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	Frequency standard - Wikipedia, the free encyclopedia
		A frequency standard is a stable oscillator used for frequency calibration or reference.
		A frequency standard generates a fundamental frequency with a high degree of accuracy and precision.
		Frequency standards in a network or facility are sometimes administratively designated as "primary" or "secondary." The terms "primary" and "secondary," as used in this context, should not be confused with the respective technical meanings of these words in the discipline of precise time and frequency.
	en.wikipedia.org /wiki/Frequency_standard (207 words)

	Time and Frequency
		Frequency standards, particularly optical frequency standards, based on stored ions have the potential for higher accuracy than the best current standards, which are based on the neutral cesium atom with a transition in the microwave region, since observation times are much longer and fractional linewidths are much smaller.
		The first atomic frequency standard, based on ammonia, was built in 1950 at NIST in Washington, D.C. Since then, we have constructed a series of seven standards based on cesium beams with performances improving at a rate of better than an order of magnitude every 10 years.
		The average of the outputs of these standards is extremely stable and serves as the operational standard for all calibrations and broadcast services.
	www.nist.gov /public_affairs/guide/time_frequency.htm (762 words)

	Integrated microwave cavity resonator and magnetic shield for an atomic frequency standard - Patent 4661782
		A microwave cavity resonator for an atomic frequency standard comprising a cavity resonator formed of highly magnetically permeable material, means for injecting microwave radiation within said resonator capable of producing atomic transitions of atoms, and means for applying a magnetic field in the presence of said cavity resonator.
		An atomic frequency standard as recited in claim 14 wherein the resonant cavity is substantially coextensive with the cell.
		An atomic frequency standard as recited in claim 19 wherein the length through the resonator cavity as transversed by the light is substantially equal to the length of said resonator cavity.
	www.freepatentsonline.com /4661782.html (3567 words)

	PRS10 - Rubidium Frequency Standard
		All commercial rubidium frequency standards operate by disciplining a crystal oscillator to the hyperfine transition at 6.834,682,612 GHz in rubidium.
		Manufacturers of rubidium frequency standards sometimes use a crystal frequency that is an exact sub-multiple of the hyperfine transition frequency in order to simplify the design of the RF frequency synthesizer.
		Frequency offsets and long-term aging of the PRS10 can be eliminated by phase-locking to a source with better long-term stability, such as the 1 pps from a GPS timing receiver.
	www.thinksrs.com /products/PRS10.htm (1111 words)

	Programmed Test Sources, Inc. - Fast Switching Low Noise Frequency Synthesizers
		Frequency synthesizers are basically variable radio-frequency generators which are very accurately and quickly settable and possess high stability.
		This output frequency is as accurate and as stable as a built-in frequency standard, usually a crystal oscillator, or as accurate and stable as an external precision standard which may be connected to the synthesizer in lieu of its own standard.
		The theoretical maximum output frequency obtainable is one-half the clock frequency, although practical filtering considerations limit the output frequency to less than 45% of the clock.
	www.programmedtest.com /technology.html (706 words)

	Definition of Frequency and Celeration
		Frequency refers to "the number of cycles or completed alternations per unit of time." In general, frequency means some count per unit of time.
		A frequency of 1 Hz means that one wave, or wave crest, passes a point in a second's worth of time.
		Frequency formed the absolutely necessary measure of behavior, and dimension of behavior, used in B.F. Skinner's two primary research books, The Behavior of Organisms, and Schedules of Reinforcement (the latter written with C.B. Ferster, who is listed as first author).
	members.aol.com /standardcharter/define.html (1103 words)

	Frequency measurements
		Of considerable importance in the measurements of frequency or wavelength are the standards against which frequency-measuring devices are compared and calibrated.
		The oscilloscope and the frequency counter are two of the other devices which may be used, but their use may require the employment of accessory equipment.
		The main frequency control that determines the rate of the flashing light is then varied until the reference mark on the moving part appears to be standing still.
	www.tpub.com /neets/book21/88e.htm (1724 words)

