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Time Standard Dilemma

But of course!

I remember all the problmes trying to sync a computer complex to WWV a few years ago, before GPS became readily available. It was a real pain finding someplace in the building that had good signal, since the building wall insulation all had a foil liner that cut the signal too much! We finally ended up 'removing' the insulation from one panel in the correct direction to get it to work.

But GPS is accurate to within a few ms, which can be more accurate than WWV if you are very far from the transmitter... 8-)

Charlie

Reply to
Charles Edmondson
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Hmm... but the GPS signal made it through enough to work, eh?

Personally, for any radio signal one really cares about, I suggest putting up outside antennas!

Reply to
Joel Kolstad

My dad bought one of those watches when I was a boy (they were a lot cheaper then. It stayed wound fine, even though he wasn't a big arm waving person, and ran well for years. Then he bought me one, which I wore for several years. No problem. Yours may need service.

--
 Thanks,
    - Win
Reply to
Winfield Hill

AT cut at around human body temperature is far from stable. The turnover point is much higher. Despite that, thickness shear is still a lot more stable than the beam bending at 32kHz.

d

Pearce Consulting

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Reply to
Don Pearce

In message , Jim Thompson writes

The first Quartz Watch (as far as I know) was the Omega Megaquartz still possibly the most accurate unsynchronised) as it employed an AT cut with its superior aging and tempco at a binary 2MHz (we did the crystal in the UK) Priced in the early 70s out of reach of the masses it was not a success. Find one as a future investment if you can

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dd
Reply to
douglas dwyer

In message , Don Pearce writes

Nice to discuss. AT cut Tc rotates about 27C as the angle of cut varies. Therefore one can expect a symmetrical excursion about this temperature. Average wrist watch temp will be below body temp and an optimally cut AT could give +-1ppm without compensation 10 to 44C and if clean and well encapsulated

Reply to
douglas dwyer

ISTR seeing "winders" for those watches that you put them into while you sleep. I have a nice Breitling "Aerospace" digital/analog that looks like an engineer's watch. ;-) But most of the time I wear a cheap $75 Alessi or an even cheaper Timex or Casio that doesn't matter if it gets broken or scratched (not that the sapphire crystal on high end watches scratches that easily). Spend a bit of time in HK and you'll start to think that $4K US just buys you a mid-range watch.

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Reply to
Spehro Pefhany

It just came back from "service". Maybe it's a dud :-(

...Jim Thompson

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|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

On Tue, 05 Apr 2005 09:16:44 -0700, Jim Thompson wrote in Msg.

I've got one of those -- a rather cheap and ugly one by Citizen, but I've grown fond of it over the 20+ years I've been wearing it. Some ten years ago it started losing accuracy; it's now losing a minute every couple of days.

--Daniel

Reply to
Daniel Haude

I retired my Zodiac GMT Aerospace automatic watch last year. I bought it in 1967 for $61.25 at the base exchange. Hopefully my new Citzen watch will last as long.

Al

Reply to
Al

Jeezis!

Send me $2400.00, I'll wind your f**king watch for you, and look up the time three different ways to make sure that you're precisely on shedule[sic].

Thanks, Rich

Reply to
Rich Grise

Heck, I've got you all beat - I've got two watches that I wear Simultaneously:

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The seconds aren't in sync, because, as I found out when I went to the watch place to get a new battery, it's two complete, independent watches in the one package, ergo, I had to buy TWO batteries! (and syncing up the seconds is WAY more PITA than I need to subject myself to, merely to know if it's day or night! It's close enough that I generally don't miss "Star Trek". ;-) )

Cheers! Rich

Reply to
Rich Grise

They send, make 1PPS, send, make 1PPS, send, make 1PPS etc. So they in fact send the data both before and after the 1PPS pulse. I still believe that the time and location are always old news before they are sent. Time can be corrected so that it would not be but location can't be.

I have done a real world test where the GPS, 1PPS and "we just passed the marker" information was recorded for both directions of travel. The GPS location, is certainly delayed in the data.

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--
kensmith@rahul.net   forging knowledge
Reply to
Ken Smith

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