Efficient Delay Tracking Methods with Sidelobes Cancellation for BOC-Modulated Signals

In positioning applications, where the line of sight (LOS) is needed with high accuracy, the accurate delay estimation is an important task. The new satellite-based positioning systems, such as Galileo and modernized GPS, will use a new modulation type, that is, the binary offset carrier (BOC) modulation. This type of modulation creates multiple peaks (ambiguities) in the envelope of the correlation function, and thus triggers new challenges in the delay-frequency acquisition and tracking stages. Moreover, the properties of BOC-modulated signals are yet not well studied in the context of fading multipath channels. In this paper, sidelobe cancellation techniques are applied with various tracking structures in order to remove or diminish the side peaks, while keeping a sharp and narrow main lobe, thus allowing a better tracking. Five sidelobe cancellation methods (SCM) are proposed and studied: SCM with interference cancellation (IC), SCM with narrow correlator, SCM with high-resolution correlator (HRC), SCM with differential correlation (DC), and SCM with threshold. Compared to other delay tracking methods, the proposed SCM approaches have the advantage that they can be applied to any sine or cosine BOC-modulated signal. We analyze the performances of various tracking techniques in the presence of fading multipath channels and we compare them with other methods existing in the literature. The SCM approaches bring improvement also in scenarios with closely-spaced paths, which are the most problematic from the accurate positioning point of view.</p

Design and Validation of a Software Receiver for Galileo

This paper presents a new concept of software-based GNSS receivers for the Binary Offset Carrier signals of the Galileo testbed satellites, Giove-A and Giove-B. The receiver designed in Matlab must be able to acquire, track and demodulate both signals. Its advantages in terms of flexibility and reconfigurability make it an excellent instrument to test new designs or new prototypes as a previous stage on a hardware implementation

Semi-Analytic Techniques for Fast MATLAB Simulations

Semi-analytic techniques are a powerful tool for the analysis of complex systems. In the semi-analytic framework, the knowledge of the system under analysis is exploited to reduce the computational load and complexity that full Monte Carlo simulations would require. In this way, the strengths of both analytical and Monte Carlo methods are effectively combined. The main goal of this chapter is to provide a general overview of semi-analytic techniques for the simulation of communications systems. Specific emphasis is given to their implementation in Matlab and two examples from the communications and navigation context are analyzed in detail. More specifically, the impact of RF interference on acquisition and tracking, the two main stages of a Global Navigation Satellite System (GNSS) receiver, are considered. Although semi-analytic techniques have been considered in textbooks on simulations, limited attention has been provided to their analysis and implementation. This chapter mainly focuses on these two aspects with specific emphasis on the potential of the Matlab environment for their implementation.JRC.G.6-Security technology assessmen

The Effects of GPS M-Code on Radar Detection

The GPS system is undergoing a modernization effort which will add several new signals to be placed at the L1, L2, and L5 frequency bands. One of the signals to be placed on L2 is a new military code (M-code) which may be transmitted at a higher power level than current GPS signals. Other users of the L2 frequency band are concerned with the potential interference that may be caused by the increase in power of the GPS signal. One particular use of the 1215-1400 MHz frequency band is Air Traffic Control (ATC) radar applications

Physical Layer Challenges and Solutions in Seamless Positioning via GNSS, Cellular and WLAN Systems

As different positioning applications have started to be a common part of our lives, positioning methods have to cope with increasing demands. Global Navigation Satellite System (GNSS) can offer accurate location estimate outdoors, but achieving seamless large-scale indoor localization remains still a challenging topic. The requirements for simple and cost-effective indoor positioning system have led to the utilization of wireless systems already available, such as cellular networks and Wireless Local Area Network (WLAN). One common approach with the advantage of a large-scale standard-independent implementation is based on the Received Signal Strength (RSS) measurements.This thesis addresses both GNSS and non-GNSS positioning algorithms and aims to offer a compact overview of the wireless localization issues, concentrating on some of the major challenges and solutions in GNSS and RSS-based positioning. The GNSS-related challenges addressed here refer to the channel modelling part for indoor GNSS and to the acquisition part in High Sensitivity (HS)-GNSS. The RSSrelated challenges addressed here refer to the data collection and calibration, channel effects such as path loss and shadowing, and three-dimensional indoor positioning estimation.This thesis presents a measurement-based analysis of indoor channel models for GNSS signals and of path loss and shadowing models for WLAN and cellular signals. Novel low-complexity acquisition algorithms are developed for HS-GNSS. In addition, a solution to transmitter topology evaluation and database reduction solutions for large-scale mobile-centric RSS-based positioning are proposed. This thesis also studies the effect of RSS offsets in the calibration phase and various floor estimators, and offers an extensive comparison of different RSS-based positioning algorithms

