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Results for “frequency standard space clock”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

A two-year history of atomic frequency standards syntonization in the Deep Space Network

The frequency and timing system (FTS) of the Deep Space Network (DSN) consists of a collection of three sets of clocks driven by independent atomic oscillators. The synchronization of the output frequencies (syntonization) of these oscillators (reference frequency standards) is reported. There is an implied specification of a + or - 5.5 X 10 to the 12th power related to the DSN time synchronization specification of a + or - 100 microseconds. Both the syntonization within the three sets and the syntonization of the sets to the international standard (International Atomic Time) are considered.

Ward, S. C.↗
NASA NTRS1974

Atomic frequency standard relativistic Doppler shift experiment

An experiment has been performed to measure possible space anisotropy as it would effect the frequency of a cesium atomic beam standard clock in a laboratory on earth due to motion relative to external coordinate frames. The cesium frequency was measured as a function of orientation with respect to an atomic hydrogen maser standard. Over a period of 34 days 101 measurements were made. The results are consistent with a conclusion that no general orientation dependance attributable to spacial anisotropy was observed. It is shown that both the airplane clock results, and the null results for the atomic beam clock, are consistent with Einstein general or special relativity, or with the Lorentz transformations alone.

Peters, H. E.↗
NASA NTRS2011

NASA Tech Briefs, February 2011

Topics covered include: Multi-Segment Radius Measurement Using an Absolute Distance Meter Through a Null Assembly; Fiber-Optic Magnetic-Field-Strength Measurement System for Lightning Detection; Photocatalytic Active Radiation Measurements and Use; Computer Generated Hologram System for Wavefront Measurement System Calibration; Non-Contact Thermal Properties Measurement with Low-Power Laser and IR Camera System; SpaceCube 2.0: An Advanced Hybrid Onboard Data Processor; CMOS Imager Has Better Cross-Talk and Full-Well Performance; High-Performance Wireless Telemetry; Telemetry-Based Ranging; JWST Wavefront Control Toolbox; Java Image I/O for VICAR, PDS, and ISIS; X-Band Acquisition Aid Software; Antimicrobial-Coated Granules for Disinfecting Water; Range 7 Scanner Integration with PaR Robot Scanning System; Methods of Antimicrobial Coating of Diverse Materials; High-Operating-Temperature Barrier Infrared Detector with Tailorable Cutoff Wavelength; A Model of Reduced Kinetics for Alkane Oxidation Using Constituents and Species for N-Heptane; Thermally Conductive Tape Based on Carbon Nanotube Arrays; Two Catalysts for Selective Oxidation of Contaminant Gases; Nanoscale Metal Oxide Semiconductors for Gas Sensing; Lightweight, Ultra-High-Temperature, CMC-Lined Carbon/Carbon Structures; Sample Acquisition and Handling System from a Remote Platform; Improved Rare-Earth Emitter Hollow Cathode; High-Temperature Smart Structures for Engine Noise Reduction and Performance Enhancement; Cryogenic Scan Mechanism for Fourier Transform Spectrometer; Piezoelectric Rotary Tube Motor; Thermoelectric Energy Conversion Technology for High-Altitude Airships; Combustor Computations for CO2-Neutral Aviation; Use of Dynamic Distortion to Predict and Alleviate Loss of Control; Cycle Time Reduction in Trapped Mercury Ion Atomic Frequency Standards; and A (201)Hg+ Comagnetometer for (199)Hg+ Trapped Ion Space Atomic Clocks.

Source record↗
NASA NTRS2000

Higher Pole Linear Traps for Atomic Clock Applications

We investigate experimentally and theoretically higher pole linear ion traps for frequency standard use. We have built a 12-pole trap and have successfully loaded ions into it from a linear quadrupole trap. By solving the Boltzmann equation describing large ion clouds where space charge interactions are important, we show that clock frequency changes due to ion number fluctuations are much smaller in ion clocks based multipole traps than comparable clocks based on quadrupole linear traps.

Prestage, John D.↗
NASA NTRS1979

Demonstration of remote clock monitoring by VLBI with three baseline closures

The capability of very long baseline interferometry (VLBI) to monitor the stability of remotely located hydrogen maser frequency standards has been demonstrated by a series of experiments conducted between Deep Space Stations in Australia, Spain, and California. The measured stabilities of the clock systems, over approximately 10 day intervals, were 1 to 3 parts in 10 to the 13th power, with the instabilities due to the oscillators, the clock distribution systems, the receiving system delays, and the VLBI measurement error. Experiments were conducted independently using two different systems (BLOCK 0 and WBDAS). Later comparison shows agreement on the order of 1 part in 10 to the 13th power. Closure was demonstrated on three separate occasions to 33, 10, and 13 ns with an error uncertainty of + or - 42 ns. The results represent an important consistency check on VLBI measurements.

Cheetham, C. M.↗
NASA NTRS2013

Next Generation JPL Ultra-Stable Trapped Ion Atomic Clocks

Over the past decade, trapped ion atomic clock development at the Jet Propulsion Laboratory (JPL) has focused on two directions: 1) new atomic clock technology for space flight applications that require strict adherence to size, weight, and power requirements, and 2) ultra-stable atomic clocks, usually for terrestrial applications emphasizing ultimate performance. In this paper we present a new ultra-stable trapped ion clock designed, built, and tested in the second category. The first new standard, L10, will be delivered to the Naval Research Laboratory for use in characterizing DoD space clocks.

