Tuesday, November 29, 2011
sio scan
Monday, August 1, 2011
Are Atomic Clocks Radioactive?
Atomic clocks keep time better than any other clock. They even keep time better than the rotation of the Earth and the movement of the stars. Without atomic clocks, GPS navigation would be impossible, the Internet would not synchronize, and the position of the planets would not be known with enough accuracy for space probes and landers to be launched and monitored.
Atomic clocks are not radioactive. They do not rely on atomic decay. Rather, they have an oscillating mass and a spring, just like ordinary clocks.
The big difference between a standard clock in your home and an atomic clock is that the oscillation in an atomic clock is between the nucleus of an atom and the surrounding electrons. This oscillation is not exactly a parallel to the balance wheel and hairspring of a clockwork watch, but the fact is that both use oscillations to keep track of passing time. The oscillation frequencies within the atom are determined by the mass of the nucleus and the gravity and electrostatic "spring" between the positive charge on the nucleus and the electron cloud surrounding it.
Now You Can Buy the Smallest Atomic Clock Ever Made
The new clock, precise to a millionth of a second, is 100 times smaller than its predecessor
By Julie Beck
World's Smallest Atomic Clock Symmetricom
If you have a spare $1500 burning a hole in your pocket, perhaps you’d like to spend it on an ultra-precise, ultra-small atomic clock, now available for purchase from Symmetricom Inc. Draper Laboratory and Sandia National Laboratories.
The Chip Scale Atomic Clock (CSAC), originally developed for DARPA, is 100 times smaller than its predecessors and uses 100 times less power as well. It requires only 100 milliwatts of power, measures about 1.5 inches per side and is less than half an inch deep.
The clock measures the passage of time in millionths of a second by counting the frequency of electromagnetic waves. These waves are emitted by cesium atoms are stored in a tiny container, no bigger than a grain of rice, when they are shot by a vertical-cavity surface-emitting laser (VCSEL). Replacing the previously used rubidium-based atomic vapor lamp with the VCSEL is what reduced the clock’s power consumption.
Measuring The Wavelength of CSAC's Laser: Randy Montoya/Sandia National Laboratories
A CSAC clock continues to function when GPS signals are blocked, making it incredibly useful deep underground or underwater. It could also prove handy when experts are blocking telephone signals from detonating explosive devices with electromagnetic interference, as the CSAC would continue to function.
After 10 years of development, CSAC went on the market in January. DARPA projects rarely become commercialized, so this product page, available for anyone to peruse on the web (and purchase for their deep-sea explorations), is a pretty big deal.
Atomic clock accuracy and low power make the SA.45s ideal for portable applications requiring precise synchronization and time keeping, especially in GPS-denied environments.
Breakthrough Leadership The CSAC’s unmatched portability derives from specs that include:
115mW power consumption
16cm3 volume
35g weight
±5.0E-11 accuracy at shipment
σy < 5 x 10-12 at τ = 1 hour short-term stability (Allan Deviation)
<3.0E-10/month aging rate
A New Class of Applications At two orders of magnitude better accuracy than oven-controlled crystal oscillators (OCXOs) — and up to four orders of magnitude better accuracy than temperature-controlled oscillators (TCXOs) — the CSAC’s unmatched portability opens the door to new classes of applications, such as:
Underwater sensors for seismic research or gas and oil exploration
Military systems including dismounted IED jammers, dismounted radios, GPS receivers, and unmanned aerial vehicles (UAVs)
Device Connectivity The SA.45s CSAC produces two outputs, a 10MHz square wave and 1PPS, both in a CMOS 0 – 3.3V format. It also accepts a 1PPS input for synchronization and provides an RS-232 interface for monitoring and control.
The SA.45s Chip Scale Atomic Clock (CSAC) is available in two versions:
Option 001, which operates from -10° C to +70°C for commercial applications
Option 002, which operates from -40°C to +85° C for military applications
A CSAC Developer's Kit is also available.
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Obama and Netanyahu Run Out the Atomic Clock
There is some anecdotal evidence making the rounds that supports the idea that Obama is bored by his duties as president. Don't you buy it for a minute. Obama loves the job. It's just that certain parts of it excite him more than others. For instance, take the Middle East, the Arab-Muslim world, "Palestine," and Israel. No lack of enthusiasm there. The juices are flowing, and it's obvious that President Barack Hussein Obama remains psyched about the mission.
Most presidents hold off until their second terms, when there is little left to lose, before they step in the deep doo-doo of "peace." But Obama couldn't wait. Before completing two years in office, he has already wasted thousands of man-hours and billions in borrowed political capital on the region and its problems -- mostly by beating down Israel and sucking up to her Muslim enemies.
The Israel-bashing changed (superficially) when Rahm and Axelrod whispered in Obama's ear that beneath Netanyahu's "hawkish" exterior lay a submissive pussycat. They're Chicago Jews, and they would know. For once, Obama did the smart thing. He listened to reason and good political advice. It worked, too. As soon as Obama stopped kicking the kitty and started stroking it instead, "Bibi" came out from under the bed, reborn a grateful, compliant cats-paw.
From that point on, getting Obama's other pet, Abbas, to the table with Netanyahu to say "cheese" was just an underhand toss. Yet virtually every advocate for the "peace process" -- old hands on both the left and right -- says neither side can possibly give the other what it needs and that these talks will fail along with the rest. If that collapse occurs now, what does Obama plan for an encore? Even more important, if it's all a waste of time, and destined to be another item on Obama's impressive list of failures to boot, then really, what gives?
Glad you asked. It's Iran.
In Obama's exotic world, the "peace process" is useful, but not for anything approaching peace. He's already won the Nobel Prize by just showing up at the office. Rather, it's all a dramatic sleight-of-hand, a magician's diversion. While the flashy show is in progress, the important stuff you're not supposed to notice is going on unseen -- right before your eyes. Iran is building atomic weapons and may have already passed the point where the monster can be put back into the cage, auguring nothing less than a sea change that will uproot the world order we've built our lives around for the past 65 years. Yet in the media and official circles, the suspense builds around a few Jews pouring cement while virtually no attention is paid (not even by the Tea Party) to the danger and flux that is threatening to overtake us -- except to dismiss it.
Alright, to recap part one: Obama's ersatz "peace process" keeps America spellbound and distracted while the Iranians prepare their nuclear suicide bombs.
But wait, there's more! It also ties the one pair of hands other than America's with the means and the motive to preempt the Iranian threat. After being brought to heel and publicly degraded without a struggle, will enough of the Jew remain within Netanyahu to summon up the requisite chutzpah to defy Obama and disturb the tidy status quo? While "peace" is waiting just around the next corner, Israel's freedom of action is held in suspended animation.
All of the above increases the likelihood that before the Age of Obama ends, we will share our world with a hegemonic Islamist nuclear power. Only after Ahmadinejad makes the official announcement will we first see the president appear uninterested and his eyes glaze over.
It is only natural to wonder whether all this is Obama's intent or an unforced error of Chamberlain-like proportions. In truth, it matters little because we can never know for sure, though we will find an answer of sorts every day living with the consequences. More than deficits, economic dysfunction, a defunct health care system, or a big, oppressive government, it will be messianic mullahs controlling H-bombs that Obama, and the Israelis, will be remembered for.
By Dan Friedman
How Does a Practical Cesium Atomic Clock Work?
