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The urgency of reliable navigation for manned and self-driving vehicles in urban environment is growing. The de facto standard of mass-produced navigation systems is global navigation satellite system (GNSS). Standalone work of a GNSS receiver is possible while receiving at least 4 signals from different navigation satellites. Operating of GNSS receiver in an "urban canyon" is broken due...
Global navigation satellite system (GNSS) receivers are vulnerable to hostile interference threads, such as jamming and spoofing. A two-stage hybrid interference suppression scheme is proposed to enable mitigating jamming and spoofing ahead of acquisition, separately or simultaneously. An orthogonal complement space of spoofing signals is constructed at the first stage to cancel potential spoofers...
Recently, utilization of position information by global navigation satellite system (GNSS) is expected in various fields. However, it's difficult to show unambiguously accuracy since positioning accuracy varies by measurement environment. We bring sky view factor (SVF) to evaluation of positioning accuracy, and evaluate it positioning accuracy of long time data in the places where SVF are high or...
Satellite selection is an important technology in Global Navigation Satellite Systems (GNSS), for which the dilution of precision (DOP) serves as the key performance metric. Selecting a satellites set with lower DOP often results more accurate positioning and timing. In this paper, the characteristics of DOP for dual-GNSS constellations is studied, where an uncertain clock offset is assumed between...
Accurate and reliable positioning of vehicles is a decisive factor for many Intelligent Transportation System (ITS) applications. Under the cooperative environment, the eco-driving at specific scenarios, like intersections, requires vehicle motion state information, which can be provided by Global Navigation Satellite System (GNSS) with an integrity monitoring capability. In order to provide effective...
In this paper results of research on RTK (Real Time Kinematic) technique used to develop small and lightweight receiver of GNSS (Global Navigation Satellite System) signals is presented. Experiments with such receivers show that they are able to deliver good quality position estimation of micro aerial vehicles in 3D space during a flight. The standard deviation of the position measurement is less...
A range of issues apply to getting time from GNSS receivers, depending strongly on what the user needs. The words "accurate time" mean very different things to different users. Accurate time from GNSS receivers becomes challenging as the required accuracy is better than a microsecond or so. While this paper discusses a broad range of issues related to accurate timing from GNSS, it focusses...
In Global Navigation Satellite Systems (GNSS), ionospheric scintillation is one of the more challenging propagation scenarios, particularly affecting high-precision receivers based on carrier phase measurements. In this contribution, we propose a new digital carrier synchronization state-space formulation for the mitigation of strong scintillation. It takes into account multi-frequency GNSS observations,...
This paper proposes a new filter design optimized for GNSS attitude determination applications using low cost devices. The filter contains all relevant constraints and observations, including double differenced carrier phase and code observations along with MEMS-IMU observations. Benefited from the unified treatment, the priori information is well used during the resolution of double differenced GNSS...
The limited availability and the lack of continuity in the service of Global Positioning Satellite Systems (GNSS) in harsh environments is a critical issue for Intelligent Transport Systems (ITS) applications relying on the position. This work is developed within the framework of vehicle-to-everything (V2X) communication, with the aim to guarantee a continuous position availability to all the agents...
In GPS measurement, the existence of cycle slip directly affects the ultimately positioning accuracy. In order to obtain high positioning accuracy, cycle slip in carrier phase observations must be detected and repaired. So detecting and repairing of cycle slip has become one of the most important parts of GPS phase data processing. This paper presents our investigation of the cycle slip detection...
This paper develops a novel real time cycle slip detection and repair method for a single dual-frequency GNSS receiver. This method is based on several carrier-phase linear combinations, including WL (1, −1), Ultra-WL (-3, 4), NL (1, 1), GF (60,-77). First, we use the mean code range rate which is estimated by the former 10 code range data to detect and repair the big cycle slip. In this step, the...
A new time and frequency transfer system compatible with BDS has been developed at NIM, and two of them are in operation at the BIPM since Jan 2017. Experiments with this equipment have been implemented to characterize the time and frequency transfer by BDS. This includes analysis of the satellites signal coverage statistics in the BIPM area, the error correction, the measurement noise of the NIM...
This paper describes the design of a simple low cost GNSS sampler with integrated storage. The sampler is built from low cost, off-the-shelf components. The proposed design stores digital IF samples from two separate front ends and record the data to a SD card for post-mission processing. The GNSS sampler currently supports GPS and GLONASS signals, but could also be configured for Galileo reception...
GNSS receiver based on vector tracking loop joints information from all channels to estimate user's position, velocity and time. In vector mode, signal tracking block and navigation processor are coupled together, so all channels can transmit and share information. The actual satellite ephemeris is adopted to verify the performance of tracking loop. Compared to STL, VTL improves weak signal tracking,...
The integration of Global Navigation Satellite System (GNSS) integrity augmentation functionalities in Unmanned Aerial Systems (UAS) has the potential to provide an integrity-augmented Sense-and-Avoid (SAA) solution suitable for cooperative and non-cooperative scenarios. In this paper, we evaluate the opportunities offered by this integration, proposing a novel approach that maximizes the synergies...
A proof-of-concept demonstrator of a cooperative integrity monitoring concept, called “local integrity” and tailored to terrestrial applications, is presented in this paper. The idea is to take advantage of a collaborative Vehicular Ad-hoc NETwork (VANET) architecture in order to perform a spatial/temporal characterization of possible local degradations of Global Navigation Satellite System (GNSS)...
In this paper, we propose a new generation of time and frequency transfer system using Global Navigation Satellite System (GNSS) dual frequency receiver for the purpose of both time and frequency synchronization. The system can be used as a timing source, remote time and frequency calibration, and to monitor the characteristic of the telecommunication primary reference clocks (PRC). A series of experiments...
The geometry dilution of precision (GDOP) has been widely used as an accuracy metric for GNSS. The conventional GDOP, mainly investigated for single GNSS, is not valid for multi-GNSS because of the system time offset among GNSSs. This paper performs a GDOP analysis for two scenarios where the system time offset is resolved respectively at system level and at user level in presence of any number of...
The Global Navigation Satellite System (GNSS) has been widely used by militaries as well as civilians. Generally, the locating accuracy is high, but the system is lack of immunity against spoofing attack, which may deceive the receiver into error positioning. In order to deal with the problem, a maximum particle weight monitoring scheme based on particle filter (PF) is proposed for spoofing detection...
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