Constant Envelope Multiplexing of Multi-Carrier DSSS Signals Considering Sub-Carrier Frequency Constraint

With the development of global navigation satellite systems (GNSS), multiple signals modulated on different sub-carriers are needed to provide various services and to ensure compatibility with previous signals. As an effective method to provide diversified signals without introducing the nonlinear distortion of High Power Amplifier (HPA), the multi-carrier constant envelope multiplexing is widely used in satellite navigation systems. However, the previous method does not consider the influence of sub-carrier frequency constraint on the multiplexing signal, which may lead to signal power leakage. By determining the signal states probability according to the sub-carrier frequency constraint and solving the orthogonal bases according to the homogeneous equations, this article proposed multi-carrier constant envelope multiplexing methods based on probability and homogeneous equations. The analysis results show that the methods can multiplex multi-carrier signals without power leakage, thereby reducing the impact on signal ranging performance. Meanwhile, the methods could reduce the computation complexity. In the case of three different carriers multiplexing, the number of optimization equations is reduced by nearly 66%.

Download Full-text

Co-location of SLR and GNSS techniques onboard Galileo and GLONASS satellites

10.5194/egusphere-egu21-7142 ◽

2021 ◽

Author(s):

Grzegorz Bury ◽

Krzysztof Sośnica ◽

Radosław Zajdel ◽

Dariusz Strugarek ◽

Urs Hugentobler

Keyword(s):

Orbital Plane ◽

Terrestrial Reference Frame ◽

Global Navigation Satellite Systems ◽

Navigation Systems ◽

Local Ties ◽

Satellite Systems ◽

The Impact ◽

Space Ties ◽

Gnss Observations

All satellites of the Galileo and GLONASS navigation systems are equipped with laser retroreflector arrays for Satellite Laser Ranging (SLR). SLR observations to Global Navigation Satellite Systems (GNSS) provide the co-location of two space geodetic techniques onboard navigation satellites.SLR observations, which are typically used for the validation of the microwave-GNSS orbits, can now contribute to the determination of the combined SLR+GNSS orbits of the navigation satellites. SLR measurements are especially helpful for periods when the elevation of the Sun above the orbital plane (&#946;&#160;angle) is the highest. The quality of Galileo-IOV orbits calculated using combined SLR+GNSS observations improves from 36 to 30 mm for &#946;>&#8201;60&#176; as compared to the microwave-only solution.&#160;Co-location of two space techniques allows for the determination of the linkage between SLR and GNSS techniques in space. Based on the so-called space ties, it is possible to determine the 3D vector between the ground-based co-located SLR and GNSS stations and compare it with the local ties which are determined using the ground measurements. The agreement between local ties derived from co-location in space and ground measurements is at the level of 1 mm in terms of the long-term median values for the co-located station in Zimmerwald, Switzerland.We also revise the approach for handling the SLR range biases which constitute one of the main error sources for the SLR measurements. The updated SLR range biases consider now the impact of not only of SLR-to-GNSS observations but also the SLR observations to LAGEOS and the microwave GNSS measurements. The updated SLR range biases improve the agreement between space ties and local ties from 34 mm to 23&#160;mm for the co-located station in Wettzell, Germany.Co-location of SLR and GNSS techniques onboard navigation satellites allows for the realization of the terrestrial reference frame in space, onboard Galileo and GLONASS satellites, independently from the ground measurements. It may also deliver independent information on the local tie values with full variance-covariance data for each day with common measurements or can contribute to the control of the ground measurements as long as both GNSS and SLR-to-GNSS observations are available.

Download Full-text

The Potential Impact of GNSS/INS Integration on Maritime Navigation

Journal of Navigation ◽

10.1017/s0373463307004614 ◽

2008 ◽

Vol 61 (2) ◽

pp. 221-237 ◽

Cited By ~ 12

Author(s):

Terry Moore ◽

Chris Hill ◽

Andy Norris ◽

Chris Hide ◽

David Park ◽

...

