Impact Assessment of the Asynchronous Clocks Between Reference and User Receivers in Differential Pseudolite Navigation System

Dou, Jie; Xu, Bing; Li, Dou

doi:10.1109/jsen.2020.3014103

Cited by 2 publications

(1 citation statement)

References 19 publications

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“…The impact of clock offset on both single-point positioning [107] and differential positioning [108] is significant. Clock discrepancies from ground-based transmitters can lead to asynchronous timing problems [109] and hinder attempts to fix integer ambiguity [110].…”

Section: Clock Synchronizationmentioning

confidence: 99%

Pseudolites to Support Location Services in Smart Cities: Review and Prospects

Liu,

Wang

et al. 2023

Smart Cities

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The location service is an important part of the smart city. A unified location service for outdoor and indoor/overground and underground activity will assist the construction of smart cities. However, with different coordinate systems and data formats, it is difficult to unify various positioning technologies on the same basis. Global navigation satellite system (GNSS)-based positioning is the only way to provide absolute location under the Earth-centered, Earth-fixed coordinate system (ECEF). Increasing indoor and underground human activity places significant demand on location-based services but no GNSS signals are available there. Fortunately, a type of satellite that is indoors, known as pseudolite, can transmit GNSS-like ranging signals. Users can obtain their position by receiving ranging signals and their resection without adding or switching other sensors when they go from outdoors to indoors. To complete the outreach of the GNSS indoors and underground to support the smart city, how to adapt the pseudolite design and unify coordinate frames for linking to the GNSS remain to be determined. In this regard, we provide an overview of the history of the research and application of pseudolites, the research progress from both the system side and the user side, and the plans for pseudolite-based location services in smart cities.

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Section: Clock Synchronizationmentioning

confidence: 99%

Pseudolites to Support Location Services in Smart Cities: Review and Prospects

Liu,

Wang

et al. 2023

Smart Cities

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Carrier loop with multi-pulse coherent integration for tracking pulsed pseudolite signal

Liu

Ouyang

et al. 2022

Review of Scientific Instruments

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The pseudolite system, an alternative to global navigation satellite systems, can provide centimeter-level positioning accuracy using carrier phase measurements. The carrier phase-based positioning accuracy is determined by the tracking performance of the phase-locked loop (PLL), since cycle slip may cause carrier phase measurement bias. To overcome the near-far problem, the pulsing scheme is often adopted in pseudolite positioning systems. For the pulsed pseudolite signal, the carrier tracking loop is more prone to cycle slip compared to the conventional continuous signal. For improving the performance of the PLL tracking the pulsed pseudolite signal at low carrier-to-noise ratios, a PLL with multi-pulse coherent integration (MPCI-PLL) is proposed. The thermal noise performance of the digital PLL (DPLL) is determined by its equivalent noise bandwidth. When the product of the design noise bandwidth and the loop update interval increases, the true equivalent noise bandwidth of DPLL tends to be larger than the design value. Then, the closed-form expression of the single-sided equivalent noise bandwidth of first-, second-, and third-order DPLL is derived by the discrete frequency domain approach. The proposed MPCI-PLL is tested in both simulations and a real experiment. Compared to the conventional method of tracking the pulsed pseudolite signal, the proposed carrier tracking loop significantly decreases the probability of a cycle slip at low signal-to-noise ratios. Simulation and experimental results show that the improvement is about 3–4 dB.

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Impact Assessment of the Asynchronous Clocks Between Reference and User Receivers in Differential Pseudolite Navigation System

Cited by 2 publications

References 19 publications

Pseudolites to Support Location Services in Smart Cities: Review and Prospects

Pseudolites to Support Location Services in Smart Cities: Review and Prospects

Carrier loop with multi-pulse coherent integration for tracking pulsed pseudolite signal

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