Global Navigation Satellite System Module Research Articles

Improved GNSS-based indoor positioning algorithm for mobile devices

The widespread use of global navigation satellite system (GNSS) receiver in mobile devices induces the adoption of effective GNSS-based indoor positioning algorithms exploiting low-cost hardware. In a previous study, we proposed a new architecture for indoor positioning system to estimate the user position by utilizing the pseudoranges from the smartphone-embedded GNSS module. The advantages of such a system are low cost and low requirements in terms of hardware-level modification for end users. However, all end users and most application developers do not have permission to read the pseudoranges from the embedded GNSS modules. Instead of pseudoranges, the user positions are easily obtained from the GNSS module in any mobile device. Thus, we further improve our positioning algorithm based on the position obtained from the embedded GNSS module rather than the pseudoranges. This position does not correspond to the true one since the indoor signal is non-line-of-sight. Thus, it is named the pseudo-position. The key to the improved algorithm is that the distances from the user terminal to the indoor transmitting antennas are calculated using the differences between the position of the outside antenna and the pseudo-position. The algorithm is tested using a simulated GNSS-based indoor positioning system which is implemented on a GNSS software receiver. The simulation results show that the indoor positioning system is able to provide horizontal positioning with meter-level accuracy in both static and dynamic situations. Additionally, the proposed method improves the robustness of the indoor positioning system to the non-synchronization measurements.

Smart Device-Supported BDS/GNSS Real-Time Kinematic Positioning for Sub-Meter-Level Accuracy in Urban Location-Based Services.

Using mobile smart devices to provide urban location-based services (LBS) with sub-meter-level accuracy (around 0.5 m) is a major application field for future global navigation satellite system (GNSS) development. Real-time kinematic (RTK) positioning, which is a widely used GNSS-based positioning approach, can improve the accuracy from about 10–20 m (achieved by the standard positioning services) to about 3–5 cm based on the geodetic receivers. In using the smart devices to achieve positioning with sub-meter-level accuracy, a feasible solution of combining the low-cost GNSS module and the smart device is proposed in this work and a user-side GNSS RTK positioning software was developed from scratch based on the Android platform. Its real-time positioning performance was validated by BeiDou Navigation Satellite System/Global Positioning System (BDS/GPS) combined RTK positioning under the conditions of a static and kinematic (the velocity of the rover was 50–80 km/h) mode in a real urban environment with a SAMSUNG Galaxy A7 smartphone. The results show that the fixed-rates of ambiguity resolution (the proportion of epochs of ambiguities fixed) for BDS/GPS combined RTK in the static and kinematic tests were about 97% and 90%, respectively, and the average positioning accuracies (RMS) were better than 0.15 m (horizontal) and 0.25 m (vertical) for the static test, and 0.30 m (horizontal) and 0.45 m (vertical) for the kinematic test.

クロスカントリースキー競技クラシカル種目におけるスキー板およびサブ走法の選択に関する研究：スケーティング走法専用スキー板を使用したダブルポーリング走法およびヘリンボーン走法に着目して

The purpose of this study was to identify differences in (1) total skiing time and (2) lap time for different course situations in cross-country skiing (uphill, flat and downhill) between classical-style sub-techniques using classical skis and double poling and herringbone sub-techniques using skating skis. The subjects were 5 college cross-country skiers who performed at maximal effort in 2 different trials: classical-style sub-techniques while wearing classical-style skis (CL), and double poling and herringbone sub-techniques while wearing skating-style skis (DP). Skiing velocity was measured with a global navigation satellite system module and mobile PDA. The sub-techniques employed were recorded with a small video camera. It was found that a strategy using DP (1) significantly increased the skiing time, (2) increased the skiing velocity on downhill and decreased it on uphill, and (3) was associated with a tendency to use double poling on uphill.

GNSS/RFID Active Transponder Design

The paper describes a design of global navigation satellite system (GNSS)/Radio frequency identification (RFID) active transponder which is primarily designed for localization of objects as a part of localization system designated for efficient handling of situations with mass casualties. The precise localization is improved by differential GNSS. The block diagram of such GNSS/RFID active transponder is described including main operation procedures of the firmware. Measurement of the localization by algorithms of RTKLIB library and by algorithms of GNSS module is compared. Dynamic tests, i.e. GNSS/RFID active transponder placed in the moving car (50~kmph), and static tests, i.e. GNSS/RFID active transponder placed in the position for 15~min, are performed.

Evaluation of RTKLIB's Positioning Accuracy Using low-cost GNSS Receiver and ASG-EUPOS

The paper focuses on a comparison of different positioning methods provided by free and open source software (FOSS) package called RTKLIB. The RTKLIB supports real-time and post-processed positioning. The most important modes of operation tested by the authors are Kinematic, Static, Fixed and Precise Point Positioning (PPP). The data for evaluation were obtained from low-cost Global Navigation Satellite System (GNSS) receiver. The tested receiver was based on the u-blox's LEA-6T GNSS module. This receiver provides different types of information including raw carrier phase measurements. It gives the possibility for centimeter-level precision of positioning. As the supporting source of data ASG-EUPOS system was used. ASG-EUPOS is a Polish network of GNSS reference stations providing the real-time corrections and post processing services for the entire territory of Poland.