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Publications (46)
Autonomous vehicle technology is rapidly advancing (see “Summary”). A key enabling factor is the advancing capabilities and declining cost of computing and sensing systems that enable sensor fusion for awareness of the vehicle’s state and surroundings (see “Nontechnical Article Summary”). For control purposes, the vehicle’s state must be estimated...
The use of GNSS as main navigation technique is limited in railway and road applications by the harsh signal reception conditions encountered in typical environments such as urban or natural canyons, buildings, tunnels etc. Therefore, in these application fields, sensor fusion frameworks are typically deployed to take advantage of the onboard senso...
This paper analyzes the signals of different commercial-off-the-shelf (COTS) privacy protection devices (PPDs), and compares several mitigation algorithms applied to these jamming signals. A review of the mitigation algorithms is presented, including the theoretical requirements. This paper allows an end-to-end comparison of the algorithms in terms...
In this paper a filter bank pulse blanking (FBPB) approach is presented as a wide-band (WB) mitigation method for chirp-like interferences. This method uses a filter bank to separate the received global navigation satellite system (GNSS) signal in different sub-bands. As the WB chirp is broken into several segments, standard time domain pulse blank...
This chapter discusses the role of global navigation satellite systems (GNSS
s) and inertial measurements in the estimation of the state vector for a maneuvering system. The chapter considers the main objectives of accuracy, continuity, availability, and integrity; and, the contributions that the different types of sensors make toward achieving the...
The accuracy and availability of the users of satellite navigation (satnav) receivers is heavily influenced by the environment they are located in. Multipath propagation, signal shadowing, and blockage lower a satnav user's experience to a large extent especially in built-up areas. A precise description of the wave propagation mechanisms is hence c...
The reception and processing of Galileo's Public Regulated Service (PRS) imposes challenges to designers of appropriate acquisition and tracking techniques. For one, high bandwidths are required to sample and process this signal, and second, the PRS is encrypted which limits its access to authorized entities. Currently available prototype receivers...
The signals of the satellites of a Global Navigation Satellite System (GNSS) are received after having traveled through different media and environments. Obstacles in the receiver's environment cause multipath propagation and result in range estimation errors. There are stochastic models for multipath propgation channels, like urban and sub-urban a...
While for airborne users integrity concepts for Global Navigation Satellite System (GNSS) are widely used, integrity algorithms for non-aviation users have not yet been developed with a comparable level of maturity. The major difference between these user groups is the threat space: For the aviation user, the main threat is an erroneous Signal-in-S...
A device for detecting and tracking vehicles includes a position-determining device for determining a current vehicle position, a transmitting device for transmitting the current vehicle position to a receiver via a communication channel, and a device for detecting an activated interfering transmitter and for triggering an action depending on the d...
This paper features an experimental Galileo PRS receiver with a novel BOC tracking method and interference mitigation algorithms in time, frequency and spatial domain. The modified BaSE-II hardware architecture is outlined including a newly designed miniaturized 2x2 array antenna. A new, reliable and robust BOC tracking method is presented that ful...
The GPS M-Code, Galileo PRS Service, and Galileo Open Service on E1 use a Binary Offset Carrier modulation. The autocorrelation function of a BOC signal has multiple peaks. The main peak of the ACF is much narrower than the peak of the corresponding BPSK signal, which offers the potential for increased tracking accuracy and better multipath resista...
The processing of Binary Offset Carrier (BOC) signals as transmitted by current Global Navigation Satellite Systems (GNSSs) offers potentially better tracking accuracy and a higher multipath rejection. Yet, the presence of multiple peaks of the BOC signals’ auto-correlation functions (acfs) results in multiple stable but false tracking points in ad...
Nearly all Global Navigation Satellite Systems (GNSS) use Binary Offset Carrier (BOC) for their current or modernized signals. Although BOC signals have many advantages over the legacy BPSK modulated ones, BOC tracking is more challenging due to its multiple peaks in the autocorrelation function. This paper describes a hardware architecture, its im...
GNSSs like the GPS, Galileo, and Compass transmit or will transmit signals which are modulated using Binary Offset Carriers (BOC). Receivers can track these signals with higher accuracy and better multipath rejection performance than the legacy GPS signals which employ Binary Phase Shift Keying modulations. A downside of these signals are the multi...
