Global Positioning System Antenna Research Articles

Hybrid Kalman and unscented Kalman filters for INS/GPS integrated system considering constant lever arm effect

In inertial navigation system (INS) and global positioning system (GPS) integrated system, GPS antennas are usually not located at the same location as the inertial measurement unit (IMU) of the INS, so the lever arm effect exists, which makes the observation equation highly nonlinear. The INS/GPS integration with constant lever arm effect is studied. The position relation of IMU and GPS’s antenna is represented in the earth centered earth fixed frame, while the velocity relation of these two systems is represented in local horizontal frame. Due to the small integration time interval of INS, i.e. 0.1 s in this work, the nonlinearity in the INS error equation is trivial, so the linear INS error model is constructed and addressed by Kalman filter’s prediction step. On the other hand, the high nonlinearity in the observation equation due to lever arm effect is addressed by unscented Kalman filter’s update step to attain higher accuracy and better applicability. Simulation is designed and the performance of the hybrid filter is validated.

Design of Microstrip Patch Antenna forGPS Applications using EBG Structures

A circularly polarized microstrip patch antenna for Global Positioning System (GPS) is proposed. In this paper we have discussed and analysed the performance of square shaped microstrip patch antenna in L1 and L2 bands. Operating range of GPS is 1.227 GHz (L2 Band) to 1.575 GHz (L1 Band). The proposed design operates at resonant frequency of fr =1.5GHz. Further EBG structure is incorporated into the actual design in stages of several iterations and various parameters such as Return Loss, VSWR are analysed. Improvement in gain and axial ratio bandwidth are observed when compared to antenna designs without EBG. The proposed antenna is designed and simulated using CST Studio suite version-14.Co-axial probe feeding technique is used.

Single‐pin, single‐layer, dual‐band patch antenna for global positioning system and satellite digital audio radio system automotive applications

A low-cost, reduced-size, single-feed, single-layer microstrip patch antenna is presented that receives right-hand circularly polarised satellite signals for the global positioning system's L1-Band (1575.42 MHz) and left-hand circularly polarised satellite signals and vertically linearly polarised terrestrial signals for the satellite digital audio radio system band (2320-2345 MHz). The proposed antenna is constructed of a main central patch and a ring surrounding it, both with truncated corners to achieve the desired circular polarisation characteristics. The two patches are connected to each other using four long and thin microstrip transmission lines. The design, simulation and measured results are presented. The effects of varying key antenna physical parameters were carefully examined and discussed in detail to characterise their effects on operational bandwidth.

Radiometer Calibration Using Colocated GPS Radio Occultation Measurements

We present a new high-fidelity method of calibrating a cross-track scanning microwave radiometer using Global Positioning System (GPS) radio occultation (GPSRO) measurements. The radiometer and GPSRO receiver periodically observe the same volume of atmosphere near the Earth's limb, and these overlapping measurements are used to calibrate the radiometer. Performance analyses show that absolute calibration accuracy better than 0.25 K is achievable for temperature sounding channels in the 50-60-GHz band for a total-power radiometer using a weakly coupled noise diode for frequent calibration and proximal GPSRO measurements for infrequent (approximately daily) calibration. The method requires GPSRO penetration depth only down to the stratosphere, thus permitting the use of a relatively small GPS antenna. Furthermore, only coarse spacecraft angular knowledge (approximately one degree rms) is required for the technique, as more precise angular knowledge can be retrieved directly from the combined radiometer and GPSRO data, assuming that the radiometer angular sampling is uniform. These features make the technique particularly well suited for implementation on a low-cost CubeSat hosting both radiometer and GPSRO receiver systems on the same spacecraft. We describe a validation platform for this calibration method, the Microwave Radiometer Technology Acceleration (MiRaTA) CubeSat, currently in development for the National Aeronautics and Space Administration (NASA) Earth Science Technology Office. MiRaTA will fly a multiband radiometer and the Compact TEC/Atmosphere GPS Sensor in 2015.