	Fine tuning of atomic frequency standards - Patent 4740761
		When the frequency of the inducing signal and the resonance center frequency coincide, the output signal 28 produced by the resonator 14 is in phase with the reference signal 20, with the result that the output 32 of the lock-in amplifier 30 is zero.
		According to the present invention, the hyperfine transition resonance center frequency of the atomic resonator 14 remains fixed, and a DC bias offset signal 38 is applied to the input of the summing integrator 34 in the frequency-lock loop.
		The frequency of the regulated output signal 12 produced by the voltage controlled crystal oscillator standard is established at an initial frequency f.sub.1.
	www.freepatentsonline.com /4740761.html (2812 words)

	IEEE UFFC Frequency Control Home
		At the beginning of the period and for several years thereafter, oven frequency standards were implemented using vacuum tubes with the crystal in an oven, often using a Dewar flask to minimize thermal loss.
		Most of the crystal frequency standards described in the remainder of this paper address units produced in the industry for use in communications and navigation equipment.
		[36] Shaull, J.M. and Shoaf, J.H., "Precision Quartz Resonator Frequency Standards," Proceedings of the IRE, Aug. 1954, pp.
	www.ieee-uffc.org /fcmain.asp?page=frerking (6889 words)

	NIST Time and Frequency Div. - 2004: Strategic Focus 1
		The Time and Frequency Division maintains standards with the accuracy, continuity, and stability essential for supporting U.S. commerce and scientific research; provides an official source of time for U.S. civilian applications; and supports coordination of international time and frequency standards, including realization of the SI second.
		A frequency standard based on optical transitions (282 nm, 1064.7 THz) in a single, laser-cooled, trapped mercury ion has potential for better accuracy than cesium fountain standards by a factor of 100 or more.
		From the point of view of the cesium transition being defined as the international frequency standard, this means the mercury ion clock frequency is stable to this level.
	physics.nist.gov /TechAct/Div847/div847.html (1678 words)

	Frequency Electronics Inc. - RUBIDIUM ATOMIC FREQUENCY STANDARDS (Site not responding. Last check: 2007-09-10)
		Frequency locking of the VCXO is accomplished by operating the Rubidium Physics Package as a frequency discriminator, i.e., departures of a frequency from an input signal (50.255+ MHz from the VCXO) from a defined center frequency (Rubidium atomic resonance) produce a DC output signal (control voltage).
		The decrease in light, when the microwave frequency is equal to the Rubidium frequency, is then converted electronically to an error signal with phase and amplitude information used to steer the VCXO via its control voltage and keep it on frequency at 50.255+ MHz.
		Option 02 is an RS -232 digitally controlled output with a frequency range of 2 x 10-7 at a resolution of 5 x 10-12.
	www.freqelec.com /FE-5650A.htm (1054 words)

	NIST Time and Frequency Division 2000 - Technical Highlights
		Calcium continues to be an attractive optical frequency standard at many laboratories in the world, since the 657 nm transition is relatively insensitive to external electric and magnetic fields, and because the entire system (trapping, laser cooling, and state probing) is operated with diode lasers.
		An important aspect of their improved evaluation of the standard is their measurement of the spin-exchange frequency shift, which results from cesium-cesium collisions within the clouds of atoms that traverse the standard.
		The standards are from NIST, the Physikalisch Technische Bundesanstalt (PTB), and the Laboratoire Primaire du Temps et Frequences (LPTF).
	physics.nist.gov /TechAct.2000/Div847/div847h.html (5015 words)

