Global Positioning System Navigation System Research Articles

Comparison of COSMIC and COSMIC-2 Radio Occultation Refractivity and Bending Angle Uncertainties in August 2006 and 2021

We compare the random error statistics (uncertainties) of COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate, C1) and COSMIC-2 (C2) radio occultation (RO) bending angles and refractivities for the months of August 2006 and 2021 over the tropics and subtropics using the three-cornered hat method. The uncertainty profiles are similar for the two RO missions in the troposphere. However, a higher percentage of C2 profiles reach close to the surface in the moisture-rich tropics, an advantage of the higher signal-to-noise ratio (SNR) in C2. C2 uses signals from both GPS (Global Positioning System) and GLONASS Global Navigation System Satellites (GNSS). The GPS occultations show smaller uncertainties in the stratosphere and lower mesosphere (30–60 km) than the GLONASS occultations, a result of more accurate GPS clocks. Therefore, C2 (GPS) uncertainties are smaller than C1 uncertainties between 30–60 km while the C2 (GLONASS) uncertainties are larger than those of C1. The uncertainty profiles vary with latitude at all levels. We find that horizontal gradients in temperature and water vapor, and therefore refractivity, are the major cause of uncertainties in the tropopause region and troposphere through the violation of the assumption of spherical symmetry in the retrieval of bending angles and refractivity.

Women Well-being Application

Abstract: Safety and security of girls is one of the most serious issues of our time; the crime rate is rapidly rising, and female wellbeing has become a greater concern than ever before in today's world. Many studies show that the majority of crimes occur late at night, but women are unable to shut themselves in from twilight till dawn. Women can't expect to work exclusively the day shift in metropolitan places, where offices, convenience stores, gas stations, and other businesses are open 24 hours a day, seven days a week. In the last five years, the use of smart phones with GPS navigation systems has risen significantly. So, if mobile phones are used for so many other purposes, why not women's security? As a result, a smart phone can be effectively employed for personal safety or a variety of other protection objectives, particularly for women. This application alerts the guardians with just a single click. SMS with the user's live location is sent to the preconfigured contact. An alarming siren goes on when the user activates the app. This application also enlists the nearby hospitals and police stations. As a result, this app has the potential to significantly assist in the rescue of women from dangerous situations. Keywords: Smartphone, Android, GPS (Global Positioning System), Alert Message, Panic Button, Safety Tips, Women Security

Simulations suggest that navigation software may not be as efficient as expected for city traffic.

We suggest a theoretical framework to study the dynamics of an open city, with cars entering at a certain rate and leaving as they reach their destinations. In particular, we assess through simulations some unexpected consequences of the massive use of GPS (global positioning system) navigation systems in the overall dynamics. One of our main interest is to identify what type of measurements would be the most relevant for an experimental study of this system, specifically, the ones useful for city traffic administrators. To do so, we solve the microdynamics using a cellular automaton model considering three different navigation strategies based on the minimization of the individual paths (unweighted strategy) or travel times (weighted strategies). Although the system is inherently stochastic, we found in our simulations an equivalent saddle-node bifurcation for all strategies where the input rate acts as a bifurcation parameter. There is also evidence of additional bifurcations for travel time minimization based strategies. Although we found that weighted strategies are more efficient in terms of car motion, there is a destabilization phenomenon that makes, in an unexpected way, a variation of the unweighted strategy more optimal at certain densities from the fuel efficiency of the overall city traffic point of view. These results bring new insight into the intrinsic dynamics of cities and the perturbations that individual traffic routing can produce on the city as a whole.

Altitude on Cartographic Materials and Its Correction According to New Measurement Techniques

Determining the correct height of mountain peaks is vital for tourism, but it is also important as a reference point for devices equipped with GPS (Global Positioning System), e.g., watches or car navigation systems. The peak altitude data are part of geographic and geodetic information. As more modern technologies and equipment become available, their precisions should increase. However, verification of peak heights is usually only conducted for the highest, well-known mountains—lower peaks or mountain passes are rarely verified. Therefore, this study focuses on an investigation of 12 altitude points on a section of the longest and most famous touristic trail in Poland (the Main Beskid Trail), located in the Orava–Żywiec Beskids Mts (Mountains). The aim of this research is to measure and verify the heights of the 12 selected mountain peaks, in addition to evaluating the chosen methods based on the quality of the obtained data and determining their suitability and opportunities for use in further research. Measurements were obtained at the most specific height points—on the 12 highest points of the summits. This study compares two modern measurement techniques: the global navigation satellite system (GNSS) and light detection and ranging (LiDAR). The obtained results were later compared with those widely used on the internet and in printed materials (period covered: 1884–2015). This analysis demonstrates that lesser-known objects are rarely the subject of remeasurement and significant altitude errors may occur, primarily because the heights originated from a source in the past when modern methods were not available. Our findings indicate that the heights of the peaks presented in cartographic materials are inaccurate. The assumed heights should be corrected by direct measurements using modern techniques.