Dynamic lever arm compensation of SINS/GPS integrated system for aerial mapping

Strapdown inertial navigation system (SINS)/global positioning system (GPS) integrated system is an important way of accurate measurement of the mapping sensors for high resolution aerial mapping. However, for keeping the mapping sensor level and appointed direction, inertially stabilized platform (ISP) will be applied and rotate its three gimbals. The lever arm between inertial measurement unit (IMU) and GPS antenna will be time-varying. Therefore, the precise compensation of the effect of the dynamic lever arm will be significant for the measurement accuracy of SINS/GPS integrated system. An algorithm which tackles the problem is proposed, the dynamic lever arm is originally considered as the summation of two relative constant lever arms. Then, with the aid of the encoder data of ISP, the algorithm of dynamic lever arm compensation is derived in the paper. As the nonlinearity of the system, the demand of the on-line and off-line processing, unscented Kalman filter and smoother for nonlinear estimation are applied. Finally, the proposed algorithm of dynamic lever arm compensation is applied to a flight data of aerial mapping experiment. It is shown from the experiment results that the proposed algorithm can more effectively compensate the degradation of the measurement information than the traditional algorithm.

Shipborne heading determination and error compensation based on a dynamic baseline

Lengthening the baseline between antennas and compensating for heading error caused by vessel motion are two challenges encountered in using global positioning system (GPS) information to estimate the heading of a sailing vessel. In this study, a heading determination system (HDS), which consists of two quadruple GPS antenna arrays, an inertial navigation system (INS), and a total station surveying apparatus (TSSA), was developed to build a dynamic long baseline between two vessels. A heading determination algorithm is then presented based on the HDS. A heading error model, which considers TSSA time delay, is also designed to compensate for heading error and improve heading accuracy. The proposed algorithm has been examined by conducting mooring and sea tests. Test results are compared with the high-accuracy heading reference provided by the same INS. The standard deviations (std) of the heading error in the mooring and sea tests are ±6? and ±17?, respectively. After parameter identification and error compensation using the heading error model, the heading error in the sea test is reduced to ±8? from ±17?, thus proving the effectiveness of the proposed error compensation method. The experimental results demonstrate the capability of the HDS for high-performance shipborne heading determination.

Design of Dual Band Circular Polarization Stacked Microstrip Antenna for GPS Applications

In this paper dual-band microstrip antenna for Global Positioning System (GPS) application is designed.This design contents on two circular patch ( upper circular patch, lower circular patch) printed on a two-layer substrate of an FR4 dielectric layer, and cutting a crossed-slot in the upper patch and four I slots in the lower patch. The antenna can work at GPS Ll band (1.575GHz) and L2 band (1.227GHz). The design achieved an approximately impedance bandwidth of 15.8 MHz for L1 for two ports, while L2 band is 11.8 MHz for two ports with maximum gain of 2.54dBi and 1.177dBi in the L1 and L2 band respectively for two ports. The resulting circular polarization (with axial ratio ≤ 3 dB) has been found to meet that required for this application. The VSWR is approximately1.1 (VSWR ≤ 2) for L1 and 1.2 for L2. Results were obtained above using the software CST, which shows that this antenna can meet the demands of the signals of satellite navigation system.The antenna dimensions are (70*70 mm 2 ). The structure is compact and has a good application prospect. The results with low-profile characteristics make the antenna suitable for GPS applications. Keywords: microstrip antenna, GPS antenna, Circular polarization, dual-band antenna, Global Positioning System.

A detailed experimental study on the benefits of electrically grounding glass mounted global positioning system antennas to the vehicle roof

The placement of global positioning system (GPS) patch antennas on vehicles is important as its location directly affects navigation system performance. GPS antennas mounted on the front glass window has been adopted by several vehicle manufacturers around the world. In this work, we present a detailed experimental study on the effect of antenna mounting parameters as well as shorting it to the roof of the vehicle on its performance characteristics. Specifically, we investigate the effect of the glass tilt angle, the distance of the antenna from the rooftop of the vehicle in addition to grounding it to the rooftop versus not-grounding to the rooftop of a vehicular platform.

재밍대응 5소자 평면 GPS 배열 안테나 설계

Abstract This paper describes the design and analysis of five-element planar array antenna of an anti-jamming satellite navigation system. We propose a design of multi-layer patch antenna for Global Positioning System(GPS) L 1 /L 2 dual bands. The proposed antenna has two ports feeding network with a hybrid chip coupler for a broad bandwidth with Right-Handed Circular Polarization(RHCP). The measurement results show the bore-sight gains of 1.10 dBic(L 1 ) and 0.37 dBic(L 2 ) for the center element. The bore-sight gains of an edge element are 0.99 dBic(L 1 ) and 0.57 dBic(L 2 ). At a fixed elevation angle of 30°, antennas show average gains of 2.08 dBic (L 1 ) and 5.33 dBic(L 2 ) for the center element, and average gains of 0.40 dBic(L 1 ) and 2.09 dBic(L 2 ) for the edge elements. The results demonstrate that the proposed array antenna is suitable for anti-jamming applications.Key words: Anti-Jamming, CRPA(Controlled Reception Pattern Antenna), Patch Antenna, Feeding Structure, Circular Polarization, Array Antenna RGEST)(Agency for Defense Development)UManuscript received February 10, 2014 ; Revised April 3, 2014 ; Accepted April 4, 2014. (ID No. 20140210-024)UCorresponding Author: Seung Mo Seo (e-mail: sms@add.re.kr)