	Frequency Standard suits laboratory and field applications., Agilent Technologies, (Site not responding. Last check: 2007-09-10)
		The Agilent 5071A primary frequency standard is now available with an optional simplified front panel that includes attention and continuous operation LEDs, and two BNC connectors for the 1PPS and SYNC signals.
		The Agilent 5071A primary frequency standard is a precision timing tool that provides accuracy, stability, reliability and ease-of-use for the most demanding laboratory and field applications.
		The Agilent 5071A primary frequency standard is currently available at prices ranging from $45,332 to $48,662, which includes either the high-performance cesium beam tube with a five-year warranty or the standard cesium beam tube with a 10-year warranty.
	news.thomasnet.com /fullstory/17785/rss/4263 (843 words)

	5071A - Primary Frequency Standard
		The 5071 offers exceptional frequency stability which is a key specification that directly affects a laboratory's ability to deliver timekeeping and calibration services to its clients.
		Stable frequency generation and frequency flexibility are required to transmit and receive signals properly between ground terminals and communication satellites.
		The 5071A primary frequency standard can work very well with a GPS timing receiver to produce and maintain highly accurate time and frequency.
	www.symmttm.com /pr_lp/5071A (371 words)

	Brooks Shera's GPS-controlled Frequency Standard
		The goal was to produce an inexpensive, but highly accurate, frequency standard by synchronizing a local crystal (or Rb) oscillator to the GPS atomic clocks.
		Below is a picture of the controller together with a GPS antenna and, in the background, a 20 year old HP frequency standard that is locked to the GPS atomic clocks by the controller.
		The residual 1 ns jitter produces the spurious short-term frequency corrections of a few parts in 10 to the 11 that are evident in the expanded plot.
	www.rt66.com /~shera/index_fs.htm (1778 words)

	Z3801A Receiver Main Page
		The Hewlett Packard Z3801A is a GPS based frequency standard that tracks global positioning satellites to get accurate timing data to adjust the long term frequency of an internal oven oscillator.
		This type of frequency standard is roughly comparable to a Rubidium standard, without the maintenance issues of the Rubidium lamp.
		The outer oven controller as implemented by HP is a standard temperature bridge with the internal oven thermistor as the variable.
	www.realhamradio.com /GPS_Frequency_Standard.htm (3115 words)

	Two-Transistor Atomic Frequency Standard
		Now the "Atomic Frequency Standard" part: The line frequency is only fairly accurate at any given instant - perhaps within a few hundred PPM - but the long term error is kept very low by comparing the frequency with national time standards which are, of course, based on an array of atomic standards!
		Most wall clock oscillators generate pulses at one or two hertz to drive a little solenoid and this circuit may be adjusted to run at this lower frequency by increasing the timing resistor.
		Adjusting the circuit to produce the line frequency without division is much less critical and more forgiving of antenna changes, etc.
	www.techlib.com /electronics/atomic.html (503 words)

	Definition: frequency standard (Site not responding. Last check: 2007-09-10)
		Note 1: A frequency standard generates a fundamental frequency with a high degree of accuracy and precision.
		Note 2: Frequency standards in a network or facility are sometimes administratively designated as "primary" or "secondary." The terms "primary" and "secondary," as used in this context, should not be confused with the respective technical meanings of these words in the discipline of precise time and frequency.
		This HTML version of Telecom Glossary 2K was last generated on Wed May 8 15:36:48 MDT 2002.
	www.its.bldrdoc.gov /projects/devglossary/_frequency_standard.html (103 words)

	Cs4000 Cesium Frequency Standard - Precision Frequency References Products
		The Symmetricom Cs4000 is a new cesium frequency standard platform that provides exceptional performance in a configurable 3U rack mount chassis.
		Because of this, the standard output signals are not affected and can be utilized along with whatever custom format is required.
		The Cs4000 meets the challenges of laboratory standards, satcom terminals, mobile communications systems and a wide variety of test and measurement applications.
	www.symmttm.com /pr_lp/Cs4000 (295 words)

	High Accuracy Frequency Standard
		The idea behind this accurate frequency standard is to lock a stable 10MHz xtal oscillator to the highly stable TV line frequency used in the UK by the BBC1, BBC2 and Channel 4 transmissions.
		This frequency is then divided by 2 in the other half of that chip to give a 7812.5Hz output which is then fed into a 74HC86 XOR gate used as a phase detector.
		This is of no consequence if the frequency standard is to be used soley to check counters and the like.
	www.g3pho.free-online.co.uk /microwaves/caesium.html (967 words)

