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198

Jul 12, 2010
07/10

by
Bahadur, H.; Parshad, R

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The frequency behavior of AT-cut quartz crystals irradiated by X -, gamma rays and fast neutrons. Initial instability in frequency for gamma and neutron irradiated crystals was found. All the different radiations first give a negative frequency shift at lower doses which are followed by positive frequency shift for increased doses. Results are explained in terms of the fundamental crystal structure. Applications of the frequency results for radiation hardening are proposed.

Topics: ATOMIC CLOCKS, CRYSTAL OSCILLATORS, MASERS, RESONATORS, GOVERNMENT/INDUSTRY RELATIONS, TECHNOLOGY...

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376

May 22, 2011
05/11

by
Bulfin, R. L.; Perdue, C. A

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The Mission Planning Division of the Mission Operations Laboratory at NASA's Marshall Space Flight Center is responsible for scheduling experiment activities for space missions controlled at MSFC. In order to draw statistically relevant conclusions, all experiments must be scheduled at least once and may have repeated performances during the mission. An experiment consists of a series of steps which, when performed, provide results pertinent to the experiment's functional objective. Since these...

Topics: ATOMIC CLOCKS, TIME MEASUREMENT, TIME SIGNALS, TRACKING NETWORKS, CESIUM, COMMUNICATION SATELLITES,...

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313

Jul 11, 2010
07/10

by
Chi, A. R.; Wardrip, S. C

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The OMEGA transmissions from North Dakota on 13.10 and 12.85 kHz were monitored at several sites using a recently developed OMEGA timing receiver specifically designed for this purpose. The experiments were conducted at Goddard Space Flight Center, Greenbelt, Maryland; U.S. Naval Observatory, Washington, D.C.; and at the NASA tracking station, Rosman, North Carolina. Results show that cycle identification of the two carrier frequencies was made at each test site, thus, coarse time (76...

Topics: ATOMIC CLOCKS, AUTOMATIC CONTROL, TIME MEASUREMENT, UNIVERSAL TIME, LORAN C, MINICOMPUTERS,...

Time between Near and Far changes by less than 1 ns for each 300s point in the PPP solution (1-sigma: 0.248 ns) A Cs atomic clock has 2-sigma instability around 100 ps at 300 s Two separate GPS traveling systems had calibrations only 450 ps apart Multi-day PPP solutions minimize day-boundary discontinuities Relative timing accuracy better than 1 ns* If the calibration works!

Topics: DTIC Archive, NAVAL OBSERVATORY WASHINGTON DC, *ATOMIC CLOCKS, *GLOBAL POSITIONING SYSTEM,...

The accuracy of International Atomic Time TAI is based on a small number of primary frequency standards (PFS) that aim at realizing the SI second, the unit of proper time. Following the 14th meeting of the Consultative Committee for Time and Frequency (April 1999), the BIPM time section is reconsidering how the PFS comparisons are used for evaluating the duration of the scale unit of TAI, uTAI, and how they are reported in Circular T and other BIPM publications. In the new procedure, it is...

Topics: DTIC Archive, BUREAU INTERNATIONAL DES POIDS ET MESURES SEVRES (FRANCE), *ESTIMATES, *FREQUENCY...

Because pulsar phase, spin rate, and spin-down rate cannot be determined a priori, a pulsar's possible contribution to a time scale is best measured using a statistic insensitive to these quantities. One such statistic is sigma sub z (tau) (Matsakis, Taylor, and Eubanks 1996, hereafter [1]), which is based upon the third-order polynomial variations of the clock phases and named in analogy to sigma sub y (tau). It is similar to measures based upon the variance of the third differences, but more...

Topics: DTIC Archive, NAVAL OBSERVATORY WASHINGTON DC, *TIME, *ATOMIC CLOCKS, *FREQUENCY STANDARDS,...

Although carrier-phase observations are thought to drive the accuracy of time and frequency transfer accuracy obtainable using geodetic GPS receivers, there has been evidence of how colored noise on the pseudorange observations reduces the effectiveness of the technique. We present a new parameterization of the GPS pseudorange and carrier-phase observations, called the decoupled-clock model, where a pseudorange bias is estimated for each clock in the system as a white noise parameter. The new...