Ultra Wide Band Signal Modeling for Radar Receiver Characterization

Results for modeling, simulation, and analysis of interference effects that modern wideband signals have on existing narrowband radar system performance are presented. In particular, radar detection performance is characterized using a basic radar receiver model and operational parameters consistent with those of the ARSR-4 air route surveillance radar. Two modern wideband signals (interferers) are addressed in this work, including the GPS military signal (M-Code signal) and a direct sequence ultra wideband (DS-UWB) waveform meeting outdoor emission restrictions imposed by the Federal Communications Commission (FCC). Interference effects are characterized for an unmodulated sinusoidal pulse as well as linear frequency modulated (LFM) and bi-phase Barker coded pulse compression waveforms. Finally, coherent pulse integration is addressed and interference mitigation demonstrated via improved detection performance. Worst case detection scenarios from the radar\u27s perspective are considered for all cases. M-Code interference results indicate that at proposed received power levels of -160 to -130 dBW, radar detection performance is severely degraded with expected improvement occurring when pulse integration is employed. DS-UWB interference results indicate that at maximum transmit power levels specified by the FCC, the DS-UWB waveform has minimal impact on detection performance for radar receiver/UWB transmitter separation distances beyond 0.5 meters. This separation distance is reduced further when pulse integration is employed. (8 tables, 42 figures, 25 refs.

Cell Wall/Surface Proteome of Candida albicans: its Application in Rapid Identification of Yeast Species by Mass Signature and Characterization by in vitro and in vivo Chemical Labelings

Candida albicans is an opportunistic fungal pathogen that may cause mucutaneous infection and/or disseminated candidasis if the host defense system is impaired (such as those in HIV patients). Cell surface of C. albicans is the frontier where initial interplay between host-pathogen takes place and therefore is of great importance in understanding the mechanism of hostpathogen interaction. MALDI-TOF-MS analysis of intact fungal cells yielded mass signatures for rapid species differentiation, strain grouping and yeast morphogenesis monitoring. Cell surface biotinylations at low temperature (4°C), enzymatic digestion of the intact fungal cell surface proteins ( whole cell shaving ), biotin-avidin affinity enrichment of biotinylated peptides, liquid chromatography mass spectrometry (LC-MS) based proteomic approach were employed for unambiguous identification of cell wall/cell wall associated proteins and the exposed peptide segments of these proteins. SILAC (Stable Isotope Labeling by Amino acids in Cell Culture) based CWP quantification analyses were performed to monitor CWP accumulation level change in response to hyphae induction. Information on surface exposed peptide segments and regulation of cell wall/surface protein during morphogenesis provided new candidates to the pool of potential peptide targets for protective vaccine development. A New type of fluorous (fluorinated alkane) affinity gained popularity due to its low level nonspecific protein/peptide binding. Fluorous labeling reagents that target primary amine groups in proteins/peptides were synthesized and characterized. The acid labile linker in the labeling reagents allows cleavage of the bulky fluorous tag moiety and the long oligo ethylene glycol (OEG) spacer after fluorous affinity purification. Upon collision induced decomposition, the labeled peptide ion yielded a characteristic fragment that could be retrieved from the residual portion of fluorous affinity tag, and serve as a marker to indicate that the relevant peptide had been successfully labeled. Results showed that both the protein/peptide labeling and affinity enrichment/separation process were highly efficient

Cell Wall/Surface Proteome of Candida albicans: its Application in Rapid Identification of Yeast Species by Mass Signature and Characterization by in vitro and in vivo Chemical Labelings

Candida albicans is an opportunistic fungal pathogen that may cause mucutaneous infection and/or disseminated candidasis if the host defense system is impaired (such as those in HIV patients). Cell surface of C. albicans is the frontier where initial interplay between host-pathogen takes place and therefore is of great importance in understanding the mechanism of hostpathogen interaction. MALDI-TOF-MS analysis of intact fungal cells yielded mass signatures for rapid species differentiation, strain grouping and yeast morphogenesis monitoring. Cell surface biotinylations at low temperature (4°C), enzymatic digestion of the intact fungal cell surface proteins ( whole cell shaving ), biotin-avidin affinity enrichment of biotinylated peptides, liquid chromatography mass spectrometry (LC-MS) based proteomic approach were employed for unambiguous identification of cell wall/cell wall associated proteins and the exposed peptide segments of these proteins. SILAC (Stable Isotope Labeling by Amino acids in Cell Culture) based CWP quantification analyses were performed to monitor CWP accumulation level change in response to hyphae induction. Information on surface exposed peptide segments and regulation of cell wall/surface protein during morphogenesis provided new candidates to the pool of potential peptide targets for protective vaccine development. A New type of fluorous (fluorinated alkane) affinity gained popularity due to its low level nonspecific protein/peptide binding. Fluorous labeling reagents that target primary amine groups in proteins/peptides were synthesized and characterized. The acid labile linker in the labeling reagents allows cleavage of the bulky fluorous tag moiety and the long oligo ethylene glycol (OEG) spacer after fluorous affinity purification. Upon collision induced decomposition, the labeled peptide ion yielded a characteristic fragment that could be retrieved from the residual portion of fluorous affinity tag, and serve as a marker to indicate that the relevant peptide had been successfully labeled. Results showed that both the protein/peptide labeling and affinity enrichment/separation process were highly efficient