	HP 5060A Cesium Beam Frequency Standard
		Cesium frequency standards work by squirting Cesium atoms from a reservoir that's heated to boil off some atoms from a small piece of cesium liquid metal.
		The U.S. standard was moved from the East coast to Colorado and was more a frequency standard than a clock.
		This appears to be like the PRS10 which has a very high Q but the actual frequency depends on a number of subtle factors.
	www.pacificsites.com /~brooke/5060A.html (1404 words)

	Walther group: Frequency Standard (Site not responding. Last check: 2007-09-10)
		They can serve as references in highly stable frequency standards and also enable precise tests of fundamental physics.
		The clock transition is excited using a frequency quadrupled Nd:YAG laser at 946 nm.
		using a frequency chain and a methane-stabilized HeNe laser that was calibrated with a cesium clock.
	www.mpq.mpg.de /Indium.html (235 words)

	Frequency Standard: Ultra-Precise and Accurate, GPS-Synchronized
		The Meridian Precision GPS TimeBase is a full-featured frequency standard that provides the most precise and stable, GPS-synchronized, time and frequency outputs in the world.
		The Meridian uses software algorithms that are the result of over 20 years of engineering experience in the frequency control industry.
		The Meridian Frequency Standard can be configured with a complete set of oscillator options ranging from a low cost OCXO with SC-cut resonator to a state-of-the-art compact Rubidium unit.
	www.endruntechnologies.com /frequency-standard-meridian.htm (386 words)

	Earth: An Oscillator and Frequency Standard
		As you can see elsewhere in the museum, oscillators and frequency standards come in many shapes and sizes: from 19" rack-mount to surface mount, from square to round.
		Hz frequency output of Earth is typically detected optically: either shine light onto earth or detect light from earth.
		If used as a time standard it may be more convenient to make one-second corrections every several hundred cycles.
	www.leapsecond.com /museum/earth (1312 words)

	Frequency Standards by Fluke and Symmetricon.
		The CsIII is a lightweight, compact, economical cesium frequency standard.
		The 4065C is a Primary Frequency and Time Standard providing the ultimate in accuracy and stability, with improved phase noise performance.
		This Primary Timing and Frequency Reference Standard has improved phase noise performance over previous models and is especially suited for communication, navigation, test and measurement.
	www.southernmarketing.com /frequency_standards.htm (210 words)

	SPACE-TALK - Atomic Frequency Standard
		These are moving at a certain rate called the atomic frequency standard.
		frequency can be changed then matter may take on a different form.
		As I understand, matter is told how to react to its universe by the vibration or frequency of an underlying theoretical partical.
	www.space-talk.com /ForumE/showthread.php3?threadid=130 (424 words)

	Time & Frequency
		It had a bug in that the switch to/from standard time/DST happened when Colorado changed, not in your time zone although there were DIP switches for time zone as well as propagation delay in ms.
		The crystal frequency was 2.5 MHz and it was the first all transistor frequency standard.
		The Rb and Cs "standards" are not absolute, they are just like a crystal in that their frequency needs to be set.
	www.pacificsites.com /~brooke/timefreq.shtml (5859 words)

	FS700 - 10 MHz LORAN-C Frequency Standard
		With the FS700 LORAN-C Frequency Standard, cesium-clock stability is now available at a fraction of the cost of atomic standards.
		Four 10 MHz sine wave outputs are available at the rear panel of the instrument, and an additional front-panel, adjustable frequency TTL source is also provided.
		A built-in phase detector measures the phase shift between an external timebase and the internal frequency source allowing you to easily calibrate precision oscillators between 100 kHz and 10 MHz.
	www.thinksrs.com /products/FS700.htm (440 words)

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