Global Positioning System Applications Research Articles

Three frontside full halo coronal mass ejections with a nontypical geomagnetic response

Forecasting potential geoeffectiveness of solar disturbances (in particular, of frontside full halo coronal mass ejections) is important for various practical purposes, e.g., for satellite operations, radio communications, global positioning system applications, power grid, and pipeline maintenance. We analyze three frontside full halo coronal mass ejections (CMEs) that occurred in the year 2000 (close to the activity maximum of solar cycle 23), together with associated solar and heliospheric phenomena as well as their impact on the Earth's magnetosphere. Even though all three were fast full halos (with plane of the sky speeds higher than 1100 km/s), the geomagnetic response was very different for each case. After analyzing the source regions of these halo CMEs, it was found that the halo associated with the strongest geomagnetic disturbance was the one that initiated farther away from disk center (source region at W66); while the other two CMEs originated closer to the central meridian but had weaker geomagnetic responses. Therefore, these three events do not fit into the general statistical trends that relate the location of the solar source and the corresponding geoeffectivity. We investigate possible causes of such a behavior. Nonradial direction of eruption, passage of the Earth through a leg of an interplanetary flux rope, and strong compression at the eastern flank of a propagating interplanetary CME during its interaction with the ambient solar wind are found to be important factors that have a direct influence on the resulting north‐south interplanetary magnetic field (IMF) component and thus on the CME geoeffectiveness. We also find indications that interaction of two CMEs could help in producing a long‐lasting southward IMF component. Finally, we are able to explain successfully the geomagnetic response using plasma and magnetic field in situ measurements at the L1 point. We discuss the implications of our results for operational space weather forecasting and stress the difficulties of making accurate predictions with the current knowledge and tools at hand.

CMOS low noise amplifiers for 1.575 GHz GPS applications

Abstract. This paper presents Low Noise Amplifier (LNA) versions designed for 1.575 GHz L1 Band Global Positioning System (GPS) applications. A 0.35 μm standard CMOS process is used for implementation of these design versions. Different versions are designed to compare the results, analyze some effects and optimize some critical performance criteria. On-chip inductors with different quality factors and a slight topology change are utilized to achieve this variety. It is proven through both on-wafer and on-PCB measurements that the LNA versions operate at a supply voltage range varying from 2.1 V to 3.6 V drawing a current of 10 mA and achieve a gain of 13 dB to 17 dB with a Noise Figure (NF) of 1.5 dB. Input referred 1 dB compression point (ICP) is measured as −5.5 dBm and −10 dBm for different versions.

Analysis and Evaluation of Various Tropospheric Modeling Approaches for High-Precision GPS Kinematic Positioning over Medium Ranges and at High Altitude: Case Study

In global positioning system (GPS) positioning, the tropospheric delay is a systematic error. Mismodeling of the tropospheric delay results in a degradation of the estimated height component, and thus constitutes a limitation to high-accuracy GPS applications. As such, it is obvious that the tropospheric delay should be modeled as accurately as possible. Modeling the tropospheric delay for some applications, such as precise airborne kinematic differential positioning, is further complicated due to the large altitude difference between the ground-based receiver and the airborne roving receiver. This study tests and analyzes three methods for modeling the tropospheric delay, in an attempt to improve the accuracy of the height component for airborne GPS kinematic positioning. As there are several other error sources in GPS, the test and evaluation have to be carefully designed, as any improvements in accuracy due to the use of any tropospheric modeling approaches could be masked by other effects, such as residual orbit errors and ionospheric delays. The analysis is performed for real airborne GPS data and data from a multiple-base station network, and model performance evaluation is based on an independently well-determined aircraft trajectory. Test results show that the estimation of residual tropospheric zenith delay simultaneously with the position parameters after applying the tropospheric delay corrections derived from a network of GPS receivers is seen as the best option with an additional 62% improvement for the height component in terms of standard deviation when compared with results from using a UNB3 tropospheric model only.

Design Enhancement of Miniature Lumped-Element LTCC Bandpass Filters

We present a novel methodology for the design of miniature lumped element components embedded in a low-temperature co-fired ceramic (LTCC) package. The entire process, from initial schematic design, through individual element design, to complete device optimization is discussed. The design and fabrication of novel miniature lumped element LTCC filters is used to validate the proposed methodology. Commercial software tools are used to accurately model and simulate all aspects of the devices to ensure design success. In addition, the filters occupy only 0.03 lambda times 0.05 lambda times 0.004 lambda of a conventional low-permittivity LTCC substrate, which is among the smallest sizes reported. An advantage of these filters is that they use a true third-order topology with three multilayer L-C resonators, leading to superior stopband performance. For the first time, measured results are shown for two new bandpass filters targeted for global positioning system applications. Measured results are in good agreement with the simulations and show an insertion loss of 2.8 dB and a return loss of 21.3 dB at the center frequency of 1.64 GHz.