The paper presents the hardware architecture of the Galileo PRS receiver developed within the BaSE project, and describes the core technologies required for using the Galileo PRS service. The approaches for increasing the robustness against radio frequency interference by using single sideband tracking techniques, adaptive notch filtering and pulse...
This paper presents the architecture, core technologies, system development, and setup of the BaSE Galileo PRS receiver. The receiver is capable of processing Galileo E1/E6 PRS signals with broad bandwidth. In particular, its hard- and software receiver components are presented and a robust tracking method of the BOCc-modulated PRS signals is discu...
Measurements based on the Galileo experimental sensor stations have confirmed the expectations regarding the stability of the atomic clocks on-board the GIOVE-A and GIOVE-B satellites. These results are very encouraging for the performance of the Master Time Reference (MTR) generated by the Clock Monitoring and Control Unit (CMCU) on-board the futu...
The use of natural features for vision based navigation of an indoor Vertical-Take-Off-and-Landing (VTOL) Micro Aerial Vehicle (MAV) named Air-Quad is presented. Air-Quad is a small four-rotor helicopter developed at the ITE.Such a helicopter needs reliable attitude information. The measurements of the used MEMS gyroscopes and accelerometers are co...
This paper focusses on the automated detection and tracking of moving objects in a camera sequence, that is provided by a small, electrically powered four-rotor helicopter in a hover-and-stare scenario. Two different algorithms for identifying independently moving areas are investigated and compared. The first approach bases on the previous compens...
Unmanned aerial vehicles (UAV) can be used for versatile surveillance and reconnaissance missions. If a UAV is capable of flying automatically on a predefined path the range of possible applications is widened significantly. This paper addresses the development of the integrated GPS/INS/MAG navigation system and a waypoint navigator for a small ver...
This paper compares several approaches of GNSS/INS integration. Tightly coupled and loosely coupled approaches are discussed as well as an approach that tightly integrates differential GNSS and inertial navigation with carrier phase ambiguity resolution. Hence, centimetre accuracy can be achieved with a tightly coupled system. The approach can be c...
During the last years, there is an increasing demand for cheap and easy to operate platforms for surveillance and reconnaissance purposes. Therefore, the development of micro aerial vehicles is receiving an increasing attention. However, VTOL-MAVs often show an inherent instability that makes at least an automatic stabilization necessary, because o...
In tightly coupled GPS/INS integration, the data fusion algorithm is faced with nonlinear system dynamics and measurement models. The extended Kalman filter (EKF) approximates the propagation of Gaussian random vectors through these nonlinear equations using a linear transformation. This captures mean and covariance to first order accuracy only. Si...
A tightly coupled GPSANS system is characterized by the fact that pseudorange and deltarange measurements are processed in the navigation filter in order to estimate the errors of the inertial navigation solution and to calibrate the inertial measurement unit. In this paper, the usage of time differenced carrier phase measurements instead of the de...
This paper describes a high accurate tightly coupled, differentially corrected GNSS/INS system for survey applications in post-processing mode. A Kalman filter is described, that calculates the navigation solution as well as the the GNSS carrier phase integer ambiguities. The LAMEBDA method is used to resolve the integer ambiguities. To achieve an...
This paper adresses the fusion of GPS measurements and inertial sensor data in tightly coupled GPS/INS navigation systems. Usually, an extended Kalman filter (EKF) is applied for this task. However, as the system dynamic model as well as the pseudorange and deltarange measurement models are nonlinear, the EKF is a sub-optimal choice from a theoreti...
An approach to enhance the performance of tightly coupled GPS/INS systems is described. First, the advantages of tightly coupled systems compared to loosely coupled systems are clarified. Then, it is shown in hardware-in-the-loop tests and in a test drive that processing time differenced carrier phase measurements instead of delta-range measurement...
We present a new method for the simulation of the power supply system on multilayer substrates of multichip modules (MCM). In particular we investigate the efficiency of extended high capacitance layers used as decoupling capacitors. The proposed method works with a lumped element FDTD technique which facilitates electromagnetic simulation of the s...
In integrated navigation systems Kalman filters are widely used to increase the accuracy and reliability of the navigation solution. Usually, an indirect Kalman filter formulation is applied to estimate the errors of an INS strapdown algorithm (SDA), which are used to correct the SDA. In contrast to that, in the direct Kalman filter formulation tot...
Thesis (doctoral)--University Fridericiana Karlsruhe, 2003.