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In the face of growing concern about spoofing attacks on GNSS transmissions, we propose a scheme to cross validate GNSS based timing against intrinsic properties of local hardware oscillators. We demonstrate our approach as being able to detect certain
Jean-Daniel Deschenes, Laura C. Sinclair, Fabrizio R. Giorgetta, William C. Swann, Esther Baumann, Hugo Bergeron, Michael A. Cermak, Nathan R. Newbury
The use of optical clocks/oscillators in future ultra-precise navigation, gravitational sensing, and relativity experiments will require time comparison and synchronization over terrestrial or satellite free-space links. Here we demonstrate full
Aviral Shrivastava, J C. Eidson, Marc A. Weiss, Ya-Shian Li-Baboud, Hugo Andrade, Patricia Derler, Kevin Stanton
Timing and synchronization play a key role in advanced cyber-physical systems (CPS). Precise timing, as often required in safety-critical CPS, depends on hardware support for enforcement of periodic measure, compute, and actuate cycles. For general CPS
Laura C. Sinclair, Jean-Daniel Deschenes, Lindsay I. Sonderhouse, William C. Swann, Isaac H. Khader, Esther Baumann, Nathan R. Newbury, Ian R. Coddington
We describe design and operation of a robust self-referenced, optically coherent frequency comb. The system robustness is derived from a combination of an optics package based on polarization-maintaining fiber, high signal-to-noise ratio (SNR) detection of
Young-Jin Kim, Ian R. Coddington, William C. Swann, Nathan R. Newbury, Joohyung Lee, Seungchul Kim, Seung-Woo Kim
We report a time-domain method of stabilizing the carrier-envelope phase (CEP) of femtosecond pulses. Temporal variations of the pulse envelope and the carrier electric-field phase were separately detected with the aid of intensity cross-correlation and
Laura C. Sinclair, Ian R. Coddington, William C. Swann, Archita Hati, Kana Iwakuni, Nathan R. Newbury
Frequency combs can support cutting-edge measurements in areas that include optical clocks and oscillators, high-accuracy frequency and time transfer, precision spectroscopy from the UV to THz regimes, high-accuracy LIDAR, precise microwave photonics, and
Laura C. Sinclair, Fabrizio R. Giorgetta, William C. Swann, Esther Baumann, Ian R. Coddington, Nathan R. Newbury
The time of flight for a laser beam through the atmosphere will fluctuate as the path-averaged index of refraction varies with atmospheric turbulence, air temperature, and pressure. We measure these fluctuations by transmitting optical pulses from a
An overview of time metrology, with emphasis on time interval measurements, and time synchronization. It covers the evolution of clocks and timekeeping, time scales, the fundamentals of time measurement, and the various time transfer technique used to
Laura C. Sinclair, Fabrizio R. Giorgetta, William C. Swann, Esther Baumann, Ian R. Coddington, Nathan R. Newbury
Atmospheric optical path-length variations are measured across a 2-km optical link through a frequency comb-based system with femtosecond-level precision. Without mitigation, the turbulent piston effect will severely restrict time-frequency transfer from
William C. Swann, Fabrizio R. Giorgetta, Laura C. Sinclair, Esther Baumann, Ian R. Coddington, Nathan R. Newbury
Precision free-space time-frequency transfer could advance fields where present microwave-based transfer is inadequate. We demonstrate an optical free-space link with femtosecond timing deviation and residual instability below 10 −18 at 1000 seconds.
Laura C. Sinclair, Ian R. Coddington, William C. Swann, Nathan R. Newbury
We demonstrate a completely polarization-maintaining fiber frequency comb operating at a 200 MHz repetition rate and show initial phase-locking of the carrier-envelope offset frequency. This design is compatible with a robust, fieldable frequency comb.
