.com

Jim Palfreyman wrote:
> 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.
>
>
>    

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