Canada's National Time Station Changes Frequency

One North American radio station has been on the air for seventy years, with the same call letters, at the same places on the dial, broadcasting the same content, minus one format tweak. But it's in for a big change come January 1, 2009.

It's CHU, the standard time station operated by the National Research Council of Canada, and located near Ottawa, Ontario. It broadcasts the time each minute, in English and French, on short wave frequencies 3.330, 7.335, and 14.670 megahertz.

Several standard time stations serve the world. They broadcast signals used by radio controlled clocks. Computers can also be programmed to automatically correct their time settings from signals sent by stations such as CHU.

Canada's standard time station signed on in 1929. Its call sign became CHU in 1938. It was operated by the Dominion Observatory of Canada until 1970. It's the first foreign language station I ever heard. I learned how to count in French from listening. On the first day of French 101, I knew how to tell time, and count up to fifty-nine, hi.

CHU's only format adjustment came in 1990. It switched from North American Eastern time to UTC, to conform with an International Telecommunications Union (ITU) convention making UTC the desired standard for the world's time stations.

In March 2007, the ITU re-allocated the portion of the frequency spectrum surrounding 7.335 megahertz, in the 41 meter short wave band, from fixed-as opposed to mobile-point to point services to broadcasting.

Point to point stations by definition transmit content not meant for public listening. Stations that can be heard on scanners-ship to shore, police, fire, and EMT services, among many others-are examples of point to point radio. Broadcasting stations do just that, broad cast programs for the general public.

CHU's original license designated it as a point to point station. After its part of the frequency spectrum was re-allocated for broadcasting, it was re-licensed by the Canadian government as a broadcasting station. A sample hour still consists of tones each second and a time announcement at the top of each minute. That's still not stuff the public tunes in and leaves on for extended periods of time. (Although some radio hobbyists do.)

Stations in other parts of the world began broadcasting close to, and in some cases on top of, CHU on its 7.335 frequency. To avoid interference in its service area, Canada, CHU is moving from 7.335 to 7.850 megahertz, in a less-crowded part of the dial.

Whenever my clocks have needed re-setting, all I've had to do was enter 7-3-3-5 on the radio's keypad and turn it up so it could be heard in every room. Around here, to paraphrase the old top-40 liner, it's been one of the more frequently frequented frequencies.

Ham radio operators, and other listeners, for various reasons, automatically tune 7.335 for CHU's time signals. They've documented, in the form of reception reports to the National Research Council, the interference CHU gets from its new neighbors in the 41 meter band.

Reception reports published in archived editions of the DX Listening Digest track CHU's effort to stay on its original 7.335 megahertz frequency.

It's easy to change a pre-set button, or just remember to enter 7-8-5-0 on the keypad. But every time something that's been around as long as CHU on 7.335 disappears, a little bit of radio history still goes with it.

Some collectors of radio airchecks save sign-ons and sign-offs, and format changes. The serious among them will be recording the last tick of the clock on 7.335, at midnight UTC on January 1 or 7 PM North American Eastern time. They'll also get the leap second that comes right before it.