Dual‐band microstrip‐fed bow‐tie antenna for GPS and WLAN application

ABSTRACTA novel microstrip‐fed bow‐tie antenna for the global positioning system (GPS) and wireless local area network (WLAN) applications is presented in this letter. The proposed antenna consists of two pairs of printed bow‐tie patches with different dimensions, which can generate dual‐band characteristics independently. Based on this design concept, a prototype of the dual‐band antenna is fabricated and measured. The simulated and measured reflection coefficients, together with the radiation patterns, are presented and compared. Measurements show that the 10‐dB impedance bandwidth of the proposed dual‐band bow‐tie antenna is about 670 MHz (1.22–1.89 GHz) and 1130 MHz (5.24–6.37 GHz), which can cover both the GPS and WLAN bands. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2088–2091, 2014

Assessing the Accuracy of Long-Term Subsidence Derived from Borehole Extensometer Data Using GPS Observations: Case Study in Houston, Texas

AbstractThis study investigated long-term land subsidence derived from borehole extensometer and Global Positioning System (GPS) observations from Addicks, a suburb located in West Houston, Texas. The Addicks borehole extensometer was built in 1974 by the USGS. Two GPS stations were installed at this site in 1993 and 1996, respectively. One GPS antenna (ADKS) is mounted on the inner pipe of the extensometer borehole, which is firmly anchored 549 m below the land surface. Another GPS antenna (PA05) is mounted on a permanent antenna pole anchored 6 m below the land surface. The horizontal distance between these two GPS antennas is 50 m. Continuous GPS data collected from the deeply anchored GPS antenna indicate that the bottom of the borehole has been stable over the past 20 years (1993–2012). Hence the compaction derived from the borehole extensometer data represents the total subsidence at this site, which should be approximately equivalent to the vertical displacement (subsidence) recorded by the shallow...

Effects of Near-Surface Soil Moisture on GPS SNR Data: Development of a Retrieval Algorithm for Soil Moisture

Global Positioning System (GPS) multipath signals can be used to infer volumetric soil moisture around a GPS antenna. While most GPS users concentrate on the signal that travels directly from the satellite to the antenna, the signal that is reflected by nearby surfaces contains information about the environment surrounding the antenna. The interference between the direct and reflected signals produces a modulation that can be observed in temporal variations of the signal-to-noise ratio (SNR) data recorded by the GPS receiver. Changes in the dielectric constant of the soil, which are associated with fluctuations in soil moisture, affect the effective reflector height, amplitude, and phase of the multipath modulation. Empirical studies have shown that these changes in SNR data are correlated with near-surface volumetric soil moisture. This study uses an electrodynamic single-scattering forward model to test the empirical relationships observed in field data. All three GPS interferogram metrics (effective reflector height, phase, and amplitude) are affected by soil moisture in the top 5 cm of the soil; surface soil moisture ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$&lt; 1\hbox{-}\hbox{cm}$</tex></formula> depth) exerts the strongest control. Soil type exerts a negligible impact on the relationships between GPS interferogram metrics and soil moisture. Phase is linearly correlated with surface soil moisture. The slope of the relationship is similar to that observed in field data. Amplitude and effective reflector height are also affected by soil moisture, although the relationship is nonlinear. Phase is the best metric derived from GPS data to use as a proxy for soil moisture variations.