Topics: DTIC Archive, NATURAL RESOURCES CANADA OTTAWA (ONTARIO), *GLOBAL POSITIONING SYSTEM, *EQUATIONS,...

Tekslec has developed the first commercial prototype of an Optically Pumped Cesium-Beam Frequency Standard with the scientific support of the Laboratotre de l'Horloge Atomique (LHA) and the financial support of the French Military Administration (DGA). This work is based on years of experience of the LHA on cesium atomic clocks, especially on short atomic clocks and and on the experience of Tekslec in time and frequency for systems (timekeeping, time distribution, synchronization, etc.) and...

Topics: DTIC Archive, TEKELEC INC TELECOM LES ULIS (FRANCE), *FREQUENCY, *CESIUM,...

An emerging use of GPS is to provide accurate navigation information for satellites in orbit. The GPS satellites are designed to provide service to terrestrial users, so the antenna array points directly towards the Earth and uses a narrow primary beamwidth. Because GEO altitudes are well above the GPS constellation, the Earth occludes most of the GPS signals to the satellite. Decreased satellite visibility is debilitating, as GPS navigation requires at least four visible satellites to...

Topics: DTIC Archive, Dainty, Benjamin G, AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF...

In this paper we present our design and prospects of a Magneto-Optical Trap (MOT)-based cold Cs-beam atomic clock physics package and report the realization and characterization of a continuous, laser-cooled Cs atomic beam from a Cs MOT. We have determined the longitudinal velocity of the cold Cs beam by Time of Flight (TOF) method to be 7 m/s with a velocity spread of 1 m/s. By adjusting the MOT parameters, we are able to tune the Cs-beam velocity from 5 m/s to 8.5 m/s while the velocity...

Topics: DTIC Archive, Wang, H, AEROSPACE CORP LOS ANGELES CA, *ATOMIC BEAMS, *CESIUM, *ATOMIC CLOCKS,...

The time transfer procedure presently used for the realization of TAI is based on the common view approach, using the CGGTTS data computed by an internal software of the time receivers. We choose here another approach and analyze the raw data available in the RINEX files produced by GPS/GLONASS geodetic receivers. We concentrate our analysis on the use of GLONASS P-code measurements. Because the frequency emitted by each GLONASS satellite is different, the measurements must be corrected for...

Topics: DTIC Archive, Roosbeek, F, BELGIAN ROYAL OBSERVATORY UCCLE, *TIME INTERVAL COUNTERS, *ATOMIC...

Velocity distributions are determined for atoms effusing out of radio frequency discharge hydrogen dissociators, of the type used in hydrogen masers. This work was motivated by long-term reliability issues related to the possible use of masers as frequency standards on satellites. A primary issue is the maser's hydrogen budget, because many of the common failure modes of a maser involve either the hydrogen source or sink. Because the focusing properties of the state-selecting magnets are...

Topics: DTIC Archive, Jaduszliwer, B, AEROSPACE CORP EL SEGUNDO CA CHEMISTRY AND PHYSICS LAB, *FREQUENCY...

Tests of local position invariance (LPI) made by comparing the relative redshift of atomic clocks based on different atoms have been carried out for a variety of pairs of atomic species. In most cases, several absolute frequency measurements per year are used to look for an annual signal, resulting in tests that can span on order of a decade. By using the output of continuously running clocks, we carry out LPI tests with comparable or higher precision after less than 1.5 years. These include...

Topics: DTIC Archive, NAVAL OBSERVATORY WASHINGTON DC, *ATOMIC CLOCKS, *INVARIANCE, *POSITION(LOCATION),...

Across a broad range of disciplines, the accurate determination of an electromagnetic wave's amplitude (either absolute or relative) has considerable relevance. Here, we demonstrate a novel and potentially very precise method for making intensity measurements based on the atomic stabilization of electromagnetic field-strength. For ease of reference, and by analogy to atomic clocks, we refer to this field-strength stabilization system as an atomic candle. While the candle's original purpose was...

