Radio-Controlled Clocks Infographic

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We at are fascinated by clocks. And, when it comes to clocks, practically nothing is as accurate as a radio-controlled clock.

Because radio-controlled clocks are becoming more and more popular, and more and more integrated into our daily lives, we thought it would be a good idea to show everyone, in very simple terms, how radio-controlled clocks work.

So everyone, sit back and enjoy, as we show you How Radio-Controlled Clocks Work (and why they simply rule), in our Radio-Controlled Clocks Infographic!

Please note that: because uses your computer’s time settings, and your computer updates its time using the Network Time Protocol (NTP or “computer time servers”), our online alarm clock is just about every bit as accurate as a radio-controlled clock, if not more so!

In fact, Online Clock likes to think of radio-controlled clocks as our brothers and sisters in the world of Clockdom 😉

Radio Controlled Clocks Infographic by

Radio Controlled Clocks Infographic by

Here’s a Thumbnail Image of our Radio-Controlled Clocks Infographic:

Thumbnail: Radio-Controlled Clocks Infographic

Thumbnail: Radio-Controlled Clocks Infographic

For those of you who may find it difficult to read the text in the Infographic, or for those of you who may have image display deactivated in your web browsers, here is a transcript of the text information found in our Infographic:

Got the Time?

Quick! What time is it? Before you answer, consider the source. If it’s that clock on the wall that you only reset twice a year or even the quartz watch on your wrist, you may be a bit behind the times. If you really want to know the time, turn to radio-controlled clocks.

What Are They?

Clocks that update themselves to the correct time using radio signals: often referred to as radio-controlled clocks.

How Do They Work?

In the U.S., signals received by radio-controlled clocks originate from NIST radio station WWVB near Fort Collins, Colorado. The radio-controlled clock has a miniature radio receiver inside that is permanently tuned to the 60kHz WWVB broadcasts.

What’s NIST?

It’s the National Institute of Standards and Technology, a federal technology agency that works with industries to develop and apply technology, measurements and standards.

The 60 kHZ signal is in a part of the radio spectrum called LF, or low frequency. This is a very accurate description because the signal WWVB emits is about 10 times lower than the lowest AM broadcast frequency.

  • WWVB : 60,000 HZ
  • AM Band : 535,000 – 1,605,000 HZ
  • FM Band : 88,100 – 108,000,000 HZ

At 60 kHz, there’s no room on the signal to carry a voice or any other audio information. All that’s sent is binary code, a series of 1s and 0s.

The low signal is also slow-moving: it takes a full minute to send a complete time code, the message that tells the clock the current date and time. So when you turn on a radio-controlled clock for the first time, it will probably take more than a minute for the clock to set itself because it will most likely miss the first time code.

Once your radio-controlled clock has decoded the signal, it will apply a time zone correction (based on the settings you provided) and synchronize itself. WWVB broadcasts its time in Coordinated Universal Time, more commonly referred to as Greenwich Mean Time.

What Is Greenwich Mean Time?

The Prime Meridian passes through Greenwich, England, making Greenwich the place from where all time zones are measured.

Once your clock has synchronized, it won’t decode WWVB’s signal again for a while. Most clocks decode the signal only once a day, but some do so more frequently. A typical quartz crystal found in a radio-controlled clock should be able to keep time to within a second for a few days or more. So you shouldn’t notice any discrepancies when you look at your clock display, since it should be accurate down to the second, even if it’s lost a nanosecond or two since the last time it synced up.

Comparing Accuracy

How long will it take to gain or lose one second?

  • Typical Quartz Wristwatch : 12 Hours
  • Atomic Clock (like the one at WWVB) : 300 Million Years

History of Radio-Controlled Clocks

While they’ve existed for decades, radio-controlled clocks have become far more common in the U.S. thanks to an increase in products that receive time signals from WWVB.

But in one form or another, radio-controlled clocks have been around for nearly a century!

Until the latter part of the 1990s, most RCCs were expensive instruments designed for laboratory applications, or kits assembled by technically minded hobbyists.

Keeping the Right Time uses your computer’s time setting to ensure accuracy, and since computers update their time using NTP servers (Network Time Protocol), is incredibly accurate…quite similar to a radio-controlled clock!

Sources Used:

  • (hey, that’s us!)

And there you have it, Clock Fans…the second piece in a series of clock-related Infographics brought to you by !

We hope you’ve found it interesting. Please give us your feedback using the comments form below.

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