WEBVTT - How do self-setting clocks work?

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<v Speaker 1>Welcome to Brain staff Fronts dot com where smart happens.

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<v Speaker 1>Hi Am Marshall Brain with today's question, how do the

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<v Speaker 1>automatic self setting clocks set themselves to the atomic clock?

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<v Speaker 1>In Colorado? Many gadget catalogs and high tech stores sell

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<v Speaker 1>radio controlled clocks and wrist watches that are able to

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<v Speaker 1>receive these radio signals. These clocks and watches truly are

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<v Speaker 1>synchronizing themselves with the atomic clock in Colorado. This feature

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<v Speaker 1>is made possible by a radio system set up and

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<v Speaker 1>operated by NIST, the National Institute of Standards and Technology,

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<v Speaker 1>located in Boulder, Colorado. NIST operates radio station w w

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<v Speaker 1>v B, which is the station that transmits the time codes.

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<v Speaker 1>W w v B is a very interesting radio station.

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<v Speaker 1>It has high transmitter power about fifty thousand watts, a

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<v Speaker 1>very efficient antenna, and an extremely low frequency of only

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<v Speaker 1>sixty thousand herds. For comparison, a typical AM radio station

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<v Speaker 1>broadcasts and a frequency of a million herds. The combination

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<v Speaker 1>of high power and low frequency gives the radio waves

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<v Speaker 1>from w w v B a lot of bounds, and

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<v Speaker 1>this single station can therefore cover all of the continental

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<v Speaker 1>United States, plus much of Canada and central America as well.

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<v Speaker 1>The time codes are sent from w w v B

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<v Speaker 1>using one of the simplest systems possible, and at a

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<v Speaker 1>very low data rate of one bit per second. For comparison,

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<v Speaker 1>a typical modem transmits over phone lines at tens of

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<v Speaker 1>thousands of bits per second. Imagine receiving a web page

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<v Speaker 1>at one bit per second. The sixty thousand hurts signal

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<v Speaker 1>is always transmitted, but every second it's significantly reduced in

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<v Speaker 1>power for a period of point two point five or

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<v Speaker 1>point eight seconds. Point two seconds of reduced power means

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<v Speaker 1>a binary, zero point five seconds of reduced power is

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<v Speaker 1>a binary, one and point eight seconds of reduced power

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<v Speaker 1>is a separator. The time code is sent in B

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<v Speaker 1>C D or binary coded decimal, and it indicates minutes, hours,

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<v Speaker 1>day of the year and year, along with information about

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<v Speaker 1>daylight savings time and leap years. The time is transmitted

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<v Speaker 1>using fifty three bits and seven separators, and therefore takes

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<v Speaker 1>exactly sixty seconds to transmit. A clock or watch can

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<v Speaker 1>contain an extremely small and relatively simple antenna and receiver

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<v Speaker 1>To decode the information in the signal and set the

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<v Speaker 1>clock's time accurately. All that you have to do is

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<v Speaker 1>set the time zone, and the clock can display a

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<v Speaker 1>very accurate time. The only thing more accurate that you

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<v Speaker 1>can carry around easily is a GPS receiver which dere

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<v Speaker 1>arrives atomic clock accuracy in real time from the atomic

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<v Speaker 1>clocks in the orbiting GPS satellite. For moralness, and thousands

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<v Speaker 1>of other topics, is it how staff works dot com