High Accuracy Pseudolite-based Navigation System: Compensating for Right-Hand Circularly Polarized Effect

2006 ◽  
Vol 59 (2) ◽  
pp. 307-320 ◽  
Author(s):  
Haeyoung Jun ◽  
Changdon Kee
Keyword(s):  
Global Positioning System ◽  
Navigation System ◽  
Line Of Sight ◽  
Positioning System ◽  
Phase Measurements ◽  
Circularly Polarized ◽  
Position Accuracy ◽  
Right Hand ◽  
Gps Satellites ◽  
Global Positioning

This paper presents further research on the SNUGL pseudolite-based navigation system presented in this journal in 2003. This system has centimetre-level accuracy, but has an error source arising from right-hand circularly polarized (RHCP) transmissions, unlike outdoor Global Positioning System (GPS). The GPS satellites and pseudolites use RHCP signals, and the polarization affects carrier-phase measurements according to the Line-of-Sight (LOS) vectors from transmitters to receivers. The RHCP error is eliminated by a double differencing process in outdoor GPS, but the error remains in the pseudolite-based system because the LOS vectors from transmitters to a reference and user receivers are different for the close transmitter constellations. This paper shows the RHCP effect on the pseudolite-based navigation system through simulations and experiments. It then shows the RHCP-compensation method improves the measurement and position accuracy by over 10%.

scholarly journals Influence of Ephemeris Error on GPS Single Point Positioning Accuracy

2013 ◽  
Vol 48 (3) ◽  
pp. 125-139
Author(s):  
Ma Lihua ◽  
Meng Wang
Keyword(s):  
Global Positioning System ◽  
Simulation Analysis ◽  
Single Point ◽  
Line Of Sight ◽  
Positioning System ◽  
Gps Satellites ◽  
Time Period ◽  
Global Positioning ◽  
Orbital Position ◽  
The Relationship

Abstract The Global Positioning System (GPS) user makes use of the navigation message transmitted from GPS satellites to achieve its location. Because the receiver uses the satellite's location in position calculations, an ephemeris error, a difference between the expected and actual orbital position of a GPS satellite, reduces user accuracy. The influence extent is decided by the precision of broadcast ephemeris from the control station upload. Simulation analysis with the Yuma almanac show that maximum positioning error exists in the case where the ephemeris error is along the line-of-sight (LOS) direction. Meanwhile, the error is dependent on the relationship between the observer and spatial constellation at some time period.

scholarly journals Optical Astrometry and the Global Positioning System

1991 ◽  
Vol 127 ◽  
pp. 284-287
Author(s):  
P.C. Kammeyer ◽  
H.F. Fliegel ◽  
R.S. Harrington
Keyword(s):  
Global Positioning System ◽  
Optical Sensors ◽  
Optical Observations ◽  
Line Of Sight ◽  
Positioning System ◽  
Charge Coupled Device ◽  
Gps Satellites ◽  
Global Positioning ◽  
Device Technology ◽  
Stellar Background

AbstractAstrometric accuracies of a few tens of milliarcseconds are expected to be attainable within five years by calibrating astrograph plates with optical observations of Global Positioning System (GPS) satellites against a stellar background. The line of sight from an observer on the Earth’s surface to a GPS satellite may be calculated with high accuracy. Motion on each day of the line of sight to the satellite and changes from day to day in the apparent path of the satellite are sufficiently slow to make it possible to reduce atmospheric errors by averaging. Advanced ground-based optical sensors, probably using charge coupled device technology, will be required for GPS optical astrometry.

scholarly journals Modified Dual-Band Stacked Circularly Polarized Microstrip Antenna

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Guo Liu ◽  
Liang Xu ◽  
Yi Wang
Keyword(s):  
Radiation Pattern ◽  
Global Positioning System ◽  
Microstrip Antenna ◽  
High Performance ◽  
Axial Ratio ◽  
Dual Band ◽  
Optimized Design ◽  
Positioning System ◽  
Circularly Polarized ◽  
Global Positioning

A novel high-performance circularly polarized (CP) antenna is proposed in this paper. Two separate antennas featuring the global positioning system (GPS) dual-band operation (1.575 GHz and 1.227 GHz for L1 band and L2 band, resp.) are integrated with good isolation. To enhance the gain at low angle, a new structure of patch and two parasitic metal elements are introduced. With the optimized design, good axial ratio and near-hemispherical radiation pattern are obtained.

Ultra-Wideband-Based Localization for Quadcopter Navigation

2016 ◽  
Vol 04 (01) ◽  
pp. 23-34 ◽  
Author(s):  
Kexin Guo ◽  
Zhirong Qiu ◽  
Cunxiao Miao ◽  
Abdul Hanif Zaini ◽  
Chun-Lin Chen ◽  
...  
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Global Positioning System ◽  
Ultra Wideband ◽  
Line Of Sight ◽  
Positioning System ◽  
Localization Algorithm ◽  
Control Loop ◽  
Flight Tests ◽  
Localization System ◽  
Global Positioning

Micro unmanned aerial vehicles (UAVs) are promising to play more and more important roles in both civilian and military activities. Currently, the navigation of UAVs is critically dependent on the localization service provided by the Global Positioning System (GPS), which suffers from the multipath effect and blockage of line-of-sight, and fails to work in an indoor, forest or urban environment. In this paper, we establish a localization system for quadcopters based on ultra-wideband (UWB) range measurements. To achieve the localization, a UWB module is installed on the quadcopter to actively send ranging requests to some fixed UWB modules at known positions (anchors). Once a distance is obtained, it is calibrated first and then goes through outlier detection before being fed to a localization algorithm. The localization algorithm is initialized by trilateration and sustained by the extended Kalman filter (EKF). The position and velocity estimates produced by the algorithm will be further fed to the control loop to aid the navigation of the quadcopter. Various flight tests in different environments have been conducted to validate the performance of UWB ranging and localization algorithm.