Efficient drone hijacking detection using two-step GA-XGBoost

Abstract With the fast growth of civilian drones, their security problems meet significant challenges. A commercial drone may be hijacked by Global Positioning System (GPS)-spoofing attacks for illegal activities, such as terrorist attacks. Ideally, comparing positions respectively estimated by GPS and Inertial Navigation System (INS) can detect such attacks, while the results may always get fault because of the accumulated errors over time in INS. Therefore, in this paper, we propose a two-step GA-XGBoost method to detect GPS-spoofing attacks that just uses GPS and Inertial Measurement Unit (IMU) data. However, tunning the proper values of XGBoost parameters directly on the drone to achieve high prediction results consumes lots of resources which would influence the real-time performance of the drone. The proposed method separates the training phase into offboard step and onboard step. In offboard step, model is first trained by flight logs, and the training parameter values are automatically tuned by Genetic Algorithm (GA). Once the offboard model is trained, it could be uploaded to drones. To adapt our method to drones with different types of sensors and improve the correctness of prediction results, in onboard step, the model is further trained when a drone starts a mission. After onboard training finishes, the proposed method switches to the prediction mode. Besides, our method does not require any extra onboard hardware. The experiments with a real quadrotor drone also show the detection correctness is 96.3% and 100% in hijacked and non-hijacked cases at each sampling time respectively. Moreover, our method can achieve 100% detection correctness just within 1 s just after the attacks start.

LoSI: Large scale location inference through FM signal integration and estimation

In this paper we present a large scale, passive positioning system that can be used for approximate localization in Global Positioning System (GPS) denied/spoofed environments. This system can be used for detecting GPS spoofing as well as for initial position estimation for input to other GPS free positioning and navigation systems like Terrain Contour Matching (TERCOM). Our Location inference through Frequency Modulation (FM) Signal Integration and estimation (LoSI) system is based on broadcast FM radio signals and uses Received Signal Strength Indicator (RSSI) obtained using a Software Defined Radio (SDR). The RSSI thus obtained is used for indexing into an estimated model of expected FM spectrum for the entire United States. We show that with the hardware for data acquisition, a single point resolution of around 3 miles and associated algorithms, we are capable of positioning with errors as low as a single pixel (more precisely around 0.12 mile). The algorithm uses a largescale model estimation phase that computes the expected FM spectrum in small rectangular cells (realized using geohashes) across the Contiguous United States (CONUS). We define and use Dominant Channel Descriptor (DCD) features, which can be used for positioning using time varying models. Finally we use an algorithm based on Euclidean nearest neighbors in the DCD feature space for position estimation. The system first runs a DCD feature detector on the observed spectrum and then solves a subset query formulation to find Inference Candidates (IC). Finally, it uses a simple Euclidean nearest neighbor search on the ICs to localize the observation. We report results on 1500 points across Florida using data and model estimates from 2015 and 2017. We also provide a Bayesian decision theoretic justification for the nearest neighbor search.

PSO-LSSVR Assisted GPS/INS Positioning in Occlusion Region.

Satellite signals are easily lost in complex observation environments and high dynamic motion states, and the position and posture errors of pure inertial navigation quickly diverges with time. This paper therefore proposes a scheme of occlusion region navigation based on least squares support vector regression (LSSVR), and particle swarm optimization (PSO), used to seek the global optimal parameters. Firstly, the scheme uses the incremental output of GPS (Global Positioning System) and Inertial Navigation System (INS) when the observation is normal as the training output and the training input sample, and then uses PSO to optimize the regression parameters of LSSVR. When the satellite signal is unavailable, the trained mapping model is used to predict the GPS pseudo position. Secondly, the observed anomaly is detected by the test statistic in the integrated navigation solution filtering estimation, and the exponential fading adaptive factor is introduced to suppress the influence of the abnormal pseudo observation value. The results indicate that the algorithm can predict the higher precision GPS position increment, and can effectively judge some abnormal observations that may occur in the predicted value, and adjust the observed noise covariance to suppress the anomaly observation, which can effectively improve the continuity and reliability of the integrated navigation system in the occlusion region.

