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  • Survey on signal processing for GNSS under ionospheric scintillation: Detection, monitoring, and mitigation
    NAVIGATION (IF 1.7) Pub Date : 2020-08-06
    Jordi Vilà‐Valls; Nicola Linty; Pau Closas; Fabio Dovis; James T. Curran

    Ionospheric scintillation is the physical phenomena affecting radio waves coming from the space through the ionosphere. Such disturbance is caused by ionospheric electron‐density irregularities and is a major threat in Global Navigation Satellite Systems (GNSS). From a signal‐processing perspective, scintillation is one of the most challenging propagation scenarios, particularly affecting high‐precision

  • Flight test of a pseudo‐ranging signal compatible with existing distance measuring equipment (DME) ground stations
    NAVIGATION (IF 1.7) Pub Date : 2020-07-29
    Sherman Lo; Yu‐Hsuan Chen; Per Enge; Wouter Pelgrum; Kuangmin Li; George Weida; Achim Soelter

    Distance measuring equipment (DME) has been a cornerstone of aviation navigation for the last 70 years. While GNSS is taking an increasingly important role in civil aviation, DME can still play an important role in a robust aviation infrastructure in the foreseeable future. Advanced concepts have been developed to improve DME performance and capabilities. One concept is a DME‐based pseudolite that

  • Kalman filtering with noncoherent integrations for Galileo E6‐B tracking
    NAVIGATION (IF 1.7) Pub Date : 2020-07-25
    Melania Susi; Daniele Borio

    The former Galileo Commercial Service (CS) will provide a High Accuracy Service (HAS) and a Commercial Authentication Service (CAS). The first will disseminate free Precise Point Positioning (PPP) corrections through the E6‐B signal whereas the second will provide authentication capabilities through the E6‐C pilot component that will be encrypted. For this reason, improved processing strategies for

  • High‐precision unambiguous tracking technique for BDS B1 wideband composite signal
    NAVIGATION (IF 1.7) Pub Date : 2020-07-17
    Yang Gao; Zheng Yao; Mingquan Lu

    In the BeiDou Navigation Satellite System (BDS) B1 band, a single‐sideband complex binary offset carrier (SCBOC) modulation is employed to combine the legacy and the modernized B1 signals into an asymmetric‐wideband composite signal for the backward compatibility. However, SCBOC modulation has only been regarded as a means to achieve the co‐existance between B1I and B1C signals, whose high‐precision

  • Improved urban navigation with shadow matching and specular matching
    NAVIGATION (IF 1.7) Pub Date : 2020-07-14
    Kirsten L. Strandjord; Penina Axelrad; Shan Mohiuddin

    As the dependence of Global Navigation Systems (GNSS) increases, so does a growing demand for GNSS accuracy in urban environments. This research aims to improve navigation in these environments by integrating non‐line‐of‐sight signals, building models, and measured signal to noise ratios in ways not typically used in GNSS positioning. We propose a technique of combining elements of shadow matching

  • Characterization and mitigation of interference between GNSS radio occultation and reflectometry signals for low‐altitude occultations
    NAVIGATION (IF 1.7) Pub Date : 2020-06-27
    Ian Collett; Y. T. Jade Morton; Yang Wang; Brian Breitsch

    This research investigates the mutual interference between a GNSS signal refracted through the atmosphere and the same signal reflected from the surface below. For low‐altitude occultations, the reflected signal can be present as multipath when tracking the direct signal. This poses a problem when making remote sensing measurements using GNSS‐RO or GNSS‐R techniques. Here, this issue is addressed in

  • Issue Information
    NAVIGATION (IF 1.7) Pub Date : 2020-06-23

    No abstract is available for this article.

  • Relative navigation of fixed‐wing aircraft in GPS‐denied environments
    NAVIGATION (IF 1.7) Pub Date : 2020-06-10
    Gary Ellingson; Kevin Brink; Tim McLain

    This work enables GPS‐denied flight on fixed‐wing UAS by accounting for fixed‐wing‐specific sensing requirements and using a methodology called relative navigation as an overarching framework. The development of an odometry‐like, front‐end, EKF‐based estimator that utilizes only a monocular camera and an inertial measurement unit (IMU) is presented. The filter uses the measurement model of the multi‐state‐constraint

  • Extracting unmodeled systematic errors from BDS orbit determination residuals and application in SPP/PPP
    NAVIGATION (IF 1.7) Pub Date : 2020-06-05
    Guangbao Hu; Shirong Ye; Dezhong Chen; Lewen Zhao; FengYu Xia; Xiaolei Dai; Peng Jiang

    To analyze the unmodeled systematic errors in BDS, a filter‐assisted Partly Ensemble Empirical Mode Decomposition (PEEMD) method is combined with Hilbert spectrum analysis to extract the feature information from BDS preprocessed orbit determination residuals (PODR). The results show that the feature extraction method can effectively extract a period of about 1 day for GEO/IGSO satellites and a period

  • Analysis of phase bias between GNSS signal components caused by nonideal group delay
    NAVIGATION (IF 1.7) Pub Date : 2020-06-09
    Yuqi Liu; Yi Yang; Lin Chen; Hongchen Pan; Yihang Ran

    Binary offset carrier (BOC) modulations are widely used in the modernized satellite navigation systems. But we find an interesting phenomenon that the signal composed of different BOC modulations suffers larger phase bias than the case that all the components have the same modulation due to the nonideal group delay of the channel. This issue is more obvious in navigation satellites for the use of a

