Kewen Sun

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In this paper, a gyroscopic mounting method for crystal oscillators to reduce the impact of dynamic loads on their output stability has been proposed. In order to prove the efficiency of this mounting approach, each dynamic load-induced instability has been analyzed in detail. A statistical study has been performed on the elevation angle of the(More)
In this paper, an improved joint time-frequency (TF) analysis method based on a reassigned smoothed pseudo Wigner-Ville distribution (RSPWVD) has been proposed in interference detection for Global Navigation Satellite System (GNSS) receivers. In the RSPWVD, the two-dimensional low-pass filtering smoothing function is introduced to eliminate the cross-terms(More)
In this paper, the efficiency of the gyroscopic mounting method is studied for a highly dynamic GNSS receiver's reference oscillator for reducing signal loss. Analyses are performed separately in two phases, atmospheric and upper atmospheric flights. Results show that the proposed mounting reduces signal loss, especially in parts of the trajectory where its(More)
Interference detection is very important for Global Navigation Satellite System (GNSS) receivers. Current work on interference detection in GNSS receivers has mainly focused on time-frequency (TF) analysis techniques, such as spectrogram and Wigner-Ville distribution (WVD), where the spectrogram approach presents the TF resolution trade-off problem, since(More)
Dimanganese(II) hydroxide vanadate was obtained from hydro-thermal reactions. The crystal structure of the title compound is isotypic with that of Zn2(OH)[VO4]. Three crystallographically independent Mn(2+) ions are present, one (site symmetry .m.) with a distorted trigonal-bipyramidal and two (site symmetries .m. and 1) with distorted octa-hedral(More)
After the acquisition stage of a GNSS receiver has roughly synchronized the received and the locally generated codes typically within less than a half chip period residual offset, a fine synchronization stage, named signal tracking, takes over and continuously maintains and corrects the best possible alignment between the two codes by means of closed loop(More)
In this paper, the problem of acquiring weak Global Navigation Satellite System (GNSS) signals of the next generation systems (such as Galileo and GPS modernization) is addressed and analyzed, focusing the majority of the attention to the Cross Ambiguity Function (CAF) peak splitting problem caused by the presence of sign transition due to the navigation(More)
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