Why don't they build a watch that measures the temperature and every time
you accurately set it, it adds to a small database of time change v
temperature and then adjusts itself internally.
Over time it would become quite accurate I would think.
Jim
On 20 December 2011 11:12, Chuck Harris
How about a turnip pocket watch with one of the new Cesium standards in it?
Harrison would approve...
Don
mike cook
Le 19/12/2011 06:47, Perry Sandeen a écrit :
Is a 10 MHz or so crystal on the horizon?
Dunno, but some 10-50MHz TCXO/VCTCXO are now available in 2mm
packages, so why not.
But the Admiralty still wouldn't pay up ...
Dave
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf
Of Don Latham
Sent: 19 December 2011 19:50
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] New precision
On Tue, 20 Dec 2011 13:12:13 +1100
Jim Palfreyman jim77...@gmail.com wrote:
Why don't they build a watch that measures the temperature and every time
you accurately set it, it adds to a small database of time change v
temperature and then adjusts itself internally.
Over time it would become
Le 21/12/2011 10:53, Attila Kinali a écrit :
On Tue, 20 Dec 2011 13:12:13 +1100
Jim Palfreymanjim77...@gmail.com wrote:
Why don't they build a watch that measures the temperature and every time
you accurately set it, it adds to a small database of time change v
temperature and then adjusts
On Mon, 19 Dec 2011 19:12:43 -0500
Chuck Harris cfhar...@erols.com wrote:
There is nothing inherent in temperature correcting a clock
that should take significantly more power than would be used
in a normal watch chip. Measuring the temperature would be
the most power hungry operation, I
I think the Grand Seikos are specified at the same +/- 10 seconds a
year accuracy as that Bulova. They use a slightly different approach
though - it's a standard 32768 Hz xtal, but its thermally compensated.
I don't know of any other watches that use a 262144 Hz xtal on its
own, but there were
With the CMOS logic used in watches, the big power hog
is due to charging and discharging the gate capacitance
of the various logic gates. The faster you charge and
discharge the gate's, the more power you loose due to
I2R losses, and E-M radiation.
Thankfully, the high capacity lithium cells
Le 19/12/2011 06:47, Perry Sandeen a écrit :
Is a 10 MHz or so crystal on the horizon?
Dunno, but some 10-50MHz TCXO/VCTCXO are now available in 2mm
packages, so why not. There might be battery longevity issues with
driving the higher frequency. I guess it comes down to whether the
On 12/19/2011 5:34 AM, Chuck Harris wrote:
It is not clear to me that a 32KHz xtal is any less stable
than a 262KHz xtal, though. I would think there would be a lot
more to be gained by using a microprocessor/thermistor to
measure the temperature within the watch, and provide an
adjustment to
dan...@verizon.net wrote:
The best crystals for room temperature use are around 4 MHz with
temperature inflections around 20C, and this is what was used in an
early Braun alarm clock I had which also had this kind of performance.
Long gone, alas.
and this is what the clock of my old german
Looking at the datasheet for the DS3232, it doesn't appear
that they mean for it to run off of a small coin cell in a
watch. Its battery operating capability is purely to keep
it running when the main power is turned off.
I would suspect that the DS3232's power consumption is due
to its being
List,
I saw an ad today for a Bulova Champlain Precisionist watch. It is supposed to
be accurate to + 10 seconds a year. What stood out in the as is that they are
using a 262,144 KHz crystal eight times the frequency commonly used.
I don’t know if it is more accurate than the Seiko (?)
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