What Time Is It?

For listeners of WWV and WWVH, that isn't a problem. Why you say? WWV and WWVH are US Government time stations. Time stations? What the heck is that?

Long before GPS, actually in the 1920's, electronics needed a time/frequency standard for accurate measurements. Time/frequency radio stations provided (and still do) that service. WWV was the first going on the air in 1920 from Washington, DC. Over the next few years WWV moved around the Washington area before settling in at Beltsville, MD from 1932 to 1966 when the station was relocated to Fort Collins, CO to better serve the lower 48 continental United States. WWV operates on five shortwave frequencies, 2.5 MHz, 5 MHz, 10 MHz, 15 MHz and 20 MHz. WWVH is located on the island of Kauai, HI with four shortwave frequencies of 2.5 MHz, 5 MHz, 10 MHz and 15 MHz and serves the Pacific Basin.

So what do you hear on WWV/WWVH? Well with a shortwave radio tuned to WWV/WWVH you hear, clock ticks, varies tones, top of the minute time announcements ("At the tone the time will be 15 hours 32 minutes Universal Coordinated Time - BEEEEP") and at certain minutes of the hour, oceanic weather conditions, solar wind conditions and shortwave propagation conditions are broadcast. And that is about it. But what you can't hear is just as important if not more.

Because WWV/WWVH uses atomic clocks to be sure they are EXACTLY on time, this also allows the transmitters to be EXACTLY on frequency. This also allows a subcarrier to be transmitted with digital information that can be read by computers for all kinds of test and measurement and standards signals and the user knows that it is as accurate as can be made.

If you remember seeing the "atomic clocks" of a few years ago, they worked on a very similar system. Instead of using shortwave of WWV or WVVH, they received a special time signal station co-located with WWV, time signal station WWVB. WWVB broadcasts on the Long Wave band below the AM band at 60 kHz. This allows the signal to be more stable and remain receivable longer with more reliability than the shortwave frequencies used by WWV/WWVH. Because the frequency is so low, WWVB doesn't use voice to broadcast information. It broadcasts computer data and these same atomic clocks that WWV/WWVH use are also used on WWVB's signal to keep corrected time and frequency.

In the late 90's NIST, the National Institute of Standards and Technology, the government agency that runs WWV/WWVH/WWVB, completely rebuilt WWVB and increased its power. WWVB had started at the Ft Collins site in 1963. The station was long overdue for a rebuild. This rebuilding is what spurred the atomic clock craze of the late 90's and early 2000's. You can't as easily find atomic clocks as you once could because of GPS, but they are still out there and there are many reasons where the NIST stations are preferred over GPS, even though GPS provides everything the NIST stations provide. WWVB reception isn't affected by the Sun as WWV/WWVH and GPS is. The 60 kHz receivers are much cheaper than GPS receivers. The data is easier to manipulate and you don't need a clear view of the sky to make it work as with GPS.

When I first went to work at the station in 1992, we had a 1980's model WWV Master Clock receive system at the studio that kept us on time for network and other programming. In the late 90's we upgraded to an early GPS Master Clock system and replaced the aging and ailing WWV Master Clock system. When we installed the new automation system a couple of years ago we had to install a better GPS Master Clock system that offered more features that the automation required. I grabbed the original GPS Master Clock system and moved it to the main transmitter building and it is really nice to have it and what it does. But at the backup transmitter building, it doesn't make sense to spend that kind of money just to tell time, which is all I need there. So two $39 Radio Shack atomic clocks work just fine. Time correction provided by WWVB, Fort Collins, Colorado of course!

Back in the tube days, test equipment at stations were not as stable as they are now and required a known frequency standard to keep the equipment and transmitters within tolerance. Cheapest way to do it? In the rack was a WWV receiver with a test port on it for the standards measurement. We had a WWV receiver at the transmitter for that very purpose. When we rebuilt the transmitter site in 1994, the receiver was finally retired. That old receiver is now in my collection. It still works!

Technically the NIST stations are utility stations because they serve a utilitarian purpose, but they are also fun to listen to. Depending on how the band conditions are, it isn't too unusual to hear WWVH under WWV at times. Since both stations are exactly on the same frequency, there is no interference and you will hear the female WWVH voice announce the time at :45 seconds followed by the WWV male voice announcing the time at :53 seconds as if from a single station. That is how you tell which station you are hearing. WWV/WWVH identify themselves at :00 minutes and :30 minutes.

Other countries have time/standards stations as well. In the US, the easiest one to hear is CHU, Ottawa, Ontario, Canada. CHU broadcasts on 3 frequencies, 3.33 MHz, 7850 MHz and 14.67 MHz. CHU alternates time announcements every minute with French on the odd minute and English on the even minute with station ID every minute. "CHU, Canada. 15 hours 32 minutes UTC."

For more info on WWV/WWVH/WWVB including pictures go to http://www.nist.gov/physlab/div847/grp40/wwv.cfm. For CHU check out http://www.nrc-cnrc.gc.ca/eng/services/inms/time-services/short-wave.html