Topics: DTIC Archive, Swan-Wood, T, AEROSPACE CORP EL SEGUNDO CA, *REFRACTIVE INDEX, *ABSORPTION,...

A paper clock model based on limited numbers of atomic clocks and a typical time interval counter was developed. The aim of this work is to use a small ensemble of cesium clocks and a traditional measurement system to generate a time scale keeping both short-term and long-term accuracy. We removed each clock's drift, then weighted the residual fluctuations. The weight function is set to be proportional to the inverse exponential of the index of each clock's frequency deviation. We find the...

Topics: DTIC Archive, Lin, Shinn Y, NATIONAL STANDARD TIME AND FREQUENCY LAB TAOYUAN (TAIWAN), *TIME...

Very accurate and stable time tagging capabilities are fundamental for Quantum Astronomy and Quantum Key Distribution. The main task of Quantum Astronomy is to find particular signatures of different astrophysical emission mechanisms or scattering processes by measuring the statistics of the arrival time of each incoming photon. This line of research will be particularly important with future extremely large telescopes. On the other hand, Quantum Key Distribution (QKD) assures a secure...

Topics: DTIC Archive, Occhipinti, Tommaso, PADOVA UNIV (ITALY), *FREQUENCY, *TIME, *ASTROPHYSICS, *QUANTUM...

In real-time Kalman filter applications involving clocks, it is common practice to model the clock errors with simply two state variables, namely phase and frequency. It has been pointed out in previous PTTI papers that such models are suboptimal because they cannot accommodate flicker noise components exactly, Thus it is desirable to have a means of assessing the goodness of fit of a proposed 2-state model in the particular application at hand. The methodology suggested here involves first...

Topics: DTIC Archive, BRADLEY UNIV PEORIA IL, *KALMAN FILTERING, *ATOMIC CLOCKS, *GLOBAL POSITIONING...

Contents: Fundamental studies and quartz crystal; Filtering techniques and crystal filters; Crystal design and engineering; Crystal measurements; Oscillators and Synthesizers; Atomic and molecular frequency control; Timekeeping and distribution.

Topics: DTIC Archive, Gerber, E A, ARMY ELECTRONICS COMMAND FORT MONMOUTH NJ, *FREQUENCY, SYMPOSIA,...

One might assume precise time metrology is the exclusive domain of national scientific laboratories, military infrastructure, or professional calibration centers. But there are a number of amateurs who in recent years have built home timing labs purely as a hobby, the performance of which now rivals that of some national labs. An even larger number of individuals, perhaps hundreds, own atomic standards and use them to satisfy or fuel their curiosity about the world of ultra-precise timekeeping....

Topics: DTIC Archive, Van Bank, Tom, SYNTONICS LLC SEATTLE WA, *GLOBAL POSITIONING SYSTEM, *PRECISION,...

One role of The Aerospace Corporation is to act as a source of technical and scientific expertise for its principal customer, the United States Air Force Space Division. In support of this role the Corporation's Chemistry and Physics Laboratory conducts a research program investigating various aspects of atomic frequency standards. The prime objective of the program is to improve the reliability and performance of the atomic frequency standards used on Air Force satellites. In meeting this...

Topics: DTIC Archive, Frueholz, R P, AEROSPACE CORP EL SEGUNDO CA CHEMISTRY AND PHYSICS LAB, *ATOMIC...

We describe a cold atom clock designed for operating in microgravity, the PHARAO project. Preliminary results have already been obtained on earth and the prototype will be tested in the reduced gravity of aircraft parabolic flights in the beginning of 1997. The PHARAO prototype is an extension of the work done at the BNM-LPTF on a cesium atomic fountain, which presents a resonance linewidth of 700 millihertz, a frequency stability of 1.5 x 10E-13 TauE-1/2 where tau is the integration time in...

Topics: DTIC Archive, BNM-LABORATOIRE PRIMAIRE DU TEMPS ET DES FREQUENCES PARIS (FRANCE), *TIME, *FREQUENCY...

