GeoScience Engineering Vol. 68 (2022), No. 2 geoscience.cz pp. 178–194, ISSN 1802-5420 DOI 10.35180/gse-2022-0080 PERFORMANCE ASSESSMENT OF KINEMATIC GNSS POSITIONING WITH SMARTPHONES BASED ON POST-PROCESSING OF RAW OBSERVATIONS Marek HALAJ, Michal KAČMAŘÍK VŠB – Technical University of Ostrava, Faculty of Mining and Geology, Department of Geoinformatics, Ostrava, Czech Republic E-mail: marek.halaj@vsb.cz ABSTRACT In recent years, there have been significant technological advances in the development of common mobile devices. This brought progress also in the area of positioning with these devices. Allowing access to raw GNSS observations recorded by mobile devices opened possibilities to apply advanced positioning techniques in order to achieve higher positioning accuracy. The paper describes the results of kinematic measurements of a single- frequency Samsung Galaxy S10+ smartphone and a dual-frequency Samsung Galaxy Note10+ smartphone. Observations were repeatedly collected at a 1.76 km long test route in an urban environment at a pedestrian speed. Real-time positioning by autonomous method as well as collection of raw observations into RINEX format and their subsequent post-processing by differential techniques and Precise Point Positioning technique were realized. The achieved results were compared against a reference line representing the real trajectory and also against results of a geodetic grade GNSS receiver. Positioning accuracy of mobile devices ranged from the first decimetres to tens of metres, depending on the environment, tested smartphone and used post-processing technique. Dual- frequency smartphone Samsung Galaxy Note 10+ provided a better performance compared to the single-frequency device. Real-time positioning based on a simple autonomous technique and smoothing algorithm for route optimization reached lower positioning errors compared to all solutions based on collecting raw observations and their consequent post-processing with mentioned techniques. Keywords: GNSS; Positioning; Post-processing; Smartphone. 1 INTRODUCTION In 2016, mobile device users with Android 7.0 operational system firstly got an opportunity to access raw observations of Global Navigation Satellite System (GNSS) signals. Mobile applications that allowed the recording of these raw observations directly to a standard RINEX (Receiver Independent Exchange) data format were developed soon afterwards. In 2018, the first smartphone with a built-in dual-frequency GNSS receiver, the Xiaomi Mi8, was launched. Since then, many more dual-frequency smartphones from other manufacturers entered the market. All the technical development led to a significant increase of interest in advanced positioning with common smartphones and other mobile devices. GNSS positioning can be performed in real-time or in post-processing mode. The first option provides user a knowledge of its position directly in the field. On the other hand, positioning based on post-processing requires an additional processing of raw GNSS data collected in the field in some specialized software. Recent progress in area of GNSS positioning with mobile devices is mainly related to the post-processing of raw observations, because, as reported in [1], there is currently no freely available application for the Android operating system that allows GNSS positioning by advanced real-time techniques such as Real-Time Kinematic (RTK).