Keyword(s):

Field Trials ◽

Global Navigation Satellite Systems ◽

Navigation Systems ◽

Inertial Navigation Systems ◽

Satellite Systems ◽

Time Period ◽

Maritime Navigation ◽

The Uk ◽

Global Navigation Satellite ◽

The Impact

A version of this paper was presented at ENC-GNSS 2007, Geneva. Its reproduction was kindly authorised by the ENC-GNSS 07 Paper Selection Committee.The General Lighthouse Authorities of the UK & Ireland commissioned an assessment of the impact that the integration of Global Navigation Satellite Systems (GNSS) with Inertial Navigation Systems (INS) would have on the aids to navigation (AtoN) services currently provided, and those to be provided in the future. There is concern about the vulnerability of GNSS, and the provision of complementary and backup systems is seen to be of great importance. The integration of INS could provide an independent and self-contained navigation system, for a limited time period, invulnerable to external intentional or unintentional interference, or the influences of changes in national policies. The study included an analysis of the potential use of GNSS-INS in three of the four phases of a vessel's voyage: coastal, port approach and docking. The project consisted of a technology assessment, looking at the different inertial technologies that might be suitable for each phase. This was followed by a technology proving stage, evaluating suitable equipment using simulation and field trials to prove that the claimed performance could be achieved in practice. The final stage of the project was to assess the effects of the availability of such systems on existing and planned aids to navigation services.

Download Full-text

The Impact of Vehicle Maneuvers on the Attitude Estimation of GNSS / INS for Mobile Mapping

Journal of Applied Geodesy ◽

10.1515/jag-2015-0002 ◽

2015 ◽

Vol 9 (3) ◽

Cited By ~ 4

Author(s):

You Li ◽

Xiaoji Niu ◽

Yahao Cheng ◽

Chuang Shi ◽

Naser El-Sheimy

Keyword(s):

Angular Velocity ◽

Attitude Estimation ◽

Global Navigation Satellite Systems ◽

Estimation Accuracy ◽

Navigation Systems ◽

Mobile Mapping ◽

Satellite Systems ◽

Angular Velocities ◽

Global Navigation Satellite ◽

The Impact

AbstractIntegrated Global Navigation Satellite Systems (GNSS) and Inertial Navigation Systems (INS) are the core of georeferencing Mobile Mapping Systems (MMS) data. Divergence of attitude errors is a dominant issue when an INS has to work as a stand-alone system for extended periods. This issue can be mitigated by taking specific vehicle maneuvers to make attitude errors observable. Since MMS applications are time consuming and costly, it is preferable to design the trajectory and motion of the mapping vehicles in advance, to guarantee the accuracy of the attitude estimation and minimize the cost. This article investigates the estimation accuracy of attitude under different vehicle maneuvers theoretically through the observability analysis method. Both theoretical analysis and tests show that the attitude estimation is significantly related with the type of vehicle maneuvers and motion parameters such as velocity, acceleration, and angular velocity. The motion with varying angular velocities is the most efficient motion to enhance the estimation of all attitude angles; the motion with varying accelerations can improve the yaw and pitch but has no effect on enhancing the roll. The uniform circular motion can improve the roll and pitch but has slight or no impact on enhancing the yaw (depending on the forward accelerometer error, the forward velocity, and the vertical angular velocity); the linear motion with a constant acceleration can improve the yaw (depending on the cross-track accelerometer error and the forward acceleration) and weakly improve the pitch but cannot improve the roll. The physical interpretations of these properties are also provided. The “S”-shaped motion with varying angular velocities is suggested for efficient attitude estimation; however, the circle, or “8”-shaped motion with uniform angular velocity, is not efficient for MMS applications.