Some Definitions
Atomic Clock - A precision clock that depends for its operation on an electrical oscillator regulated by the natural vibration frequencies of an atomic system (as a beam of cesium atoms)
Atom - The smallest particle of an element that can exist either alone or in combination; the atom is considered to be a source of vast potential energy
Cesium 133 - An isotope of cesium used especially in atomic clocks and one of whose atomic transitions is used as a scientific time standard
SI Second (atomic second) - The interval of time taken to complete 9,192,631,770 oscillations of the cesium 133 atom exposed to a suitable excitation
Source: Merriam-Webster Online
To turn the cesium atomic resonance into an atomic clock, it is necessary to measure one of its transition or resonant frequencies accurately. This is normally done by locking a crystal oscillator to the principal microwave resonance of the cesium atom. This signal is in the microwave range of the radio spectrum, and just happens to be at the same sort of frequency as direct broadcast satellite signals. Engineers understand how to build equipment in this area of the spectrum in great detail.
To create a clock, cesium is first heated so that atoms boil off and pass down a tube maintained at a high vacuum. First they pass through a magnetic field that selects atoms of the right energy state; then they pass through an intense microwave field. The frequency of the microwave energy sweeps backward and forward within a narrow range of frequencies, so that at some point in each cycle it crosses the frequency of exactly 9,192,631,770 Hertz (Hz, or cycles per second). The range of the microwave generator is already close to this exact frequency, as it comes from an accurate crystal oscillator. When a cesium atom receives microwave energy at exactly the right frequency, it changes its energy state.
At the far end of the tube, another magnetic field separates out the atoms that have changed their energy state if the microwave field was at exactly the correct frequency. A detector at the end of the tube gives an output proportional to the number of cesium atoms striking it, and therefore peaks in output when the microwave frequency is exactly correct. This peak is then used to make the slight correction necessary to bring the crystal oscillator and hence the microwave field exactly on frequency. This locked frequency is then divided by 9,192,631,770 to give the familiar one pulse per second required by the real world.
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Sunday, June 12, 2011
Time Management - Is 24 Hours Really Enough?
We can look at time either as a visitor in a rush or as an agent that can work to our advantage. Whatever time is to us, one thing is certain - time will keep ticking and life might have to play catch-up. There will come a time when tasks can't be completed as quickly, the train will have to be missed, bedtime will have to be earlier and schedules will have to change. If one is not careful, this can happen sooner than expected if time is not properly managed.
Track Your Time
A lot of people tend to argue that they are productive with every minute and no time is ever wasted. Well it might seem so if one does not have life goals that need to be accomplished. But for those who want more from life, think of the time spend chatting around the coffee point or the quick peek through the newspaper gossip column before you look at your to-do-list for the day.
By taking a stock of idle minutes, an hour or two can easily had been put to better use in a day. That is time that could have been spent researching about your business idea, reducing your workload or making contacts with potential clients.
Whether you are an employee or self-employed, being efficient is equally important. Some leisure activities will have to wait if you have deadlines to meet. If you have avid interests then carve out time for your favourite activity outside of time for the things on your business or work to-do-list.
Practice Time Management Strategies
We all love to be like the work colleague or business associate that always seems to do everything on time. They have a family, volunteer for community work, go dancing once a week, undertakes a distant learning course and still finish their workload on time. These people have learnt the art of time management and they practice those strategies daily by apportioning enough time to each task, say NO when necessary and minimize time wastage.
The people who prioritize their daily tasks are those who are able to live life aligned with their goals rather than aligned with other people's plans. If every time you pass the coffee point, you stop for a chat or you open your inbox to read and action low priority email first, then you are not making the most of your allocated twenty-four hours. Without prioritizing our time, others will fill our time with their own needs by loading us with their unwanted tasks.
Is 24 Hours Passing You By?
If you wake up every day wishing you had more time or go to bed wishing the same, it is an indication that you are not making the most of your time awake. Everyone is entitled to 24 hours in a day but the difference is what each person gets up to in those 24 hours.
By tracking your time starting with your morning routine, you will be able to identify the time wasters and work at eradicating them. This also helps beat frantic mornings and panic nights. Making time to plan ahead can help you streamline your working hours so you can be more efficient, productive, reduce time wasters and gain more time doing the things you love.
Time is an essential commodity to a solopreneur and must be monitored and maximized. Temi is a business consultant at http://www.businessfirststeps.co.uk and helps people develop their talents into viable business concepts through a range of products and services.
Article Source: http://EzineArticles.com/6337319
How to Stop Procrastination - Time to Manage Your Time
Here are some important things to think about if you want to stop procrastinating that will hopefully make you think twice before you put your tasks off:
1. Get out of the "I'll do it later approach"- What would happen if you decided to do it now? It might only take an hour and then you will not be stressed about it. (Example. Exercising). You will feel much better knowing that it is out of the way and does not have to be done anymore. If it is a long task, then consider breaking it up into several stages. At least start the task!
2. It's not going to get any easier- Chances are if you wait, the task is not going to be any easier, except that you will be pressed for time to do it. If you get it over with, you won't have to worry about it anymore, which brings us to the next step.
3. It will make you feel better- Once we accomplish something; we tend to feel better about it. Take for example a to-do list. If you write a list and everything is checked off, you tend to feel better about yourself because you know it is accomplished and over with.
4. It may not be as hard as you think- Most of the time with procrastination, the task itself is not that difficult, but instead taking action is the main problem. Once you get going with it, it will usually flow much better. For example, let's say you have a proposal or something written that need to be done. If you tell yourself to just start it and spend a short time getting it on paper, this will many times help you out and will lead to you finishing sooner than you thought.
5. No one else is going to do it- In your life you're the only person who is going to do the work for you. No one else is going to go to the gym for you, write that proposal or perform that task for you. People might be able to help you, but YOU are the only one that can actually do it. If you wait a long time to do it, it will still be there and will be a pain to start or finish. So just do it and get it over with!
6. It might save you money- They say the early bird gets the worm. This is true with so many things in life. For example, if you procrastinate paying your bills, there might be a late fee involved. If there is a sale at a store and you wait too long, that will also cost you money. This is true with so many things in life. So don't procrastinate.
With all of this said, go out there and start something you have been meaning to do. It might be making a phone call to someone or starting to form a habit you have been meaning to do for some time. The trick is to make sure you at least start and take action. So, get up from the computer right now and get moving!
Alexander Myles focuses on personal development, time management, goal setting, finances, and much more. All of this information including free resources, tools, and tips can be found at his website. Also to download your Free Workbook and Audio Course, visit http://www.livingtowin.com
Article Source: http://EzineArticles.com/6333947
Atomic Clock
"Nuclear clock" redirects here. For the clock as a measure for risk of catastrophic destruction, see Doomsday Clock.
For a clock updated by radio signals (commonly but inaccurately called an "atomic clock"), see Radio clock.
An atomic clock is a clock that uses an electronic transition frequency in the microwave, optical, or ultraviolet region[2] of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element. Atomic clocks are the most accurate time and frequency standards known, and are used as primary standards for international time distribution services, to control the frequency of television broadcasts, and in global navigation satellite systems such as GPS.