The GPS Master Control Station (MCS) currently makes significant use of the Allan Variance. This two-sample variance equation has proven excellent as a handy, understandable tool, both for time domain analysis of GPS Cesium frequency standards, and for fine tuning the MCS's state estimation of these atomic clocks. The Allan Variance does not explicitly converge for the noise types of a less than or equal to -3, and can be greatly affected by frequency drift. Because GPS Rubidium frequency...

Topics: DTIC Archive, 2D SPACE OPERATIONS SQUADRON FALCON AFB CO, *GLOBAL POSITIONING SYSTEM, *KALMAN...

Optical frequency combs serve as the clockwork of optical clocks, which are now the best time-keeping systems inexistence. The use of precise optical time and frequency technology in various applications beyond the research lab remains a significant challenge, but one that integrated microresonator technology is poised to address. Here, we report a silicon-chip-based microresonator comb optical clock that converts an optical frequency reference to a microwave signal.

Topics: DTIC Archive, Papp,Scott B, California Institute of Technology Pasadena United States, resonators,...

It has already been shown than even with a simple daily averaging of GLONASS data at each site, continental GLONASS time transfer can be achieved at a level of several tens of nanoseconds. A further step is to carry out observations of GLONASS satellites by the common-view method. This paper reports a comparison of GPS and GLONASS common-view time transfers between Russia and Western Europe. At each site, a GPS receiver and a GLONASS receiver are connected to the same atomic clock. Both GPS...

Topics: DTIC Archive, BUREAU INTERNATIONAL DES POIDS ET MESURES SEVRES (FRANCE), *ATOMIC CLOCKS, *GLOBAL...

Atomic clocks represent critical equipment for a satellite navigation system. A Passive Hydrogen Maser (PHM), with its excellent frequency stability performance, has been chosen as the master clock in the Galileo navigation satellite payload, and will be the first one of its type ever to fly. Temex Neuchatel Time is responsible for the industrialization of the Physics Package (PP) of the PHM and has been developing numbers for the PP, including Engineering Qualification, Qualification,...

Topics: DTIC Archive, Wang, Qinghua, TEMEX TIME NEUCHATEL (SWITZERLAND), *ATOMIC CLOCKS, *TIME STANDARDS,...

The objective of the research program is an investigation into the feasibility of using the stimulated resonance Raman effect in an atomic beam for time and frequency standards, as well as spectroscopic applications in the microwave to the far infrared frequency range. Keywords: Stimulated resonance Raman effect; Portable Cesium Beam Clocks; Spectroscopic applications; Microwave and far infrared frequency range.

Topics: DTIC Archive, Ezekiel,S, MASSACHUSETTS INST OF TECH CAMBRIDGE RESEARCH LAB OF ELECTRONICS, *LASER...

We have constructed a link between Physikalisch-Techniche Bundesanstalt (PTB) in Braunschweig, Germany and the National Institute of Standards and Technology (NIST) in Boulder, Colorado using carrier-phase Global Positioning System (GPS) receivers. The link will provide a direct measurement of the frequency difference between UTC(PTB) and UTC(NIST), and can also be used to provide a direct comparison between the primary frequency standards at the two laboratories. Based on our previous work...

Topics: DTIC Archive, NATIONAL INST OF STANDARDS AND TECHNOLOGY BOULDER CO, *COMPARISON, *TIME STANDARDS,...

The first Block IIR GPS navigation satellite, placed in orbit on July 22, 1997, carried a new generation of rubidium clocks. Since then, two of these clocks have been activated, and both are performing well. This paper reports on those early results, and compares the in-orbit performance with ground acceptance test data. EG&G has delivered about two-thirds of the 66 Rubidium Atomic Frequency Standards (RAFS) needed for the Block IIR GPS program Composite frequency and time stability plots...

Topics: DTIC Archive, EG AND G FREQUENCY PRODUCTS SALEM MA, *GLOBAL POSITIONING SYSTEM, *NAVIGATION...