Naval Research Laboratory (NRL)↗
NASA NTRS1997

Spacecraft Tests of General Relativity

Current spacecraft tests of general relativity depend on coherent radio tracking referred to atomic frequency standards at the ground stations. This paper addresses the possibility of improved tests using essentially the current system, but with the added possibility of a space-borne atomic clock. Outside of the obvious measurement of the gravitational frequency shift of the spacecraft clock, a successor to the suborbital flight of a Scout D rocket in 1976 (GP-A Project), other metric tests would benefit most directly by a possible improved sensitivity for the reduced coherent data. For purposes of illustration, two possible missions are discussed. The first is a highly eccentric Earth orbiter, and the second a solar-conjunction experiment to measure the Shapiro time delay using coherent Doppler data instead of the conventional ranging modulation.

Anderson, John D.↗
NASA NTRS1990

GPS Block 2R Time Standard Assembly (TSA) architecture

The underlying philosophy of the Global Positioning System (GPS) 2R Time Standard Assembly (TSA) architecture is to utilize two frequency sources, one fixed frequency reference source and one system frequency source, and to couple the system frequency source to the reference frequency source via a sample data loop. The system source is used to provide the basic clock frequency and timing for the space vehicle (SV) and it uses a voltage controlled crystal oscillator (VCXO) with high short term stability. The reference source is an atomic frequency standard (AFS) with high long term stability. The architecture can support any type of frequency standard. In the system design rubidium, cesium, and H2 masers outputting a canonical frequency were accommodated. The architecture is software intensive. All VCXO adjustments are digital and are calculated by a processor. They are applied to the VCXO via a digital to analog converter.

Baker, Anthony P.↗
NASA NTRS1989

Stability of laser oscillator systems

One of the goals of the Stanford University-NASA Laser-In-space Technology Experiment (SUNLITE) program is to develop ultrastable optical frequency oscillators that can lead to high resolution time standards and ultimately standard clocks. During the past year or two there was remarkable progress towards achieving in the laboratory the fundamental quantum limits for the frequency stability of nonplanar ring oscillator (NPRO) lasers. The quantum theoretical limits for laser oscillator stability are reviewed, measured stability levels compared, and some applications of such ultrastable laser oscillator systems suggested.

Hafele, Joseph C.↗
NASA NTRS1996

Gravitational Redshift in a Local Freely Falling Frame: A Proposed New Null Test of the Equivalence Principle

We consider the gravitational redshift effect measured by an observer in a local freely failing frame (LFFF) in the gravitational field of a massive body. For purely metric theories of gravity, the metric in a LFFF is expected to differ from that of flat spacetime by only "tidal" terms of order (GM/c(exp 2)R)(r'/R )(exp 2), where R is the distance of the observer from the massive body, and r' is the coordinate separation relative to the origin of the LFFF. A simple derivation shows that a violation of the equivalence principle for certain types of "clocks" could lead to a larger apparent redshift effect of order (1 - alpha)(G M/c(exp 2)R)(r'/R), where alpha parametrizes the violation (alpha = 1 for purely metric theories, such as general relativity). Therefore, redshift experiments in a LFFF with separated clocks can provide a new null test of the equivalence principle. With presently available technology, it is possible to reach an accuracy of 0.01% in the gravitational field of the Sun using an atomic clock orbiting the Earth. A 1% test in the gravitational field of the galaxy would be possible if an atomic frequency standard were flown on a space mission to the outer solar system.

Krisher, Timothy P.↗
NASA NTRS1983

Design of the stift time and frequency transfer microwave ground terminal

The Satellite Time and Frequency Transfer System is intended to provide, simultaneously, global time comparisons at the subnanosecond level and frequency comparisons to better than 1 part in 10 to the 14th power. It utilizes an orbiting hydrogen maser clock and frequency standard that communicates, via microwave links, time and frequency information to Earth terminals operated by hydrogen masers controlling local clocks. A two-way microwave link, to and from the space vehicle provides Doppler information used to cancel the Doppler shifts in a one-way link from the spaceborne oscillator. Pseudo-random noise (PRN) modulation in the two-way link also provides range information to cancel the range delay in the PRN time transfer between space and Earth. The pseudo-random noise modulation system for time difference measurement and its incorporation in the Doppler cancellation system for frequency comparison is explained. The particular PRN code sequence selected and an analysis of the system is discussed.

Penfield, H.↗
NASA NTRS1981

The operational performance of hydrogen masers in the deep space network: The performance of laboratory reference frequency standards in an operational environment

Hydrogen masers used as aids in meeting the routine frequency and time operational requirements within the 64 m antenna Deep Space Network. Both the operational syntonation (frequency synchronization) and the the clock (epoch) synchronization requirements were established through the use of specifically calibrated H-P E215061A flying clock. The sync/synt to UTC was maintained using LORAN and TV in simultaneous reception mode. The sync/synt within the 64 m net was maintained through the use of very long base interferometry. Results indicate that the hydrogen masers perform well within the required specifications.

Ward, S. C.↗
NASA NTRS2017

Optimetrics for Precise Navigation

Optimetrics for Precise Navigation will be implemented on existing optical communication links. The ranging and Doppler measurements are conducted over communication data frame and clock. The measurement accuracy is two orders of magnitude better than TDRSS. It also has other advantages of: The high optical carrier frequency enables: (1) Immunity from ionosphere and interplanetary Plasma noise floor, which is a performance limitation for RF tracking; and (2) High antenna gain reduces terminal size and volume, enables high precision tracking in Cubesat, and in deep space smallsat. High Optical Pointing Precision provides: (a) spacecraft orientation, (b) Minimal additional hardware to implement Precise Optimetrics over optical comm link; and (c) Continuous optical carrier phase measurement will enable the system presented here to accept future optical frequency standard with much higher clock accuracy.

Precise↗