After 84 Years, Canada Stops Broadcasting Time From Its Atomic Clocks

October 26, 2023 by Duane Benson

Despite being based on cesium atomic clocks—reportedly accurate within one second over 300 million years—the broadcast was shut down over concerns about its accuracy when received via digital streaming.

[Editor's note: article updated 10/31/23]  There was a time when we didn’t spend every moment with a time-keeping device on or near our person. Today, our smartphones, computers, televisions, cars, and appliances are in constant communication with internet service providers (ISPs), which are connected to a national standard timekeeping system. Before this system existed to keep all internet-connected devices in sync with the rest of the world, people relied on more personal means of keeping accurate time.


A family’s connection to the world

Circa 1930, the radio was the family’s connection to the world. Image used courtesy of BBC


Back to an Era of Mechanical Timekeeping

Early in the 20th century, rural, agriculture-based societies did not rely on precise timekeeping in the way we do today. If it was light enough to be out in the fields, you were out in the fields.  If it was dark, you were not. 

Those who needed more time specificity used mechanical clocks and watches. These devices typically held time to within a few minutes of accuracy per day. For most people, “being connected” meant traveling to town, church, or a grange hall by foot, horse, or for the lucky few, a sputtering motor car. Church bells and town clocks would ring at the top of the hour or on the half-hour so those without clocks could keep in sync. Within the first few decades of the 20th century, however, radio began conveying time in a new way. 

Radio Canada, also known as the Canadian Broadcasting Corporation (CBC), began broadcasting on the shortwave amplitude-modulated (AM) band in 1936 to better connect the geographically large country. By 1939, more than 75% of Canadian residents were within CBC coverage, and with the World War reaching England, CBC radio became a much-needed lifeline to the world. The country-wide war effort made the need for a common time reference via radio even more important.


Connecting the Clocks

The National Research Council (NRC) Canada, located in Ottawa and founded in 1916, maintained the official national standard time. On November 5, 1939, the still-new CBC began a daily announcement of the standard time from the NRC. From 1939 until October 9, 2023, radio listeners have been able to set their clocks once a day based on the following message, or some variation thereof:

“The beginning of the long dash indicates exactly 1 o’clock Eastern Standard Time.”

When the daily time broadcast started in 1939, the NRC relied on pendulum clocks painstakingly calibrated through astronomical means. At the time, the pendulum clocks were reported to be accurate to within one second per year. Recent examinations of clocks with more accurate instruments have determined that they are actually accurate to one second in 12 years.

In the 1940s, the NRC converted to quartz oscillator-based clocks, and in the 1950s, to atomic clocks. Today, the council uses advanced cesium-beam atomic clocks. According to the NRC, its time signal is precise. Today, the cesium clocks its uses to keep Canada's official time are accurate to 1 second per 1.4 million years.

Shortt-Synchronome clock
Shortt-Synchronome clock, the highest standard from 1921 to 1940. Image used courtesy of Wikimedia Commons

Prior to the internet, people relied on public standards like the CBC time broadcast to keep their clocks accurate. Those in the U.S. could call a phone number to hear an automated announcement: “At the tone, the time will be…”.

Today, the cloud has taken charge of our schedules. Microsoft Outlook will tell us when we need to be there, digital API calls ensure our financial transactions are recorded properly, and satellite networks do the navigation for us.


Inaccurate Time in the Age of Atomic Clocks

Though no longer necessary for modern life, the CBC broadcast continued well into the internet era as a once-a-day event. For some, it had become almost a ceremony of sorts. Some people reportedly even trained pets to eat when the tone was broadcast. The announcement was the audio equivalent of comfort food but no longer a required staple.

While the Canadian time standard is as accurate as any in the world, the listener’s reception of the broadcast was not.  Prior to the internet, the signal was broadcast over AM and shortwave radio. In most places, the time was accurate, being just a few milliseconds off due to propagation delay through broadcast electronics and speed-of-light radio wave travel. That was close enough when the need was largely just that of setting standalone clocks and watches.

Cesium atomic clock
Cesium atomic clock. Image used courtesy of NRC Canada

Today, however, CBC is not a radio broadcast in the traditional sense. It is a digital signal streamed over the internet, either for all or part of its journey from source to listener. Network buffering and the switch to HD radio have added delays, and both the streaming process and the satellite relay introduced additional delays of up to nine seconds. A household could have a digital AM HD receiver, a satellite receiver, and internet streaming on at the same time, all three of which would deliver the time stamp several seconds apart from each other—and none would be correct. 

The NRC told All About Circuits that it proposed several technical solutions, and worked with CBC/Radio-Canada to solve the delay in digital broadcasts. But, in the end, with numerous other ways of keeping standard time, CBC/Radio-Canada made the decision to stop broadcasting the NRC's official time signal. on October 9, 2023.

Even though you can't get accurate time info anymore on CBC/Radio-Canada, for its part, the NRC continues to provide Canadians with accurate time on these plaforms:


Some Traditions Disappear in Silence

Some traditions leave us with great fanfare, but others just broadcast one day and not the next. For many years, the daily Canadian standard time notification remained as an institution instead of a necessity, a way to ground oneself with the understanding that throughout Canada and beyond, you were anchored to a common time and place. The broadcast was a viewport from a complex world into a simpler time when the radio was both the center of home entertainment and the family connection to the broader world. That era has passed, and now, the time broadcast viewport is closed as well.

1 Comment
  • CubaPeteAgain February 13, 2024

    Standards should never die.  At some time in the future, if dire predictions are any real thing, people may marvel at these things and say that they were not possible…they must have been ideas but not real.  We take into account the pyramids and do the same today, yet there they are.  Illogical ideas without shreds of evidence be damned.

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