Development of GNSS data processing procedures for pedestrian navigation in challenging environments

High sensitivity GPS receivers have expanded the use of the GNSS to areas with difficult reception of the signals from the satellites. Difficult conditions indicate attenuation and reflection of the signals. Receivers achieve higher sensitivity of signal reception by larger number of correlators and longer integration time. The present doctoral dissertation deals with classical methods of observation processing in normal conditions used for observation processing in challenging environments. Some of the methods are more effective in difficult conditions than others. Processing of observation data in dynamic and quick changing conditions requires careful and consistent treatment. Otherwise a gross error in position determination can occur. Multipath has the biggest influence on final results and has a special effect on code observations. Therefore, Doppler observations are also included in the position determination. The custom developed procedure of positioning in challenging environments beside well known and established methods includes additional methods which assure higher accuracy and reliability of the determined position. Processing procedures have been tested in different conditions in static and kinematic cases. The acquired results have been compared to those processed inside the receiver. A so-called conditional DGPS has been developed, which determines the position differentially by using only data from strong signals.