Galileo AltBOC signal multiresolution acquisition strategy

Herein, some critical aspects related to the acquisition of the future Galileo signals are discussed. In particular, the Alternative Binary Offset Carrier (AItBOC) modulation that will be used by the Galileo satellites to broadcast navigation signals on the E5 band is considered, addressing acquisition issues only partially analyzed in previous works. The implementation of an acquisition section for the AltBOC signals is not straightforward, since several different receiver architectures can be used and remarkable differences are required with respect to the conventional signal processing used in GPS receivers. The main problems that must be handled (risk of false lock, resolution of the search space, and computational burden) are outlined in the following. An innovative technique, called multiresolution acquisition and tailored to the AltBOC signals, is then proposed as an effective solution to previous problems. As demonstrated by means of simulations, this novel strategy can be successfully used in coherent dual-band AltBOC receiver architectures with a feasible implementation complexity and it leads to remarkable advantages in terms of acquisition time.     

Ballistics of a nonfragmenting meteor body with allowance made for mass outflow in the non-isothermal atmosphere. I

The paper is devoted to studying the motion of meteor bodies with mass outflow in a planet’s atmosphere, taking into account the non-isothermal character of the latter. Analytical solutions are obtained at the constant parameter of mass outflow in the model of a nonfragmenting meteoroid. A theoretical analysis of the derived regularities of the ballistics of such bodies is presented.     

Automatic target recognition of time critical moving targets using1D high range resolution (HRR) radar

Synthetic Aperture Radar (SAR) imaging and Automatic Target Recognition (ATR) of moving targets pose a significant challenge due to the inherent difficulty of focusing moving targets. As a result, ATR of moving targets has recently received increased interest. High Range Resolution (HRR) radar mode offers an approach for recognizing moving targets by forming focused HRR profiles with significantly enhanced target-to-(clutter+noise) (T/(C+N)) via Doppler filtering and/or clutter cancellation. A goal of HRR ATR transition is the implementation and evaluation of algorithms exhibiting robustness under extended operating conditions (EOC). The public domain Moving and Stationary Target Acquisition and Recognition (MSTAR) data set was used to study 1D template-based ATR development and performance. Due to the unavailability of a statistically significant moving ground target data set, this approach was taken as an interim step in assessing the separability of ground targets when using range only discriminants. This report summarizes the data and algorithm methodology, simulated performance results, and recommendations     

Ozone mini-hole observation over the Balkan Peninsula in March 2005

Areas with dimensions of 1000–3000 km in which the total ozone content (TOC) decreases fast are called ozone mini-holes. They are generated mainly dynamically in two ways, either by poor-ozone air mass transport from the tropics to higher latitudes by planetary wave activity or, they are connected with strong adiabatic uplifting of the tropopause height. An ozone mini-hole, generated by the second mechanism, was observed over the Balkan Peninsula on 19/21 March 2005. In the middle of March, the polar vortex was strongly disturbed by Rossby waves, reaching up to the lower stratosphere. Warming episodes over a geographical area, covering the Barents Sea and the Polar Sea north from Central Siberia, displaced a polar vortex fragment extremely southwards. However, the vorticity was weak and the stratospheric temperatures did not reach low values, providing conditions for ozone chemical destruction via heterogenic reactions. At the same time, a Rossby wave ridge was located below the European polar fragment. In the period from 13 to 19 March, the thermal tropopause over Sofia was uplifted almost by 3 km. Ozone distributions observed by the SCIAMACHY instrument on 18–21 March show a fast TOC decrease westwards from Ireland, which was moving eastwards during the next days, increasing the area in which the ozone content decreased. On 20/21 March low ozone content was observed above the Stara Zagora (42°N, 25°E) ground-based station by means of the GASCOD instrument, using DOAS technique. The TOMS Earth probe instrument detected 237 DU over Sofia. This is a record low March value from the beginning of the TOMS instrument measurements in 1978. In March/April the ozone distribution was characterized by its mean annual maximum of 360 DU at 42°N.     

Would contact with extraterrestrials benefit or harm humanity? A scenario analysis

While humanity has not yet observed any extraterrestrial intelligence (ETI), contact with ETI remains possible. Contact could occur through a broad range of scenarios that have varying consequences for humanity. However, many discussions of this question assume that contact will follow a particular scenario that derives from the hopes and fears of the author. In this paper, we analyze a broad range of contact scenarios in terms of whether contact with ETI would benefit or harm humanity. This type of broad analysis can help us prepare for actual contact with ETI even if the details of contact do not fully resemble any specific scenario.