Download Full-text

Robust TOA-Based UAS Navigation under Model Mismatch in GNSS-Denied Harsh Environments

Remote Sensing ◽

10.3390/rs12182928 ◽

2020 ◽

Vol 12 (18) ◽

pp. 2928

Author(s):

Jan Mortier ◽

Gaël Pagès ◽

Jordi Vilà-Valls

Keyword(s):

Intelligent Transportation Systems ◽

Autonomous Systems ◽

Real Life ◽

Transportation Systems ◽

Urban Environments ◽

Global Navigation Satellite Systems ◽

Ultra Wideband ◽

Time Of Arrival ◽

Navigation Systems ◽

Satellite Systems

Global Navigation Satellite Systems (GNSS) is the technology of choice for outdoor positioning purposes but has many limitations when used in safety-critical applications such Intelligent Transportation Systems (ITS) and Unmanned Autonomous Systems (UAS). Namely, its performance clearly degrades in harsh propagation conditions and is not reliable due to possible attacks or interference. Moreover, GNSS signals may not be available in the so-called GNSS-denied environments, such as deep urban canyons or indoors, and standard GNSS architectures do not provide the precision needed in ITS. Among the different alternatives, cellular signals (LTE/5G) may provide coverage in constrained urban environments and Ultra-Wideband (UWB) ranging is a promising solution to achieve high positioning accuracy. The key points impacting any time-of-arrival (TOA)-based navigation system are (i) the transmitters’ geometry, (ii) a perfectly known transmitters’ position, and (iii) the environment. In this contribution, we analyze the performance loss of alternative TOA-based navigation systems in real-life applications where we may have both transmitters’ position mismatch, harsh propagation environments, and GNSS-denied conditions. In addition, we propose new robust filtering methods able to cope with both effects up to a certain extent. Illustrative results in realistic scenarios are provided to support the discussion and show the performance improvement brought by the new methodologies with respect to the state-of-the-art.

Download Full-text

Assessment of the Implementation of GNSS into Gliding

MAD - Magazine of Aviation Development ◽

10.14311/mad.2017.04.01 ◽

2017 ◽

Vol 5 (4) ◽

pp. 6

Author(s):

Tomáš Kubáč ◽

Jakub Hospodka

Keyword(s):

Global Navigation Satellite Systems ◽

Navigation Satellite ◽

Navigation Systems ◽

Satellite Systems ◽

Global Navigation ◽

Global Navigation Satellite ◽

Global Navigation Systems ◽

Usage Preference ◽

Selection Of ◽

Wide Usage

Global navigation satellite systems are increasingly part of our lives and many industries including aviation. Glider flying is no exception in this trend. Global navigation satellite systems were part of gliding since the early 1990s. First as official recording devices for simple evidence of sporting performances, then as navigation systems, anti-collision systems and emergency location transmitters. Development of recording application was initiated and supported by International Gliding Commission of World Air Sports Federation in way of certifications for flight recorders. The use of navigation and other modern instruments in gliders has brought many benefits but also risks. However, the advantages outweigh the disadvantages and these systems are now integral part of gliding. With this wide usage of global navigation satellite systems devices, there is great many possibilities how and in which way one can use these systems. Pilots must orient themselves in varied selection of products, which they can use to choose one solution, that fits him. Therefore, to find out how and if pilots use these devices, we created questionnaire survey among 143 Czech glider pilots. We found out, that 84% of them are using global navigation satellite systems devices for official record of flight and for navigation as well. More than half of pilots is using free, not built-in devices. Most common devices are mobile phones up to 5 inches of screen diagonal in combination with approved flight recorder without display. If pilots use mobile device for navigation, 52% of them is using one with Windows Mobile operating system, 33% use Android. Navigational software on these mobile devices is then almost tied between SeeYou Mobile, XCSoar and LK8000. Knowledge about usage preference of global navigation systems devices should help pilots with selection and overall orientation in subject.

Download Full-text

Validating the impact of various ionosphere correction on mid to long baselines and point positioning using GPS dual-frequency receivers

Journal of Applied Geodesy ◽

10.1515/jag-2021-0040 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Alaa A. Elghazouly ◽

Mohamed I. Doma ◽

Ahmed A. Sedeek

Keyword(s):

