Precise point positioning is analysed with new ionosphere-free mixed code-carrier combinations of satellite-satellite single difference (SD) measurements. The large wavelength of 3.215 m and the low ...noise level of 3.76 cm of an L1-E5 linear combination enable reliable fixing of ambiguities with a sequential bootstrapping and an integer decorrelation transformation. This linear combination suppresses the L1 code noise and multipath by 23.5 dB. The bias estimation accuracy is improved by an additional ionosphere-free L1-E5 linear combination of time-differenced measurements that is uncorrelated with respect to the first linear combination. The SD biases of the discrimination maximizing linear combination are determined at a single reference station with an accuracy between a few millimeters and 1 cm within 5 min. These biases refer to a geometry-preserving linear combination and are directly applicable at the mobile receiver. Moreover, the SD phase and code biases on L1 and E5 are determined separately by subdividing the Galileo E5 band into the E5a, E5b and E5c band whereas the latter one corresponds to the central lobe between E5a and E5b.
Near-field antenna measurements can be efficiently performed with Unmanned Aerial Vehicles (UAVs). An accurate knowledge of the position of the UAV is needed for determination of the 3D antenna ...pattern. In this paper, we perform a Real-Time Kinematic (RTK) positioning of UAVs with Global Navigation Satellite System (GNSS) signals and assess the accuracy with a laser tracker that provides ranging measurements with a precision of up to 16μm. The measurement results show that the positioning solutions of the GNSS RTK system and of the Laser tracker agree within a few centimeters. This accuracy is also correctly indicated by the self-assessment of the RTK system.
The Snow Water Equivalent (SWE) is a key parameter for hydrological applications. In this paper, we describe a novel snow monitoring station that determines SWE solely from differential carrier phase ...measurements of both GPS and Galileo satellites. The SWE estimates are compared with several traditional sensors to demonstrate the achievable performance. The measurement results also show that just 4 Galileo satellites reduce the combined fixing time of RTK positioning by up to 3 minutes.
In this paper, a maximum a posteriori probability estimator is derived for determining the relative position and carrier phase integer ambiguities with GPS carrier phase measurements. The estimator ...is also applied to real measurements and enabled a heading determination with an accuracy of 0.5°/ baseline length m.
Real-Time Kinematic (RTK) positioning with Global Navigation Satellite Systems (GNSS) enables centimeter-level positioning accuracies. However, the small wavelength of the GNSS carrier signals often ...prevents a reliable ambiguity resolution. This paper proposes a cascaded RTK positioning with multifrequency linear combinations. The combinations are characterized by a large wavelength, which enables a robust ambiguity resolution even in the presence of uncorrected geometric and ionospheric biases at the price of a slightly increased noise level.
The World Health organization in its latest report on road safety states that 22% of all road traffic deaths comprise pedestrians, approximately 275,000 pedestrians worldwide. Based on an overview of ...typical accident scenarios, we argue how an ideal pedestrian safety system should look like. Then we investigate how much our approach of a pedestrian safety system, which we call "Wireless Seat Belt" (WSB), can satisfy the requirements of such an ideal system in terms of position accuracy. Next, we experimentally show what can be done with current smartphones in terms of these requirements. We show that current smartphone accuracy is not sufficient for reliable collision avoidance. To address this problem, we introduce and evaluate two approaches using context information to enable "off-the-shelf" smartphones to reach the required accuracy requirements.
Near-field antenna measurements with an Unmanned Aerial Vehicle (UAV) require an accurate 3D position and 3D attitude information. In this paper, we estimate the position and velocity of the UAV, the ...quaternion that describes its attitude, the carrier phase integer ambiguities related to both the attitude and position, and the accelerometer bias with a Kalman filter. The raw measurements were obtained from the ANavS Multi-Sensor RTK module with its 3 Multi-frequency, Multi-GNSS receivers and a MEMS-based Inertial Measurement Unit (IMU). We used the UAV of AeroXess to validate our method and achieved a centimeter-level positioning accuracy in both static and kinematic conditions.
Almanacs are satellite position and clock data of reduced precision, which are transmitted by navigation satellites to fasten signal acquisition. Currently, each satellite is transmitting the ...almanacs of all satellites independent of the receiver-satellite geometry. This means that the transmission of the complete almanacs takes 12 minutes for GPS. This paper suggests an optimized almanac transmission scheme, which takes the receiver-satellite geometry into account and thereby reduces the number of almanac transmissions for each satellite. The optimization of the subsets of satellites and of the order of transmissions within each subset reduces the number of almanac transmissions from 27 to 8 for Galileo. Moreover, the optimization of the almanacs also enables an approximately two times faster signal acquisition.
PDF
