Exactly seventy-five years ago, Canadian radio listeners first heard the famous tone that signals the exact time.

The National Research Council Time Signal can still be heard on radio stations across Canada today, helping listeners set their clocks in sync. Many stations now just play the tone, but some may remember the constant phrase "Now from Ottawa, the National Research Council official time signal. The beginning of the long dash will indicate exactly 12 o'clock Eastern Standard Time."

Today, many of the devices Canadians own, such as our cable boxes, computer and cellphones, automatically set their own clocks. They change the moment we switch from Daylight Saving Time to Standard Time, and even update themselves the moment we step off a plane in a new time zone, meaning we don't often have to think about getting the time right these days.

But, according to a statement from the National Research Council, which operates the precision clocks that disseminate the time signal, computers, GPS systems and stock exchanges all rely ensuring their clocks are millisecond-accurate.

"Metrology and measurement standards lie at the heart of every industrial process, from research and product development to commerce and international trade," according to the NRC.

The time at NRC is accurate to approximately 100 nanoseconds of the international time. The council uses atomic clocks, where the atoms vibrate at a consistent rate, to tell the time.

"Over the decades, Canadians and Canadian businesses have depended on the long dash as the standard by which to set their clocks," said Minister of State for science and technology Ed Holder in a statement. "Our government will continue to support the NRC Measurement Science and Standards, which has important implications in radio astronomy, spectroscopy, geodesy, length measurement, voltage measurement, broadcasting and even electronics manufacturing-fields in science and industry that create jobs and prosperity for Canadians."

Here is a behind-the-scenes look at how Canada's official time is kept.