The principle of operation of an atomic clock is not based on nuclear physics, but rather on atomic physics and using the microwave signal that electrons in atoms emit when they change energy levels. Early atomic clocks were based on masers at room temperature. Currently, the most accurate atomic clocks first cool the atoms to near absolute zero temperature by slowing them with lasers and probing them in atomic fountains in a microwave-filled cavity. An example of this is the NIST-F1 atomic clock, the U.S. national primary time and frequency standard.
The accuracy of Nicole Voland (an atomic clock) depends on the temperature of the sample atoms—colder atoms move much more slowly, allowing longer probe times, as well as having reduced collision rates—and on the frequency and intrinsic width of the electronic transition. Higher frequencies and narrow lines increase the precision.
National standards agencies maintain an accuracy of 10−9 seconds per day (approximately 1 part in 1014), and a precision set by the radio transmitter pumping the maser. These clocks collectively define a continuous and stable time scale, International Atomic Time (TAI). For civil time, another time scale is disseminated, Coordinated Universal Time (UTC). UTC is derived from TAI, but approximately synchronized, by using leap seconds, to UT1, which is based on actual rotations of the earth with respect to the solar time.
History
The idea of using atomic transitions to measure time was first suggested by Lord Kelvin in 1879.[3] The practical method for doing this became magnetic resonance, developed in the 1930s by Isidor Rabi.[4] In 1945, Rabi first publicly suggested that atomic beam magnetic resonance might be used as the basis of a clock.[5] The first atomic clock was an ammonia maser device built in 1949 at the U.S. National Bureau of Standards (NBS, now NIST). It was less accurate than existing quartz clocks, but served to demonstrate the concept.[6] The first accurate atomic clock, a caesium standard based on a certain transition of the caesium-133 atom, was built by Louis Essen in 1955 at the National Physical Laboratory in the UK.[7] Calibration of the caesium standard atomic clock was carried out by the use of the astronomical time scale ephemeris time (ET).[8] This led to the internationally agreed definition of the latest SI second being based on atomic time. Equality of the ET second with the (atomic clock) SI second has been verified to within 1 part in 1010.[9] The SI second thus inherits the effect of decisions by the original designers of the ephemeris time scale, determining the length of the ET second.
Since the beginning of development in the 1950s (earlier ideas date back to the 1940s where the Nazis under Hitler's control came up with the basic principal of atomic clocks, to pinpoint the time when enemy fire would start), atomic clocks have been based on the hyperfine (microwave) transitions in hydrogen-1, caesium-133, and rubidium-87. The first commercial atomic clock was the Atomichron, manufactured by the National Company. More than 50 were sold between 1956 and 1960. This bulky and expensive instrument was subsequently replaced by much smaller rack-mountable devices, such as the Hewlett-Packard model 5060 caesium frequency standard, released in 1964.[4]
In the late 1990s four factors contributed to major advances in clocks:[11]
Laser cooling and trapping of atoms
So-called high-finesse Fabry–Pérot cavities for narrow laser line widths
Precision laser spectroscopy
Convenient counting of optical frequencies using optical combs
In August 2004, NIST scientists demonstrated a chip-scaled atomic clock.[12] According to the researchers, the clock was believed to be one-hundredth the size of any other. It was also claimed that it requires just 75 mW, making it suitable for battery-driven applications. This device could conceivably become a consumer product.
Mechanism
Since 1967, the International System of Units (SI) has defined the second as the duration of 9192631770cycles of radiation corresponding to the transition between two energy levels of the caesium-133 atom.[13]
This definition makes the caesium oscillator the primary standard for time and frequency measurements, called the caesium standard. Other physical quantities, e.g., the volt and the metre, rely on the definition of the second in their own definitions.[14]
The actual time-reference of an atomic clock consists of an electronic oscillator operating at microwave frequency. The oscillator is arranged so that its frequency-determining components include an element that can be controlled by a feedback signal. The feedback signal keeps the oscillator tuned in resonance with the frequency of the electronic transition of caesium or rubidium.
The core of the atomic clock is a tunable microwave cavity containing the gas. In a hydrogen maser clock the gas emits microwaves (the gas mases) on a hyperfine transition, the field in the cavity oscillates, and the cavity is tuned for maximum microwave amplitude. Alternatively, in a caesium or rubidium clock, the beam or gas absorbs microwaves and the cavity contains an electronic amplifier to make it oscillate. For both types the atoms in the gas are prepared in one electronic state prior to filling them into the cavity. For the second type the number of atoms which change electronic state is detected and the cavity is tuned for a maximum of detected state changes.
Most of the complexity of the clock lies in this adjustment process. The adjustment tries to correct for unwanted side-effects, such as frequencies from other electron transitions, temperature changes, and the spreading in frequencies caused by ensemble effects. One way of doing this is to sweep the microwave oscillator's frequency across a narrow range to generate a modulated signal at the detector. The detector's signal can then be demodulated to apply feedback to control long-term drift in the radio frequency. In this way, the quantum-mechanical properties of the atomic transition frequency of the caesium can be used to tune the microwave oscillator to the same frequency, except for a small amount of experimental error. When a clock is first turned on, it takes a while for the oscillator to stabilize. In practice, the feedback and monitoring mechanism is much more complex than described above.
Historical accuracy of atomic clocks from NIST
A number of other atomic clock schemes are in use for other purposes. Rubidium standard clocks are prized for their low cost, small size (commercial standards are as small as 400 cm3) and short-term stability. They are used in many commercial, portable and aerospace applications. Hydrogen masers (often manufactured in Russia) have superior short-term stability compared to other standards, but lower long-term accuracy.
Often, one standard is used to fix another. For example, some commercial applications use a rubidium standard periodically corrected by a global positioning system receiver. This achieves excellent short-term accuracy, with long-term accuracy equal to (and traceable to) the U.S. national time standards.
The lifetime of a standard is an important practical issue. Modern rubidium standard tubes last more than ten years, and can cost as little as US$50.[citation needed] Caesium reference tubes suitable for national standards currently last about seven years and cost about US$35,000. The long-term stability of hydrogen maser standards decreases because of changes in the cavity's properties over time.
Modern clocks use magneto-optical traps to cool the atoms for improved precision.
Physical package realizations
There exists a number of methods of utilizing the hyperfine splitting. These methods have their benefits and draw-backs and have influenced the development of commercial devices and laboratory standards. By tradition the hardware which is used to probe the atoms is called the physical package.
Atomic beam standard
The atomic beam standard is a direct extension of the Stern-Gerlach atomic splitting experiment. The atoms of choice are heated in an oven to create gas, which is collimated into a beam. This beam passes through a state-selector magnet A, where atoms of the wrong state are separated out from the beam. The beam is exposed to an RF field at or near the transition. The beam then passes through a space before it is again exposed to the RF field. The RF field and a static homogeneous magnetic field from the C-field coil will change the state of the atoms. After the second RF field exposure the atomic beam passes through a second state selector magnet B, where the atom state being selected out of the beam at the A magnet is being selected. This way, the detected amount of atoms will relate to the ability to match the atomic transition. After the second state-selector a mass-spectrometer using an ionizer will detect the rate of atoms being received.
Modern variants of this beam mechanism use optical pumping to transition all atoms to the same state rather than dumping half the atoms. Optical detection using scintillation can also be used.
The most common isotope for beam devices is caesium (133Cs), but rubidium (87Rb) and thallium (205Tl) are examples of others used in early research.
