Antonio Saitto

THE INVENTION CONCERNS ORBITAL SPACE VEHICLES, INCLUDING THE TYPE PLATFORM 1 AND SEVERAL DIFFERENT PAYLOADS AMONG WHICH SEVERAL TELECOMMUNICATION ANTENNA WITH AT LEAST ONE POWER SUPPLY 5A 5D A REFLECTOR AND A MAIN 3A, 3B. THE PROBLEM IS TO AVOID iNTERFERENCE, A PERMIT TO INCREASE THE SIZE OF OFFICES, TO AVOID THE REPLACEMENT OF A COMPLETE ANTENNA AND INCREASING LIFE OF THE PLATFORM. FOLLOWING THE INVENTION, SUCH VEHICLE INCLUDES A MAIN REFLECTOR COMMON 3A, 3B FOR MULTIPLE ANTENNA SYSTEMS AND WHAT THIS COMMON REFLECTOR mOUNTED PERMANENTLY ON DECK 1, SO AS TO BE PART OF INTEGRAL FINALLY, WHILE THE DIFFERENT POWER SUPPLIES A 5A 5B OF THESE SYSTEMS ARE mOUNTED ANTENNA IN ORDER TO COOPERATE WITH THIS POWER REFLECTOR COMMON 3A, 3B. THE iNVENTION IS MAINLY USED ON SATELLITE multimission.

The paper considers the antennas mounted on the Orbital Test Communication Satellite (OTS), the European Communication Satellite (ECS), and the Improved European Communication Satellite (IECS) which employ the frequency reuse technique through polarization discrimination in the frequency band around 11 GHz for transmission to the earth and around 14.25 GHz for reception from the earth. The main requirements and their impact on antenna configuration are discussed for OTS, ECS and IECS. The corresponding antenna systems are briefly described along with their performance. Relevant merits and limitations are included.

The Orbital Test Satellite (OTS) uses antennas with two channels for frequency reuse by means of polarization discrimination in the 11 GHz for transmitting and 14 GHz for receiving. The antennas will be both in dual linear and in dual circular polarization. Main requirements for the antennas are efficiency and polarization purity. Furthermore, the pointing of the antenna boresight has to be known with great accuracy. The test range set up for the OTS antennas is discussed and the results obtained are presented. The measurement activities are described for co/cross pattern, gain, and pointing, together with the achieved accuracy. Future improvements of test range and test methods are suggested.

The paper presents the architecture of a low bit rate digital direct sequence spread spectrum modem for satellite communications with CDMA (Code Division Multiple Access) access technique. The main algorithms of code, clock and carrier recovery are described underlining the statistical criteria which support the evaluation of the control parameters. A modem performance evaluation carried out on the laboratory prototype and the foreseen future modem family improvements conclude the paper.

The development of a set of dual-polarized antennas for the Orbital Test Satellite (OTS) is discussed. Optimization studies led to the initial selection of a circular parabolic reflector front fed by a corrugated cylindrical horn for the circularly symmetrical beam (Spot beam). A parabolic reflector was selected for the elliptical beam (Eurobeam). An edge taper of -15 dB and an F/D ratio of 0.5 were adopted. The qualification testing of three prototypes is discussed. Test data are compared with theoretical results.

The Italsat system, after four years of development has reached is final phase. The satellite was launched at the beginning of 1991, the first traffic stations being installed at the end of the Summer of 1991. Considering that this is the first time that a regenerative payload will be used on a communications satellite, a long test campaign was carried out on the ground to integrate the different components of the network, using the satellite EM payload and three traffic stations, with one of them hosting the control center. This activity was very helpful in calibrating some parameters of the regenerative payload. The test environment and philosophy are described and the major results obtained are analyzed. All is seen as the first step to integrate a network of 64 stations in the Italian domestic telephone network.

This paper analyzes the performance of a digital spread spectrum modem for satellite communications in terms of error probability. In addition, loss is evaluated in terms of Ec/No, with the required error probability being equal, for an ideal case (ideal code gain). A comparison between the theoretical result and experimental measurements carried out on a laboratory prototype concludes the article.

A satellite terminal (334) designed to be installed on board a train (33) and configured to: * store georeferencing data of a train railway route (33); * receive navigation signals from satellites belonging to one or more satellite navigation systems; * extract from the received navigation signals the positioning data corresponding to the satellites that have transmitted said navigation signals; and * determine, on the basis of stored georeferencing data and received navigation signals, a train position (33) along the railway route and an integrity level associated with said determined position; characterized in that it is further configured to: * if said satellite terminal (334) receives navigation signals from only two satellites, determine the position of the train (33) along the railway route by calculating a train position limit for the railway route based on stored georeference data and positioning data corresponding to said two satellites; and * if said satellite terminal (33...

