Mercury Ion Clock for a NASA Technology Demonstration Mission

Tjoelker, R. L.; Prestage, J. D.; Burt, Eric A.; Chen, Pin; Chong, Y. J.; Chung, Sang K.; Diener, W.; Ely, Todd A.; Enzer, Daphna G.; Mojaradi, Hadi; Okino, Clayton; Pauken, Michael; Robison, David; Swenson, Bradford L.; Tucker, B.; Wang, Rabi

doi:10.1109/tuffc.2016.2543738

Cited by 51 publications

(18 citation statements)

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“…In the case of the observations with the 65 m Tianma, this corresponds to 45 % of the noise budget. This could be mitigated by performing two-way radio occultation experiment or by using a USO with higher frequency stability such as the Deep Space Atomic Clock (DSAC) (Tjoelker et al 2016).…”

Section: Discussionmentioning

confidence: 99%

Venus Express radio occultation observed by PRIDE

Bocanegra-Bahamón

Calvés

Gurvits

et al. 2019

A&A

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Context. Radio occultation is a technique used to study planetary atmospheres by means of the refraction and absorption of a spacecraft carrier signal through the atmosphere of the celestial body of interest, as detected from a ground station on Earth. This technique is usually employed by the deep space tracking and communication facilities (e.g., NASA's Deep Space Network (DSN), ESA's Estrack). Aims. We want to characterize the capabilities of the Planetary Radio Interferometry and Doppler Experiment (PRIDE) technique for radio occultation experiments, using radio telescopes equipped with Very Long Baseline Interferometry (VLBI) instrumentation. Methods. We conducted a test with ESA's Venus Express (VEX), to evaluate the performance of the PRIDE technique for this particular application. We explain in detail the data processing pipeline of radio occultation experiments with PRIDE, based on the collection of so-called open-loop Doppler data with VLBI stations, and perform an error propagation analysis of the technique. Results. With the VEX test case and the corresponding error analysis, we have demonstrated that the PRIDE setup and processing pipeline is suited for radio occultation experiments of planetary bodies. The noise budget of the open-loop Doppler data collected with PRIDE indicated that the uncertainties in the derived density and temperature profiles remain within the range of uncertainties reported in previous Venus' studies. Open-loop Doppler data can probe deeper layers of thick atmospheres, such as that of Venus, when compared to closed-loop Doppler data. Furthermore, PRIDE through the VLBI networks around the world, provides a wide coverage and range of large antenna dishes, that can be used for this type of experiments.

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Section: Discussionmentioning

confidence: 99%

Venus Express radio occultation observed by PRIDE

Bocanegra-Bahamón

Calvés

Gurvits

et al. 2019

A&A

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“…A. Output Frequency f out and Microwave Synthesizer Frequency f msyn First, we derive an update on the often-used formula for the shot-noise-limited output-ADEV in atomic clocks (see [1] or [7])…”

Section: Shot-noise-limited Adevsmentioning

confidence: 99%

“…1 shows a typical block diagram, whereas Fig. 2 shows the more complex version we use for this article, based on the Deep Space Atomic Clock (DSAC) mission architecture [1], [5]. The difference between the two is that DSAC, rather than flying a tunable LO, adds a user-output synthesizer to tune the clock output (with synthesizer referenced to the LO).…”

mentioning

confidence: 99%

Allan Deviation of Atomic Clock Frequency Corrections: A New Diagnostic Tool for Characterizing Clock Disturbances

Enzer

Murphy

Burt

2021

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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As atomic clocks and frequency standards are increasingly operated in situations where they are exposed to environmental disturbances, it becomes more necessary to understand how variations of each clock component impact the clock output, in particular the local oscillator (LO). Most microwave atomic clocks in operation today use quartz crystal LOs with excellent short-term noise variation but large unwanted long-term drift. Fortunately, this slow drift is mitigated by repeatedly comparing the atomic reference frequency to the LO and applying corrections each iteration through a control algorithm. This article focuses on the shot-to-shot corrections themselves. To optimize clock performance, it is important to determine whether disturbances on the output are due to variations of the LO that the control loop failed to remove or variations of the reference frequency itself. Some of this can be diagnosed using the output frequency's Allan deviation (ADEV), the traditional measure of clock performance. However, the ADEV of the corrections reveals somewhat different information, specifically more direct information about all disturbances that the measurement system detects and compensates for, from the LO or elsewhere. In this article: we 1) derive the baseline shot-noise-limited noise floor for this ADEV, 2) validate and adjust for the complexities of our control loop with a computer model, and 3) examine model results and laboratory data that lie on or diverge from the noise floor to understand what divergences reveal about LO and/or clock behavior. Ultimately, we show how to use this corrections-ADEV as a diagnostic to help identify the source of disturbances and drift observed on the clock output.

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“…The current state of the art of portable microwave clocks and frequency standards are based on beam-tubes [1], vapor cells [2,3], and trapped ions in buffer gas [4,5,6]. In beam-tube clocks the linewidth of the atomic resonance is proportional to the length of the beam-tube and this places limits to the extent to which they can be miniaturized.…”

Section: Introductionmentioning

confidence: 99%

Laser-cooled ytterbium-ion microwave frequency standard

et al. 2019

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We report on the development of a trappedion, microwave frequency standard based on the 12.6 GHz hyperfine transition in lasercooled ytterbium-171 ions. The entire system fits into a 6U 19-inch rack unit (51×49×28 cm) and comprises laser, electronics and physics package subsystems. As a first step towards a full evaluation of the system capability, we have measured the frequency instability of our system which is 3.6 × 10 −12 / √ τ for averaging times between 30 s and 1500 s.

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Mercury Ion Clock for a NASA Technology Demonstration Mission

Cited by 51 publications

References 10 publications

Venus Express radio occultation observed by PRIDE

Venus Express radio occultation observed by PRIDE

Allan Deviation of Atomic Clock Frequency Corrections: A New Diagnostic Tool for Characterizing Clock Disturbances

Laser-cooled ytterbium-ion microwave frequency standard

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