Optimal data processing strategy in precise GPS leveling networks

GPS (Global Positioning System) technique has become a major tool in contemporary surveying and geodesy. This concerns mostly measurements of horizontal point coordinates, where centimeter-level accuracies are usually required and easily achievable. For the height component, however, these requirements are higher and millimeter-level accuracy is necessary. On the other hand, the intrinsic precision of GPS-derived heights is clearly lower comparing to the horizontal components. This is due to unfavorable satellite geometry, adverse effects of the troposphere or GPS antenna phase center offset and variations. In order to overcome these effects one has to carefully model all the error sources and rigorously process the GPS data. This paper presents studies on the optimal GPS data processing strategy suitable for precise leveling. This was done through the extensive testing and selection of the most appropriate observational session duration, ambiguity resolution strategy, network geometry, troposphere and ionospheric delay reduction methods, signal linear combination, elevation angle cut-off, etc. The analyzed processing strategies were evaluated through the processing of a test network. The test network consisted of 19 monitored points and 5 control points, and covered the area of 20 km x 60 km. The obtained results show that the precise GPS leveling with the selected optimal processing strategy allows for about 3 mm repeatability of height measurements when processing 4-hour long sessions. In our opinion GPS leveling may serve as fast and cost-effective replacement of classic geometric leveling, especially in applications where the heights in orthometric or normal height systems are not necessary. This is the case in, e.g., ground deformation studies.

Behavioral characteristics of composite-antenna-structure covering three bands under compression load

A composite-antenna-structure covering three bands of global positioning system (1.575 GHz), digital multimedia broadcasting (2.62 GHz) and direct broadcast satellite (11.7–13.5 GHz) was designed and fabricated as a part of the structure surfaces. A new concept of antennas integrated into a composite sandwich structure provides a design that is an electrically and structurally effective multi-functional antenna structure. We designed two types of antennas. One is an annular ring patch antenna for global positioning system and digital multimedia broadcasting. The other is a microstrip patch antenna for direct broadcast satellite. In the design process, the effects of the composites and adhesive films are considered for in the design processes, because structural materials affect the antenna performance. Additionally, the composite-antenna-structure was designed by considering the coupling effect in a strict substrate. The measured results of buckling tests have provided useful information regarding not only the compression behavioral characteristics but also its degradation in electrical performance before and after the test. The experimental results have shown good results for compressive tolerance, though the specimens after compression loading returns to their original shape before failure. Additionally, an acoustic emission system is implemented in the buckling test system to study the inner behavior of the composite-antenna-structure for the reliability of secure mechanical performance. The antenna performance, as measured by the return loss and radiation pattern, remained excellent after the compression tests. These electrical performance results suggest that antennas with composite laminates will function well despite damage.

A Global Positioning System guided automated rice transplanter

We have developed a new Global Positioning System (GPS) guided rice transplanter. We developed GPS and IMU guided rice transplanter in previous researches. Those were guided with GPS position data and inertia measurement unit (IMU) direction data. New one is guided with GPS position data with tilt correction during straight driving and guided with IMU direction data during turning at the headland. The GPS antenna is set to 1.5m height and 0.4m front offset from vehicle front axle. The actuator control command and data communication protocols comply with through the controller area network (CAN) bus. Steering and transmission are controlled by electrical actuators according to the location in a field. We report results of experiment.

AUTOWAGON

This paper deals with research and development of Vehicle Monitoring and Security System which is GPS based vehicle tracking system used for security applications. It uses two main underlying concepts. These are GPS (Global Positioning System) and GSM (Global System for Mobile Communication). The main application of this system is tracking the vehicle to which the GPS is connected, giving the information about its position whenever required and for the security of each person travelling by the vehicle. This is done with the help of the GPS satellite and the GPS module attached to the vehicle which needs to be tracked. The GPS antenna present in the GPS module receives the information from the GPS satellite in NMEA (National Marine Electronics Association) format and thus it reveals the position information. This information got from the GPS antenna has to be sent to the Base station wherein it is decoded. For this GSM module is used which has an antenna too. Thus we have at the Base station; the complete data about the vehicle. Along with tracking the vehicle, the system is used for security applications as well. Each passenger/employee will have an ID of their own and will be using a remote containing key for Entry, Exit and Panic. The Panic button is used by the driver or the passenger so as to alert the concerned of emergency conditions. On pressing this button, an alarm will be activated which will help the passenger/employee in emergencies and keep them secure throughout the journey. The vehicle can also be immobilized remotely.