Comparison of Satellite Repeat Shift Time for GPS, BDS, and Galileo Navigation Systems by Three Methods

The characteristic of the satellite repeat shift time can reflect the status of the satellite operation, and is also one of the key factors of the sidereal filtering multipath correction. Although some methods have been developed to calculate the repeat shift time, few efforts have been made to analyze and compare the performance of this feature for the GPS (Global Positioning System), BDS (BeiDou System), and Galileo in depth. Hence, three methods used for calculating the repeat shift time are presented, and used to compare and analyze the three global systems in depth, named the broadcast ephemeris method (BEM), correlation coefficient method (CCM), and aspect repeat time method (ARTM). The experiment results show that the repeat shift time of each satellite is different. Also, the difference between the maximum and minimum varies from different systems. The maximum difference is about 25 s for the BDS IGSO (Inclined Geosynchronous Orbit) and the minimum is merely 10 s for the GPS system. Furthermore, for the same satellite, the shift time calculated by the three methods is almost identical, and the maximum difference is only about 7 s between the CCM and the ARTM method for the BDS MEO (Medium Earth Orbit) satellite. Although the repeat shift time is different daily for the same satellite and the same method, the changes are very small. Moreover, in terms of the STD (Standard Deviation) of the BS (between satellites) and MS (mean shift for the same satellite), the GPS system is the best, the performance of the BDS system is medium, and the Galileo performs slightly worse than the GPS and BDS.

Field trial of IRNSS receiver

AbstractIRNSS is an independent regional navigation system being developed by Indian Space Research Organization, India. Ionospheric scintillations are very important to satellite‐based radio communication and navigation. Ionospheric variations are responsible for most of the range error which yields in inaccurate position coordinates and degradation in signal power (carrier to noise power ratio).This article represents a comparative analysis of position error and Ionospheric delay among IRNSS (Indian Regional Navigation Satellite System) and GPS (Global Positioning System) considering the ionospheric correction algorithms being used in both satellite constellations. Grid based ionospheric correction, dual frequency delay correction, and coefficient based have been considered for comparison of both IRNSS and GPS navigation system.

Novel Anti-spoofing Methods Based on Discrete Wavelet Transform in the Acquisition and Tracking Stages of Civil GPS Receiver

The growing dependence of critical civil infrastructure on Global Positioning System (GPS) makes GPS interference not only a safety threat, but also a matter of national security. Spoofing could pose a major threat for GPS navigation systems, so the GPS users have to gain an in-depth understanding of GPS spoofing. Therefore, spoofing countermeasure is a significant subject of research these days. In this paper, we utilize wavelets transform (WT) as a tool that effectively hinders the adverse activities of these groups, and then introduce two novel methods to mitigate spoofing in the acquisition and tracking processes. In the first suggested algorithm, using WT in the acquisition process, we control satellite constellation to mitigate spoofing errors. After generating the in-phase and quadrature correlator output signals, called I and Q respectively, we apply the wavelet db3 to the Q samples to remove their noise components. In the second method, WT is used in a tracking loop. In this way, we apply sym4 to the Q arm, which results in spoofing reduction. We apply our new algorithms to both simulated and measurement data sets, to shed light on its performance. Results show that both methods successfully mitigate the spoofing effect on the tested data sets.

Mathematical Modelling of Indian Regional Navigation Satellite System Receiver

<p class="p1">At present the armoured fighting vehicles are equipped with either global positioning system (GPS) receivers or integrated inertial navigation system (INS)/GPS navigation systems. During hostile situations, the denial/degradation of the GPS satellite signals may happen. This results in the requirement of an indigenous satellite based navigation system. Indian Space Research Organisation has developed an indigenous Indian regional navigation satellite system (IRNSS), with a seven satellite constellation to provide independent position, navigation and timing services over India and its neighbouring regions. In this paper, the development of IRNSS receiver using MATLAB as per IRNSS signal in space interface control document for standard positioning service is discussed. A method for faster IRNSS signal acquisition in frequency domain and delay locked loop code tracking for the acquired satellite signals are used. Models for navigation message decoding and pseudo range/user position calculations are developed using the algorithms provided in IRNSS ICD.</p>