For a decade and a half GPS Common-View time transfer has greatly served the needs of primary timing laboratories for regular intercomparisons of remote atomic clocks. However, GPS as a one-way technique has natural limits and may not meet all challenges of the comparison of the coming new generations of atomic clocks. Two-Way Satellite Time and Frequency Transfer (TWSTFT) is a promising technique which may successfully complement GPS. For two years, regular TWSTFT's have been performed between...

Topics: DTIC Archive, NATIONAL PHYSICAL LAB TEDDINGTON (UNITED KINGDOM), *ARTIFICIAL SATELLITES, *GLOBAL...

Highly stable atomic frequency standards are of increasing importance for a variety of space applications, ranging from communication to navigation and time transfer to tests of fundamental science. The requirements for an atomic clock vary significantly depending on the application, and for many space systems compactness and robust design are at a premium, and stability dominates over absolute accuracy. We report on progress with our design for a compact laser-cooled Cs-beam atomic clock...

Topics: DTIC Archive, Buell, Walter F, AEROSPACE CORP LOS ANGELES CA, *ARTIFICIAL SATELLITES, *ATOMIC...

The Space Applications Branch at the U.S. Naval Research Laboratory is engaged in GPS Space Clock Development, GPS On-orbit Analysis, GPS Receiver Development, GPS receiver Calibration, GPS Clock Life Testing, and other time and frequency programs. The present status of these activities and their future developments is reported.

Topics: DTIC Archive, Beard, Ronald, NAVAL RESEARCH LAB WASHINGTON DC, *GLOBAL POSITIONING SYSTEM, *NAVAL...

The Physikalisch-Technische Bundesanstalt (PTB) maintains the German national time scale, disseminates time and frequency for both business and general public, and undertakes research to improve its facilities. This report covers the activities of PTB's Time Dissemination Working Group during 2008 and 2009. PTB's time scale UTC (PTB) is based on the primary clock CS2 and an associated phase micro-stepper to keep the time scale in reasonable agreement with UTC. CS2 and the other primary...

Topics: DTIC Archive, PHYSIKALISCH-TECHNISCHE BUNDESANSTALT BRAUNSCHWEIG (GERMANY), *TIME, *FREQUENCY,...

The work of main time laboratories in Poland concentrates on the improvement of national time scales UTC (PL) and TA (PL), and the development of new time receivers. The Polish Independent Atomic Time Scale TA (PL) is obtained as the weighted average of about eight atomic clocks working at different laboratories in Poland, and its long-term stability is about 5 x 10(exp -15). In the recent years, the important achievement was the development of the TTS-2 multi-channel GPS time receiver based on...

Topics: DTIC Archive, Nawrocki, Jerzy, CENTRAL OFFICE OF MEASURES (GUM) WARSAW (POLAND), *TRANSFER, *TIME...

The GPS Operational Control System (OCS) has five monitor stations located world-wide. These stations continuously track all satellites in view, and this raw tracking data is transmitted to the master control station at the Consolidated Space Operations Center (CSOC) for further real time processing. The data is stored on tape and is available for post processing as well. This paper discusses a variety of ways the tracking data can be analyzed to obtain useful information regarding Navstar...

Topics: DTIC Archive, AEROSPACE CORP EL SEGUNDO CA, *ATOMIC CLOCKS, *SATELLITE TRACKING SYSTEMS, *GLOBAL...

In this paper, we present measurement results of the Digital Locked Loop system, developed by AGH University of Science and Technology, for microwave frequency distribution (here, 5 or 10 MHz) over optical fiber with precise stabilization of propagation delay in a relatively wide range of temperature variations. The main principle of the operation of the electronic delay lines is explained and the first measurement results obtained with the experimental setup using 20 km of optic fiber link are...

Topics: DTIC Archive, CENTRAL OFFICE OF MEASURES (GUM) WARSAW (POLAND), *DELAY LINES, *FREQUENCY STANDARDS,...

The authors have implemented several enhancements to the U.S. Naval Observatory (USNO) Master Clock system. Design changes to the system include the use of a Kalman filter for phase and frequency estimates, decreasing the time interval between steers, and the redesign of control parameters. The present control system utilizes real-time data estimates of the differences between the Master Clock and a time scale that combines hydrogen masers and commercial cesium frequency standards with a...