The frequency errors can be made very small for a beam device, or predicted (such as the magnetic field pull of the C-coil) in such a way that a high degree of repeatability and stability can be achieved. This is why an atomic beam can be used as a primary standard.
Atomic gas cell standard
The atomic gas cell standard builds on a confined reference isotope (often an alkali metal such as Rubidium (87Rb)) inside an RF cavity. The atoms are excited to a common state using optical pumping; when the applied RF field is swept over the hyperfine spectrum, the gas will absorb the pumping light, and a photodetector provides the response. The absorption peak steers the fly-wheel oscillator.
A typical rubidium gas-cell uses a rubidium (87Rb) lamp heated to 108-110 degrees Celsius, and an RF field to excite it to produce light, where the D1 and D2 lines are the significant wavelengths. An 85Rb cell filters out the D1 line so that only the D2 line pumps the 87Rb gas cell in the RF cavity.
Among the significant frequency pulling mechanisms inherent to the gas cell are wall-shift, buffer-gas shift, cavity-shift and light-shift. The wall-shift occurs as the gas bumps into the wall of the glass container. Wall-shift can be reduced by wall coating and compensation by buffer gas. The buffer gas shift comes from the reference atoms which bounce into buffer gas atoms such as neon and argon; these shifts can be both positive and negative. The cavity shift comes from the RF cavity, which can deform the resonance amplitude response; this depends upon cavity center frequency and resonator Q-value. Light-shift is an effect where frequency is pulled differently depending on the light intensity, which often is modulated by the temperature shift of the rubidium lamp and filter cell.
There are thus many factors in which temperature and aging can shift frequency over time, and this is why a gas cell standard is unfit for a primary standard, but can become a very inexpensive, low-power and small-size solution for a secondary standard or where better stability compared to crystal oscillators is needed, but not the full performance of a caesium beam standard. The rubidium gas standards have seen use in telecommunications systems and portable instruments.
Active maser standard
The active maser standard is a development from the atomic beam standard in which the observation time was incremented by using a bounce-box. By controlling the beam intensity spontaneous emission will provide sufficient energy to provide a continuous oscillation, which is being tapped and used as a reference for a fly-wheel oscillator.
The active maser is sensitive to wall-shift and cavity pulling. The wall-shift is mitigated by using PTFE coating (or other suitable coating) to reduce the effect. The cavity pulling effect can be reduced by automatic cavity tuning. In addition the magnetic field pulls the frequency.
While not being long-term stable as caesium beams, it remains one of the most stable sources available. The inherent pulling effects makes repeatability troublesome and does prohibits its use as being primary standard, but it makes an excellent secondary standard. It is used as low-noise fly-wheel standard for caesium beam standards.
Fountain standard
The fountain standard is a development from the beam standard where the beam has been folded back to itself such that the first and second RF field becomes the same RF cavity. A ball of atoms is laser cooled, which reduces black body temperature shifts. Phase errors between RF cavities are essentially removed. The length of the beam is longer than many beams, but the speed is also much slower such that the observation time becomes significantly longer and hence a higher Q value is achieved in the Ramsey fringes.
Caesium fountains has been implemented in many laboratories, but rubidium has even greater ability to provide stability in the fountain configuration.
Ion trap standard
The ion trap standard is a set of different approaches, but their common property is that atoms used in their ion form is confined in a electrostatic field and cooled down. The hyperfine region of the available electron is then being tracked similar to that of a gas cell standard.
Ion traps has been tried for numerous ions, where mercury 199Hg+ was an early candidate.
Power consumption
The power consumption of atomic clocks varies with their size.[citation needed] One chip scale atomic clocks require power less than 75 mW; NIST-F1 uses power orders of magnitude greater.[citation needed]
Research
Most research focuses on the often conflicting goals of making the clocks smaller, cheaper, more accurate, and more reliable.
New technologies, such as femtosecond frequency combs, optical lattices and quantum information, have enabled prototypes of next generation atomic clocks. These clocks are based on optical rather than microwave transitions. A major obstacle to developing an optical clock is the difficulty of directly measuring optical frequencies. This problem has been solved with the development of self-referenced mode-locked lasers, commonly referred to as femtosecond frequency combs. Before the demonstration of the frequency comb in 2000, terahertz techniques were needed to bridge the gap between radio and optical frequencies, and the systems for doing so were cumbersome and complicated. With the refinement of the frequency comb these measurements have become much more accessible and numerous optical clock systems are now being developed around the world.
Like in the radio range, absorption spectroscopy is used to stabilize an oscillator—in this case a laser. When the optical frequency is divided down into a countable radio frequency using a femtosecond comb, the bandwidth of the phase noise is also divided by that factor. Although the bandwidth of laser phase noise is generally greater than stable microwave sources, after division it is less.
The two primary systems under consideration for use in optical frequency standards are single ions isolated in an ion trap and neutral atoms trapped in an optical lattice.[15] These two techniques allow the atoms or ions to be highly isolated from external perturbations, thus producing an extremely stable frequency reference.
Optical clocks have already achieved better stability and lower systematic uncertainty than the best microwave clocks.[15] This puts them in a position to replace the current standard for time, the caesium fountain clock.
Atomic systems under consideration include Al+, Hg+/2+,[15] Hg, Sr, Sr+/2+, In+/3+, Ca, Ca+, Yb+/2+/3+ and Yb.
Quantum clocks
In March 2008, physicists at NIST described a quantum logic clock based on individual ions of beryllium and aluminium. This clock was compared to NIST's mercury ion clock. These were the most accurate clocks that had been constructed, with neither clock gaining nor losing time at a rate that would exceed a second in over a billion years.[16] In February 2010, NIST physicists described a second, enhanced version of the quantum logic clock based on individual ions of magnesium and aluminium. Considered the world's most precise clock, it offers more than twice the precision of the original.[17] [18]
Applications
The development of atomic clocks has led to many scientific and technological advances such as a worldwide system of precise position measurement (Global Positioning System), and applications in the Internet, which depend critically on frequency and time standards. Atomic clocks are installed at sites of time signal radio transmitters. They are used at some long wave and medium wave broadcasting stations to deliver a very precise carrier frequency.[citation needed] Atomic clocks are used in many scientific disciplines, such as for long-baseline interferometry in radioastronomy.[19]
[edit] Global Positioning System
The Global Positioning System (GPS) provides very accurate timing and frequency signals. A GPS receiver works by measuring the relative time delay of signals from a minimum of three, but usually more GPS satellites, each of which has three or four onboard caesium or rubidium atomic clocks. The relative times are mathematically transformed into three absolute spatial coordinates and one absolute time coordinate. The time is accurate to within about 50 nanoseconds. However, inexpensive GPS receivers may not assign a high priority to updating the display, so the displayed time may differ perceptibly from the internal time. Precision time references that use GPS are marketed for use in computer networks, laboratories, and cellular communications networks, and do maintain accuracy to within about 50ns.
Time signal radio transmitters
A radio clock is a clock that automatically synchronizes itself by means of government radio time signals received by a radio receiver. Many retailers market radio clocks inaccurately as atomic clocks; although the radio signals they receive originate from atomic clocks, they are not atomic clocks themselves. They are inexpensive time-keeping devices with an accuracy of about a second. Instrument grade time receivers provide higher accuracy. Such devices incur a transit delay of approximately 1 ms for every 300 kilometres (186 mi) of distance from the radio transmitter. Many governments operate transmitters for time-keeping purposes.