On stress-forecasting strategy of earthquakes from stress buildup, stress shadow and stress transfer (SSS) based on numerical approach

Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR), used for monitoring crust deformation, are found to be very promising in earthquake prediction subject to stress-forecasting. However, it is recognized that unless we can give reasonable explanations of these curious precursory phenomena that continue to be serendipitously observed from time to time, such high technology of GPS or InSAR is difficult to be efficiently used. Therefore, a proper model revealing the relation between earthquake evolution and stress variation, such as the phenomena of stress buildup, stress shadow and stress transfer (SSS), is crucial to the GPS or InSAR based earthquake prediction. Here we address this question through a numerical approach of earthquake development using an intuitive physical model with a map-like configuration of discontinuous fault system. The simulation provides a physical basis for the principle of stress-forecasting of earthquakes based on SSS and for the application of GPS or InSAR in earthquake prediction. The observed SSS associated phenomena with images of stress distribution during the failure process can be continuously simulated. It is shown that the SSS are better indicators of earthquake precursors than that of seismic foreshocks, suggesting a predictability of earthquakes based on stress-forecasting strategy.

Effect of TEC Variation on GPS Precise Point at Low Latitude

The ionosphere is a dispersive medium of charged particles between the satellite and the user on Earth. These dispersive ionized media play a vital role in the various applications of GPS (Global Positioning Systems) because the ionosphere directly influences transionospheric radio waves propagating from the satellite to the receiver. Solar flares affect the ionization state of the ionosphere with their high intensity. Sometimes the intensity is so severe that it accelerates the rate of ionization, resulting in ionospheric storms; during the ionospheric storms the concentration of charged particles varies. Among the various phenomena in the ionosphere, TEC (Total Electron Content) is responsible for range error which produces a time delay in the radio signal. The rate of change of TEC with respect to time is abbreviated as ROT. It is one of the parameters that express the ionospheric irregularities with respect to time. This work investigates the effect of ROT fluctuation on the precise positioning of GPS receivers during low solar activity periods in the equatorial anomaly region. Good geometry and a sufficient number of locked satellites provide more accuracy within the centimeter level, but the case may be different when there are any ionospheric storms. Even a few satellite signals passing through the ionospheric irregularities can cause a significant error in positioning. Thus, it is important to understand the ionospheric irregularities observed by GPS receivers in order to correct them. The ROT (TEC/Minute) parameter is used here to study the occurrence of TEC fluctuation and its potential effect on GPS, such as a horizontal positional error or the satellite geometry of the GPS receiver. This investigation is based on the analysis of a one-year observation of a fixed GPS receiver installed at Bhopal (23.2020N, 77.4520E), India during low solar active period in 2005. The GPS receiver used here is a GISTM-based dual frequency NovAtel OEM4 GPS receiver.

The empirical study of automotive telematics acceptance in Taiwan: comparing three Technology Acceptance Models

Automotive telematics comprises the applications of Global Positioning System (GPS) navigation, multimedia entertainment, wireless communications and automatic driving assistance systems. This study examined users' acceptance of automotive telematics. Following the theory comparison approach, we evaluated including the Technology Acceptance Model (TAM), the Theory of Planned Behaviour (TPB) and Combined Technology Acceptance Model (TAM)-TPB model (C-TAM-TPB), that could explain users' automotive telematics acceptance decisions. The respective models were evaluated using web-based survey data collected from 345 users about their perceptions of automotive telematics. Overall, the results revealed that the effect of Perceived Ease Of Use, Attitude and Perceived Behavioural Control were very important but that usefulness and Subjective Norm did not influence an individual's Behavioural Intention. The implications of this study were also discussed.

Levantamento gravimétrico na região do Alto Estrutural de Pitanga

O levantamento gravimétrico regional e o conhecimento geológico e estruturalprévio da área do Alto Estrutural de Pitanga, situado na porção centro-leste do Estadode São Paulo, forneceram informações essenciais para formular hipóteses, criar, confirmar e/ou refinar modelos propostos sobre a evolução da área. Os resultados permitiram identificar assinaturas gravimétricas lineares de direções preferenciais NW-SE,possivelmente associadas a zonas de fraqueza preexistentes no embasamento. Feições lineares de menor extensão, de direções NE-SW, E-W e N-S, são correlacionadas às reativações mais recentes ocorridas na bacia. A modelagem dos valores observadosestá em conformidade com o arcabouço lito-estrutural. A aplicação do método DGPS (Differential Global Positioning System) mostrou-se uma ferramenta importante para a melhor precisão dos dados.

