Michael Meurer

German Aerospace Center (DLR) | DLR · Department of Navigation

For applications such as autonomous car driving and unmanned aerial vehicles (UAV), ensuring reliability, high accuracy and integrity of navigation services is crucial. This requires a sufficiently accurate modeling of potential threats and error contributions as well as monitoring the performance of Global Satellite Navigation Systems (GNSS). Inte...

The emergence of applications such as autonomous vehicles and UAVs (Unmanned Aerial Vehicles) has lately brought high precision positioning into the focus of the GNSS (Global Navigation Satellite System) community. Simultaneously, such autonomous applications fall under the category of SoL (Safety of Life), applications and therefore require strict...

One of the major error components of differential global navigation satellite systems is a multipath error in a reference station. This paper introduces a deep neural network based multipath modeling method. A signal to noise ratio, as well as satellite geometry, is used as a feature parameter to capture the variation of the multipath error caused...

In global navigation satellite systems (GNSSs), multipath propagation is to this day a major source of error. Especially in urban environments, satellite signals are reflected by buildings and other objects, leading to additional delayed signal replicas at the receiver. The frequent blockage of line-of-sight (LOS) signals further increases complexi...

The high relevance of GNSS for positioning and timing in different applications increase the risk of (intended or unintended) radio interference (e.g. jamming or spoofing). One of the most sophisticated and efficient countermeasure against this threat is an antenna array, which can utilize a spatial filter to mitigate malevolent signals (e.g. by pl...

Global navigation satellite systems (GNSSs) are the most significant service for global positioning and timing. The high relevance and wide spread of these systems contrast with the risk for interference or even manipulations of GNSS signals. One specific threat is GNSS spoofing. A spoofer counterfeits satellite signals to mislead the receiver to a...

Camera based visual navigation has great potentials for various applications, especially in satellite-signal-degenerated environments. However, the lack of integrity protections has constrained its utilization in safety-critical applications. Integrity characterizes the quality of the information that a navigation system delivers. Integrity framewo...

New GNSS applications demand resilience against radio interference and high position accuracy. Separately, these demands can be fulfilled by multi-antenna systems using spatial filtering and carrier phase positioning algorithms like real time kinematics (RTK), respectively. However, combining these approaches encounters a severe issue: The spatial...

Multipath propagation is still a major source of error in Global Navigation Satellite Systems (GNSSs), especially in urban areas. Here, satellite signals can be reflected by obstacles in the closer receiver environment, resulting in additional delayed signal replicas at the receiver. As a result, conventional GNSS receivers provide biased range est...

In Global Navigation Satellite Systems (GNSSs), multipath propagation is still a major source of error, in particular in urban environment. Obstacles in the nearer receiver environment can reflect satellite signals leading to additional delayed signal replicas at the receiver. This causes conventional GNSS receivers to provide biased range estimate...

Multipath propagation is to this day a major source of error in Global Navigation Satellite Systems (GNSSs), in particular in urban environments. Here, additional delayed signal replicas reach the receiver via one or multiple reflections from nearby obstacles. This causes biased range estimates in conventional receivers leading to Position, Velocit...

Interference signals are a severe threat to any GNSS receiver. Due to the low reception power of satellite signals, even comparably weak interferences can significantly decrease the positioning accuracy of the receiver or lead to a complete signal loss. Therefore, any active interference signal has to be mitigated to ensure a continuous and safe op...

The use of GNSS positioning in highly automated systems, like packet delivering using drones or self-driving cars, demands a reliable and accurate position estimation. At the same time the risk of radio-frequency interference(RFI), intentional or unintentional, increases. A promising countermeasure is to suppress the interference in the spatial dom...

For navigation in aviation, high performance requirements in terms of integrity, accuracy, continuity, availability, and robustness against interference need to be achieved. The Global Navigation Satellite System (GNSS) alone is not sufficiently accurate and cannot provide precision approach with the required integrity. The Ground Based Augmentatio...