Next Generation Multi-System Multi-Frequency GNSS Receivers

Nowadays we have satellites available from GPS, GLONASS, Galileo and BeiDou systems. This will lead to an increased demand for solutions, which utilize multiple Global Navigation Satellite Systems (GNSS). Such solutions can have great market potential since they can be applied in numerous applications involving GNSS navigation, e.g. smartphones and car navigators. The aim of this thesis is to present the issues that arise in modern high sensitivity receivers, and to present research results of navigation algorithms suitable for the next generation multi-system multi-frequency GNSS receivers.With the availability of multiple satellites systems, the user benefits mostly from the improved visibility of the satellites. The increased availability of satellites naturally increases the computational requirements in the receiver. The main focus of the presented algorithms is on critical factors like provided accuracy versus low cost, low power consumption. In addition, the presented algorithms have been collected into a comprehensive navigation algorithm library where they have additional value for educational purposes.The presented navigation algorithms focus mainly in the GPS and Galileo systems, with the combination of L1/E1 & L5/E5a frequencies. A novel GPS + Galileo dual frequency receiver was developed by the team over the years. Where applicable, the thesis collects important facts from modern GLONASS and BeiDou systems.The first part of the thesis introduces all available open service signals from the GNSS systems, revealing how vast the scope of multi-system, multi-frequency receiver design is. The chapter continues with introduction to the basics of GNSS systems, and description of the problems that the receiver designer must overcome. The chapter further continues by describing a basic receiver architecture suitable for multi-system multi-frequency reception. The introductory part also has a short section is dedicated for underlining the importance of testing mechanisms for a novel receiver under development.The second part of the thesis concentrates on the baseband processing of the GNSS receiver. Topics cover acquisition and tracking, with multi-system multi-frequency implementation Abstract details kept in mind. The chapter also contains sections for issues that must be handled in high sensitivity receivers, e.g. cross-correlation and cycle slip detection. The second part of the thesis is concluded with a description how Assisted-GNSS capability would alter many of the design considerations.The third part of the thesis describes algorithms related to the data bit decoding issues. All the different satellite systems have their own low-level navigation data structure with additional layers of error detection / correction mechanisms. This part of the thesis provides the algorithms for successful decoding of the data.The final part of the thesis describes the basic navigation solution algorithms suitable for the mass-market receivers. In this part, the method of combining the measurements from the different satellite systems is discussed. Additionally, all the issues of processing multisystem signals are collected here, and in the end the Position, Velocity, and Time (PVT) solution is obtained

Design of pilot channel tracking loop Systems for high sensitivity Galileo receivers

Global Navigation Satellite Systems (GNSS) have been in the center stage of the recent technological upheaval that has been initiated by the rise of smartphones in the last decade. This is clearly reflected in the development of many applications based on GNSS technology as well as the emergence of multi-constellation GNSS with the launch of the first Galileo satellites at the end of the year 2011. GNSS does not only guarantee global positioning, navigation and timing services but also extends to applications in banking, agriculture, mapping, surveying, archaeology, seismology, commerce, ionosphere scintillation monitoring, remote sensing (soil moisture, ocean salinity, type of surface), wind speed monitoring, ocean surface monitoring, altimetry and many others. In the last decade, Location Based Services (LBS) have increased significant market demand where GNSS has been coupled with technologies based on terrestrial communication links in order to meet strict positioning accuracy requirements. In these conditions, relying on GNSS technology alone, raises a few challenges for signal synchronization even before positioning attempts and are mainly due to a considerable signal attenuation as it propagates through construction material and into indoor environments. Ionosphere scintillation induces a similar challenge where in addition to amplitude fading, the carrier phase and frequency suffer from indeterministic fluctuations. This research activity is devoted to explore and design the elements constituting pilot channel scalar tracking loop systems, specifically tailored to Galileo signals. It is expected that running such systems with extended integration intervals offers robust synchronization of the incoming signal which is heavily affected by external indeterministic fluctuations. In some conditions, it is desired to follow these fluctuations as in ionosphere scintillation monitoring while in other instances it is mainly desired to filter them out as noise to guarantee positioning capabilities. This is the objective of this research study which applies for both indoor environments and ionosphere scintillation affected signals. Towards this endeavor, a comprehensive theoretical study of the carrier and code tracking loops elements is undertaken, and particular attention is directed to the following aspects: • carrier frequency and phase discriminators and the relative optimum integration time • Galileo specific code discriminators and code tracking architecture especially tailored to Composite Binary Offset Carrier (CBOC) modulated signals. • optimum loop filters designed in the digital domain for different types of phase input signals • local signal generation using a numerically controlled oscillator and loop filter estimates • front-end filter bandlimiting effects on the tracking performance. This design is further tested with simulated Galileo signals with and without ionosphere scintillation as well as raw Galileo signals in an equatorial region during March 2013. Tracking performance comparison is carried out between the customized Galileo receiver developed in this research activity and an ionosphere scintillation dedicated professional GNSS receiver, the Septentrio PolaRxS PRO R receiver