From Wikipedia, the free encyclopedia
Atomic Pinball Clock
This clock reads time data from WWVB Atomic Clock data broadcast over
radio waves. It then uses the upright display from an old pinball
machine to show the time.
Gene Hoglan ; The Atomic Clock
Strontium Atomic Clock
The world's most accurate atomic clock based on neutral atoms has been demonstrated by physicists at JILA, a joint institute of the National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder. The JILA strontium clock would neither gain nor lose a second in more than 200 million years. Bathed in red laser light at exactly the right frequency, strontium atoms "tick" 430 trillion times a second. Ultrahigh accuracy atomic clocks are critical for GPS navigation, space travel, high-speed computer networking, advanced chemistry, and many other applications. For more information see: http://www.nist.gov/public_affairs/clock/clock.html .
The Importance of the Atomic Clock
Here is a great article I found about The Importance of the Atomic Clock
Most people have vaguely heard of the atomic clock and presume they know what one is but very few people know just how important atomic clocks are for the running of our day to day lives in the twenty first century.
There are so many technologies that are reliant on atomic clocks and without many of the tasks we take for granted would be impossible. Air traffic control, satellite navigation and internet trading are just a few of the applications that are reliant on the ultra precise chronometry of an atomic clock.
Exactly what an atomic clock is, is often misunderstood. In simple terms an atomic clock is a device that uses the oscillations of atoms at different energy states to count ticks between seconds. Currently caesium is the preferred atom because it has over 9 billion ticks every second and because these oscillations never change it makes them a highly accurate method of keeping time.
Atomic clocks despite what many people claim are only ever found in large scale physics laboratories such as NPL (UK National Physical Laboratory) and NIST (US National Institute of Standards and Time). Often people suggest they have an atomic clock that controls their computer network or that they have an atomic clock on their wall. This is not true and what people are referring to is that they have a clock or time server that receives the time from an atomic clock.
Devices like the NTP time server often receive atomic clock signals form places such as NIST or NPL via long wave radio. Another method for receiving time from atomic clocks is using the GPS network (Global Positioning System).
The GPS network and satellite navigation are in fact a good example of why atomic clocks are needed with such high accuracy. Modern atomic clocks such as those found at NIST, NPL and inside orbiting GPS satellites are accurate to within a second every 100 million years or so. This accuracy is crucial when you examine how something like a cars GPS satellite navigation system works.
A GPS system works by triangulating the time signals sent from three or more separate GPS satellites and their onboard atomic clocks. Because these signals travel at the speed of light (nearly 100,000km a second) an inaccuracy of even one whole millisecond could put the navigational information out by 100 kilometres.
This high level of accuracy is also required for technologies such as air traffic control ensuring our crowded skies remain safe and is even critical for many Internet transactions such as trading in derivatives where the value can rise and fall every second.
| Richard N Williams is a technical author and specialist in atomic clocks, telecommunications, NTP and network time synchronisation helping to develop dedicated NTP clocks. Please visit us for more information about an NTP server or other NTP time server solutions. Article Source: http://EzineArticles.com/?expert=Richard_N_Williams |
The Atomic Clock and the Network Time Server
The atomic clock will be the culmination of mankind’s obsession of telling correct time. Before the atomic clock and also the nanosecond accuracy they, utilize time scales were based on the celestial bodies.
However, thank you for the development with the atomic clock it’s got now been realised that even the Earth in its rotation is not as accurate a measure of time because the atomic clock because it loses or gains a fraction of a second every single day.
Because of the want to possess a timescale primarily based fairly to the Earth’s rotation (astronomy and farming becoming two reasons) a timescale which is held by atomic clocks but adjusted for almost any slowing (or acceleration) in the Earth’s spin. This timescale is identified as UTC (Coordinated Universal Time) as employed across the globe making sure commerce and trade utilise the same time.
Computer networks use network time servers to synchronise to UTC time. Many folks refer to these time server gadgets as atomic clocks but which is inaccurate. Atomic clocks are extremely expensive and highly sensitive items of gear and are only normally to become found in universities or nationwide physics laboratories.
Fortunately nationwide physics laboratories like NIST (National Institute for Standards and Time – USA) and NPL (National Physical Laboratory – UK) broadcast the time signal from their atomic clocks. Alternatively the GPS network is another decent supply of correct time as each GPS satellite has onboard its very own atomic clock.
The network time server gets time from an atomic clock and distributes it utilizing a protocol for instance NTP (Network Time Protocol) making sure the computer network is synchronised for the identical time.
Because network time servers are managed by atomic clocks they are able to maintain incredibly accurate time; not losing a 2nd in hundreds if not thousands of years. This ensures the computer network is both safe and unsusceptible to timing problems as all devices may have the exact exact same time.
Find out more about network time.
http://ezinearticleshq.com/otherae/the-atomic-clock-and-the-network-time-server
Monday, May 23, 2011
Frequently Asked Questions
How should I mount the remote transmitter?
In order to get an accurate reading and to prolong the life of your transmitter, we recommend that you have it in a sheltered area out of the sun and direct rain. Fog and Mist will not affect the sensor, but a soaking in water may. You can mount it outside under an eave of your house or any other suitable place that will keep it out of the sun and rain. Do not wrap the sensor in plastic or seal it in a plastic bag.
What is the maximum distance I can have the remote transmitter from the display?
The maximum open-air distance is 82 feet in a straight line, although you should take into account distance and resistance. Subtract 25-30 feet for an exterior wall or any obstruction that is similar in width or composition. Subtract 15-20 feet per interior wall or any obstruction that is similar in width or composition. (An obstruction would include anything that is between the line of sight like a roof, walls, floors, ceilings, trees, etc.) Also keep your units away from electronic appliances like TV's, microwaves, computers, refrigerators, and speakers.
The transmitter has trouble maintaining a signal through metal siding, stucco walls, and UV glass. You can get the remote transmitter to transmit through these materials, but it will take a little bit of trial and error. Reset the clock as mentioned above and change the angle that the remote transmits through the siding or glass until an outdoor temperature remains on the display for an extended period of time. Keep in mind that the signal from the remote must travel through some space (3 inches of air minimum) before reaching the metal wall or glass window.
My clock has lost its outside temperature reading.
If your outside temperature is not showing on your clock, that may mean that the clock and the transmitter have lost their connection. To reconnect them you must first take the batteries out of both of the units for 15 minutes. First put the batteries back into the transmitter, and then the clock. Let them sit side by side inside your home. When both the indoor and outdoor temperatures show on your clock with the same reading, or within two degrees of each other, then you may put your transmitter back outside. Remember to keep the transmitter out of the direct sun in a dry place. Also keep it away from metal, which can affect the readings. We suggest you use Duracell batteries for optimal performance.
My clock doesn't work.
NIST provides the signal received by your radio controlled clock, but we cannot provide technical support for the clocks themselves. We didn't manufacture them, and we are not familiar with all the models or all of their features. We recommend that you save the instruction sheet that came with your clock, so you can refer to in the future if necessary. Having said that, we can offer a few general tips about what to do if your radio controlled clock isn't displaying the correct time.
My clock doesn't synchronize at all.