Geomagnetic Storms ◽

Global Navigation Satellite Systems ◽

Electron Content ◽

Assessment Procedure ◽

Vertical Total Electron Content ◽

Dual Frequency ◽

Total Electron ◽

Satellite Systems ◽

Point Positioning ◽

The Impact

Abstract Due to the ionosphere delay, which has become the dominant GPS error source, it is crucial to remove the ionospheric effect before estimating point coordinates. Therefore, different agencies started to generate daily Global Ionosphere Maps (GIMs); the Vertical Total Electron Content (VTEC) values represented in GIMs produced by several providers can be used to remove the ionosphere error from observations. In this research, An analysis will be carried with three sources for VTEC maps produced by the Center for Orbit Determination in Europe (CODE), Regional TEC Mapping (RTM), and the International Reference Ionosphere (IRI). The evaluation is focused on the effects of a specific ionosphere GIM correction on the precise point positioning (PPP) solutions. Two networks were considered. The first network consists of seven Global Navigation Satellite Systems (GNSS) receivers from (IGS) global stations. The selected test days are six days, three of them quiet, and three other days are stormy to check the influence of geomagnetic storms on relative kinematic positioning solutions. The second network is a regional network in Egypt. The results show that the calculated coordinates using the three VTEC map sources are far from each other on stormy days rather than on quiet days. Also, the standard deviation values are large on stormy days compared to those on quiet days. Using CODE and RTM IONEX file produces the most precise coordinates after that the values of IRI. The elimination of ionospheric biases over the estimated lengths of many baselines up to 1000 km has resulted in positive findings, which show the feasibility of the suggested assessment procedure.

Download Full-text

An Advanced Receiver Autonomous Integrity Monitoring (ARAIM) Ground Monitor Design to Estimate Satellite Orbits and Clocks

Journal of Navigation ◽

10.1017/s0373463320000181 ◽

2020 ◽

Vol 73 (5) ◽

pp. 1087-1105

Author(s):

Yawei Zhai ◽

Jaymin Patel ◽

Xingqun Zhan ◽

Mathieu Joerger ◽

Boris Pervan

Keyword(s):

Measurement Errors ◽

Satellite Orbit ◽

Global Navigation Satellite Systems ◽

Estimation Accuracy ◽

Satellite Orbits ◽

Integrity Monitoring ◽

Satellite Systems ◽

Receiver Autonomous Integrity Monitoring ◽

The Impact ◽

Advanced Receiver

This paper describes a method to determine global navigation satellite systems (GNSS) satellite orbits and clocks for advanced receiver autonomous integrity monitoring (ARAIM). The orbit and clock estimates will be used as a reference truth to monitor signal-in-space integrity parameters of the ARAIM integrity support message (ISM). Unlike publicly available orbit and clock products, which aim to maximise estimation accuracy, a straightforward and transparent approach is employed to facilitate integrity evaluation. The proposed monitor is comprised of a worldwide network of sparsely distributed reference stations and will employ parametric satellite orbit models. Two separate analyses, covariance analysis and model fidelity evaluation, are carried out to assess the impact of measurement errors and orbit model uncertainty on the estimated orbits and clocks, respectively. The results indicate that a standard deviation of 30 cm can be achieved for the estimated orbit/clock error, which is adequate for ISM validation.

Download Full-text

Impact of robot antenna calibration on dual-frequency smartphone-based high-accuracy positioning: a case study using the Huawei Mate20X

GPS Solutions ◽

10.1007/s10291-020-01048-0 ◽

2020 ◽

Vol 25 (1) ◽

Author(s):

Francesco Darugna ◽

Jannes B. Wübbena ◽

Gerhard Wübbena ◽

Martin Schmitz ◽

Steffen Schön ◽

...

Keyword(s):

