Wednesday, March 25, 2009
Sunday, March 8, 2009
EDA Approves Next-Gen Space-Based Military Surveillance System
The European Defence Agency (EDA) has agreed to approve a project for the next generation of European military earth observation satellites.
The multinational space-based imaging system (MUSIS) project has been launched by six European Union Member States: Belgium, Germany, Greece, France, Italy and Spain.
The MUSIS project aims at establishing a multinational space-based imaging system for surveillance, reconnaissance and observation to ensure continuity of services from the current French Helios II, German SAR LUPE and Italian Cosmo-Skymed and Pléiades systems, from 2015-2017 onwards.
EDA Head, Javier Solana said that he welcomed the initiative of the EU member states in approving this critical capability.
"Space-based related assets are critical to improve European military capabilities, including for information gathering," Solana said.
EDA's chief executive, Alexander Weis said that the EDA was proving its value by bringing together member states as well as by connecting military to civil space agendas.
"We will liaise with the commission and the European Space Agency to ensure complementing research and technology, and to seek other synergies," said Weis.
One of the roles for EDA will be to seek synergies with earth observation programmes on the civilian side, in particular with the global monitoring for environment and security (GMES) programme of the European Commission.
Friday, February 20, 2009
RONSARD Radar: Implementation of Dual Polarization on a C-Band Doppler Weather Radar
The French C-band meteorological Doppler radar Recherche sur les Orages et Nuages par un Systeme Associe de Radars Doppler (RONSARD) was recently equipped with dual polarization. This modification required, on the one hand, an additional receiver and, on the other hand, a new design for the antenna geometry in order to decrease strongly the sidelobe level. This new radar configuration allows us to choose between two complementary modes: (1) the previous single-polarization mode, still preserved with fast Fourier transform calculations of the first three momentums of the Doppler spectrum, i.e., horizontal (H) reflectivity, radial wind velocity, and wind velocity variance calculated both in precipitation areas and clear air areas (depending on the gate), and (2) the dual-polarization mode with pulse pair processing of H and vertical reflectivities and velocities, differential phase shift, and coherence coefficient. Moreover, both modes work over contiguous gates along each direction, allowing fine radial range resolution. Thanks to the flexibility between these two modes, the RONSARD radar becomes a new major facility aimed at studying the dynamics-microphysics interactions within precipitation and their environment. - Reference
Statistical analysis of the zero-phase method for aligning noisy high-resolution radar signals
Automatic target recognition using high-range resolution radars is a difficult task. Variations in the distance to the target cause circular shifts of the received signal, and most of the classification algorithms are very sensitive to shifts over the input signal. This fact makes the alignment of each signal prior to any classification stage very important. Here the alignment of noisy signals using the zero phase method is studied. In order to evaluate the performance of the alignment method, a theoretical analysis of the sensitivity to noise of this alignment method is carried out. As a result, an analytical expression that predicts the error of the alignment method is obtained. The validity of this expression is also confirmed by experimental results. A database of high-range resolution radar profiles containing patterns belonging to six different targets has been used, and a comparative study of the sensitivity to noise estimated using the profiles of the database and predicted by the analytical expression is carried out. The results demonstrate that the proposed analytical expression is useful to analyse the sensitivity to noise of the zero-phase alignment method for medium and high signal-to-noise ratio values. - Reference
Discrete frequency-coded radar signal design
A modified simulated annealing algorithm (MSAA) is proposed as combinatorial multivariable optimisation technique to design discrete frequency-coding (DFC) sequence sets with good auto- and cross-correlation properties. The proposed algorithm is a combination of simulated annealing and Hamming scan algorithm. MSAA has global minimum estimation capability of simulated annealing and fast convergence rate of Hamming scan algorithm. Some of the synthesised results are presented, the properties of the sequence sets are shown to be better than the other sequence sets known in the literature. Synthesised DFC sequence sets have properties far better than polyphase sequence sets. The synthesised DFC sequence sets are promising for practical application to netted radar/multiple radar systems. - Reference
Subscribe to:
Posts (Atom)