Camera-based visual navigation techniques can provide six degrees-of-freedom estimates of position and orientation (or pose), and can be implemented at low cost in applications including autonomous driving, indoor positioning, and drone landing. However, feature matching errors may occur when associating measured features in camera images with mapp...

Radio frequency interference (RFI) poses a severe problem for conventional GNSS receivers. Even low powered RFI can block the reception of satellite signals and prevent a position determination. Antenna array systems have been proven suitable to counteract RFI by incorporating spatial processing techniques. The large size of uniform rectangular arr...

This paper analyzes the effect of error correlation on the SISRE bounding for GPS and Galileo satellites. For a given period of data collection, it computes the effective number of independent samples contained in a dataset applying an estimation variance analyses. Results show that the time between effective independent samples is highly dependent...

The use of GNSS positioning in highly automated systems, like packet delivering using drones or self-driving cars, demands a reliable and accurate position estimation. At the same time the risk for radio frequency interference (RFI), intentional or unintentional, increases. A promising countermeasure to this issue is RFI mitigation with spatial fil...

Global navigation satellite systems (GNSS) are used in many applications and have been part of our daily life since years. In this work error contributions based on the satellite hardware have been investigated and their impact on safety critical applications has been assessed. The paper starts with an introduction of the measurement facility and a...

The paper focuses on the use of GNSS constellation simulators for the performance evaluation of advanced anti-jamming and anti-spoofing techniques of GNSS receivers using multiple antennas in an antenna array. The use of antenna arrays and array signal processing enables a GNSS receiver to apply extremely efficient countermeasures to counteract rad...

Global Navigation Systems (GNSS) have an important role in the navigation in the air, at land and the sea. Especially for safety critical applications like advanced receiver autonomous integrity monitoring (ARAIM), ground based augmentation systems (GBAS) or using space based augmentation systems (SBAS) in general, the estimation and modeling of po...

The use of GNSS positioning in highly automated systems, like packet delivering using drones or self-driving cars, demands a reliable and accurate position estimation. At the same time the risk for interference, intentional or unintentional, increases. A promising countermeasure is to suppress the interference with spatial filters using an antenna...

An adequate design of the analogue frontend plays a crucial role for the achievable interference robustness of multi-antenna GNSS receivers. The behaviour of filtering, amplification and digital-to-analogue conversion are limiting factors for the effectiveness of all subsequent digital signal processing techniques. Any error in the analogue design...

While many existing systems are capable of supporting current and near-term plans in Alternative Position, Navigation, and Timing (APNT) services, it has become apparent that state-of-the-practice technologies will not support the most demanding Performance-Based Navigation (PBN) services. Specifically, to achieve the most demanding Required Naviga...

Ambiguous direction-of-arrival estimation is a key problem for uniformly distributed antenna arrays with inter-element spacing exceeding half of the carrier wavelength. The primary reason behind such ambiguity are the grating lobes generated in the radiation patterns due to insufficient spatial sampling. An L-shaped orthogonal arrangement of radiat...

This work presents signal analysis results based on observations of the new BeiDou 3 signals, which appeared in the years 2017 to 2019. After a brief introduction of the measurement facility, the basic analysis of the quality of the signals in spectral and modulation domains is introduced. This covers the transition from BeiDou 2 up to BeiDou 3 inc...

The global positioning system (GPS) is the pioneer under the present and developing global Navigation satellite systems (GNSS). In the beginning of this year a new milestone has been reached with the start of the signal transmission of the first GPS Block III space craft, which was launched with a Falcon 9 rocket from Cape Canaveral, Florida, on De...

The signal-in-space of the first GPS Block III spacecraft is analyzed based on radio frequency measurements collected with a 30-m high-gain dish antenna as well as data from geodetic GPS receivers. The spectral properties and modulation characteristics are discussed with focus on the L1 band, which employs a novel interlaced majority voting techniq...

In this paper we present a novel approach to interference mitigation. We propose to equip a GNSS receiver with a diversely polarized antenna array in order to combine signal processing in the spatial and in the polarization domain in a novel way. The new algorithm is evaluated by means of measurement data achieved during a measurement campaign whic...

