Mixed graphic architecture for radar displays

The current state of the art in designing radar displays is first analyzed. An advanced architecture is proposed that overcomes the previous display limitations by using the mixed vector-raster concept. Design tradeoffs are identified, and feasible solutions are given. A simplified prototype that realizes these concepts is presented     

Radar signals analysis and modellization in the presence of JEMapplication to civilian ATC radars

This paper describes the application of a simulation software and the comparison of its results with actual data recorded from operating ATC radars in S and L bands. Results obtained in an application on actual signals (relative to commercial aircraft echoes) collected from observations on the echo received at an ATC radar system are presented. These signals were recorded along many field experiments carried out by the authors on a recording system specifically developed for this purpose. Due to the constitutive and operative characteristics of the systems, the results are affected by a low spectral resolution and a strong aliasing which give rise to problems in a correct analysis. The observed results have been related to the physical phenomena generated by the structure of the complex target we suppose to be made of a rigid body and rotating parts which originate such a modulation on the echo signal that it is known in related literature as Jet Engine Modulation (JEM). These phenomena may be regarded as a signature of the particular couple “engine-aircraft body” and in some flight conditions may offer significant help to a correct characterization of the aircrafts     

A-SMGCS routing and guidance functions

In the present work it is presented an implementation of two specific functions which are going to be of growing importance in Advanced Surface Movement Guidance and Control Systems (A-SMGCS). Namely the two functions are Routing and Guidance. Routing provides a means to suggest to the airport ground control a best path from any given point on the airfield to any other given point according to a number of constraints and rules. Guidance provides an interface between the system and the pilot and provides guidance aids to the pilot in order to have the airplane on the route generated by the Routing function. Both Functions have been developed under the European Union “Vision” project, in the frame of the Telematics Application Program. A complete A-SMGCS is working now at Navia with simulation scenarios for various airports and will be installed and tested at, at least, two of them. The system is completely modular and can be installed in a number of configurations. In fact, every function is a self-contained program, communicating with each other by the means of computer networks     

The Interstellar Boundary Explorer High Energy (IBEX-Hi) Neutral Atom Imager

The IBEX-Hi Neutral Atom Imager of the Interstellar Boundary Explorer (IBEX) mission is designed to measure energetic neutral atoms (ENAs) originating from the interaction region between the heliosphere and the local interstellar medium (LISM). These ENAs are plasma ions that have been heated in the interaction region and neutralized by charge exchange with the cold neutral atoms of the LISM that freely flow through the interaction region. IBEX-Hi is a single pixel ENA imager that covers the ENA spectral range from 0.38 to 6 keV and shares significant energy overlap and overall design philosophy with the IBEX-Lo sensor. Because of the anticipated low flux of these ENAs at 1 AU, the sensor has a large geometric factor and incorporates numerous techniques to minimize noise and backgrounds. The IBEX-Hi sensor has a field-of-view (FOV) of 6.5°×6.5° FWHM, and a 6.5°×360° swath of the sky is imaged over each spacecraft spin. IBEX-Hi utilizes an ultrathin carbon foil to ionize ENAs in order to measure their energy by subsequent electrostatic analysis. A multiple coincidence detection scheme using channel electron multiplier (CEM) detectors enables reliable detection of ENAs in the presence of substantial noise. During normal operation, the sensor steps through six energy steps every 12 spacecraft spins. Over a single IBEX orbit of about 8 days, a single 6.5°×360° swath of the sky is viewed, and re-pointing of the spin axis toward the Sun near perigee of each IBEX orbit moves the ecliptic longitude by about 8° every orbit such that a full sky map is acquired every six months. These global maps, covering the spectral range of IBEX-Hi and coupled to the IBEX-Lo maps at lower and overlapping energies, will answer fundamental questions about the structure and dynamics of the interaction region between the heliosphere and the LISM.     

The IBEX-Lo Sensor

The IBEX-Lo sensor covers the low-energy heliospheric neutral atom spectrum from 0.01 to 2 keV. It shares significant energy overlap and an overall design philosophy with the IBEX-Hi sensor. Both sensors are large geometric factor, single pixel cameras that maximize the relatively weak heliospheric neutral signal while effectively eliminating ion, electron, and UV background sources. The IBEX-Lo sensor is divided into four major subsystems. The entrance subsystem includes an annular collimator that collimates neutrals to approximately 7°×7° in three 90° sectors and approximately 3.5°×3.5° in the fourth 90° sector (called the high angular resolution sector). A fraction of the interstellar neutrals and heliospheric neutrals that pass through the collimator are converted to negative ions in the ENA to ion conversion subsystem. The neutrals are converted on a high yield, inert, diamond-like carbon conversion surface. Negative ions from the conversion surface are accelerated into an electrostatic analyzer (ESA), which sets the energy passband for the sensor. Finally, negative ions exit the ESA, are post-accelerated to 16 kV, and then are analyzed in a time-of-flight (TOF) mass spectrometer. This triple-coincidence, TOF subsystem effectively rejects random background while maintaining high detection efficiency for negative ions. Mass analysis distinguishes heliospheric hydrogen from interstellar helium and oxygen. In normal sensor operations, eight energy steps are sampled on a 2-spin per energy step cadence so that the full energy range is covered in 16 spacecraft spins. Each year in the spring and fall, the sensor is operated in a special interstellar oxygen and helium mode during part of the spacecraft spin. In the spring, this mode includes electrostatic shutoff of the low resolution (7°×7°) quadrants of the collimator so that the interstellar neutrals are detected with 3.5°×3.5° angular resolution. These high angular resolution data are combined with star positions determined from a dedicated star sensor to measure the relative flow difference between filtered and unfiltered interstellar oxygen. At the end of 6 months of operation, full sky maps of heliospheric neutral hydrogen from 0.01 to 2 keV in 8 energy steps are accumulated. These data, similar sky maps from IBEX-Hi, and the first observations of interstellar neutral oxygen will answer the four key science questions of the IBEX mission.     

Measurement and stability of the pointing of the BepiColombo Laser Altimeter under thermal load

The BepiColombo Laser Altimeter (BELA) has been selected to fly on ESA?s BepiColombo mission to Mercury. The instrument will be the first European laser altimeter designed for interplanetary flight. This paper describes the setup used to characterize the angular movements of BELA under the simulated environmental conditions that the instrument will encounter when orbiting Mercury. The system comprises a laser transmitter and a receiving telescope, which can move with respect to each other under thermal load. Tests performed using the Engineering Qualification Model show that the setup is accurate enough to characterize angular movements of the instrument components to an accuracy of ≈10 μrad. The qualification instrument is thermally stable to operate during all mission phases around Mercury proving that the transmitter and receiver sections will remain within the alignment requirements during its mission.