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2003, Proceedings of the …
Locata Corporation has invented a new positioning technology called Locata, which is designed to overcome severe limitations in other positioning systems currently available. Part of the "Locata technology" consists of a time-synchronised pseudolite transceiver called a LocataLite. A network of LocataLites forms a LocataNet, which transmits GPS-like signals that allow single-point positioning using carrier-phase measurements for a mobile device (a Locata). The SNAP group at UNSW has assisted in the development of a Locata and testing of the new technology. In this paper, the prototype "Locata technology" is described, and the results of a performance test experiment are presented.
2000
Locata positioning technology was developed to address the shortcomings of current technologies for reliable positioning in challenging environments such as when GPS satellite coverage is poor or not available. Previous research in this area has demonstrated proof-of-concept for the Locata technology using a first generation prototype system. In this paper details of Locata's next generation system are discussed, and positioning
Locata is a Pseudolite-based Positioning System (PPS) operating in the licence-free 2.4GHz Industrial Scientific and Medical (ISM) frequency band. Unlike its predecessors, Locata utilises time-diversity methods to overcome the near-far problem. Therefore Locata is able to operate over larger regions than previous PPSs. Since the School of Surveying & Spatial Information Systems (SSIS) at the University of New South Wales (UNSW) has considerable experience in designing GNSS receivers, the integration of PPS signal processing within its own GNSS receiver (known as "Namuru") is currently being investigated. Research into Locata's signal structure is aimed at gaining insight and detailed technical knowledge to support alternate receiver designs for processing terrestrial PPS-type signals. In this investigation, several important signal variables were identified via coaxially connecting the Locata transmitter to a Radio Frequency (RF) down-converter, high speed digitiser an...
2017
GNSS has limitations or cannot be applied in specific environments with poor geometry likecity streets, tunnels, bridges, quarries, mines, ports or in indoor environment in general. In 2003Locata Corporation from Australia began with the development of a new, completelyindependent technology called Locata, which was designed to overcome the limitations ofGNSS. It can be combined with GNSS, or can be used as an independent measuring system, where the GNSS limitations are the biggest. Within the project “Wearable outdoor augmentedreality system for enrichment of touristic content” for the first time one Locata system wasimplemented in Croatia. Established LocataNet consists of six LocataLites and two Locatareceivers. Before establishing LocataNet it was necessary to simulate different networkconfigurations to get insight into geometry influence on positioning accuracy, i.e. the dilutionof precision (DOP) values inside LocataNet. The most demanding task was to achievereasonable VDOP va...
2006
Despite the popularity and maturity of RTK GPS (GNSS), acceptable performance is heavily dependent on a relatively unobstructed sky-view, where there are at least five satellites with good geometry available, and on the reliability of the wireless data link used for differential corrections. In so-called "difficult" environments where satellite obstruction is common, such as open-pit mining and urban environments, the
Location Based Services and …, 2009
The Global Positioning System (GPS) has a typical outdoor positioning accuracy of up to 15m for civilian users. Thus, it has become a viable method for civilian to carry out coarse positioning. However, it has its shortcomings; it is available only in indoors with a clear view of the sky. Since WiFi has become another proven positioning technology that is capable of performing positioning in indoor environments and urban canyons, it is desirable to combine both of these technologies for ubiquitous positioning. Therefore, by means of integrating GPS positioning with a WiFi positioning system, indoor and outdoor positioning may be performed using only one device. The device can be implemented using FPGA embedded systems technology that allows easy reconfiguration of the device. Such a combination allows GPS and WiFi positioning technology to transition seamlessly.
Journal of Navigation, 2010
Classically difficult positioning environments often call for augmentation technology to assist the GPS, or more generally the Global Navigation Satellite System (GNSS) technology. The “Locata” ground-based ranging technology offers augmentation, and even replacement, to GPS in such environments. However, like any other system relying on wireless technology, a Locata positioning network also faces issues in the presence of RF interference (RFI). This problem is magnified due to the fact that Locata operates in the licence-free 2·4 GHz Industrial, Scientific and Medical (ISM) band. The licence-free nature of this band attracts a much larger number of devices using a wider range of signal types than for licensed bands, resulting in elevation of the noise floor. Also, harmonics from out-of-band signals can act as potential interferers. WiFi devices operating in this band have been identified as the most likely potential interferer, due partially to their use of the whole ISM band, but ...
