A5006596897- Advanced Frequency and Time Standards
- Pulsars and Gravitational Waves Research
- Geophysics and Gravity Measurements
- GNSS positioning and interference
- Geophysics and Sensor Technology
- Superconducting Materials and Applications
- Atomic and Subatomic Physics Research
- High-pressure geophysics and materials
- Radio Astronomy Observations and Technology
- Astrophysical Phenomena and Observations
- Astro and Planetary Science
- Gamma-ray bursts and supernovae
- Network Time Synchronization Technologies
- Economic Theory and Policy
- Particle Accelerators and Free-Electron Lasers
- Inertial Sensor and Navigation
- Cold Atom Physics and Bose-Einstein Condensates
- Satellite Communication Systems
- Cybersecurity and Information Systems
- Radio Wave Propagation Studies
- Radar Systems and Signal Processing
- Mobile Agent-Based Network Management
- UAV Applications and Optimization
- Scientific Measurement and Uncertainty Evaluation
- Indoor and Outdoor Localization Technologies
National Physical Laboratory
2003-2020
Qinetiq (United Kingdom)
2005
University of Manchester
1991-2000
SKA Observatory
1996-2000
Shemar & Lyne have previously presented observations and an analysis of 32 glitches their subsequent relaxations observed in a total 15 pulsars. These data are brought together this paper with those published by other authors. We show quantitatively how glitch activity decreases linearly decreasing rate slow-down. As indicated from studies the Vela pulsar, suggests that 1.7 per cent moment inertia typical neutron star is normally contained pinned superfluid which releases its excess angular...
view Abstract Citations (121) References (55) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS EGRET High-Energy Gamma-Ray Pulsar Studies. I. Young Spin-powered Pulsars Thompson, D. J. ; Arzoumanian, Z. Bertsch, L. Brazier, K. T. S. Chiang, D'Amico, N. Dingus, B. Esposito, A. Fierro, M. Fichtel, C. E. Hartman, R. Hunter, Johnston, Kanbach, G. Kaspi, V. Kniffen, Lin, Y. Lyne, Manchester, Mattox, Mayer-Hasselwander, H. Michelson, P. F. von Montigny, Nel, Nice,...
view Abstract Citations (68) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Young, Glitching Pulsar near the Direction of W28 Kaspi, V. M. ; Lyne, A. G. Manchester, R. N. Johnston, S. D'Amico, Shemar, L. Timing observations PSR B1758-23 (PSR J1801-23) made over a 6 yr period using 64-m Parkes radio telescope and 76-m Lovell show that this pulsar is young located close to edge supernova remnant W28. The pulsar's characteristic age 58,000...
A clock prediction and steering algorithm has been developed to produce a UTC(k) timescale that may be maintained close UTC. The is based on predicting individual (UTC - C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</sub> ) offsets which are then combined form physical timescale. designed use data from all the available laboratory clocks without of ensemble algorithm. performance underlying Kalman filter predictor examined in depth, along...
Local representations of the international time scale, Coordinated Universal Time (UTC), are maintained by approximately 69 national measurement institutes and other laboratories. These laboratories contribute their clock transfer measurements for use in computation UTC. Although local UTC, commonly called UTC(k) scales, vary considerably, example numbers atomic clocks available, they also share many characteristics. In this paper, we examine rationale requirements maintaining a...
A new collaborative European project "International timescales with optical clocks" (ITOC) aims to tackle the key challenges that must be addressed prior a redefinition of SI second. coordinated programme comparisons will carried out between clocks developed in five different laboratories, enabling their performance levels validated at an unprecedented level accuracy. Supporting work evaluate relativistic effects influence comparisons, including gravitational redshift clock transition...
We carried out a 26-day comparison of five simultaneously operated optical clocks and six atomic fountain located at INRIM, LNE-SYRTE, NPL PTB by using two satellite-based frequency techniques: broadband Two-Way Satellite Time Frequency Transfer (TWSTFT) Global Positioning System Precise Point (GPS PPP). With an enhanced statistical analysis procedure taking into account correlations gaps in the measurement data, combined overall uncertainties range $1.8 \times 10^{-16}$ to $3.5 for clock...
Galileo System Time (GST) is the cornerstone for operations and performance of Galileo, European GNSS (Global Navigation Satellite System). GST must be stable, traceable to UTC, always available. currently generated from an ensemble physical on-ground clocks steered UTC. This approach limits certain types performance. For example, if a clock breaks down, downtime caused or procedure needs put in place switch redundant clock. Moreover, very long time periods (comparable design operational...
In recent years the National Physical Laboratory (NPL) has been developing a Kalman filter-based atomic clock ensemble algorithm. The algorithm is being used to form composite time scale which will ultimately be employed improve stability of UK's national UTC(NPL) and its robustness hardware failures. optimised for both short-term long-term stability. Flicker Frequency Modulation (FFM) noise modelled using linear combination integrated Markov processes. We present here results obtained data...
Data fusion from spatially separated radars is increasingly being considered within network centric warfare to mitigate complex threats. Propagation of signals through differing atmospheric environments, however, can introduce significant errors in target positioning and ranging. For example, simulations illustrate that two by 100 km viewing the same single different tropospheres could place positions over 200 m. Attempts at fusing data resolving information into a object result operational...
Two-way satellite time and frequency transfer (TWSTFT) has been used operationally by the international community for several years. This paper describes analysis techniques being developed at National Physical Laboratory processing of TWSTFT measurements.
view Abstract Citations (13) References (16) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Six Year Timing Solution for PSR B1951+32 Foster, R. S. ; Lyne, A. G. Shemar, L. Backer, D. C. years of pulse time-of-arrival measurements have been collected from observations the young, fast pulsar B1951 + 32 in CTB 80 supernova remnant using Jodrell Bank and Arecibo radio telescopes. The combined data allow determination a phase connected solution between 1987...
Abstract The Resilient Enhanced Time Scale Infrastructure (RETSI) is an atomic clock network distributed geographically in secure locations, that being developed as part of work the National Timing Centre programme. It will become source UTC(NPL), physical realisation Coordinated Universal (UTC) maintained by Physical Laboratory (NPL) United Kingdom (UK). Dissemination points called User Access Nodes link to RETSI via Orchestration Nodes, allowing users access time and / or frequency...
A family of second-difference statistics has been designed for use on regular but unevenly spaced two-way satellite time and frequency transfer (TWSTFT) series. The characteristics these new are compared with those the Allan variance (AVAR) modified (MVAR). used to estimate values AVAR, MVAR TVAR. Direct comparisons made estimates quantities based an interpolated Confidence interval determination is discussed. application variances TWSTFT geodetic GPS data presented.
The accuracy of the Two-Way Time and Frequency Transfer (TWSTFT) technique has been shown to be limited by propagation delay instabilities present in Earth station hardware. In this paper National Physical Laboratory (NPL) investigated a scheme for reducing order improve its time frequency transfer. Tests show that cables propagating signals at 70 MHz or L-band have much lower temperature coefficients than Ku-band when measured with TWSTFT modem. A improving stability through wherever...