Nowadays, one can use four global navigation satellite systems (GNSS). Two of them are complete constellations (GPS, Glonass) and two (BeiDou, Galileo) are already providing initial services and will be finished in the near future. Additionally, satellite-based augmentation systems (SBAS) and regional systems like WAAS, EGNOS, GAGAN or QZSS complem...

Electromagnetic interference can degrade civil GNSS signals and services, and in some cases result in integrity failures. The aviation community is well-aware of such threats due to the proliferation of interfering-capable equipment including personal electronic devices (PEDs), personal privacy devices (PPDs), GNSS repeaters, mis-operated test equi...

In this work, we present mitigation algorithms to protect GNSS receivers against malicious interference. Maritime appli- cations with an antenna array-based receiver are considered as a use case. A two-stage mitigation algorithm, that tackles multipath and radio frequency interference (RFI), caused by personal privacy devices (PPD) or additive whi...

This paper presents a methodology to build multipath models for aviation use of new GPS and Galileo signals. The estimation of airframe multipath errors makes use of carrier phase measurements, thus it is affected by the integer ambiguities. A new method for removing the ambiguities from the multipath estimation is presented. The method is suitable...

In this work, we present an antenna array based algorithm to detect GNSS repeater and/or spoof- ing attacks with an experimental validation. With an ar- ray receiver capable of measuring the impinging rang- ing signals direction of arrival in terms of azimuth and elevation, it is possible to estimate the antenna plat- forms attitude. The fact that...

An international maritime measurement campaign on board of a large container ship was carried out in order to detect and record radio frequency interference events in the frequency bands allocated to open services of global satellite navigation systems. The measurement set-up consists of a conformal seven elements antenna array, a data recorder sys...

The use of GNSS in safety critical applications imposes stringent requirements in terms of signal quality and integrity. A central element of the GNSS signal quality evaluation is the verification of the available power levels at user location. Given that the state of the GNSS satellite antenna may suffer some level of degradation due to the heavy...

In terms of satellite navigation being resistant against deliberate and non-deliberate interference, state-of-the-art antenna array systems suffer from the required large installation area, leaving them essentially to specific applications in ground-based traffic like platooning or precision farming. To address the needs of typical passenger cars o...

Durch die systembedingt sehr niedrige Empfangsleistung der Navigationssignale von GNSS sind Empfänger allgemein sehr leicht durch elektromagnetische Störungen zu beeinflussen. Unbeabsichtigte Störungen beispielsweise durch terrestrische Radarsignale oder absichtliche Störungen mit so genannten Personal Privacy Devices (PPD) können eine Positionsbes...

Antenna array systems have been proven suitable to counteract radio frequency interference. The large size of uniform rectangular arrays with half-wave antenna spacing for the GNSS frequency bands impedes an installation in the consumer automotive area, where aesthetic design is a unique selling point and hence desired by the industry and its custo...

The use of GNSS positioning in highly automated systems, like packet delivering using drones or self-driving cars, demands a reliable position estimation. One major risk to the position estimation is the so called spoofing threat. A spoofer fakes satellite signals in order to mislead a GNSS receiver into estimating a wrong user position. A lot of r...

With the increasing number of satellites broadcasting signals on a second ARNS frequency (L5/E5a) available the dual frequency processing becomes a promising option for the next generation aviation users. In this context, characterizing the error sources of the navigation solution is crucial. This evaluation is particularly important because the ne...

The ionospheric delay of global navigation satellite systems (GNSS) signals typically is compensated by adding a correction value to the pseudorange measurement. We examine the ionospheric signal distortion beyond a constant delay. These effects become increasingly significant with increasing signal bandwidth and hence more critical for the new bro...

The combination of Global Navigation Satellite Systems (GNSS) and Inertial Navigation System (INS) has become the baseline of many vehicular applications. However, in challenging GNSS scenarios, classical GNSS/INS integration estimators are very sensitive to multiple measurement faults (e.g., due to multipath). In this work, we design a tightly-cou...