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Kokua Line
June Watanabe

Sunday, August 21, 2005





‘Atomic’ clocks are
not as effective in Hawaii

Question: I was told that atomic clocks being sold all over Honolulu don't really work in Honolulu. Could you find out why? If it doesn't work here, it doesn't make any sense for them to be sold here.

Answer: We turned to experts at the National Institute of Standards and Technology for help in explaining what atomic clocks are and why so-called "atomic clocks" might not work in Hawaii.

First off, those "atomic clocks" you see on the market aren't atomic clocks.

They are clocks and watches automatically set to official U.S. time by radio broadcasts from the National Institute of Standards and Technology's station, WWVB, in Colorado, explained Tom O'Brian, chief of NIST's Time and Frequency Division.

O'Brian says those devices should more accurately be labeled "radio-controlled clock" or "radio-controlled timepiece."

"Note that these timepieces are built by a couple of dozen different manufacturers, and are not built by NIST, nor does NIST have any regulatory authority over these products," he said by e-mail.

A true atomic clock "uses fundamental vibrations of atoms to measure time extremely accurately," O'Brian explained. They "are large, complex devices costing many thousands to millions of dollars, depending on accuracy."

(NIST operates one of the world's most accurate atomic clocks, NIST-F1, in its laboratories in Boulder, Colo. It serves as the primary time and frequency standard in the United States and contributes to the international group of atomic clocks that define Coordinated Universal Time, the official world time.)

O'Brian said WWVB radio broadcasts, which originate about 70 miles north of Boulder, are indirectly synchronized to the NIST-F1 atomic clock.

"It is this indirect connection that some marketers mean when they refer to 'atomic clocks,'" he said.

O'Brian noted that, because the major market for radio-controlled timepieces is in the 48 contiguous states, many products might not permit setting to the Hawaii time zone, or it might be difficult to make that setting.

That said, O'Brian explained that radio-controlled timepieces can work in Hawaii, although not as well as on the mainland.

In a radio-controlled timepiece, the watch or clock is synchronized to official U.S. time one or more times a day from radio broadcasts from WWVB, he said.

"The radio broadcast also sends the correct date, and automatically takes care of such things as daylight saving time, leap years and leap seconds. Using a radio-controlled timepiece, you can be confident that your clock or watch is synchronized to official U.S. time without you having to periodically set it -- but this works only if you have good reception of the radio broadcast," O'Brian said.

The single WWVB station "provides good coverage of most of the 48 contiguous states, using a special low-frequency radio signal that travels significantly further than typical AM or FM radio broadcasts," he said.

But there are limits as to how far the WWVB radio signal can travel and be strong enough to work.

Factors include the condition of the ionosphere and the weather. Depending on those conditions, the WWVB signals might not be strong enough to set radio-controlled timepieces in Hawaii, O'Brian said.

Local radio interference -- from such things as computer monitors, electrical lines, military signals and even electric appliances -- also might prevent a timepiece from synchronizing to NIST time, he said.

NIST does have a radio station on Kauai, WWVH, but it is not capable of broadcasting the special time code to set consumer radio-controlled timepieces, he said.

"NIST would like to develop an additional time code broadcast station to serve Hawaii, and we hope to be able to do so in the relatively near future, if resources are available," he said.

Bottom line, according to O'Brian: "Radio-controlled timepieces can work in Hawaii, although not as well as on the mainland. Radio-controlled timepieces can probably synchronize to NIST time once every couple of days on average, which is frequently enough to keep good time. Local interference can present problems, but there are steps one can try to minimize those effects."

He suggested going to the NIST Web site -- tf.nist.gov/stations/radioclocks.htm -- to find out more about radio-controlled clocks. Other informative Web sites to check: tf.nist.gov/stations/wwvb and tf.nist.gov/cesium/fountain.htm.

Spa Fitness

I want to clarify the Aug. 18 Kokua Line regarding the Spa Fitness Center (now Punahou Fitness and Spa). Owner Gary Groendyke said that the old members do not pay anything. This is false. Yes, the amount is very reasonable. I pay $5 a month plus an annual $1 renewal fee -- $61 per year. I earned this benefit after paying several hundred dollars for the initiation fee and $20 per month the first two years. I have been a member for about 15 years. -- Dale

Groendyke said more than 50 percent of active members were not paying anything -- not that all longtime members were getting in free. He said he had to start charging new fees to members who had joined prior to April 1, 2001, when he bought the business, because of rising costs.


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