Global Positioning System Navigation Above 76,000 KM for NASA'S Magnetospheric Multiscale Mission

NASA's Magnetospheric Multiscale (MMS) mission, launched in March of 2015, consists of a controlled formation of four spin-stabilized spacecraft in similar highly elliptic orbits reaching apogee at radial distances of 12 and 25 Earth radii (RE) in the first and second phases of the mission. Navigation for MMSis achieved independently on-board each spacecraft by processing Global Positioning System (GPS) observables using NASA Goddard Space Flight Center (GSFC)'s Navigator GPS receiver and the Goddard Enhanced Onboard Navigation System (GEONS) extended Kalman filter software. To our knowledge, MMS constitutes, by far, the highest-altitude operational use of GPS to date and represents a high point of over a decade of high-altitude GPS navigation research and development at GSFC. In this paper we will briefly describe past and ongoing high-altitude GPS research efforts at NASA GSFC and elsewhere, provide details on the design of the MMS GPS navigation system, and present on-orbit performance data from the first phase. We extrapolate these results to predict performance in the second phase orbit, and conclude with a discussion of the implications of the MMS results for future high-altitude GPS navigation, which we believe to be broad and far-reaching.

A DSRC Doppler/IMU/GNSS Tightly-coupled Cooperative Positioning Method for Relative Positioning in VANETs

Relative position awareness is a vital premise for the implementation of emerging intelligent transportation systems. However, commercial Global Satellite Navigation Systems (GNSS) receivers do not satisfy the requirements of these applications. Fortunately, Cooperative Positioning (CP) systems, based on inter-vehicle communications, have improved performance of relative positioning in a Vehicular Ad Hoc Network (VANET). CP techniques rely primarily on measurements from the Global Positioning System (GPS) to deliver measurements or positions that describe the location of individual vehicles. In urban environments, the reduced quality or complete unavailability of GPS measurements challenges the effectiveness of any CP algorithm. In this paper, a new enhanced tightly–coupled CP technique is presented by adding the measurements from low-cost inertial sensors and the Doppler shift of the carrier of Dedicated Short-Range Communications (DSRC) signals. In the enhanced CP method proposed here, vehicles communicate their Inertial Measurement Unit (IMU) data and GPS measurements. Each vehicle fuses the GPS measurements and IMU data and the inter-node range-rates based on the Doppler shift of the carrier of DSRC signals. Based on analytical and experimental results, in a full GPS coverage environment, the new tight integration CP outperforms tight CP with Inertial Navigation System (INS), tight CP and differential GPS by at least by 6%, 15%, and 28%, respectively. In a GPS outage, the performance improvement can be up to 60%, 55%, and 66% respectively.

Integration of Beidou and GPS in Vessel Monitoring System

A novel method has been proposed for integrated Beidou and GPS (Global Positioning System) navigation system in vessel monitoring system. Application of integrated Beidou and GPS navigation system's high precision positioning and SMS (Short Messaging Service) communication technology in vessel can well solve the problem of vessel navigation, positioning, remote monitoring and commanding. Based on 27 stations of Crustal Moment Observation Network of China, satellite visibility and availability of integrated Beidou and GPS are calculated and analyzed in detail. A data compression algorithm is proposed for Beidou SMS communication technology to get the continuous location and other state of the target vessel. Experimental results reveal that the integrated Beidou and GPS system is superior to any single system in all respects of positioning performance.

The Development of GPS Navigation Systems in Civil Aircraft

The industry of civil aviation is developing in a fast manner to occupy the increasing needs for a fast, safe and comfortable transportation. To achieve these needs, some effective programs, plans, and systems designs are required. The current reliable aircraft navigation and landing systems have relatively a low level of accuracy especially in aircraft landing stage. The best landing category could be achieved requires a runway visual range up to 50 meters and automatic landing system is not in operation yet all over the world. Aircraft navigates using Radar, Radio and Satellite navigation systems. The Federal Aviation Administration (FAA) plans to replace legacy navigation systems with satellite based navigation technology. Currently, the Global Positioning System (GPS) and its augmentations is the main satellite navigation system used all over the world for air navigation applications. The development of aircraft navigation has been performed with the enhancement of GPS augmentation systems. In this paper, aircraft navigation systems and techniques will be presented in this paper to evaluate the integrity and reliability of each system, and to make a comparison among these systems according to accuracy, integrity and availability.

