Articles in the Positioning Category

Jan 2011 | No Comment

A very interesting feature of the transmitter approach is the possibility to locate transmitters underneath the receiver. The transmitter-based approach is an indoor positioning method, based on the use of a local infrastructure, aiming to provide accuracies of 1 to 2 meters. The GNSS signals are received by an outdoor antenna located in a place with an unobstructed view of the satellites. Note that another possibility is to use a GNSS signal generator (generating one or 4 satellites) instead of the outdoor antenna.

Oct 2010 | No Comment

The Arctic ice is receding at a faster pace than expected a few years ago, and is quickly opening for increased human activities beyond the Arctic Circle (66.56° N). This drives a growing demand for navigation in the Arctic area, which is mainly composed of marine expanses and the land masses of Norway, Iceland, Greenland (Denmark), Northern Canada, Alaska (USA), and the Northern parts of Russia…

Dec 2009 | No Comment

Phase multipath is one of the most crucial error sources in centimetre or millimetre level GNSS high precision positioning. Short-delay multipath is still especially difficult to detect or mitigate by the state-of-the-art hardwarebased techniques. Therefore, processing algorithm-based multipath mitigation methods are crucial for the further improvement of positioning accuracy, either integrated with other techniques or in a stand-alone mode…

May 2009 | Comments Off on Flight evaluation of a ‘GADA’
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For the final evaluation of a GPS attitude determination algorithm (GADA), it was determined its true performance in terms of its accuracy, reliability and dynamic response. To accomplish that, a flight test campaign was carried out at the Brazilian Flight Test Division (GEEV) to validate the attitude determination algorithm. In this phase, the measured aircraft attitude was compared to a reference attitude, to allow the determination of the errors…

Feb 2009 | One Comment
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Satellite positioning is the term used to describe the determination of the absolute and relative coordinates of points on (or above) the Earth’s land or sea surface by processing measurements to, and/or form, artifi cial Earth Satellites. In this context, absolute coordinates refer to the position of a point in a specified coordinate system, whereas relative coordinates refer to the position of one point with respect to another…

Feb 2009 | No Comment
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GNSS positioning/navigation devices are rapidly merging into and changing our modern lives, just like the personal computer in the 1980’s and the cellular phone in the 1990’s. It is predicted that by 2012, the annual shipment of navigation devices will increase to over 65 million units, which is more than three times the 19.8 million shipped in 2006 [1]. Also in a situation personal computer and cellular phone ever faced, a higher standard service…

Dec 2008 | No Comment
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SWEPOS™ is a network of GPS/GLONASS reference stations which began as a co-operation between the National Land Survey of Sweden and Onsala Space Observatory. The early design phases of SWEPOS were made in 1992. It was already then stated that the network should be of both scientific and practical benefit to the professional GNSS users and the public. The purposes of SWEPOS are mainly to [1]…

Sep 2008 | No Comment
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The system presented in the paper is designed according to the scheme of compensation and processes navigation data with use of a Complementary Extended Kalman Filter (CEKF). The INS/TACAN/ALT system works with a feed-forward correction, i.e. there is no feedback to INS and its errors are corrected externally. The structure of system is shown in the Fig. 1…

May 2008 | No Comment
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Alternative location methods for absolute positioning in areas where no GNSS position determination is possible due to obstruction of the satellite signals are needed in mobile positioning. Active RFID (Radio Frequency Identification) can be used also for position determination, although the system was not only developed for positioning and tracking but mainly for identification of objects. Using RFID in positioning, different approaches can be distinguished, i.e., cell-based positioning if the RFID tags are installed at active landmarks (i.e., known locations) in the surroundings, trilateration if ranges to the RFID tags are deducted from received signal strength (RSS in RFID terms) values and location fingerprinting where the measured signal power levels are used directly to obtain a position fix. Using Cell of Origin (CoO) the achievable positioning accuracy depends on the size of the cell and is therefore usually several metres up to 10’s of metres using long range RFID equipment. Higher positioning accuracies can be obtained using trilateration and fingerprinting. In this paper the use of trilateration is investigated.

Apr 2007 | Comments Off on TEC values estimation over a permanent GPS station

The ionosphere represents one of the most important error sources that affecting GPS positioning. It is strongly related to solar activity and geomagnetic ?eld. The GPS satellites and dual frequency receivers can be used to measure the Total Electron Content (TEC) of the Earth’s ionosphere. Global electron content maps have been produced by various research centers using the world-wide permanent network of GPS receivers. In this study a rapid method of monitoring the ionospheric disturbance using dual frequency GPS data of the Aristotle University Thessaloniki (AUT1) permanent station is presented. The Total Electron Content can be determined using the so called Single Layer Model (SLM) of the ionosphere. The SLM is based on the assumption that all free electrons are concentrated in a spherical layer of in?nitesimal thickness (single layer) at height H above the earth’s surface. The Total Electron Content is modeled as a truncated Taylor series with the geographical latitude and the hour angle of the sun as independent variables, using the L4 – geometry free linear combination. The results are con?rmed using global information for Sun spot and geomagnetic activity from NOAA and Kyoto University respectively.