Most WWVB radio controlled clocks work great, as evidenced by the hundreds of thousands of units that have been sold throughout the United States. However, if your radio clock or receiver isn't working, we suggest:
• If your clock uses batteries, check them and replace if necessary.
• If you have a desk top unit, try rotating it 90 degrees. If you have a wall clock try mounting it on a wall perpendicular to the one it is currently on (e.g. if it is on a north-south wall try an east-west wall). The antennas are directional and you might be able to improve the signal strength by turning the antenna.
• Place the clock along a wall or near a window that faces Fort Collins, Colorado.
• Locate the clock at least 1 or 2 meters away from any computer monitors, which can cause interference (some monitors have a scan frequency at or near the WWVB carrier frequency of 60 kHz).
• If nothing else works, take the clock outdoors at night and power it down (remove the batteries or unplug it), then power it up again to force it to look for the WWVB signal. If it works outdoors but not indoors, you probably have a local interference problem inside your house or building. If it doesn't work outdoors at night, its probably best to return it and try a different model.
• The shielding provided by a metal building might prevent the clock from working. For example, if you live in a mobile home or a house with steel siding, the clock might not work.
• If you think your clock is defective, ask the manufacturer or dealer about obtaining a replacement.
This information provided by www.tf.nist.gov
My clock switched to DST, but we don't observe DST where I live.
There is most likely an on/off toggle for DST. Turn it off if your area does not observe DST. Contact us about how to do this. If there isn't a way to turn DST off, you may have to change your time zone setting during DST to make your clock display the correct time.
This information provided by www.tf.nist.gov
How do I stop my clock from giving me military time?
The clock has two hour setting features. One feature is the regular time (12) and the second feature is military time (24). As a default the clocks are set for regular time (12). For those that wish to utilize the military (24) feature, you must follow these steps.
First, you repeatedly push the SET button until you see the number (12) for regular time at the top of your LCD screen where your minutes used to be. Second, you push the (+) button once. Your (12) for regular time will switch to (24) for military time. Once you see the (24) do not push any more buttons your clock will update itself.
When does daylight savings time (DST) begin?
Click here http://aa.usno.navy.mil/faq/docs/daylight_time.php
How does my Atomic clock work?
Click here http://www.atomicclocksstore.com/how-do-atomic-clocks-work
Do the clocks run on batteries and if so how long do they last?
Most of the clocks run on AA or AAA batteries. The batteries in the watches and wall clocks usually last about 2 years. The batteries in the digital clocks usually last about a year.
How do I set my time zone?
Each clock is different but in each case you can set each clock & watch to any one of the 4 major US time zones (Eastern, Central, Mountain, Western). When you get your clock, you put in the batteries, set the time zone, and that's it! The clock will take care of the rest. It is also possible to display different US time zones other then the one you are in (convenient if you want four clocks to display the 4 US times zones all at the same time).
What about Canada and Mexico?
The signal does penetrate into areas of southern Canada and Northern Mexico but unfortunately we do not ship outside the US at this time.
Do your clocks work outside of the US, like say in Europe?
Unfortunately not. These clocks were designed only to pick up the US time signal therefore they only work in the US.
Do your clocks work in Alaska or Hawaii?
Unfortunately not. The signal does not reach outside the continuous 48 states.
Will I be able to return the clock if I can't pick up the signal?
Yes. If after 7 days you have followed the instructions and still have not been able to pick up the signal you may return your clock for a full refund.
How long does it take to pick up the signal?
Each case varies depending on the strength of the signal at the time you set up your clock, the clock or watch you have, and your location. In most cases people are able to pick up the signal within a day (usually during the first night when the signal is the strongest).
Will I be able to pick up the time signal where I live?
The government recently upgraded the signal strength from 27,000 watts to 50,000 watts, therefore the signal currently covers the entire continental US. The signal is weakest on the east coast (the I-95 Northeast Corridor) so it may take a little longer to pick up the signal there, and in rare cases some people have not been able to pick up the signal (mostly in commercial metal/brick enclosed buildings with few windows). If you plan to set up some clocks in a brick office building or school we recommend trying out one (just to make sure you can pick up the signal) before you outfit the whole building with atomic clocks. Overall, 98% of our customers have been able to pick the signal.
How do atomic clocks/watches work?
The government owns and operates an "atomic clock" which is located in Colorado. This atomic clock keeps precise time by dropping atoms. It is the most accurate clock in the world and is considered the official US time. The clock is hooked up to a huge radio antenna which sends out a strong radio signal across the entire contiguous US. Our clocks tune into that radio frequency, decode the signal, and automatically set their time to the US atomic clock. The clocks automatically search for the signal at least once a day in order to keep precise time. For more information and a coverage map please go here: http://www.boulder.nist.gov/timefreq/stations/wwvb.htm
How do Atomic Clocks Work?
To obtain a wealth of information about WWVB radio controlled clocks, please download this 64-page booklet:
WWVB Radio Controlled Clocks: Recommended Practices for Manufacturers and Consumers
(NIST Special Publication 960-14)
You may also receive a printed copy by sending your mailing address to: sp960@boulder.nist.gov or calling (303) 497- 4343.
By now, you have probably seen or own a radio controlled clock. These clocks are sold in all forms: as wall clocks, desk clocks, travel alarms, and wristwatches. They have a tremendous advantage over conventional clocks, they are always right! When working properly, radio controlled clocks always display the correct time, down to the exact second. And you never have to adjust them. During the transition from standard time to daylight saving time (DST) they "spring forward" one hour, and when DST is finished they "fall back" one hour.
Due to technology advances and the economies of scale, radio controlled clocks are now very inexpensive, often costing just a few dollars more than conventional clocks. This page provides information about radio controlled clocks, including how they work, where they work, and what to do when they don’t work.
How They Work
Some manufacturers refer to their radio controlled clocks as "atomic clocks", which isn’t really true. An atomic clock has an atomic oscillator inside (such as a cesium or rubidium oscillator). A radio controlled clock has a radio inside, which receives a signal that comes from a place where an atomic clock is located.
In the United States, the signals received by radio controlled clocks originate from NIST Radio Station WWVB, which is located near Fort Collins, Colorado. WWVB broadcasts on a frequency of 60 kHz. Your radio controlled clock actually has a miniature radio receiver inside, which is permanently tuned to receive the 60 kHz signal.
The 60 kHz signal is located in a part of the radio spectrum called LF, which stands for low frequency. This is an appropriate name, because the FM radio and TV broadcasts that we are accustomed to listening to use frequencies thousands of times higher. The lowest frequency received by any of the other radios in your house is probably 530 kHz, the bottom of the AM broadcast band. Even that frequency is nearly 10 times higher than the WWVB signal.
At 60 kHz, there isn’t enough room on the signal (bandwidth) to carry a voice or any type of audio information. Instead, all that is sent is a code, which consists of a series of binary digits, or bits, which have only two possible values (0 or 1). These bits are generated at WWVB by raising and lowering the power of the signal. They are sent at a very slow rate of 1 bit per second, and it takes a full minute to send a complete time code, or a message that tells the clock the current date and time. When you turn a radio controlled clock on, it will probably miss the first time code, so it usually takes more than one minute to set itself (sometimes 5 minutes or longer) depending on the signal quality and the receiver design.