Using GPS to Provide Prayer Times onboard an Airplane while in Motion

INTRODUCTION Muslims around the world share the same fundamental practice of performing five prayers a day. The five prayers (fajr, zuhur, asar, maghrib, and isha) are speard around the 24 hours based on astronomical position of the sun. Prayers' times are determined using length of the shadow and start and end of twilight (light from sky when sun is below horizon especially in the evening) (Cooper, 1969) . Therefore, prayer times are not the same from one place to another depending on observers' longitude and latitude. Prayers are usually headed by call for prayer known as Athan. This study will employ GPS to help determine accurate prayer time while traveling across the world. Large number of civilian applications benefits from GPS signals. The ability to determine the receiver's location allows GPS receivers to perform as an aid to navigation. This study will add one more GPS civilian application that will help determining prayer time for Muslim travelers while onboard an airplane. The GPS receiver will be used to periodically determine the latitude, longitude and elevation of the location of the aircraft. It will communicate with the GPS and based on the time and location, it will update and display the upcoming prayer time. PURPOSE OF THE STUDY Large number of airplanes travels the world carrying Muslim onboard every day. Plains owned by Muslim countries provide direction for the Kaabah in Mecca, where Muslims should face while making prayers. However, none of which tells travelers when it is time to say prayers while traveling around the globe. Traveling Muslims usually estimate prayer times while onboard of an airplane based their best judgment. Computing appliances have been developed for businesses, students, games for all ages, and for the disabled (McMurtrey, McGaughey, & Downey, 2008). The same computing power can be used to design and develop applications can benefits from GPS signals, to provide a fully automated and accurate prayer time while in motion. Millions of traveling Muslims will benefit from this service. GLOBAL POSITIONING SYSTEM AND CIVILIAN APPLICATIONS The Global Positioning System GPS, while originally a military project has significant applications for both the military and the civilian industry. Concerning military applications, GPS allows accurate targeting of various military weapons such as precision-guided missiles. It is also used to navigate and coordinate the movement of troops and supplies. [FIGURE 1 OMITTED] GPS OVERVIEW The Global Positioning System (GPS) is a U.S. space-based radio navigation system based on a constellation of about 28 satellites (Diggelen & Abraham, 2001) orbiting the earth at altitudes of approximately 12,000 miles (McNamara, 2004). GPS was developed by the United States Department of Defense (DOD), for its tremendous application as a military locating utility. The system provides location and time information in all weather, day and night, anywhere in the world. GPS is made up of three parts: satellites orbiting the Earth; control and monitoring stations on Earth; and the GPS receivers owned by users (see figure 1). A satellite has three key pieces of hardware: 1) Computer that controls its flight among other functions; 2) A clock that keeps accurate time within three nanoseconds; and 3) A radio transmitter that sends signals to Earth. The signals broadcasted by the GPS satellites are picked up and identified by GPS receivers. Each GPS receiver then provides three-dimensional location (latitude, longitude, and altitude) plus the time. GPS has become a widely used aid to navigation worldwide, and a useful tool for map-making, land surveying, commerce, and scientific uses. GPS also provides a precise time reference which makes it perfect reference for prayer time. Many GPS receivers can relay position data to a PC or other device using the NMEA 0183 protocol (Mihai, 2004). …

Where on Earth Am I?: Global Navigation Satellite Systems

Measuring your absolute global position to within a few centimetres or relative changes in position anywhere on Earth to within a millimetre or so, seemed impossible just a decade or so ago. The Global Positioning System (GPS) has made this not just possible but routine. In addition everyone is familiar with the fact that ‘Satnavs’ will guide you with uncanny accuracy to any selected destination. How does GPS achieve such precision? This short review will explain the basic geometrical principles, the practical implementation and some of the burgeoning applications of GPS. But first a word about nomenclature. Although the ‘GPS’ is often used to describe the satellite based global location system, there are in fact several other systems in development which provide or will provide equal or even enhanced precision within the next few years. The generic description for these is Global Navigation Satellite Systems (GNSS), but like ‘Hoover’ and ‘Biro’, ‘GPS’ has become the generic acronym often casually used to refer to the overall system. Throughout this article the information and examples refer to the GPS. More about the proliferating rivals to GPS later.