Topics: DTIC Archive, Koppang, P, NAVAL OBSERVATORY WASHINGTON DC, *TIME INTERVALS, *CONTROL SYSTEMS,...

Atomic clocks have been instrumental in science and technology, leading to innovations such as global positioning, advanced communications, and tests of fundamental constant variation. Timekeeping precision at 1 part in 10 (exp 18) enables new timing applications in relativistic geodesy, enhanced Earth- and space-based navigation and telescopy, and new tests of physics beyond the standard model. Here, we describe the development and operation of two optical lattice clocks, both using...

Topics: DTIC Archive, MASSACHUSETTS INST OF TECH CAMBRIDGE, *ATOMIC CLOCKS, *INSTABILITY, ATOMIC ENERGY...

The U.S. Naval Observatory recently completed a new facility to house its rubidium fountains as well as hydrogen masers, cesium-beam-tube clocks, and future clocks. The design and performance of the building itself is key to providing a good environment to house the clocks. Additionally, the measurement, dissemination, and future capabilities of the infrastructure electronics are critical to achieving mission goals and supporting requirements into the future. This paper reviews some of the...

Topics: DTIC Archive, NAVAL OBSERVATORY WASHINGTON DC TIME SERVICE DIV, *ATOMIC CLOCKS, *RUBIDIUM, *NAVY,...

Kernco, Inc. was selected to design the Cesium Atomic Frequency Standards (CAPS) for the GPS Block IIR NAVSTAR satellites. These spacecraft are scheduled to be launched in the mid-1990s to replenish and upgrade the existing constellation of Global Positioning System satellites. The Block IIR CAFS output frequency is 13.4003378 MHz, the 686th submultiple of the cesium atomic resonance frequency. Using an integer submultiple simplifies the design of the atomic frequency standard's rf multiplier...

Topics: DTIC Archive, Wisnia, Jeffry A, KERNCO INC DANVERS MA, *FREQUENCY STANDARDS, *NAVIGATION...

This paper describes a triply-redundant precision time frequency standard. The standard combines three high performance, field-proven Frequency Electronics devices; namely, the cesium beam frequency standard, the rubidium frequency standard and the SC-cut quartz oscillator in a single 5-1/4 inch high rack-mounted instrument. Switching between redundant subsystems is accomplished automatically in a glitch-free manner (i.e., negligible phase perturbation), utilizing a process of dynamic...

Topics: DTIC Archive, FREQUENCY ELECTRONICS INC MITCHEL FIELD NY, *NANOSECOND TIME, *ATOMIC CLOCKS,...

The current definition of Coordinated Universal Time (UTC) is related to the unpredictable, variable rotation rate of the Earth. This is accomplished by irregular insertions of leap seconds, which create unpredictable discontinuities in the UTC. With the increasing importance of a continuous, uniform time scale for users, it is appropriate to re-examine the current definition of this time scale. There are several ways to address this problem, and it is appropriate that the International...

Topics: DTIC Archive, McCarthy, Dennis D, NAVAL OBSERVATORY WASHINGTON DC, *LIMITATIONS, *ASTRONOMY,...

This is a brief report on the work done by the International Astronomical Union (IAU) working group Relativity for Celestial Mechanics and Astrometry. The first central task of the working group was to recommend some specific form of the metric tensor that is related to the distance of two neighboring points in space-time with coordinates. The metric tensor allows one to derive translational and rotational equations of motion of bodies, to describe the propagation of light, set the rates of...

Topics: DTIC Archive, Soffel, M, TECHNISCHE HOCHSCHULE DRESDEN (GERMANY), *MATHEMATICAL MODELS, *EQUATIONS...

Previous investigations of cesium (Cs) frequency standards demonstrated that Rabi pulling and cavity pulling were the most significant effects that translated microwave power variations into output frequency variations. It was also shown that there exist optimum values of the C-field that make the output frequency insensitive to variations in microwave power. Using a completely automated measurement system, we performed a similar study on a dual-beam, high-performance Cs frequency standard. The...