Ambiguity Resolution ◽

High Accuracy ◽

Global Navigation Satellite Systems ◽

Test Case ◽

Dual Frequency ◽

Main Site ◽

Satellite Systems ◽

The Individual ◽

The Impact ◽

Antenna Calibration

Abstract The access to Android-based Global Navigation Satellite Systems (GNSS) raw measurements has become a strong motivation to investigate the feasibility of smartphone-based positioning. Since the beginning of this research, the smartphone GNSS antenna has been recognized as one of the main limitations. Besides multipath (MP), the radiation pattern of the antenna is the main site-dependent error source of GNSS observations. An absolute antenna calibration has been performed for the dual-frequency Huawei Mate20X. Antenna phase center offset (PCO) and variations (PCV) have been estimated to correct for antenna impact on the L1 and L5 phase observations. Accordingly, we show the relevance of considering the individual PCO and PCV for the two frequencies. The PCV patterns indicate absolute values up to 2 cm and 4 cm for L1 and L5, respectively. The impact of antenna corrections has been assessed in different multipath environments using a high-accuracy positioning algorithm employing an undifferenced observation model and applying ambiguity resolution. Successful ambiguity resolution is shown for a smartphone placed in a low multipath environment on the ground of a soccer field. For a rooftop open-sky test case with large multipath, ambiguity resolution was successful in 19 out of 35 data sets. Overall, the antenna calibration is demonstrated being an asset for smartphone-based positioning with ambiguity resolution, showing cm-level 2D root mean square error (RMSE).

Download Full-text

Kalman Filter-Based RAIM for Reliable Aircraft Positioning with GPS and NavIC Constellations

Sensors ◽

10.3390/s20226606 ◽

2020 ◽

Vol 20 (22) ◽

pp. 6606

Author(s):

Susmita Bhattacharyya ◽

Dinesh Mute

Keyword(s):

Kalman Filter ◽

Weighted Least Squares ◽

Unmanned Aircraft ◽

Global Navigation Satellite Systems ◽

Navigation Systems ◽

Satellite Systems ◽

Vector Tracking ◽

Receiver Autonomous Integrity Monitoring ◽

Global Navigation Satellite ◽

Computational Resources

This paper presents a novel Kalman filter (KF)-based receiver autonomous integrity monitoring (RAIM) algorithm for reliable aircraft positioning with global navigation satellite systems (GNSS). The presented method overcomes major limitations of the authors’ previous work, and uses two GNSS, namely, Navigation with Indian Constellation (NavIC) of India and the Global Positioning System (GPS). The algorithm is developed in the range domain and compared with two existing approaches—one each for the weighted least squares navigation filter and KF. Extensive simulations were carried out for an unmanned aircraft flight path over the Indian sub-continent for validation of the new approach. Although both existing methods outperform the new one, the work is significant for the following reasons. KF is an integral part of advanced navigation systems that can address frequent loss of GNSS signals (e.g., vector tracking and multi-sensor integration). Developing KF RAIM algorithms is essential to ensuring their reliability. KF solution separation (or position domain) RAIM offers good performance at the cost of high computational load. Presented range domain KF RAIM, on the other hand, offers satisfactory performance to a certain extent, eliminating a major issue of growing position error bounds over time. It requires moderate computational resources, and hence, shows promise for real-time implementations in avionics. Simulation results also indicate that addition of NavIC alongside GPS can substantially improve RAIM performance, particularly in poor geometries.

Download Full-text

An Innovative Approach for Atmospheric Error Mitigation Using New GNSS Signals

Journal of Navigation ◽

10.1017/s0373463311000373 ◽

2011 ◽

Vol 64 (S1) ◽

pp. S211-S232 ◽

Cited By ~ 7

Author(s):

Lei Yang ◽

Zeynep Elmas ◽

Chris Hill ◽

Marcio Aquino ◽

Terry Moore

Keyword(s):

High Accuracy ◽

Global Navigation Satellite Systems ◽

Tropospheric Delay ◽

Atmospheric Effects ◽

Navigation Satellite ◽

Navigation Systems ◽

Satellite Systems ◽

Error Mitigation ◽

Satellite Navigation Systems ◽

Global Navigation Satellite

New signals from the modernised satellite navigation systems (GPS and GLONASS) and the ones that are being developed (COMPASS and GALILEO) will present opportunities for more accurate and reliable positioning solutions. Successful exploitation of these new signals will also enable the development of new markets and applications for difficult environments where the current Global Navigation Satellite Systems (GNSS) cannot provide satisfying solutions. This research is aiming to exploit the improvement in monitoring, modelling and mitigating the atmospheric effects using the increased number of signals from the future satellite systems. Preliminary investigations were conducted on the numerical weather parameter based horizontal tropospheric delay modelling, as well as the ionospheric higher order and scintillation effects. Results from this research are expected to provide a potential supplement to high accuracy positioning techniques.

Download Full-text