Crystal Clock
![]() |
![]() NEW HAYWARD AQUATROL AQ TROL RJ POOL SALT CHLORINE SYSTEM DEAL US $422.90
|
![]() FERTILITY Gemstone Bracelet Turtle Charm for ConceptionHealthy PregnancySALE US $16.60
|
![]() BRAND NEW LUXPRO PSP511C 5 2 Programmable Thermostat US $19.99
|
![]() HOWARD MILLER Picture Book Clock New unboxed ROSEWOOD QUARTZ Movement US $49.99
|
![]() Bulova Desktop Crystal Sailboat Clock Beautiful Heavy Glass with Wooden Base US $35.00
|
![]() White Crystal House Shaped White Dial Alarm Clock US $5.96
|
![]() Crystal Plastic Night Light Handy Hour Alarm Clock US $6.13
|
![]() New Bulova Metal Quartz Alarm Clock with Crystal Accents US $65.00
|
![]() Fertility BraceletMulti Gemstone for Healthy Pregnancy and Hormone Boost SALE US $18.17
|
![]() Matching FERTILITY Bracelets Gemstone Crystal Healing Conception Pregnancy NEW US $29.23
|
![]() Round Smile Dial Crystal White Night Light Alarm Clock US $6.97
|
![]() BNIB PINK CRYSTAL QUARTZ CLOCK 475 TALL US $7.88
|
![]() FIRST ALERT AUTO THERMOSTAT CONTROL ATTACHMENT TO TEMP ADJ LEVER AS555 NEW US $4.99
|
![]() NUDE FAIRY LADY DIAMOND FLIGHT Faerie Cold Cast Bronze Wall Hanging Plaque US $22.10
|
![]() Crystal Plastic Casing Kelly Green Dial Alarm Clock US $6.34
|
![]() Natural QUARTZ Crystal desk Ornament Clock or Photo frame US $15.78
|
![]() Magic Plasma Crystal NEON BALL Home Interior Light gift Usb Green Base US $7.75
|
![]() Rare Vintage Gzhel Mantle or Desk Clock US $31.00
|
![]() MIKASA QUARTZ GERMAN CRYSTAL DESK CLOCK VERY NICE CLOCK US $24.95
|
![]() Godinger SHANNON Crystal Mantle Clock 4 NEW in box Mothers Day Desk Bed US $12.95
|
![]() Night Light Quartz Crystal Casing Handy Alarm Clock US $6.97
|
![]() Heavy Glass Crystal 9 Grandfather clock US $19.99
|
![]() Modern Interior Decorative Wall Clock Self Adhesive DIY Black or White US $10.99
|
![]() O O O Crystal Cut Prism DESK Clock with Original Box Attractive US $24.00
|
![]() Seiko QHG102GL Crystal Brass Carriage Clock BRAND NEW IN BOX US $99.99
|
![]() HERITAGE QUARTZ ALARM CLOCK US $9.99
|
![]() shannon crystal small hollow grandfather clock US $19.99
|
![]() Waterford Metropolitan Style Clock US $43.00
|
![]() Fifth Avenue Quartz Crystal LTD Clock US $5.50
|
![]() SUNBEAM Nautical Theme Ships Clock Desk Shelf Table Clock Works Great US $49.99
|
![]() MAINSTAYS MS30 061 003 03 FUCHSIA WALL CLOCK NEW IN BOX US $9.99
|
![]() Quartz Danbury Clock 24 Lead Crystal US $19.99
|
![]() Contemporary Modern SASAKI 24 lead crystal glass Quartz CLOCK mantle desktop US $17.99
|
![]() Godinger Crystal Legends Flower Clock US $9.99
|
![]() SEIKO table clock watch solid brass QHG354GLH US $14.99
|
![]() Oak Wood Eastlake Victorian Style Clock Wall Shelf US $79.99
|
![]() Mahagony Wood Eastlake Victorian Style Clock Wall Shelf US $79.99
|
![]() Nautical Beach Boat Decor Wall Clock Life Preserver Applique with miniatures US $9.99
|
![]() Contemporary Modern Antique Large Metal Art Numeric Pendulum Wall Clock 001 US $35.99
|
![]() STUDIO NOVA QUARTZ GERMAN CRYSTAL DESK CLOCK VERY NICE CLOCK US $24.95
|
![]() Crystal Legends White Desk Clock Crystal US $.99
|
![]() PRETTY CRYSTAL QUARTZ TABLETOP DESKTOP NIGHTSTAND CLOCK US $9.99
|
![]() Waterford Crystal Quartz Clock US $60.00
|
![]() BEAUTIFUL ROUND STAGER CUT CRYSTAL OFFICE DESK CLOCK GERMANY FRANCE FELT BOTTOM US $27.00
|
![]() Crystal Clear 24 Lead Crystal Clock US $4.99
|
![]() GODINGER VINTAGE CRYSTAL LEGENDS DESK CLOCK LEAD CRYSTAL NICE US $7.99
|
![]() Double Sided Outdoor Clock Thermometer 364286 US $55.00
|
![]() Crystal Clear Clock 5 1 2 Oval US $25.00
|
![]() Crystal Clear Clock 6 Square US $25.00
|
![]() Miniature Gold Tone Brass Desk Clock Used Xanadu Quartz US $.01
|
![]() BW Modern Interior Decoration DIY Wall Clock Self Adhesive Numbers US US $19.00
|
![]() Modern Kitchen Pendant Light Island Ceiling Lamp Aluminum Wire New US US $51.40
|
![]() VTG Twos Company Silverplate Candlesticks Set of 3 with Faux Crystal Drops US $49.95
|
![]() New 8 Section Plastic Medicine Storage Box Toolbox NEW Plastic Home Organization US $2.55
|
![]() New Big 99mm Invicta 1786 Russian Diver Limited Edition Black Desk Clock US $175.00
|
![]() Antique Bronze Vintage Traditional Look Table Clock NEW US $9.95
|
![]() GLOBE CRYSTAL GLOBE MAHOGANY STAND US $74.95
|
![]() Floating Wall Shelf Wood Bookshelf Decorative DIY Wall shelves MDF Board 3 color US $81.50
|
![]() Modern Kitchen Pendant Light Island Ceiling Lamp NEW CA US $49.90
|
![]() 8 Section Plastic Medicine Storage Box Toolbox NEW Plastic Home Organization US $2.55
|
![]() MOVADO TABLE OR MANTLE CLOCK WITH ROTATING DIALS US $59.99
|
![]() CONCEPT QUARTZ CRYSTAL DESK CLOCK VERY NICE CLOCK US $19.95
|
![]() PARK AVENUE QUARTZ PARK AVENUE CRYSTAL DESK CLOCK VERY NICE US $24.95
|
![]() STAIGER QUARTZ GERMAN CRYSTAL DESK CLOCK VERY NICE CLOCK US $19.95
|
![]() Seiko Mantel Clock With Westminster and Whittington Chime NIB US $19.99
|
![]() godinger shannon crystal column clock quartz in box glue came off as is US $7.00
|
![]() VERSCAE ROSENTHAL MEDUSA TEASURY CRYSTAL CHIMNEY CLOCK RARE US $195.00
|
![]() CRYSTAL LEGENDS BY GODINGER MANTEL CLOCK US $2.99
|
![]() Bulova B2257 World Time Desk Clock US $80.00
|
![]() VINTAGE FRENCH CHANDELIER 6 ARM ROCOCO MARIE THERESA STYLE GLASS METAL US $960.00
|
![]() VINTAGE 1950 FRENCH ROCOCO CHANDELIER GOLD GLASS PUTTI CHERUBS 6 ARMS US $549.00
|
![]() Cut Crystal Glass shelf mantel Clock US $18.95
|
![]() HOWARD MILLER QUARTZ ACCOLADE DESK CLOCK UNUSED US $24.99
|
![]() Beautiful Shannon Fine Crystal Marie Clock US $9.99
|
![]() Howard Miller 625 355 Santa Fe Wall Clock NH US $16.99
|
![]() VINTAGE 1950 FRENCH CHANDELIER ROCOCO 6 ARMS GLASS AND METAL CANDLES US $510.00
|
![]() NO RESERVE Hayward Above Ground Pool AquaTrol Salt Chlorine Generator System US $217.50
|
![]() LARGE PAIR MARIE THERESA STYLE GLASS WALL SCONCES FROM ITALY WITH SWAGS CANDLES US $880.00
|
![]() Mini Durable Transparent LCD Display Digital Car Electronic Clock with Sucker 1 US $2.59
|
![]() FRENCH LEAD CRYSTAL WITH STAIGERT GERMAN QUARTZ CLOCK US $.99
|

