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Efficient frequency jumps detection algorithm for atomic clock comparisons

Marszalec Michał, Lusawa Marzenna, Osuch Tomasz

Metrology and Measurement Systems

2021

Vol. 28, nr 1

107--121

In this paper a new method of frequency jumps detection in data from atomic clock comparisons is proposed. The presented approach is based on histogram analysis for different time intervals averaging phasetime data recorded over a certain period of time. Our method allows identification of multiple frequency jumps for long data series as well to almost real-time jump detection in combination with advanced filtering. Several methods of preliminary data processing have been tested (simple averaging, moving average and Vondrak filtration), to achieve flexibility in adjusting the algorithm parameters for current needs which is the key to its use in determining ensemble time scale or to control systems of physical time scales, such as UTC(PL). The best results have been achieved with the Vondrak filter.

Design and numerical analysis of a highly sensitive ultrasonic acoustic sensor based on π-phase-shifted fiber Bragg grating and fiber Mach-Zehnder interferometer interrogation

Dwivedi Krishna Mohan, Trivedi Gaurav, Khijwania Sunil K., Osuch Tomasz

Metrology and Measurement Systems

2020

Vol. 27, nr 2

289--300

A π-phase-shifted fiber Bragg grating (π-FBG) shows high sensitivity to the ultrasonic (US) wave as compared to the conventional FBG due to the strong slow-light phenomenon at the resonance peak. However, its sensitivity is limited by the interrogation schemes. A combination of π-FBG and unbalanced fiber Mach-Zehnder interferometer (F-MZI) are theoretically analyzed and optimized for the highly sensitive acoustic sensor. The coupled-mode theory (CMT) and transfer matrix method (TMM) are used to establish the numerical modelling of π-FBG. For the optimized grating parameters of π-FBG, the proposed sensing system shows the high strain sensitivity of 1.2x108/ε, the highest dynamic strain resolution of 4.1fε/√Hz, and the highest wavelength shift resolution of 4.9x10-9 pm. Further, the proposed sensing system strongly supports both time and wavelength division multiplexing techniques. Therefore, the proposed sensing system shows extreme importance in single as well as quasi-distributed US acoustic wave sensing networks.