Once your radio controlled clock has decoded the signal from WWVB, it will synchronize its own clock to the message received by radio. Before it does so, it applies a time zone correction, based on the time zone setting that you supplied. The time broadcast by WWVB is Coordinated Universal Time (UTC), or the time kept at the Prime Meridian that passes through Greenwich, England. While a few users like their clocks to display UTC (ham radio operators, for example), most prefer to display local time. This means that the time in your area is corrected by the number of hours shown in the table.
| Time Zone | Difference from UTC During Standard Time | Difference from UTC During Daylight Time |
|---|---|---|
| Pacific | -8 hours | -7 hours |
| Mountain | -7 hours | -6 hours |
| Central | -6 hours | -5 hours |
| Eastern | -5 hours | -4 hours |
Once your radio controlled clock has synchronized, it won’t decode the signal from WWVB again for a while. Some clocks only decode the signal once per day, others do it more often (like every 4 hours or every 6 hours). Those that decode the signal just once per day usually do it at night, since the signal from WWVB is much stronger once the sun goes down. In between synchronizations, the clocks keep time using their quartz crystal oscillators. A typical quartz crystal found in a radio controlled clock can probably keep time to within 1 second for a few days or longer. Therefore, you shouldn’t notice any error when you look at your clock display, since it will appear to be on the right second, even though it has probably gained or lost a fraction of a second since the last synchronization.
Where They Work
WWVB radio controlled clocks should be able to work in most places in North America. The red areas on the coverage maps below show where a WWVB radio controlled clock should be able to synchronize. Note that the red area is largest at night, and smallest in the daytime (click on the map to see a larger image). For example, 0600 UTC is about midnight in the central United States.
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These maps are based on a field strength of 100 microvolts per meter, which in theory should be a large enough signal for most receivers to work with. In fact, some receivers have much better sensitivity (20 or 30 microvolts per meter). However, simply having a large signal doesn't mean that the receiver will work. What really matters is the signal-to-noise ratio, or the size of the signal compared to the size of the electrical noise near the same frequency. Raising the noise level is just as harmful as reducing the signal level. For example, if the radio controlled clock is near a source of interference (like a computer monitor) the noise level will increase, and the clock might not be able to synchronize. If the radio controlled clock is in a building with a metal roof, much of the signal will be blocked. Therefore, the signal level will be reduced, and the clock might not be able to synchronize.
Therefore, use the coverage maps as a rough indicator only. We have heard from many owners of radio controlled clocks whose clocks do not work inside the coverage area shown on the maps. This is probably due to a local source of interference. We have also heard several reports from Alaska that the clocks work fine, even though Alaska is outside the coverage area shown on the maps. This is probably due to the low amount of radio “background” noise found in a sparsely populated area.
What to Do When They Don’t Work
NIST provides the signal received by your radio controlled clock, but we cannot provide technical support for the clocks themselves. We didn’t manufacture them, and we are not familiar with all the models or all of their features. We recommend that you save the instruction sheet that came with your clock, so you can refer to in the future if necessary. Having said that, we can offer a few general tips about what to do if your radio controlled clock isn’t displaying the correct time.
My clock doesn’t synchronize at all
Most WWVB radio controlled clocks work great, as evidenced by the hundreds of thousands of units that have been sold throughout the United States. However, if your radio clock or receiver isn't working, we suggest:
- If your clock uses batteries, check them and replace if necessary.
- If you have a desk top unit, try rotating it 90 degrees. If you have a wall clock try mounting it on a wall perpendicular to the one it is currently on (e.g. if it is on a north-south wall try an east-west wall). The antennas are directional and you might be able to improve the signal strength by turning the antenna.
- Place the clock along a wall or near a window that faces Fort Collins, Colorado.
- Locate the clock at least 1 or 2 meters away from any computer monitors, which can cause interference (some monitors have a scan frequency at or near the WWVB carrier frequency of 60 kHz).
- If nothing else works, take the clock outdoors at night and power it down (remove the batteries or unplug it), then power it up again to force it to look for the WWVB signal. If it works outdoors but not indoors, you probably have a local interference problem inside your house or building. If it doesn’t work outdoors at night, its probably best to return it and try a different model.
- The shielding provided by a metal building might prevent the clock from working. For example, if you live in a mobile home or a house with steel siding, the clock might not work.
- If you think your clock is defective, ask the manufacturer or dealer about obtaining a replacement.
My clock is off by one or more hours
Remember, minutes and seconds are the same in all time zones within the WWVB coverage area; only hours are different. If your clock is off by one or more hours, it probably has to do with a time zone setting. Make sure you have properly selected your time zone using the instructions that came with your radio controlled clock.
If you live in an area that does not observe Daylight Saving Time (Arizona, Hawaii, parts of Indiana), make sure that DST is disabled on your radio controlled clock. Not all clocks have this feature, so you might have to select another time zone to make your clock display the correct time when DST is in effect.
Some radio controlled clocks only allow you to select four different time zones (Pacific, Mountain, Central, and Eastern). Some clocks allow you to select any time zone, even those time zones that are outside the coverage area. When purchasing a clock, make sure that it can handle your time zone. For example, we’ve heard from a few users who purchased clocks in Hawaii but can’t select the Hawaiian Time Zone.
My clock is off by a few minutes or seconds
This can be due to a number of different problems as listed below:
Reception Problem - If your clock isn’t currently receiving the signal, the time will “drift” and gradually get further and further from the correct time. Remember, if the signal isn’t being received, your clock isn’t radio controlled any longer, it’s just a regular quartz clock. Its accuracy will depend on the quality of the quartz crystal. Most quartz clocks can keep time to 1 second per day or better, but some will be off by several seconds per day.
Most digital radio controlled clocks have an indicator on the display that tells you if the signal is being received properly. Some analog clocks have an audio indication (a button you can push that indicates through a series of tones or beeps if the signal is there). If you are not sure if the signal is being received, try powering down the clock (unplug it or remove the batteries), then turn it on again to see if it can synchronize. If it doesn’t, see the tips above for improving your reception.
Alignment Problem - If you have an analog clock, its possible that the hands aren’t properly aligned. This could cause the clock to be off by a second or more even if it is receiving the signal properly. The clock might not have been properly aligned at the factory, or it might have been jostled during shipment, causing the hands to move. Some manufacturers explain how to align the hands on their instruction sheet. If you aren’t sure how to do this, and the small error bothers you, it's best to return the clock.
Checking your clock - There is no need to check a properly working WWVB clock, it should always display the correct time. However, you might want to check it if you suspect you have a problem. You can check your clock by using the NIST web clock, or by listening to NIST Radio Station WWV using a shortwave radio or telephone (dial 303-499-7111).
When checking an analog clock, make sure you are looking straight at the clock face, and not viewing it from an angle. If you view if from an angle, you can think its off by a few seconds, even if its not. This is similar to trying to read the speedometer from the passenger seat of a car, and thinking the speed is faster or slower than it actually is.
We switched to Daylight Saving Time, and my clock didn’t change
This is probably due to a reception problem. Your clock hasn’t received the signal recently, so it didn’t know about the time change. Most digital radio controlled clocks have an indicator on the display that tells you if the signal is being received properly. Some analog clocks have an audio indication (a button you can push that indicates through a series of tones or beeps if the signal is there). If you are not sure if the signal is being received, try powering down the clock (unplug it or remove the batteries), then turn it on again to see if it can synchronize. If it doesn’t, see the tips above for improving your reception.