Navigation, 1996
The concept of using a pseudolite in the reverse mode where the pseudolite is positioned with respect to receivers deployed at known points is presented. Two types of double-difference positioning approaches for eliminating clock and other code and carrier-phase biases are described and analyzed-pseudolite positioning with satellite reference (PPSR) and pseudolite positioning with pseudolite reference (PPPR). Results are given for an initial test conducted in a land vehicle at Holloman APB, New Mexico. The test range consisted of a 600 m course surrounded by six receivers deployed in a noncoplanar configuration at distances ranging from 100 to 1,500 m from the vehicle. The pseudolite position was calculated using both integer and floating-point carrier-phase ambiguities, and the resulting trajectory was analyzed to assess the differential positioning performance of this inverted GPS system.
Locata's positioning technology was designed to be used as an alternative to GNSS in classically-difficult GNSS signal environments. A network of time-synchronized terrestrial transceivers (LocataLites) forms a positioning network (LocataNet) that can operate entirely independent of GNSS. Operating in the 2.4GHz ISM licence-free band, the Pseudolite Positioning System (PPS) is immune to the near-far problem due to the usage of TH/DS-CDMA signal. Conversely, the use of such signals results in the degradation of code tracking performance in comparison to an equivalent DS-CDMA system. The relative performance degradation is proven via theoretical derivation and simulation to be directly related to the duty factor of the TH/DS-CDMA signal. The transient behavior of the signal is also observed and compared to the conventional DS-CDMA signal. This type of signal provides an efficient way to track multiple transmitter using only one tracking loop.
2007
This paper describes the current efforts to develop an open source, privacy sensitive, location determination software component for mobile devices. Currently in mobile computing, the ability of a mobile device to determine its own location is becoming increasingly desirable as the usefulness of such a feature enhances many commercial applications. There have been numerous attempts to achieve this from both the network positioning perspective and also from the wireless beacon angle not to mention the integration of GPS into mobile devices. There are two important aspects to consider when using such a system which are privacy and cost. This paper describes the development of a software component that is sensitive to these issues. The ICiNG Location Client (ILC) is based on some pioneering work carried out by the Place Lab Project at Intel. (Hightower et al., 2006) The ILC advances this research to make it available on mobile devices and attempts to integrate GSM, WiFi, Bluetooth and ...
2006 IEEE/ION Position, Location, And Navigation Symposium, 2006
GPS is undoubtedly the most popular and widely used three-dimensional positioning technology today, but despite this, cannot provide the positioning requirements in many everyday environments, such as urban and indoors. Locata's solution to these "challenging" environments is to deploy a network of terrestrially-based transceivers that transmit ranging signals. For any terrestrially-based radio frequency (RF) systems, typically the signal from the transmitter arrives at the receiver antenna at a very low (less than 10 degree) or negative elevation angle, and as a result suffer from severe multipath in the form of signal fading. In this paper Locata's "signal diversity principle" solution to this "real-world" problem is presented. It is shown that in a moderate signal fading environment a system of dual transmit LocataLites, employing spatial diversity principles, can provide cm-level accurate RTK position solutions 100% of the time.
Journal of Global Positioning Systems, 2003
Today, GPS is the most popular and widely used three-dimensional positioning technology in the world. However, in many everyday environments such as indoors or in urban areas, GPS signals are not available for positioning (due to the very weak signals). Even with high sensitivity GPS receivers, positioning for urban and indoor environments cannot be guaranteed in all situations, and accuracies are typically of the order of tens to hundreds of meters at best. Other emerging technologies obtain positions from systems that are not designed for positioning, such as mobile phones or television. As a result, the accuracy, reliability and simplicity of the position solution is typically very poor in comparison to GPS with a clear view of the sky.
Giftet Journal of geolocation, geo-information, and geo-intelligence, 2017
2014
GPS has become an almost indispensable part of our infrastructure and modern life. Yet because its accuracy, reliability, and integrity depend on the number and geometric distribution of the visible satellites, it is not reliable enough for the safety of life, environmental or economically critical applications.
