A Multi Antenna Receiver for Galileo SoL Applications

One of the main features of the Galileo Satellite Navigation System is integrity. To ensure a reliable and robust navigation for Safety of Life applications, like CAT III aircraft landings, new receiver technologies are indispensable. Therefore, the German Aerospace Centre originated the development of a complete safety-of-life Galileo receiver to demonstrate the capabilities of new digital beam-forming and signal-processing algorithms for the detection and mitigation of interference. To take full advantage of those algorithms a carefully designed analogue signal processing is needed. The development addresses several challenging questions in the field of antenna design, frontend development and digital signal processing. The paper will give an insight in the activity and will present latest results

A Graphical Approach to GPS Software-Defined Receiver Implementation

Global positioning system (GPS) software-defined receivers (SDRs) offer many advantages over their hardwarebased counterparts, such as flexibility, modularity, and upgradability. A typical GPS receiver is readily expressible as a block diagram, making a graphical approach a natural choice for implementing GPS SDRs. This paper presents a real-time, graphical implementation of a GPS SDR, consisting of two modes: acquisition and tracking. The acquisition mode performs a twodimensional fast Fourier transform (FFT)-based search over code offsets and Doppler frequencies. The carrier-aided code tracking mode consists of the following main building blocks: correlators, code and carrier phase detectors, code and carrier phase filters, a code generator, and a numerically-controlled oscillator. The presented GPS SDR provides an abstraction level that enables future research endeavors.Aerospace Engineering and Engineering Mechanic

Benchmarking CPUs and GPUs on embedded platforms for software receiver usage

Smartphones containing multi-core central processing units (CPUs) and powerful many-core graphics processing units (GPUs) bring supercomputing technology into your pocket (or into our embedded devices). This can be exploited to produce power-efficient, customized receivers with flexible correlation schemes and more advanced positioning techniques. For example, promising techniques such as the Direct Position Estimation paradigm or usage of tracking solutions based on particle filtering, seem to be very appealing in challenging environments but are likewise computationally quite demanding. This article sheds some light onto recent embedded processor developments, benchmarks Fast Fourier Transform (FFT) and correlation algorithms on representative embedded platforms and relates the results to the use in GNSS software radios. The use of embedded CPUs for signal tracking seems to be straight forward, but more research is required to fully achieve the nominal peak performance of an embedded GPU for FFT computation. Also the electrical power consumption is measured in certain load levels.Peer ReviewedPostprint (published version

PRETTY: Grazing altimetry measurements based on the interferometric method

The exploitation of signals stemming from global navigation systems for passive bistatic radar applications has beenproposed and implemented within numerous studies. The fact that such missions do not rely on high power amplifiersand that the need of high gain antennas with large geometrical dimensions can be avoided, makes them suitable forsmall satellite missions. Applications where a continuous high coverage is needed, as for example disaster warning,have the demand for a large number of satellites in orbit, which in turn requires small and relatively low cost satellites.The proposed PRETTY (Passive Reflectometry and Dosimetry) mission includes a demonstrator payload for passivereflectometry and scatterometry focusing on very low incidence angles whereby the direct and reflected signal will bereceived via the same antenna. The correlation of both signals will be done by a specific FPGA based hardwareimplementation. The demonstration of a passive reflectometer without the use of local code replica implicitly showsthat also signals of unknown data modulation can be exploited for such a purpose.The PRETTY mission is proposed by an Austrian consortium with RUAG GmbH as prime contractor, relying on theresults from a previous CubeSat mission (OPS-SAT) conducted by TU Graz under ESA contract [18]. Within thepresent paper we will describe the architecture of the passive reflectometer payload within this 3U CubeSat mission anddiscuss operational routines and constraints to be elaborated in the frame of the proposed activity

Development of a Nanosatellite Software Defined Radio Communications System

Communications systems designed with application-specific integrated circuit (ASIC) technology suffer from one very significant disadvantage - the integrated circuits do not possess the ability of programmability. However, Software Defined Radio’s (SDR’s) integrated with Field Programmable Gate Arrays (FPGA) provide an opportunity to update the communication system on nanosatellites (which are physically difficult to access) due to their capability of performing signal processing in software. SDR signal processing is performed in software on reprogrammable elements such as FPGA’s. Applying this technique to nanosatellite communications systems will optimize the operations of the hardware, and increase the flexibility of the system. In this research a transceiver algorithm for a nanosatellite software defined radio communications is designed. The developed design is capable of modulation of data to transmit information and demodulation of data to receive information. The transceiver algorithm also works at different baud rates. The design implementation was successfully tested with FPGA-based hardware to demonstrate feasibility of the transceiver design with a hardware platform suitable for SDR implementation

Software-Defined Radio Technologies forGNSS Receivers: A Tutorial Approach to a SimpleDesign and Implementation

The field of satellite navigation has witnessed the advent of a number of new systems and technologies: after the landmark design and development of the Global Positioning System (GPS), a number of new independent Global Navigation Satellite Systems (GNSSs) were or are being developed all over the world: Russia's GLONASS, Europe's GALILEO, and China's BEIDOU-2, to mention a few. In this ever-changing context, the availability of reliable and flexible receivers is becoming a priority for a host of applications, including research, commercial, civil, and military. Flexible means here both easily upgradeable for future needs and/or on-the-fly reprogrammable to adapt to different signal formats. An effective approach to meet these design goals is the software-defined radio (SDR) paradigm. In the last few years, the availability of new processors with high computational power enabled the development of (fully) software receivers whose performance is comparable to or better than that of conventional hardware devices, while providing all the advantages of a flexible and fully configurable architecture. The aim of this tutorial paper is surveying the issue of the general architecture and design rules of a GNSS software receiver, through a comprehensive discussion of some techniques and algorithms, typically applied in simple PC-based receiver implementations