Also, some clocks have a way to disable Daylight Saving Time. Make sure it isn’t disabled if your area observes DST.
My clock switched to Daylight Saving Time, but we don't observe DST where I live
There is most likely an on/off toggle for DST. Turn it off if your area does not observe DST. Contact the manufacturer about how to do this. If there isn't a way to turn DST off, you may have to change your time zone setting during DST to make your clock display the correct time.
info from this page is courtesy of http://www.nist.gov/
Specifications:
- Time
- 12/24 hour display in hh: mm ss format
- Auto receive function
- Manual receive function
- Signal: US WWVB, Europe DCF77, Japan JJY40/JJY60
- Full Auto Calendar
- Auto calculation of different month lengths (28, 30 or 31 days) and leap year 2000-2099
- Daily Alarm
- Stopwatch
- Elapsed time, split time and final time are measured with 1/100-sec accuracy
- Counter Timer with Chime
- Adjustable up to 23 Hr 59 Min 59 Sec
- Water Resistance
- 3 ATM (100ft or 30m)
- Power
- 1 CR1620 battery (included)
- Dimensions
- Diameter of face: 1.75" (45mm)
- Wrist size: approx. 6.1" - 8.5"(155mm - 215mm)
Maps showing ranges of the atomic time signal (click on images to enlarge)
| Atomic Time Signal | Descriptions | |
| DCF77 | Germany: transmitting from Mainflingen (near Frankfurt) at 77.5 kHz, with a range up to 2000 km, which covers most of Western, e.g. UK and some of Central Europe. | |
| JJY40/JJY60 | Japan: transmitting from Mount Otakadoya (near Fukushima) at 40 kHz and 60 kHz, and from Mount Hagane (located on Kyushu Island) at 60 kHz, which together cover all of Japan and parts of Korea and East Asia e.g. Hong Kong, Beijing & Taiwan. | |
| WWVB | U.S.A.: transmitting from Fort Collins, Colorado, at 60 kHz, which covers all 4 zones in the continental U.S.A. and most places in North America. |
Tuesday, April 12, 2011
New Citizen Watches
CITIZEN BLUE ANGELS JY0040-59L SKYHAWK ATOMIC ECO DRIVE
The 3rd generation Skyhawk redefines atomic timekeeping with radio controlled accuracy and Eco-Drive Technology. Radio signals are received both automatically and on-demand by the fully loaded Skyhawk A-T.Atomic Timekeeping wit Radio Controlled Accuracy
Solar Powered - No need to change a battery
World Time in 43 Cities
2 Alarms
1/100 Second Chronograph Measures up to 24 Hours
99 Minute Countdown Timer
Perpetual Calendar
Digital Display Light
Water Resistant to 200 Meters (660 Feet)
Greenwich Mean Time Display
Rotating Slide Rule Bezel
Stainless Steel Case and Bracelet
Non-Reflective Mineral Glass Crystal
Power Reserve Indicator (180 Day Power Reserve when fully charged - 2.5 Year Power Reserve with Power Save Function - *150 Hours in Average Lighting to Acheive a full charge)
Bracelet Features a Fold Over Clasp with Double Hidden Push Button Release
Official Blue Angels Insignia appears on Caseback
45mm Case Width (Approximately 1 3/4") http://www.atomicclocksstore.com/product/CITIZEN%20JY0040-59L
=============================================================
CITIZEN ATOMIC RADIO CONTROL ECODRIVE WATCH CB0020-50E
* BRUSHED-POLISHED STAINLESS STEEL CASE & BRACELET
** BLACK TEXTURED DIAL
** SILVER TONE-LUMINOUS HOUR AND MINUTE HANDS
** WHITE TIMER HAND
** SILVER TONE-LUMINOUS HOUR MARKERS
** DATE DISPLAY AT 3:00 POSITION
** ATOMIC TIMEKEEPING WITH RADIO CONTROLLED ACCURACY
** BLACK BEZEL W/WORLD TIME FOR 26 CITIES
** ALARMS
** PERPETUAL CALENDAR
** ROTATING INNER CALCULATION RING
** POWER RESERVE INDICATOR FOR 180 DAY
** NON-REFLECTIVE SAPHIRE CRYSTAL
** WATER RESISTANT TO 200 METERS
** ECO-DRIVE MOVEMENT
** MODEL TYPE: ATOMIC
** MODEL NUMBER: CB0020-50E
** CASE DIAMETER: 43MM
** CASE THICKNESS: 11MM
** BRACELET WIDTH 20MM
** COMES IN ORIGINAL CITIZEN BOX
http://www.atomicclocksstore.com/product/CITIZENCB0020-50E
=============================================================
CITIZEN ATOMIC SKYHAWK MENS ECODRIVE WATCH JY0005-50E
Featuring light-powered Eco-Drive technology, the ultra-sporty Skyhawk AT watch #JY0005-50E from Citizen offers sleek, athletic-inspired styling with an eco-friendly design. This versatile watch boasts digital quartz movement for reliability, atomic timekeeping with radio-controlled accuracy, and 1/100 second chronograph and 24 hour recorder. World time for 43 cities, two alarms, perpetual calendar, and a 99 minute countdown also keep your day, or workout, on-track. Polished silver-tone hands markers with luminous accents add a sleek look, while a brushed stainless steel black ion plated slide rule bezel imparts professional polish. Water resistant to 200 meters (660 feet), the Skyhawk is made to withstand the elements and still look great, year after year.Summary of Features:
Atomic timekeeping with radio-controlled accuracy
World time in 43 cities
2 alarms
1/100 second chronograph that measures up to 24 hours
99 minute countdown timer
Perpetual calendar
Digital display light
Greenwich Mean Time display
Rotating slide-rule bezel
Non-reflective mineral crystal
Power-reserve indicator
Ecologically friendly, light powered Eco-Drive Caliber U600 Japanese-quartz movement; charges in natural sunlight or indoor light
Max power reserve: 180 days to 30 Months with Power Save; low charge warning: 3 days; charge time from stop state to max charge: Incandescent Light - 150 hrs, Outdoors, Cloudy (10,000 Lux) - 60 hrs, Outdoors, Sunny (100,000 Lux) - 20 hrs
Durable, hardened non-reflective mineral crystal; case diameter: 48 mm; 2 Alarms; 1/100 second chronograph measures up to 24 hours; 99 minute countdown timer; rotating slide rule bezel
Stainless steel case; black dial; perpetual-calendar; world time (43 cities) functions; Greenwich Mean Time display; atomic timekeeping with radio-controlled accuracy
Water-resistant to 660 feet (200 M)
Watch Information
Brand Name: Citizen
Model number: JY0005-50E
Part Number: JY0005-50E
Model Year: 2010
Dial window material type: Mineral
Display Type: digital
Clasp: fold-over-clasp-with-double-push-button-safety
Metal stamp: no-metal-stamp
Case material: stainless-steel
Case diameter: 48 millimeters
Case Thickness: 16 millimeters
Band material: stainless-steel
Band length: mens
Band width: 21 millimeters
Band Color: black
Dial color: black
Bezel material: stainless-steel
Bezel Function: Slide-rule
Calendar: perpetual-calendar
Movement: japanese-quartz
Water resistant depth: 660 Feet
http://www.atomicclocksstore.com/product/CITIZENJY0005-50E