New Approach of Indoor and Outdoor Localization Systems, 2012
2000
In this paper, three general classes of pseudolite system configurations are discussed. The first is GPS augmentation with pseudolite(s), which is suitable for circumstances where direct GPS signal availability is restricted. The second is indoor applications of pseudolite-based positioning, where pseudolites can, in principle, completely replace the GPS satellite constellation. The last class of configurations is an inverted pseudolite-based positioning system, where a 'constellation' of GPS receivers with precisely known 'orbits' track a mobile pseudolite. In the case of pseudolite-only or hybrid pseudolite-GPS positioning systems there are some additional issues that need to be addressed. These include multipath, atmospheric delay effects, and location-dependent errors such as receiver and pseudolite location biases. In May 1999, the Satellite Navigation and Positioning (SNAP) Group, The University of New South Wales (UNSW), purchased a pseudolite and commenced research into this technology. In December 2000 some experiments were carried out using NovAtel GPS receivers and IntegriNautics IN200CXL pseudolite instruments (two borrowed from the ). The experimental results indicate that these pseudolite-based positioning systems are feasible. Their performance will be demonstrated through several case study examples.
1999
The concept of an inverted positioning system using pseudolites is discussed whereby a 'constellation' of GPS receivers tracks a mobile pseudolite. The system consists of the mobile pseudolite, a stationary reference pseudolite, and an array of GPS receivers.
Satellite GPS is undoubtedly the most popular and widely used three dimensional positioning technology in the world today, but despite this, cannot provide the positioning requirement in many every day requirements in different environments, such as urban and indoor due to the very weak signals from satellites. Even with high sensitivity GPS receiver cannot be given guaranteed in all situations and accuracies are typically of the order of tens to hundreds of meter at best. Accurate indoor positioning is required for a variety of commercial applications, including warehouse automation, asset tracking, emergency first-responders, and others. In fact, the general expectation of users today is for "GPS-like" positioning performance anywhere they go. Terrestrial GPS positioning is a new positioning technology, developed to address the failure of current satellite technologies for reliable ubiquitous (outdoor and indoor) positioning. In this paper key aspects of the new technology "terrestrial GPS positioning system" are discussed. Particular emphasis is given on the components like PseudoLite, PseudoNet, Rover (Moving terminal) and TimeLoc and their functionality. The technique and mathematical model used in terrestrial GPS positioning system is described in detail. The Results of installed Terrestrial GPS Positioning Systems are demonstrated and compared with Satellite GPS Positioning System.
2013
BACKGROUND For many years Locata has been focused mainly on the Position and Navigation portions of GPS technology's essential Position, Navigation and Time (PNT) components. Nevertheless, the "T" component-time transfer and synchronization-is at the very heart of Locata via the TimeLoc ™ invention which creates Locata's core network technology. UNSW researchers wanted to specifically test a Locata network's real-world long-distance time transfer capability. As a performance benchmark comparison they used today's most demanding IEEE synchronization standard for next-generation 4G mobile phone networks. Therefore, in November 2013, the UNSW set up two independent research experiments designed to quantify-for the first time-Locata's long range time transfer capabilities. Many critical modern systems (4G mobile phone networks, banking, electricity grids, etc) demand high-accuracy time and frequency stability across specified areas, as set out in IEEE specification standard 1588. Today's desired minimum performance levels are: Synchronization: 1.5 to 5s (millionths of a second) Frequency stability: 16-50ppb (parts per billion) These levels of precision are difficult to achieve. They represent the cutting edge of real world technology performance and require specialised, dedicated infrastructure. The preferred way to achieve this IEEE-specified performance within critical systems is via synchronization from GPS or other space-based positioning systems. But, as stated clearly throughout industry literature: "the vulnerability of GPS signals is of growing concern".
Dr. Ilir F. Progri is the President and CEO of Giftet Inc. a privately held company for developing Global Navigation Software, and Web Solutions (Giftet). Dr. Progri's eleven year career in GPS consists of all aspects of signals and system specifications, simulation, software development and implementation of significant new capabilities in GPS and indoor geolocation systems. Dr. Progri has led research and development engineering projects for over eight years. He has over fifty published papers and one patent in all aspects of geolocation systems. Ilir has received over thirty citations from experts, researchers, and scientists of US,
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