Potential of Global Positioning System (GPS) to measure frequencies of oscillations of engineering structures

Global Positioning System (GPS) has been successfully used to measure displacements of oscillating flexible civil engineering structures such as long suspension bridges and high-rise buildings, and to derive their modal frequencies, usually up to 1 Hz, but there is evidence that these limits can be exceeded using high frequency GPS receivers. Based on systematic experiments in computer controlled oscillations with one- and three-degrees of freedom we investigated the potential of GPS, first to record higher oscillation frequencies, at least up to 4 Hz at the minimum resolution level of this instrument for kinematic applications (⩾5 mm), and second, to identify more than one dominant frequency. Data were processed using least squares-based spectral analysis and wavelet techniques which permit to analyze entire time series, even those of too short duration or those characterized by gaps, in both the frequency and the time domain. The ability of GPS to accurately measure frequencies of oscillations of relatively rigid (modal frequencies 1–4 Hz) civil engineering structures is demonstrated in the cases of two bridges. The outcome of this study is that GPS is suitable for the identification of dynamic characteristics of even relatively rigid (modal frequencies up to 4 Hz) civil engineering structures excited by various loads (wind, traffic, earthquakes, etc.) if displacements are above the uncertainty level of the method (⩾5 mm). Structural health monitoring of a wide range of structures appears therefore a promising field of application of GPS.

Design of a miniature and harmonic control patch dual‐mode bandpass filter with transmission zeros

AbstractA miniature and harmonic control patch dual‐mode bandpass filter (BPF) with transmission zeros for application of global positioning system (GPS) is proposed. The right crossed‐slots of the patch resonator are used to determine the main passband frequency of the BPF. In this study, by using a pair of square etched areas (SEAs) acted as perturbation elements, the dual mode filtering performance can be excited and two transmission zeros located on either side of the passband are clearly observed. It is found that two transmission zeros can improve the selectivity of the BPF as well as the stopband rejection effectively, thus avoiding the interference from other communication systems. The measured results of the fabricated BPF are in good agreement with full wave simulation. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2161–2163, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23604

Ionospheric scintillation effects on single frequency GPS

Ionospheric scintillation of Global Positioning System (GPS) signals threatens navigation and military operations by degrading performance or making GPS unavailable. Scintillation is particularly active within, although not limited to, a belt encircling the Earth within 20 degrees of the geomagnetic equator. As GPS applications and users increase, so does the potential for degraded precision and availability from scintillation. We examined amplitude scintillation data spanning 7 years from Ascension Island, U.K.; Ancon, Peru; and Antofagasta, Chile in the Atlantic/American longitudinal sector as well as data from Parepare, Indonesia; Marak Parak, Malaysia; Pontianak, Indonesia; Guam; and Diego Garcia, U.K. in the Pacific longitudinal sector. From these data, we calculate percent probability of occurrence of scintillation at various intensities described by the S4 index. Additionally, we determine Dilution of Precision at 1 min resolution. We examine diurnal, seasonal, and solar cycle characteristics and make spatial comparisons. In general, activity was greatest during the equinoxes and solar maximum, although scintillation at Antofagasta, Chile was higher during 1998 rather than at solar maximum.

Direct transformation of coordinates for GPS positioning using the techniques of genetic programming and symbolic regression

Transformation of coordinates usually invokes level-wised processes wherein several sets of complicated equations are calculated. Unfortunately, the accuracy may be corrupted due to the accumulation of inevitable errors between the transformation processes. This paper presents a genetic-based method for generating regressive models for direct transformation from global positioning system (GPS) signals to 2-D coordinates. Since target coordinates for a GPS application can be obtained by using simpler transformation formulas, the computational costs and inaccuracy can be reduced. The proposed method, though does not exclude systematic errors due to the imperfection on defining the reference ellipsoid and the reliability of GPS receivers, effectively reduces the statistical errors when the accurate Cartesian coordinates are known from the independent sources. From the experimental results where the target datums TWD67 is investigated, it seems that the proposed method can serve as a direct and feasible solution to the transformation of GPS coordinates.

