Pseudolites are ground based GNSS signal transmitters that have already been used in the project where visibility to the GNSS satellites is limited, however there are still many issues that need enhancement. A prototype of a low-cost pseudolite is being designed and assembled at the University of Warmia and Mazury. The goal of the project is to apply the pseudolite as an augmentation to GNSS positioning tasks in geodetic engineering projects. This paper presents the results of first prototype testing in the area of code generation, carrier frequency and signal power.
This paper presents the analysis of PDOP factors for a ZigBee ground - based augmentation systems. It presents the idea of such a system followed by the results of assessment of application in Gdansk Marina. The results of the experiment show that the application of ZigBee can significantly improve PDOP value in harsh measurement environment. The analysis shows that it is possible to select an optimal location of ground-based transceiver on the basis of predicted trajectory and obstructions measured with laser scanning.
This paper presents ambiguity resolution in the range-based ZigBee positioning system. The system is using the phase shift measurements to determine the distances between user and anchors. In this paper, the ambiguity is defined as the number of full reps of a certain distance added to the measurement result. The way of resolving ambiguities in the positioning system is described and an experiment results are presented. Featured algorithm is successful in finding ambiguities and correct location of the user.
Dariusz Tomaszewski, Jacek Rapiński and Renata Pelc-Mieczkowska
Nowadays, along with the advancement of technology one can notice the rapid development of various types of navigation systems. So far the most popular satellite navigation, is now supported by positioning results calculated with use of other measurement system. The method and manner of integration will depend directly on the destination of system being developed. To increase the frequency of readings and improve the operation of outdoor navigation systems, one will support satellite navigation systems (GPS, GLONASS ect.) with inertial navigation. Such method of navigation consists of several steps. The first stage is the determination of initial orientation of inertial measurement unit, called INS alignment. During this process, on the basis of acceleration and the angular velocity readings, values of Euler angles (pitch, roll, yaw) are calculated allowing for unambiguous orientation of the sensor coordinate system relative to external coordinate system. The following study presents the concept of AHRS (Attitude and heading reference system) algorithm, allowing to define the Euler angles.The study were conducted with the use of readings from low-cost MEMS cell phone sensors. Subsequently the results of the study were analyzed to determine the accuracy of featured algorithm. On the basis of performed experiments the legitimacy of developed algorithm was stated.