속도 측정치를 활용한 GPS/INS 통합 항법의 Lever arm 오차 보상

GPS/INS 항법시스템의 설치에 있어서 대다수의 경우 GPS 수신기 안테나는 차량의 외부에 설치하게 되고 IMU는 내부에 설치하게 된다. Lever Arm 오차는 이와 같이 센서의 장착 위치 차이로 인하여 발생하는 구조적인 오차에 해당한다. Lever Arm 오차는 항법성능에 직접적으로 영향을 주기 때문에 적절한 보상이 반드시 필요하다. 본 논문에서는 GPS와 INS의 속도 측정치를 활용하여 임의의 위치에 장착된 두 센서의 Lever Arm 오차를 효과적으로 추정하고 보상하는 방식을 제안하였다. 실험을 통해 제안한 알고리즘의 타당성을 검증하였으며, 항체의 회전운동 구간에서 Lever Arm 오차 보상이 특히 중요함을 보였다. In GPS(Global Positioning System)/INS(Inertial Navigation System) integrated navigation systems, GPS antennas and an inertial measurement units are usually installed outside and inside of the vehicle, respectively. By the difference of installed locations, performance of GPS/INS integrated navigation systems is affected by lever arm errors. For more accurate navigation, lever arm errors need to be compensated correctly since it directly affects the accuracy of navigation states. This paper proposes an effective lever arm error compensation method that utilizes velocity measurements of GPS and INS. By an experiment, feasibility of the proposed algorithm is verified. It is also shown that lever arm compensation is especially important when vehicles are experiencing rotational movements.

GPS phase scintillation associated with optical auroral emissions: First statistical results from the geographic South Pole

Ionospheric irregularities affect the propagation of Global Navigation Satellite System (GNSS) signals, causing radio scintillation. Particle precipitation from the magnetosphere into the ionosphere, following solar activity, is an important production mechanism for ionospheric irregularities. Particle precipitation also causes the aurorae. However, the correlation of aurorae and GNSS scintillation events is not well established in literature. This study examines optical auroral events during 2010–2011 and reports spatial and temporal correlations with Global Positioning System (GPS) L1 phase fluctuations using instrumentation located at South Pole Station. An all‐sky imager provides a measure of optical emission intensities ([OI] 557.7 nm and 630.0 nm) at auroral latitudes during the winter months. A collocated GPS antenna and scintillation receiver facilitates superimposition of auroral images and GPS signal measurements. Correlation statistics are produced by tracking emission intensities and GPS L1 σφ indices at E and F‐region heights. This is the first time that multi‐wavelength auroral images have been compared with scintillation measurements in this way. Correlation levels of up to 74% are observed during 2–3 hour periods of discrete arc structuring. Analysis revealed that higher values of emission intensity corresponded with elevated levels of σφ. The study has yielded the first statistical evidence supporting the previously assumed relationship between the aurorae and GPS signal propagation. The probability of scintillation‐induced GPS outages is of interest for commercial and safety‐critical operations at high latitudes. Results in this paper indicate that image databases of optical auroral emissions could be used to assess the likelihood of multiple satellite scintillation activity.

Compact Circularly Polarized Composite Cavity-Backed Crossed Dipole for GPS Applications

In this paper, we present a circularly polarized (CP) composite cavity-backed crossed dipole antenna for global positioning system (GPS) applications. We produce the CP radiation by crossing two dipoles through a <TEX>$90^{\circ}$</TEX> phase delay line of a vacant-quarter printed ring, which also has a broadband impedance matching characteristic. Two techniques, insertion of meander lines in the dipole arm and arrowhead-shaped trace at its end, are employed to reduce the sizes of the primary radiation element. The compact radiator is backed by a cavity reflector to achieve a wide CP radiation beamwidth. The proposed antenna exhibits a measured bandwidth of 1.450~1.656 GHz for a voltage standing wave ratio (VSWR) < 2 and 1.555~1.605 GHz for AR < 3-dB. At 1.575 GHz, the antenna has a gain of 7 dBic, a frontto-back ratio of 27 dB, AR of 1.18 dB, and 3-dB AR beamwidths of <TEX>$130^{\circ}$</TEX> and <TEX>$132^{\circ}$</TEX> in the x-z and y-z planes, respectively.

Indoor positioning based on global positioning system signals

AbstractThe Global Positioning System (GPS) is highly reliable and accurate when used outdoors.However, in indoor environments, due to the additional signal loss incurred by the walls of the buildings, the detection and decoding of GPS signals becomes a difficult task. As a solution to the indoor area coverage problem, an indoor positioning system based on GPS repeaters and a modified positioning algorithm is proposed, designed, and tested. A prototype indoor positioning system for 1D/2D positioning is built using directional GPS antennas and low‐noise amplifiers (LNA). The modified positioning algorithm is used for the real time processing of captured live GPS data. All the system components are integrated and positioning is obtained for the evaluation of the system performance. Results of the experiments show that the proposed system can be used for indoor positioning in locations where there is no GPS signal reception. The proposed system facilitates the continuation of GPS services indoors with hardware additions to the buildings and only a software update to a standard GPS receiver. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1091–1097, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27520