Quantifying Position Accuracy of Multimodal Data from Global Positioning System–Enabled Cell Phones

2007 ◽  
Vol 1992 (1) ◽  
pp. 54-60 ◽  
Author(s):  
David P. Aguilar ◽  
Sean J. Barbeau ◽  
Miguel A. Labrador ◽  
Alfredo J. Perez ◽  
Rafael A. Perez ◽  
...  
Keyword(s):  
Global Positioning System ◽  
Cell Phones ◽  
Positioning System ◽  
Multimodal Data ◽  
Position Accuracy ◽  
Global Positioning

scholarly journals LIDAR Self Driving Car

2021 ◽  
Vol 9 (10) ◽  
pp. 1334-1337
Author(s):  
Soham Phansekar
Keyword(s):  
Global Positioning System ◽  
Electromagnetic Waves ◽  
Traffic Accidents ◽  
Positioning System ◽  
Automated Driving ◽  
Sensing Technology ◽  
Gps Satellites ◽  
Global Positioning ◽  
Total Travel Time ◽  
Car Navigation System

Abstract: Increasing population is the major issue of transportation nowadays. People who live and work in the major cities of the world are faced with increasing levels of congestion, delays, total travel time, costs, frustration, accidents and loss of life. The objective of this project is to help prevent traffic accidents and save people’s time by fundamentally changing car use. The system would have sensors to detect the obstacles and to be able to react according to their position. In this project we have developed an automated driving system which drives the car automatically. We have developed a technology for cars that drives it automatically using LIDAR. This car is capable of sensing the surroundings, navigating and fulfilling the human transportation capabilities without any human input. It continuously tracks the surrounding and if any obstacle is detected vehicle senses and moves around and avoids the obstacle. An autonomous car navigation system based on Global Positioning System (GPS) is a new and promising technology, which uses real time geographical data received from several GPS satellites to calculate longitude, latitude, speed and course to help navigate a car. As we know the development of gps is more improved now the accuracy of gps we can see centimetre also so Like for our car to go at specific inputted location we use this gps technology.Lidar is used for sensing the surroundings. Like radar, lidar is an active remote sensing technology but instead of using radio or microwaves it uses electromagnetic waves. Keywords: Congestion, Traffic Accident, LIDAR sensor, Global Positioning System, Electromagnetic waves

scholarly journals Global positioning system resurvey of Southern California Seismic Network stations

1995 ◽  
Vol 85 (1) ◽  
pp. 361-374
Author(s):  
Jennifer S. Haase ◽  
Egill Hauksson ◽  
Hiroo Kanamori ◽  
Jim Mori
Keyword(s):  
Global Positioning System ◽  
Southern California ◽  
Seismic Station ◽  
Seismic Network ◽  
Positioning System ◽  
Dual Frequency ◽  
Time Data ◽  
Phase Measurements ◽  
Station Coordinates ◽  
Global Positioning

Abstract Systematic errors in travel-time data from local earthquakes can sometimes be traced to inaccuracies in the published seismic station coordinates. This prompted a resurvey of the stations of the Caltech/USGS Southern California Seismic Network (SCSN) using the Global Positioning System (GPS). We surveyed 241 stations of the SCSN using Trimble and Ashtech dual-frequency GPS receivers and calculated positions accurate to 3 m using differential positioning from carrier phase measurements. Twelve percent of the stations that were surveyed were found to be mislocated by more than 500 m. Stations of the TERRAscope and USC networks were also surveyed, as well as a network of portable seismic stations deployed shortly after the 1992 Joshua Tree and Landers earthquakes. The new coordinates and the offsets from the old coordinates are given below. The new coordinates are being used in SCSN locations as of 1 January 1994.

scholarly journals An autonomous navigational system using GPS and computer vision for futuristic road traffic

2022 ◽  
Vol 12 (1) ◽  
pp. 179
Author(s):  
Prabha Ramasamy ◽  
Mohan Kabadi
Keyword(s):  
Computer Vision ◽  
Global Positioning System ◽  
Navigation System ◽  
Autonomous Navigation ◽  
Road Traffic ◽  
Positioning System ◽  
Traffic System ◽  
Global Positioning ◽  
Navigational System

Navigational service is one of the most essential dependency towards any transport system and at present, there are various revolutionary approaches that has contributed towards its improvement. This paper has reviewed the global positioning system (GPS) and computer vision based navigational system and found that there is a large gap between the actual demand of navigation and what currently exists. Therefore, the proposed study discusses about a novel framework of an autonomous navigation system that uses GPS as well as computer vision considering the case study of futuristic road traffic system. An analytical model is built up where the geo-referenced data from GPS is integrated with the signals captured from the visual sensors are considered to implement this concept. The simulated outcome of the study shows that proposed study offers enhanced accuracy as well as faster processing in contrast to existing approaches.

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