How Radio Clocks Work Brandon McKeon

What is a Radio Clock? Clock + Radio receiver = Radio Clock Clock + Radio receiver = Radio Clock Made to receive a radio signal from WWVB, a radio station made to broadcast atomic time. Made to receive a radio signal from WWVB, a radio station made to broadcast atomic time.

What is Atomic Time? Technically called International Atomic Time (TAI) Technically called International Atomic Time (TAI) It is the most accurate time standard used by man. It is the most accurate time standard used by man. Measured using atomic clocks Measured using atomic clocks

The Radio Signal The signal sent from WWVB is set at a really low frequency, with really high power, and really slow broadcasting rate.

Frequency Frequency = 60 kHz Frequency = 60 kHz A typical AM radio station broadcasts at a frequency of 1,000 kHz. A typical AM radio station broadcasts at a frequency of 1,000 kHz. A frequency of 60 kHz is too low for any audio information, so that is why code is used. A frequency of 60 kHz is too low for any audio information, so that is why code is used. The lowest radio frequency in your house is probably 530 kHz, the bottom of the AM broadcast band. The lowest radio frequency in your house is probably 530 kHz, the bottom of the AM broadcast band.

Power Power of the radio signal from WWVB is 50,000W. Power of the radio signal from WWVB is 50,000W. The code is sent by lowering the power for a specific amount of time, but I will get back to this later. The code is sent by lowering the power for a specific amount of time, but I will get back to this later.

Broadcasting Rate Data is sent at a rate of one bit per second A bit is one piece of data; a single “1” or “0” in the binary code in this instance. An average modem transmits over the phone lines at tens of thousands of bits per second

The Code When the power is decreased by.2 seconds, that represents a binary 0. A power decrease for.5 seconds represents a binary 1. A power decrease for.8 seconds represents a separator.

The Code (cont.) The code uses 53 bits of data and 7 separators The code uses 53 bits of data and 7 separators Every bit takes one second to transmit, so… Every bit takes one second to transmit, so… The entire code takes 1 minute to send and receive. The entire code takes 1 minute to send and receive. The code is constantly transmitted and updated. The code is constantly transmitted and updated.

The Code (Again)

From Code to Time The radio receiver is programmed with the WWVB time code format, so it can decode the signal and change it into the data the clock needs to set its time. It changes from binary to “Clock lingo.” Then the clock is able to display the correct time for your every day use.

So… What is a Radio Clock? A really cool Clock! A really cool Clock!