Atomic Clocks and Ntp Servers
In conventional electronic clocks time is kept by running an electrical current through an oscillator which produces a repetitive electrical signal this is then governed by a quartz crystal to keep precision. These crystal oscillators are far more accurate than mechanical clocks but will still drift, perhaps over a second a week.
For day-to-day use crystal oscillators are a fine way to keep track of time; in the everyday running of our lives, a second makes very little difference, however, as light or radio waves can travel 300,000 miles in a second, some high technologies such as satellite navigation or global communication, require far more accuracy to be possible.
Atomic clocks are a timekeeping device that uses the known atomic resonance frequency of an atom to keep time. The first truly accurate atomic clock was built in 1955 at the National Physical Laboratory in the UK and was based on the caesium atom -133 which oscillates at exactly 9,192,631,770 every second.
This oscillation is actually a repetitive signal from the microwave radiation emitted by electrons in an atom when they change energy levels. Much of an atomic clock is designed to create the correct state to cause and augment oscillations.
Although other atoms can be used, the oscillation (9,192,631,770 a second) of the caesium -133 atom is now accepted by the International System of Units (SI) as being the definition of one second.
Atomic clocks are generally very large and constitute many highly technical apparatus such as vacuums and require whole teams of scientists to maintain and monitor the clocks. Much of which goes into compensating for unwanted side-effects such as frequencies of other atoms in the clock and even gravitational dilation (where according to Einstein’s theory clocks at different heights run differently because of the differences in the gravitational field) This makes atomic clocks highly expensive.
Fortunately many large scale national physical laboratories transmit radio time signals from their atomic clocks which can be used to synchronise standard crystal oscillators too.
Atomic clocks are also the basis of GPS (Global Positioning System) as each satellite contains an atomic clock as accurate time is integral for positioning (a position anywhere is made up of a direction, a velocity and time).
GPS signals can also be used to capture a time signal. This is now the most common way computer networks retain accurate time which is also essential in many communications and applications.
Most computer networks use a NTP server (Network Time Protocol) to synchonise their devices to an atomic time signal received via the GPS network.
A universal timescale, UTC (Coordinated universal Time), has been developed based on the time told by atomic clocks, TAI (International Atomic Time). UTC accounts for the slowing of the Earths rotation by adding leap seconds to TAI so as to prevent the gradual drift of night into day (although that would take 40,000 years or so) and allows the whole world to communicate using the same timescale.
About the Author
Richard N Williams is a technical author and a specialist in the telecommunications and network time synchronisation industry helping to develop dedicated NTP clocks. Please visit us for more information about NTP or other network time server solutions.



US $422.90















































































Posted in
Tags: