GPS World: USNO's Fountain: Time at 100 Trillionths of a Second

USNO's Fountain: Time at 100 Trillionths of a Second
http://uc.gpsworld.com/gpsuc/content/printContentPopup.jsp?id=576197

Jan 19, 2009
GPS World

The ultra-precise timing technology that enables GPS and high-speed Internet
communication
soon may resolve the measure of time to 100 trillionths of a second, according
to the U.S.
Naval Observatory, a central contributor to the international determination of
time.

"To know when an event occurred, you need a clock. We are that clock," said
Geoff Chester,
public affairs officer at the USNO. He explained the development of this new
timing
technology during the January 15 "Armed with Science: Research and Applications
for the
Modern Military" radio program on BlogTalkRadio.com.

"Atomic clocks define time scales in terms of a certain number of oscillations
of a
certain type of atom that take place in the course of one second. The master
clock at the
Naval Observatory is an ensemble of dozens of these devices, and we take a
weighted
average of all of them to determine our base-reference time scale."

"We guarantee that no two seconds that come out of here over the course of a
year will
differ by more than one billionth of a second," Mr. Chester said. "Our clock is
so precise
that it will not gain or lose one second on the order of 3 million years."

By 2010, USNO hopes to release an operational version of its fountain clock,
which uses
laser beams to induce oscillations of the rubidium atom. This rubidium fountain
clock will
provide a measure of time accurate to 100 trillionths of a second, about 10 to
100 times
more precise than the current master clock.

"Rubidium atoms are smaller and easier to manipulate [than cesium atoms]," Mr.
Chester
explained. "They allow us to keep a much better time scale than what we keep
today."

The U.S. Naval Observatory, one of about 50 scientific laboratories concerned
with
timekeeping, maintains one-third of the operational atomic clocks deployed
around the world.

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----------------------
Please note carefully what is written here
just above !!!

GPS is not based on GR theory!!!

it is a rial and error technique !!!
just write it before yourself
and internalize the conclusions
ie dont boggle our minds
that GPS is a profe for GR !!

ATB
Y.Porat
-----------------------------

Y.Porat wrote:


The relativity corrections are written into the Interface Control
Document ICD-GPS-200D, Porat.
http://www.navcen.uscg.gov/gps/geninfo/IS-GPS-200D.pdf

Perhaps Porat would benefit from a bit of self education
http://edu-observatory.org/gps/gps_books.html#relativity

On Jan 23, 8:14 am, Sam Wormley wrote:


Hmmm... You are taking a couple poorly written application notes as
the Bible.

When conducting an acquisition, if you have three satellites, it is
necessary to synchronize the ground and the satellite clocks.
However, when four satellites are acquired, there is no need to impose
a synchronization of the ground and the satellite clocks as long as
the clocks on all the satellites are synchronized among themselves.
Synchronization of the clocks between the ground and the satellite is
much more difficult to achieve than satellite-to-satellite.

That so-called professor from Norway somewhere realized that. To
continue to spread the nonsense of GR, he immediately pounded his feet
to claim the synchronization must be achieved through the operating
frequencies of the satellites and ground equipments. Well, given 500
parts in a trillion, just how accurate do you want these frequency
errors to be? Remember we are talking about a broadband application
with very low actual data bit rate.

Defending a passage from an application note that you know nothing
about is very hilarious indeed, Sam! This is another example of why
the engineers in general are more intelligent than physicists.

Koobee Wublee wrote:

The beautiful thing about GPS is that observational data is available
to all most anyone and be compared to predictions of GTR... GPS is a
wonderful relativity laboratory.

Relativistic Effects on Satellite Clocks
http://relativity.livingreviews.org/open?pubNo=lrr-2003-1&page=node5.html
http://relativity.livingreviews.org/Articles/lrr-2003-1/frctfrq.png

Take some time to learn what really happens.