Fabrizio R. Giorgetta, William C. Swann, Laura C. Sinclair, Esther Baumann, Ian R. Coddington, Nathan R. Newbury
The transfer of high-quality time-frequency signals between remote locations underpins many applications, including precision navigation and timing, clock-based geodesy, long-baseline interferometry, coherent radar arrays, tests of general relativity and
YaShian Li-Baboud, Julien M. Amelot, Dhananjay Anand, Gerard N. Stenbakken, Thomas L. Nelson, James Moyne
One of the key lessons learned from the 2003 Northeast Blackout in the United States was the need for improved timing. The problem began as an isolated issue, but cascaded through the Northeastern grid. Timely situational awareness would likely have
A previous publication showed problems with the current NIST Time and Frequency Division primary GPS receiver [1] when used for Precise Point Positioning (PPP)-based carrier phase time transfer. We confirm that, for this receiver, boundary discontinuities
William C. Swann, Fabrizio R. Giorgetta, Ian R. Coddington, Esther Baumann, Jean-Daniel Deschenes, Laura C. Sinclair, Alexander M. Zolot, Nathan R. Newbury
We demonstrate a method to compare optical clocks approaching 10 -17 uncertainties through the exchange of optical pulses from phase-locked frequency combs. We discuss results over a 120 m air path and prospects for longer distances.
Ward L. Johnson, Thomas M. Wallis, Pavel Kabos, Eduard Rocas, Juan C. Collado Gomez, Li-Anne Liew, Albert Davydov, Alivia Plankis, Paul R. Heyliger
The design, modeling, fabrication, and characterization of a vibrationally trapped thickness-shear MEMS resonator is presented. This device is intended to avoid various limitations of flexural MEMS resonators, including nonlinearity, clamping losses
Kevin O. Knabe, Paul A. Williams, Fabrizio R. Giorgetta, Chris Armacost, Michael Radunsky, Nathan R. Newbury
The instantaneous optical frequency of an external-cavity quantum cascade laser (QCL) is characterized by comparison to a near-infrared frequency comb. Fluctuations in the instantaneous optical frequency are analyzed to determine the frequency noise power
Fabrizio R. Giorgetta, William C. Swann, Ian R. Coddington, Esther Baumann, Jean-Daniel Deschenes, Laura C. Sinclair, Alexander M. Zolot, Nathan R. Newbury
We demonstrate a free-space link for clock comparisons based on the two-way exchange of pulse trains from combs. The residual uncertainty is 5 * 10^17 in 100 seconds over a 120 m air path, with longer distances possible.
Tara Fortier, Matthew S. Kirchner, Jennifer A. Taylor, James C. Bergquist, Yanyi Jiang, Andrew Ludlow, Christopher W. Oates, Till P. Rosenband, Scott Diddams, Franklyn Quinlan, Nathan D. Lemke
A frequency-stabilized femtosecond laser optical frequency comb serves as a source of microwave signals having very low close-to-carrier phase noise. Comparison of two independent systems shows combined absolute phase noise of -100 dBc/Hz at an offset of 1
Frequency combs, like many ground-breaking technologies, are simple in concept; they results from the spectrum of any regular train of optical pulses. What is remarkable is that this simple picture can be actually realized in a number of different
Michael A. Lombardi, Andrew N. Novick, J. Mauricio Lopez-Romero, Francisco Jimenez, Eduardo de Carlos Lopez, Jean-Simon Boulanger, Raymond Pelletier, Ricardo de Carvalho, Raul Solis, Harold Sanchez, Carlos A. Quevedo, Gregory Pascoe, Daniel Perez, Eduardo Bances, Leonardo Trigo, Victor Masil, Henry Postigo, Anthony Questelles
The Sistema Interamericano de Metrologia (SIM) is a regional metrology organization (RMO) whose members are the national metrology institutes (NMIs) located in the 34 nations of the Organization of American States (OAS). The SIM/OAS region extends
The Time and Frequency Bulletin provides information on performance of time scales and a variety of broadcasts (and related information) to users of the NIST services.
The National Institute of Standards and Technology (NIST) now offers a service that provides customers with an oscillator locked to UTC(NIST), the United States national standard for frequency and time. A NIST disciplined oscillator (NISTDO) works by
We evaluate a dual-frequency, multi-channel GPS receiver for time and frequency transfer applications. The receiver is able to lock its internal clock to an external reference frequency and synchronize the receiver clock to an external timing signal. The
Navigation signal integrity is paramount for aviation and safety of life services. Hitherto GPS signal anomaly alerting has been provided primarily by ground based augmentations. Significantly improved navigation signal integrity and quality may be