Navigation-based self-optimization handover mechanism for mobile relay stations in WiMAX networks

Organic Computing has similar characteristics of organism which can be self-adjustment for a variety of conditions. Moreover, during the wireless communication technological evolution progress, WiMAX (Worldwide Interoperability for Microwave Access) offers ability of high capacity and far distance transmission. WiMAX provides high-speed access and a coverage range across several kilometers, but the actual coverage range was merely a few kilometers due to the shelter of buildings or terrain. IEEE 802.16 working group designed 802.16j-based RS (Relay Station) to overcome above problem. In this paper, we present a mechanism called Self-Optimization Handover Mechanism. This mechanism is using GPS (Global Positioning System) navigation system to gather the related information for the position and combine the mobility characteristics of Mobile Relay Station. Especially, the concept of Self-Optimization of Organic Computing has been integrated into this mechanism. There are some advantages for this new mechanism, including: (1) The base station can provide advance plan and select the path. (2) The mechanism can reduce the number of possible handover and hop. (3) The mechanism can reduce the time of channel scan.

A Fault Tolerant SINS/GPS/CNS Integrated Navigation Scheme Realized through Federated Kalman Filter

The complementary characteristics of the Strapdown Inertial Navigation System (SINS) and external non-inertial navigation aids like Global Positioning System (GPS) and Celestial Navigation System (CNS) make the integrated navigation system an appealing and cost effective solution for various applications. SINS exhibits position errors owing to errors in initialization of the inertial measurement unit (IMU) and the inherent accelerometer biases and gyroscope drifts. SINS also suffer from diverging azimuth errors and an exponentially increasing vertical channel error. Pitch and roll errors also exhibit unbounded growth with time. To mitigate this behavior of SINS, periodic corrections are opted for through measurements from external non-inertial navigation aids. These corrections can be in the form of position fixing, velocity fixing and attitude fixing from external aids like GPS, GLONASS (Russian Satellite Navigation System), BEIDU(Chinese Satellite Navigation System) and Celestial Navigation Systems (CNS) etc. In this research work GPS and CNS are used as external aids for SINS and the navigation solutions of all three systems (SINS, GPS and CNS) are fused using Federated Kalman Filter (FKF). The FKF differs from the conventional Central Kalman Filter (CKF) because each measurement is processed in Local Filters (LFs), and the results are combined in a Master Filter (MF). FKF is a partitioned estimation method that uses a two stage data processing scheme, in which the outputs of sensor related LFs are subsequently combined by a large MF. Each LF is dedicated to a separate sensor subsystem, and uses data from the common reference such as SINS. The SINS acts as a cardinal system in the combination, and its data is also available as measurement input for the master filter. In this research work, information from the GPS and the CNS are dedicated to the corresponding LFs. Each LF provides its solutions to the master filter all information is fused together forming a global solution. Simulation for the proposed architecture has validated the effectiveness of the scheme, by showing the substantial precision improvement in the solutions of position, velocity and attitude as compared to the pure SINS or any other standalone system.

Lists, Spatial Practice and Assistive Technologies for the Blind

Lists, Spatial Practice and Assistive Technologies for the Blind

Proposal for a new localisation method using tightly coupled integration based on a precise estimation of trajectory from GPS Doppler

Driver assistance systems require the function of precise localisation. However, the accuracy of standard global positioning system (GPS) is inadequate for this. In this paper, a new method for precise localisation using the tightly coupled integration of inertial navigation system (INS) and raw GPS data is investigated. GPS Doppler corresponds to the relative velocity between the satellite and the receiver. Our new method enables us to make a robust and accurate estimation of the vehicle trajectory based on INS and GPS Doppler. Furthermore, the total optimisation by combining GPS pseudorange data with the accurate trajectory enables us to estimate the position of the vehicle precisely.

Integrated Navigation of Mobile Robot Based on Neural Network and Fault Detection

When global positioning system (GPS) signal outages, the integrated navigation accuracy of GPS and strap-down inertial navigation system (SINS) will decline with time, and even navigation system cannot work. To avoid this, a new design is introduced. When GPS works normally, square root filter estimates the errors of position, velocity and attitude and compensates the outputs of SINS. When GPS is out of order, back propagation neural network (BPNN) will take the place of GPS to calculate the error parameters, thus the accuracy of navigation will enhance. And in this paper, the unit of fault detection is added to detect whether GPS signal outages or not. The simulation results show the effectiveness of this method