Experimental demonstration of ship target detection in GNSS-based passive radar combining target motion compensation and track-before-detect strategies

This work discusses methods and experimental results on passive radar detection of moving ships using navigation satellites as transmitters of opportunity. The reported study highlights as the adoption of proper strategies combining target motion compensation and track-before-detect methods to achieve long time integration can be fruitfully exploited in GNSS-based passive radar for the detection of maritime targets. The proposed detection strategy reduces the sensitivity of long-time integration methods to the adopted motion models and can save the computational complexity, making it appealing for real-time implementations. Experimental results obtained in three different scenarios (port operations, navigation in open area, and river shipping) comprising maritime targets belonging to different classes show as this combined approach can be employed with success in several operative scenarios of practical interest for this technology

The Feasibility of R-Mode to Meet Resilient PNT Requirements for e-Navigation

Position, Navigation, and Timing (PNT) is part of the critical infrastructure necessary for the safety and efficient of vessel movements, especially in congested areas such as the North Sea. GNSS (primarily GPS and GLONASS) has become the primary PNT source for maritime operations. The GNSS position is used both for vessel navigation and as the position source for AIS. Unfortunately, GNSS is vulnerable to jamming and interference – not intentional and unintentional. This can lead to the loss of positioning information or even worse, to incorrect positioning information. The user requirement is for dependable PNT information at all times, even under GNSS jamming conditions. One potential source of resilient PNT services is Ranging Mode (R-Mode) using signals independent of GNSS. The German Federal Waterways and Shipping Administration has contracted for a feasibility study of R-mode using MF-DGNSS and VHF AIS signals as well as those signals in combination and in combination with eLoran. The first part of the study focused on the feasibility of using MF-DGNSS signals for ranging and timing. It examined the state of the art, identified potential solution methods, and, after examining Pros and Cons of the various options, selected a few options for further study. Part 2 examined the proposed solutions in depth and identified the modifications required for both the reference stations (transmitters) and user equipment (beacon receivers). Part 3 and 4 of the study repeated Parts 1 and 2, but using AIS signals rather than MF. Part 4 of the study examined the possibility of combining MF and AIS R-mode or combining MF R-Mode and eLoran. This paper presents the results of this study including recommended R-Mode implementations and bounds on the positioning performance using the various R-Mode methods. Included are predictions of DGNSS and AIS R-Mode coverage and the resulting HDOP using existing and preposed DGNSS and AUS sites with specific detail in the area of the planned test bed in the North Sea

Vessel collision threat detection for offshore oil and gas installations

There is a potential for major structural damage to offshore installations leading to fatalities and serious injuries in the event of collision by either a passing or an in-field seagoing vessel. Both categories of collision have occurred on the UK Continental Shelf (UKCS) although to date only significant, rather than catastrophic, consequences have occurred. Internationally, collisions have occurred that have caused both loss of life and environmental damage. This report considers collision threat detection and updates Research Report RR514 (2006). RR1154 considers the Ship/Platform Collision Incident Database which was previously described in Research Report RR053 (2001). Collision threat detection via radar and visual watch keeping is one of the major duties that the Emergency Response and Rescue Vessel (ERRV) crew needs to conduct for monitoring and appraisal of risks to UKCS installations. Detection tools are subject to a number of limitations and this report investigates technological advancements including: (1) deployment of automated radar detection and tracking devices to supplement the work of ERRV crews and assist in the overall collision risk management strategy; and (2) the implementation of Automatic Identification System (AIS) equipment in the global marine regulatory system which has also had an impact on vessel identification and the processes through which an errant vessel can be warned off. Results are discussed in terms of both how they may affect current operations and how they may be adopted in future to enhance offshore safety

Modern Random Access for Satellite Communications

The present PhD dissertation focuses on modern random access (RA) techniques. In the first part an slot- and frame-asynchronous RA scheme adopting replicas, successive interference cancellation and combining techniques is presented and its performance analysed. The comparison of both slot-synchronous and asynchronous RA at higher layer, follows. Next, the optimization procedure, for slot-synchronous RA with irregular repetitions, is extended to the Rayleigh block fading channel. Finally, random access with multiple receivers is considered.Comment: PhD Thesis, 196 page

Planning assistance for the NASA 30/20 GHz program. Network control architecture study.

Network Control Architecture for a 30/20 GHz flight experiment system operating in the Time Division Multiple Access (TDMA) was studied. Architecture development, identification of processing functions, and performance requirements for the Master Control Station (MCS), diversity trunking stations, and Customer Premises Service (CPS) stations are covered. Preliminary hardware and software processing requirements as well as budgetary cost estimates for the network control system are given. For the trunking system control, areas covered include on board SS-TDMA switch organization, frame structure, acquisition and synchronization, channel assignment, fade detection and adaptive power control, on board oscillator control, and terrestrial network timing. For the CPS control, they include on board processing and adaptive forward error correction control

Design and implementation of a software-defined VHF-DSC multichannel monitoring system

Nell’ambito di questa tesi vengono proposti il progetto e l’implementazione di un sistema per il monitoraggio delle comunicazioni marittime (vocali e digitali) in banda VHF, utilizzando la tecnologia Software Defined Radio. Partendo dal framework GNU Radio e la periferica di acquisizione (Universal Software Radio Peripheral ) collegata ad esso, e` possibile ricevere simultaneamente tutti i canali VHF con una sola interfaccia radio. A partire dalla porzione di spettro acquisito, tutte le successive elaborazioni del segnale sono effettuate via software da un applicativo server, che effettua l’analisi e demodulazione della porzione di banda acquisita, e da un applicativo client che permette all’utente la selezione e l’ascolto di uno dei canali voce. La comunicazione tra client e server avviene tramite IP (UDP/Multicast), consentendo la distribuzione simultanea dei canali voce a piu` client.E` anche presente un applicativo dedicato alla decodifica dei messaggi DSC (Digital Selective Calling), usati dal sistema GMDSS (Global Maritime Distress and Safety System) per trasportare informazioni di emergenza o di servizio

NASA Tech Briefs, August 2005

Topics include: Hidden Identification on Parts: Magnetic Machine-Readable Matrix Symbols; System for Processing Coded OFDM Under Doppler and Fading; Multipurpose Hyperspectral Imaging System; Magnetic-Flux-Compensated Voltage Divider; High-Performance Satellite/Terrestrial-Network Gateway; Internet-Based System for Voice Communication With the ISS; Stripline/Microstrip Transition in Multilayer Circuit Board; Dual-Band Feed for a Microwave Reflector Antenna; Quadratic Programming for Allocating Control Effort; Range Process Simulation Tool; Simulator of Space Communication Networks; Computing Q-D Relationships for Storage of Rocket Fuels; Contour Error Map Algorithm; Portfolio Analysis Tool; Glass Frit Filters for Collecting Metal Oxide Nanoparticles; Anhydrous Proton-Conducting Membranes for Fuel Cells; Portable Electron-Beam Free-Form Fabrication System; Miniature Laboratory for Detecting Sparse Biomolecules; Multicompartment Liquid-Cooling/Warming Protective Garments; Laser Metrology for an Optical-Path-Length Modulator; PCM Passive Cooling System Containing Active Subsystems; Automated Electrostatics Environmental Chamber; Estimating Aeroheating of a 3D Body Using a 2D Flow Solver; Artificial Immune System for Recognizing Patterns; Computing the Thermodynamic State of a Cryogenic Fluid; Safety and Mission Assurance Performance Metric; Magnetic Control of Concentration Gradient in Microgravity; Avionics for a Small Robotic Inspection Spacecraft; and Simulation of Dynamics of a Flexible Miniature Airplane