Avoid Delta and Atlanta

Jim Ley writes:

If they didn't set them accurately (well if they didn't set them all
to be the same to a reference clock, the only available reference
clock being the GPS clock system) then their network would stop
working, accurate clocks are essential for the protocols.

Relatively accurate time measurement is required by the protocols I've
seen, but the absolute time of day need not be as accurately kept.

Why? For what purpose?

Why do I need to justify it? It costs no more than wris****ches with
much lower accuracy. It has no disadvantages, so why not?

--
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Miguel Cruz writes:

I don't think the service would work without accurate clocks; extremely
accurate timekeeping is a key element of the system used to select cells
and hand off calls.

If it works like GSM, it has to be relatively accurate, but not
absolutely accurate with respect to time of day.

Yes, I have used NTP to keep my computer's clock accurate for at least
10 years. Which is why its agreement with my cell phone is so
confidence-inspiring for me.

I've written a program that beeps like the time signal from WWV. It
soothes me at night to leave it running. All the hands of all the
clocks in my apartment move in lock step, in perfect synchronization
with the beeps. Even my watches do that.

I can think of a practical use for extremely accurate time, by the
way: watching solar eclipses. Totality is often measured in seconds,
and if your watch is off, you miss the show. I used GPS timing for
the last one I observed.

It's nice to hear, by the way, that Windows has finally caught up in
this regard.

It required widespread, continuous access to the Internet, which is a
fairly recent phenomenon for home computers, if not office computers.

You may want that, but I don't see why it's important or why 99.99% of
people would care.

Since it has no disadvantages, why not use it?

People buy more quartz watches than mechanical watches, and greater
accuracy is part of their motivation.

--
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Mxsmanic wrote:
Miguel Cruz writes:
I don't think the service would work without accurate clocks;
extremely accurate timekeeping is a key element of the system used
to select cells and hand off calls.

If it works like GSM, it has to be relatively accurate, but not
absolutely accurate with respect to time of day.

The most reasonable way to ensure they are relatively accurate is to
ensure they are absolutely accurate.

I find it hard to believe they would take any other, more complicated
approach.

You may want that, but I don't see why it's important or why 99.99%
of people would care.

Since it has no disadvantages, why not use it?

For people who are already carrying around a cell phone, a watch has the
disadvantage of being another thing to carry/wear.

miguel
--
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Miguel Cruz writes:

The most reasonable way to ensure they are relatively accurate is to
ensure they are absolutely accurate.

Not necessarily. It may be cheaper to provide very stable time
references for the network for relative measurement rather than try to
derive those measures from an ultra-accurate time-of-day source. This
is especially true since the accuracy required might be microseconds
or better, and this is expensive to derive from the time of day.

For example, most time of day sources provide extremely high long-term
accuracy at low cost, but they provide poor short-term accuracy unless
a great deal of effort and money is expended. A radio source will
keep your network locked to the correct time of day with long-term
accuracy equal to that of the best atomic clocks, but the short-term
accuracy may be off by hundreds of milliseconds per day unless you
spend a great deal on either continuous synchronization or a local
reference that is extremely accurate when free-running. In the latter
case, you might as well skip the time-of-day reference.

In summary, for timing of protocols, you don't necessarily need
accurate time of day. However, for things like time stamps, and
synchronization of events with precision over long periods or
distances, time of day can be very useful.

One application that illustrates this is live television. In the days
when live television was common and nationally broadcast, sometimes
studios on one coast would pick up where another left off. If they
didn't have their clocks synchronized to within a fraction of a
second, either there would be a period of dead air or a period of
confusion whenever one location handed off to another.

Accurate time of day is important for things like electronic money
transfers and stock operations, too.

--
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On Mon, 14 Aug 2006 00:19:53 +0200, Mxsmanic
wrote:

Jim Ley writes:

How does a chain make you remember to transfer it between clothes, or
remember to have it with you?

When you put the clothing on, it's there. When you take it off, you
can feel it dangling around. Pocket watches are heavier than
wris****ches.

What happens to it in the intervening 8 hours whilst you're sleeping,
and how does feeling it dangling around 8 hours before remind you to
transfer it to the new clothes the next morning.

I concede it may not be an issue if you only have one set of clothes,
although rembering to remove it whilst you walk through a public
carwash to get clean might be another problem.

Jim.

On Mon, 14 Aug 2006 00:28:06 +0200, Mxsmanic
wrote:

Jim Ley writes:

How do you update it for leap-seconds?

The radio signals to which it synchronizes cover leap years, leap
seconds, and daylight saving time. No manual adjustment is ever
necessary.

In any case, your watch is not accurate to what you claimed, as there
is more inaccuracy in the radio tranmission than your quoted figure,
there is also reportedly more accuracy with a GPS system.

So a GPS connection would be more reliable, so a CDMA phone would be
more accurate.

It's not a function of the phone, it's a function of the network -
anything that is CDMA based or the majority of the 3G methods (AIUI)
have clocks synchronised with the base-station, which are GPS sync'd.

Which _can_ be GPS synchronized.

No all CDMA systems are, there's no other available clocks.


GSM (the standard used everywhere else in the world) provides for time
synchronization,

Oops, have you not heard of 3G roll outs, GSM is not as ubiquitous as
it was - although they roll over to it obviously.

Jim.

On Mon, 14 Aug 2006 00:30:06 +0200, Mxsmanic
wrote:

Relatively accurate time measurement is required by the protocols I've
seen, but the absolute time of day need not be as accurately kept.

no, obviously it does not need to be absolutely accurate (they could
all synchronise to 3 weeks ago last tuesday) however there are few
sources of accurate clocks you can synchronise base stations too other
than GPS signals, which are highly accurate atomic clock signals
giving the correct time. So they all have the right time.

Why? For what purpose?

Why do I need to justify it?

because you're suggesting your experience would be relevant beyond
yourself, because of that, justification is kind of important.

Jim.

Mxsmanic wrote:

JohnT writes:


You would only be able to verify that claim if you measured the time errors
over 3 million years. Not even you could do that.


You can measure the error over one day and extrapolate.

So, you have the ability to measure the error for one day and
extrapolate over 3 million years, meaning you have measured the daily
error, and found it to be less than 1 billionth of a second off?

Dave Frightens Me wrote:
On 10 Aug 2006 18:01:31 -0700, "Tchiowa" wrote:

Utter rubbish. These people are no more likely to have links with Al
Qaeda and the Taliban than anyone else. They were just rounded up so
the USA could have some spoils.

And your proof of that?

They are being deprived due process only because many of them would be
found to have done nothing.

And your proof of *that*???

Just read the ****ing article and educate yourself. They have been
assumed guilty, and have no way of proving otherwise.

In other words you have to proof and you are willing to believe any
slanted article you can find.

Can you spell "gullible"?

Mxsmanic wrote:
Tchiowa writes:

That's because property can't commit a crime. But the civil forfeiture
is a result of the criminal conduct. And it all has to be approved by a
judge.

Criminal conduct is decided by a jury, not a judge.

Wrong. Criminal conduct may be decided by a judge if parties approve.

And civil forfeiture occurs before anything is proved by anyone.

Wrong again. The process can be started immediately but it must be
approved by a judge to be final and anyone can challenge and appeal in
court.

Therefore, no due process.

3 times wrong in 2 sentences.

Not bad.