  • A simple model for GPS C/A‐code self‐interference
    NAVIGATION (IF 1.7) Pub Date : 2020-06-07
    Christopher J. Hegarty

    The GPS C/A‐code is the most widely utilized GNSS signal today. The C/A‐code design includes (1) a short (length‐1023) spreading code that repeats every 1 ms and (2) a low (50 bps) data rate. These two characteristics can lead to undesired interactions between received C/A‐code signals within user equipment. In this paper, a simple model is derived for predicting the impact of C/A‐code self‐interference

  • Autonomous clock ensemble algorithm for GNSS applications
    NAVIGATION (IF 1.7) Pub Date : 2020-06-23
    Michael J. Coleman; Ronald L. Beard

    The US Naval Research Laboratory (NRL) has developed clock ensembles for a number of vital GNSS projects and services throughout the US and international community. Some efforts include algorithms for local realization of Coordinated Universal Time; participation in the upgrade of the Global Positioning System (GPS) system time; the initial implementation of a coherent geophysical reference time known

  • Signal deformation fault monitors for dual‐frequency GBAS
    NAVIGATION (IF 1.7) Pub Date : 2020-06-04
    Junesol Song; Carl Milner; Ikhlas Selmi

    This paper proposes a new dual‐frequency signal deformation fault monitor, which can effectively reduce the time delay at the Ground‐Based Augmentation System (GBAS) airborne user from the airborne filter initialization to the time when it incorporates ground corrections and user measurements for navigation, assuring the system integrity at the same time. The new monitor is applied together with the

  • Resilient multipath prediction and detection architecture for low‐cost navigation in challenging urban areas
    NAVIGATION (IF 1.7) Pub Date : 2020-06-11
    Ivan Smolyakov; Mohammad Rezaee; Richard B. Langley

    A twofold architecture based on GNSS multipath environment prediction and detection is presented in a context of loosely coupled and tightly coupled IMU/GNSS integration for navigation in urban areas. A signal quality monitoring group of techniques is applied for a platform self‐contained effort to detect and exclude multipath‐contaminated GNSS signals. Additionally, the sensor integration Kalman filter

  • Characterization of on‐orbit GPS transmit antenna patterns for space users
    NAVIGATION (IF 1.7) Pub Date : 2020-06-16
    Jennifer E. Donaldson; Joel J.K. Parker; Michael C. Moreau; Dolan E. Highsmith; Philip D. Martzen

    The GPS Antenna Characterization Experiment (GPS ACE) has made extensive observations of GPS L1 signals received at geosynchronous (GEO) altitude, with the objective of developing comprehensive models of the signal levels and signal performance in the GPS transmit antenna side lobes. The GPS ACE architecture has been in place collecting observations with extreme sensitivity for several years, enabling

  • Issue Information
    NAVIGATION (IF 1.7) Pub Date : 2020-06-23

    No abstract is available for this article.

  • Assessment of errors in NavIC observables for stationary receivers
    NAVIGATION (IF 1.7) Pub Date : 2020-05-12
    Althaf Azeez; Hari Hablani

    Our objective in this paper is to assess all errors in NavIC's pseudorange so that they can be mitigated or accounted for appropriately in the dynamics model to achieve high‐accuracy navigation. Multipath errors in the L5 and S1 pseudoranges are different; hence, oscillatory multipath is removed using sidereal repeatability for these frequencies separately for accurate iono delay estimation. Iono delay

  • Generation of crustal movement correction parameter considering valid period and accuracy guarantee
    NAVIGATION (IF 1.7) Pub Date : 2020-04-04
    Yuki Ichikawa; Mikihiro Hosoi

    In recent years, due to the development of precise point positioning (PPP), the inconsistency of map and satellite positioning results due to crustal deformation has come to the surface. In order to solve this problem, a parameter for correcting the crustal deformation is necessary, and if it is provided as a service, the validity period and the accuracy guarantee are also necessary. In this research

  • High‐parity vertical Reed‐Solomon codes for long GNSS high‐accuracy messages
    NAVIGATION (IF 1.7) Pub Date : 2020-03-26
    Ignacio Fernández‐Hernández; Tommaso Senni; Daniele Borio; Giovanni Vecchione

    This paper presents in detail an outer‐coding proposal for long GNSS messages disseminated by multiple satellites. The proposal minimizes the message reception time, or Time To Retrieve Data (TTRD), over a page erasure channel in most types of environments and visibility conditions. A message M consisting of k pages is encoded into a set C consisting of n pages, such that when any subset C ′ of C of

  • Integrity risk evaluation of impact of ionospheric anomalies on GAST D GBAS
    NAVIGATION (IF 1.7) Pub Date : 2020-01-03
    Moonseok Yoon; Jiyun Lee; Sam Pullen

    This study develops a three‐step Monte Carlo method to evaluate the worst possible integrity risk of ionospheric spatial gradients for GAST D GBAS. Impact simulation parameters are classified into two groups, “worst‐case” and “average,” based on the underlying integrity requirements. Unlike “average” parameters, “worst‐case” parameters are those for which a clear basis for averaging could not be established

  • Multi‐constellation ARAIM exploiting satellite motion
    NAVIGATION (IF 1.7) Pub Date : 2020-01-03
    Mathieu Joerger; Boris Pervan

    In this work, a new time‐sequential positioning and fault detection method is developed for dual‐frequency, multi‐constellation Advanced Receiver Autonomous Integrity Monitoring (ARAIM). Unlike conventional “snapshot” ARAIM, sequential ARAIM exploits changes in satellite geometry at the cost of slightly higher computation and memory loads. From the perspective of users on Earth, the motion of any given

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