Topics: DTIC Archive, Karuza, S K, AEROSPACE CORP EL SEGUNDO CA ELECTRONICS TECHNOLOGY CENTER, *CESIUM,...

Precision frequency metrology has valuable applications in cutting edge science, technology, and engineering. Current optical frequency standards utilize ultra cold ions or atoms, which requires complicated, nonportable infrastructure. The novel technique in our proposal allows us to access the narrow linewidth properties of an optical clock transition in a thermal mercury vapor cell. Using a thermal vapor cell removes all of the complicated infrastructure requirements and leaves us with a...

Topics: DTIC Archive, MICHIGAN UNIV ANN ARBOR, *ATOMIC CLOCKS, *METROLOGY, *OPTICAL PROPERTIES, CRYSTALS,...

This report addresses the least-squares (l.s.) polynomial approximation of gaussian random walk (r.w.) segments. The r.w.'s treated are assumed to be generated by the summation of zero mean, stationary, gaussian random sequences of real numbers. Expressions are developed that relate the statistics of these stationary underlying sequences to the statistics of the associated coefficients and residuals of fit of the approximating l.s. polynomials. When more than one segment of a given r.w. has...

Topics: DTIC Archive, Young,Phillip L, NAVAL SURFACE WEAPONS CENTER DAHLGREN VA,...

The Johns Hopkins University Applied Physics Laboratory (JHU/APL) Ultra-stable Oscillator (USO) has been demonstrated in nearly 50 years of space applications to be a strategic asset to the space timekeeping and signal technologies of the United States. Therefore, advancing the JHU/APL USO capability by improving its frequency stability, without diminishing reliability, is uniquely valuable to the operations of space communication and navigation systems. Ultimately, we expect that the call for...

Topics: DTIC Archive, JOHNS HOPKINS UNIV LAUREL MD APPLIED PHYSICS LAB, *STABILITY, *FREQUENCY STABILIZERS,...

This report shows the relationship between output frequency shifts and the absorption cell magnetic field during microwave power fluctuations on a commercial rubidium frequency clock. Changes in the clock output frequency relative to the 10 MHz reference were monitored as changes in the absorption cell magnetic field (0.01 to 1.0 Gauss) and changes in the cell's interrogation microwave power were varied from the nominal specification (PO) at four discrete values (+1.3. -1.1, -2.2, -4.OdB). The...

Topics: DTIC Archive, Sarosy, Edward B, AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF...

The delay fluctuations in earth stations have become the main source of instability that degrades the accuracy of two-way satellite time and frequency transfer. We had installed a satellite simulator system on an earth station for measuring the variations of signal path delays in the station. The purpose of this paper is to analyze delay variations associated with the environmental temperature. With the data collected over 2 months, we observed that the long-term and short-term temperature...

Topics: DTIC Archive, Tseng, W H, CHUNGHWA TELECOM TAOYUAN (TAIWAN) TELECOMMUNICATION LABS, *DIFFERENTIAL...

Recently, there has been considerable interest in the use of single-mode diode lasers in atomic frequency standards. In this report, theoretical calculations were performed to quantify the expected performance improvement upon incorporation of diode lasers in rubidium gas cell atomic frequency standards. We assume that clock signal shot noise, the diode laser's quantum noise, and diode laser frequency locking noise all contribute to the atomic frequency standard's stability. Keywords include:...

Topics: DTIC Archive, Camparo,James C, AEROSPACE CORP EL SEGUNDO CA CHEMISTRY AND PHYSICS LAB,...

Reports are listed under the following subheadings: Force and Temperature Sensitivity of Quartz Crystal Resonators; Quartz Crystal Resonators Design, Measurement and Application; Resonator Processing; Fundamental Properties of Materials; Filters; Surface Acoustic Wave Resonators and Filters; Oscillator Specification and Measurement; Oscillators; Frequency and the Control Aspects of Digital Communication; Time Distribution and Synchronization; Atomic and Molecular Frequency Standards; Far...

Topics: DTIC Archive, ARMY ELECTRONICS COMMAND FORT MONMOUTH NJ, *TIME SIGNALS, *QUARTZ RESONATORS,...