Mobile GPS carrier phase tracking using a novel intelligent dual‐loop receiver

AbstractCarrier phase information is necessary for accurate measurements in global positioning system (GPS) applications. This paper presents a novel intelligent GPS carrier tracking loop with variable‐bandwidth characteristics for fast acquisition and better tracking capability in the presence of dynamic environments. Our dual‐loop receiver is composed of a frequency‐locked loop‐assisted phase‐locked loop structure, the fuzzy controllers (FCs), and the ATAN discriminator functions. The soft‐computing FCs provide the time‐varying loop gains to perform accurate and reliable control of the dual‐loop paradigm. Once the phase dynamic errors become large under kinematic conditions, the fuzzy loop gains increase adaptively and achieve rapid acquisition. On the other hand, when the tracking errors approach zero in the steady state, the loop gains decrease and the corresponding dual‐loop receiver returns to a narrowband system. Four types of carrier phase signals, i.e. phase offset, decaying sinusoidal phase jitter, frequency offset, and frequency ramp offset, are considered to emulate realistic mobile circumstances. Simulation results show that our proposed receiver does achieve a superior performance over conventional tracking loops in terms of faster settling time and wider acquisition range while preventing the occurrence of cycle slips. Copyright © 2008 John Wiley & Sons, Ltd.

A Circular Polarization Microstrip Stacked Structure Broadband Antenna

This paper describes a single-feed S-Ring type stacked microstrip structure antenna for broadband applications. The antenna is designed for RHCP/LHCP at a center frequency of 2.1GHz. The design of the antenna is aimed at obtaining both wider bandwidth on the impedance and better circular polarization AR (Axial-Ratio) for GPS (global positioning system) applications. The feeding technique and structures of the present antenna has been analyzed. The results of simulations and measurements results show that the antenna has an impedance bandwidth (VSWR.52) of 30% and a 3-dB AR bandwidth more than 23%.

Effect of Scintillation on Timing Applications of GPS in Indian Subcontinent

On the Indian subcontinent, scintillations are quite frequent and intense and have a longer duration during a peak period of an 11-year solar cycle. This phenomenon quite significantly informs us about the performance of the Global Positioning System (GPS). A special experiment has particularly been conducted to study the effect of scintillations on GPS time. This paper discusses the findings of this experiment. A degradation of timing accuracy of the order of 60 ns has been observed.

GPS RECEIVERS TIMING DATA PROCESSING USING NEURAL NETWORKS: OPTIMAL ESTIMATION AND ERRORS MODELING

The Global Positioning System (GPS) is a network of satellites, whose original purpose was to provide accurate navigation, guidance, and time transfer to military users. The past decade has also seen rapid concurrent growth in civilian GPS applications, including farming, mining, surveying, marine, and outdoor recreation. One of the most significant of these civilian applications is commercial aviation. A stand-alone civilian user enjoys an accuracy of 100 meters and 300 nanoseconds, 25 meters and 200 nanoseconds, before and after Selective Availability (SA) was turned off. In some applications, high accuracy is required. In this paper, five Neural Networks (NNs) are proposed for acceptable noise reduction of GPS receivers timing data. The paper uses from an actual data collection for evaluating the performance of the methods. An experimental test setup is designed and implemented for this purpose. The obtained experimental results from a Coarse Acquisition (C/A)-code single-frequency GPS receiver strongly support the potential of methods to give high accurate timing. Quality of the obtained results is very good, so that GPS timing RMS error reduce to less than 120 and 40 nanoseconds, with and without SA.

A dual‐band antenna design for GPS and UMTS applications

AbstractThe design of an integrated dual‐band antenna for global positioning system (GPS) and universal mobile telecommunications system (UMTS) is presented. A circularly polarized square‐ring corner truncated microstrip antenna is designed for GPS application, and a monopolar shorted square patch antenna embedded within the center of the square‐ring is designed for UMTS application. Both proposed antenna elements demonstrated desirable isolation, radiation pattern; polarization, and bandwidth requirement. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1935–1939, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22597

A Genetic Approach for Coordinate Transformation Test of GPS Positioning

Transformation of coordinates usually invokes level-wise processes wherein several sets of complicated equations are calculated. Unfortunately, the accuracy may be corrupted due to the accumulation of inevitable errors between the transformation processes. This letter rephrases the transformation of coordinates from global positioning system (GPS) signals to 2-D coordinates as a regression problem that derives target coordinates from the inputs of GPS signals directly. In this letter, a genetic-based solution is proposed and implemented by the techniques of symbolic regression and genetic programming. Since coordinates for a GPS application are obtained by using simpler transformation formulas, the computational costs and inaccuracy can be reduced. The proposed method, although it does not exclude systematic errors due to the imperfection on defining the reference ellipsoid and the reliability of GPS receivers, effectively reduces statistical errors when accurate Cartesian coordinates are known from independent sources. To our best knowledge, this letter is the first attempt to use genetic-based methods in coordinate transformation for GPS positioning. From the experimental results where the target datums TWD67 and TWD97 are investigated, it seems that the proposed method can serve as a direct and feasible solution to the transformation of GPS coordinates