Showing papers by "Fred L. Walls published in 1999"

Measurement of Frequency, Phase Noise and Amplitude Noise

Abstract: The sections in this article are 1 Basic Concepts and Definitions 2 Measurement Systems 3 Carrier Suppression Measurement Systems

Noise considerations for locking to the center of a lorentzian line

Abstract: Many areas of science require locking a probe signal to the center of a Lorentzian line. In this paper we experimentally explore the limits to the resolution for locking a sine-wave modulated probe signal to a Lorentzian line. Surprisingly we find that in some cases relatively high-frequency phase modulation ~PM! noise on the probe signal ~even 100 times the linewidth of the resonance! can significantly degrade the stability of the lock. The 6.835-GHz hyperfine transition in Rb was used as a test bed for these studies because it affords very high resolution for investigating this effect. The details presented here should prove useful for testing a complete theory of this effect and give some insight into the requirements of PM noise of local oscillators to be locked to a Lorentzian line. @S1050-2947~99!02401-4#

PARCS: a Primary Atomic Reference Clock in Space

Abstract: NIST, in collaboration with the Jet Propulsion Laboratories (JPL), the University of Colorado, Politecnico di Torino and Harvard Smithsonian Center for Astrophysics (SAO) is building a laser-cooled cesium-beam atomic clock for flight on the International Space Station (ISS). The clock, named PARCS (Primary Atomic Reference Clock in Space) is designed to perform certain tests of relativity and fundamental physics and to serve as a primary frequency standard.

Cs frequency synthesis: a new approach

Abstract: This paper describes a new approach to synthesizing the Cs hyperfine frequency of 9.192 GHz that is designed to be sufficiently rugged for use in space, specifically for the primary atomic reference clock in space (PARCS) planned for the International Space Station, as well as ground applications. This new approach requires no narrow band filters or frequency multiplication and the primary source of cooling is conduction. Instead of frequency multiplication, it uses a custom regenerative divider stage followed by two commercial binary dividers and several mixing stages. A fractional frequency step of 2/spl times/10/sup -17/ is achieved by mixing the output of a 48 bit numerically controlled oscillator with the microwave signal. Preliminary tests on the new synthesizer design indicates an internal fractional frequency stability of 1/spl times/10/sup -15/ at 10 s and 1/spl times/10 at 1 day, dominated by the daily room temperature variations. The phase and amplitude noise are similar to our previous designs that used frequency multiplication and narrow band filters. The temperature coefficient is less than 0.2 ps//spl deg/C.

1-bit memory using one electron: Parametric oscillations in a Penning trap

Abstract: The parametric oscillation of a single trapped electron is studied and used to measure enhanced spontaneous emission. Hysteresis in this motion provides a 1-bit memory to store information about excitations made with the electron ``in the dark.'' The time dependence and stability criteria for the parametric excitation are examined. The cyclotron motions for one and two electrons are also studied.

Frequency Standards, Characterization

Abstract: The sections in this article are 1 Accuracy 2 Stability 3 Conversion Between Time-Domain Measures and Frequency-Domain Measures 4 Confidence Intervals For σ2y(τ) and Mod σ2y(τ)

Experimental studies of noise in a dual mode oscillator

Abstract: We present preliminary results of an experimental study of phase modulation and amplitude modulation noise in a specific type of dual mode oven controlled crystal oscillator. Our experiments indicate some correlation between the amplitude modulated and phase modulated noise in two anharmonically resonant oscillations. No correlation was found between the PM noise in both oscillations.

Accuracy evaluations and frequency comparison of NIST-7 and CRL-O1

Abstract: CRL and NIST have completed the development of CRL-O1, an improved optically pumped primary frequency standard. The results of the first evaluation of the new standard and its comparison with NIST-7, the US primary frequency standard are presented.