Sunday, April 21, 2013

Telling Time

Does anybody really know what time it is?  Does anybody really care?

The answer to both is Yes … and Kauaʻi, Hawaiʻi has the distinction of being one of only two official Time broadcast points in the United States (the other is in Fort Collins, Colorado.)

At first, I thought “Time” was a pretty simple thing.  Oh yeah, every now and then we need to mentally add or subtract an extra hour between points on the continent – and most folks there need to adjust for “Daylight” or not – but in looking into the Kauaʻi operation, I quickly learned that there are many variables of “Time.”

OK, let’s fast forward past the daylight-darkness, sundial, wind-up and quartz watch timing eras … nowadays, transportation, communication, financial transactions, manufacturing, electric power and many other technologies have become dependent on accurate clocks; folks need to be more accurate than being “about” a certain time.

In addition, some folks need time referenced to the Earth’s rotation for applications such as celestial navigation, satellite observations of the Earth and some types of surveying.  For those folks, Time relative to the motion of the Earth is more important than the accuracy of the atomic clock (even though Earth time fluctuates by a few thousandths of a second a day.)

For the rest of us, highly accurate atomic clocks and the agreement in 1967 on what a “second” is (the duration of 9,192,631,770 cycles of the radiation associated with a specified transition of the cesium atom) led to a compromise time scale of the Coordinated Universal Time (UTC.)

The National Institute of Standards and Technology (NIST - an agency of the US Department of Commerce) laboratories in Boulder, Colorado does the computing for us and even broadcasts the UTC(NIST) via various means.  (UTC(NIST) is the US national standard for measurements of time-of-day, time interval and frequency.

Here’s the official statement on what they do: “UTC(NIST) is the coordinated universal time scale maintained at NIST. The UTC(NIST) time scale comprises an ensemble of cesium beam and hydrogen maser atomic clocks, which are regularly calibrated by the NIST primary frequency standard. The number of clocks in the time scale varies, but is typically around ten.”

“The outputs of the clocks are combined into a single signal by using a weighted average. The most stable clocks are assigned the most weight. The clocks in the UTC(NIST) time scale also contribute to the International Atomic Time (TAI) and Coordinated Universal Time (UTC).”

“UTC(NIST) serves as a national standard for frequency time interval, and time-of-day. It is distributed through the NIST time and frequency services and continuously compared to the time and frequency standards located around the world.”

Whoa, that’s waaay more information than I needed; … and, I think you are confusing me with someone who cares.  (Short answer, those guys “keep” the time.)  OK, let’s move on.

If you really want to know what Time it is, go to , select your desired time zone in the US and the time will be displayed for you.

Or, call to hear the “Time” broadcasts by dialing (303) 499-7111 for WWV (Colorado) and (808) 335-4363 for WWVH (Hawaiʻi).

These are not toll-free numbers; callers outside the local calling area are charged for the call at regular long-distance rates.  The telephone time-of-day service is used to synchronize clocks and watches and for the calibration of stopwatches and timers. It receives about 2,000 calls per day.

OK, back to Kauaʻi.

At Kokole Point at Mānā, Kauaʻi, the NIST radio station WWVH broadcasts time and frequency information 24 hours per day, 7 days per week to listeners worldwide.  (These are the guys who “tell” the time.)

The information broadcast by WWVH includes time announcements, standard time intervals, standard frequencies, UT1 time corrections (time derived by astronomers who monitor the speed of the Earth's rotation,) a BCD time code (time data is coded binary coded decimal (BCD) digits in the form HH:MM:SS:FF,) geophysical alerts, marine storm warnings and Global Positioning System (GPS) status reports.

Voice announcements are made from WWVH once every minute.  The announced time is "Coordinated Universal Time" (UTC).   Coordination with the international UTC time scale keeps NIST time signals in close agreement with signals from other time and frequency stations throughout the world.

UTC differs from local time by the number of time zones between your location and the zero meridian (which passes through Greenwich, England.) (In Hawaiʻi, it’s UTC – 10 (the online and telephone time broadcasts are calibrated for Hawaiʻi.))

UTC is a 24-hour clock system.  When local time changes from Daylight Saving to Standard Time, or vice versa, UTC does not change. However, the difference between UTC and local time may change by 1-hour.  UTC runs at an almost perfectly constant rate, since its rate is based on cesium atomic frequency standards.

In addition to the time-related data, NOAA uses WWVH to broadcast geophysical alert messages that provide information about solar terrestrial conditions. Marine storm warnings are broadcast for the Atlantic and Pacific oceans and the Gulf of Mexico. The National Weather Service provides the storm warning information.  (This information is broadcast at specific time intervals in each hour.)

Another critical function of the WWV system (especially for Hawaiʻi) is keeping the clocks on the GPS satellites in sync.  GPS technology requires very accurate timekeeping as the difference in radio signal arrival is a big part of fixing your location.  Without WWVH, the GPS system would drift off and lots of transportation and related functions would be affected (airplanes, ships, self-driving cars, etc.)

WWVH began operation on November 22, 1948 at Kihei on the island of Maui (the site now houses the Hawaiian Islands Humpback Whale National Marine Sanctuary offices.)   In July 1971, the station moved to its current location, near Kekaha, Kauaʻi.

For those wondering why these two facilities, that are west of the Mississippi River, have call signs that start with “W” (typically, station call signs west of the Mississippi start with “K” and those east start with “W,”) the time station’s early location was in Washington, DC (May 1920) – when it moved to Fort Collins (1966,) it kept the call sign.  For consistency, Kauaʻi followed the call sign pattern.

The image shows the WWVH facility on Kauaʻi; in addition, I have added other related images in a folder of like name in the Photos section on my Facebook and Google+ pages.

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