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DGPS transmits pseudorange correction (PRC) to user receivers to improve the position precision. Spoofer generates a fake GPS signal and transmits this signal to the target receiver. If a DGPS reference receiver is spoofed, not only reference position but also many user positions are affected. Moreover, DGPS reference station is easy to spoof because its position is known and fixed. Therefore, the...
This paper proposes the multiplexing technique that combines signal detector, decision logic, and anti-J modules to counteract narrowband continuous wave interference and spoofing signal in global navigation satellite system (GNSS) receivers. The signal detector is to detect the presence of different types of jammers. The decision logic is utilized to select different anti-jam strategies against jammers...
In this article the effect of decimation before acquisition stage in conventional Parallel Code Phase Search Acquisition (PCPSA) is discussed. In PCPSA, correlation function of the incoming signal and a locally generated Pseudo Random Noise (PRN) code is extracted by taking the Fast Fourier Transform (FFT) of the incoming signal and multiplying by conjugate FFT of a locally PRN code. Afterward, the...
This paper proposes a joint acquisition strategy of Global Navigation Satellite Systems (GNSS) satellites to reduce the number of correlations required in the acquisition process. The proposed method generates a local satellite signal replica, which contains the sum of two or more satellite codes, and performs a grid search with this augmented local replica. The grid is then analyzed with a test statistic...
This article presents a methodology related to the computation of civil aviation acquisition, tracking and data demodulation thresholds adapted to the case of Galileo E1 OS/SoL signal. These thresholds are compared against worst case link budgets representing operational scenarios. It is shown that these thresholds provide a positive margin although these theoretical results would probably require...
In order to use GPS at the position of high orbits, it is necessary to research acquisition of weak GPS signal in the environment of high orbit. BAP (Block Averaging Pre-Processing) method is an effective algorithm to process weak signal, but it assumes that the receiver does work in the indoor environment with little dynamic effects. Based on the analysis of orbit parameters' effects on the Doppler...
This paper describes an innovative receiver architecture for the satellite-based Automatic Identification System (AIS). The receiver performance has been fully validated in the presence of the typical satellite channel characteristics. In particular, it is shown that the devised receiver provides an excellent performance against the noise, as well as a large resilience against message collisions,...
An important system in the field of global maritime surveillance is the Automatic Identification System (AIS), which is responsible for communicating ship- and voyage-related data of surface vessels. In order to improve the performance of the existing land-based AIS system, a consortium led by OHB has been responsible for the development of a full-fledged European space-based AIS system. The main...
The first stage of the signal processing chain in a Global Positioning System (GPS) receiver is the acquisition, which provides for a desired satellite coarse code phase and Doppler frequency estimates to subsequent stages. Thus, acquisition is a two-dimensional search, implemented as demodulation and non-coherent correlation. For a certain Doppler estimate, software-defined GPS receivers typically...
It is difficult for GPS receivers to obtain continual and usable GPS signal under high dynamic rotating conditions. There has no efficacious method to measure the trajectory of high dynamic rotating carrier with high accuracy. In this paper, a method that multi-antenna are adopted to continually cover GPS satellites under rotating conditions is presented, a new acquisition and tracking tactic that...
In order to meet both the dynamic qualities and the acquisition accuracy of multi-mode receiver, this paper gives a variable sampling FFT+PMF Fast Acquisition method on the basis of analyzing the every system signals' characteristics and related technologies. Combine with DSP+FPGA, it forms a hardware platform, gives part of the capture program and DSP capture process.
In this paper, the vector delay lock loop/frequency lock loop (VDLL and VFLL) tracking algorithm for tracking the L1 civilian GPS signal is analyzed and simulated. In vector mode, the navigation processor controls the code and carrier numerically controls oscillators (NCOs) replacing the tracking loops. A major advantage of this method is that after once a good position, velocity and time (PVT) solution...
The introduction of new modulations on the global navigation satellite systems brings potential improvements for ground positioning. Clever receiver designs taking advantage of the characteristics of the new signals will be able to achieve better accuracy, higher sensitivity, improved multipath mitigation and tracking robustness. In this context, this paper focuses on the Galileo E5a signal and study...
This paper describes the design and implementation of a prototype GPS receiver for space applications using a radiation tolerant microprocessor. The special characteristics of space environment were considered during design. All the modules necessary for basic functionality were implemented: signal acquisition, synchronization, tracking, ephemeris decodification, and navigation solution calculation...
This paper describes an approach of implementing software based GPS receiver acquisition and tracking for L1 C/A signal. In this paper, in the deep research GPS signal capture principle's foundation, carried on the simulation using Matlab to the GPS signals capture process to realize and to analyze. The simulation result further confirmed this method's accuracy and the feasibility, this to further...
Under the development of high technology, GPS software receiver has been more and more highly developed, thus becoming the hot issue in the GPS receiver research field. This paper demonstrates GPS software receiver using IF signal from the NewStar210A IF signal sampler as the raw data, then using Matlab as the software for signal acquisition and tracking. The navigation data, pseudo range, carrier...
In GPS signal indoor positioning system, the signal intensity received by the different channels of receiver are diverse when GPS signal penetrate buildings. In the process of weak signal acquisition, the cross correlation interference between the strong and weak signal will lead to the decrease of the signal to noise ratio of weak signal. However, it is difficult to assess the attenuation degree...
In a GPS system, the process of acquisition costs most time of the whole, which is due to the large number of required operations in the correlator. Common methods usually use FFT or PFA(prime factor algorithm) to calculate the correlation, choosing float as the data type of the operation, which will obviously increase computational complexity. In consideration of the specific storage mode of GPS...
Intelligent robotic navigation requires precise positioning information. The Global Navigation Satellite System (GNSS) enables such navigation by providing precise timing, velocity and positioning information to any adequately equipped receiver world-wide. A core capability of these receivers is to identify all visible satellites from a snapshot of received signal. This identification process, called...
This paper discusses the INS aided signal acquisition method based on GNSS software receivers. In order to overcome low dynamics and sensitivity to RF interference which are the two vulnerabilities of GNSS receivers, INS velocity information is used to assist the fast signal search. The research aims at analyzing the acquisition performance varying with dynamics and INS accuracy. The relation between...
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