The design approach to developing a network-controller and capacity-assignment software package for the Italsat satellite switched/time division multiple-access (SS/TDMA) network is covered. The network consists of TDMA traffic stations (TS) allowing a full mesh connectivity ...

IEE802.15.4 technology is widely deployed to monitor environmental changes without being tethered off of a wired network. In order to have good performance and no loss of information or alarm an accurate plan-ning of indoor radio systems is required. It means to characterize the propagation channel. Moreover to know the behavior of the WSN chan-nel model or RFID technologies allows to localize the positions of the sensors through techniques range or time to arrival based of the radio signals. Starting from experimental data obtained in two typical indoor environments we show the parameters, obtained by fitting, concerning One Slope (OS) and Multi-Wall (MW) models with reference to the office like environment. Differently from the standard MW model indicated in the literature, we include losses due to doors and different kind of wall that may lead to significant contributions to the overall attenuation. The developed channel model MW is used in a computer simulator in order to evalua...

This paper presents the main achievements of a project, focused on the design of an integrated system composed of a satellite segment and a MANET to provide telecommunication services in emergency scenarios, in terms of network design, focusing in particular on the development of the interface between the two systems and showing the results of field trials. Copyright # 2007 John Wiley &

The importance of telecommunications services for the management and control of critical situations dedicated to security of citizens has always been recognized: in particular, in this work we describe the solution designed and developed in an Italian research project, called CI6 (Centro Integrato per Servizi di Emergenza Innovativi). Focus of this project was to develop an integrated centre able to provide important informations concerning the state and possibile evolution of the crisis for decision makers. The knowledge base is managed by means of homogeneous schema to represent information (ontology of domain) and by means of semantic rules defined by the analysis of the domain. The communication layer has been provided by the CHIMERA platform we have developed, which is able to connect analogical / digital local radio network and satellite system for remote communications as well as to provide fast availability of communication and broadband using legacy equipment.

Dans un systeme radar a ouverture synthetique (1) surveillant une zone contenant au moins une cible mobile (2) pour identification, la cible (2) est equipee d'un dispositif d'identification (3), qui recoit le signal radar (RS) transmis par le systeme radar (1), et transmet un signal radar traite (ES) obtenu en modulant le signal radar entrant (RS) avec un signal de modulation (MODS) contenant des informations relatives a la cible (2) (ID, MSG), telles que des informations d'identification (ID) et d'etat (MSG), et en amplifiant le signal radar module (RS) ; le signal echo radar (RES) reflechi par la zone surveillee et contenant le signal radar traite (ES) est recu et traite par un poste de commande (8) du systeme radar (1) pour localiser la cible (2) sur une carte de la zone surveillee, et pour extraire les informations relatives a la cible (2) (ID, MSG) pour identifier la cible (2).

A satellite communications system to extend communications between a vehicle (1) and a satellite in a zone (2) of non visibility of the satellite, comprising a fixed transceiver system and a system of mobile transceiver; the fixed transceiver system one fixed satellite antenna (11) located outside the area (2) of non visibility of the satellite, and at least one buried fixed antenna (12) coupled to the fixed satellite antenna (11) and located in comprising area (2) of non visibility of the satellite; the fixed transceiver system being configured to: - receive through the fixed satellite antenna (11) signals downlink transmitted by the satellite in at least one carrier frequency downlink; and - transmitting signals downlink received in at least one carrier frequency downlink area (2) of non visibility of the satellite through at least one fixed ground antenna (12); system mobile transceiver installed in the vehicle (1) and comprising being: - a mobile satellite antenna (14) which is ...

The importance of telecommunications services for the management and control of critical situations f or the security of citizens has been always recognized: in particul ar, in this work we describe the solution designed and developed in an Italian research project, called CI6 (Centro Integrato per Servizi di Emergenza Innovativi). In this project the focus was to develop an integrated centre able to provide the decision make r with all the possible value added information concerning the sta e and the possible evolution of the crisis. From a technology research viewpoint, a 2-layered m iddleware merging a communication middleware (the CHIMERA platform) and an agent-based SW middleware has been integrate d and implemented as CI6 service-enabling platform: this 2-layered IC platform natively supports data gathering & aggregation coming from various sources to produce value added informa tion (say CI6 information) as CI6 service content: on-field operations data, external uncorrelated ...

The feasibility of extending the Inmarsat coverage to the polar caps is discussed, and possible configurations are examined. These are (1) low-altitude orbiting systems (below the Van Allen belts); (2) high-altitude orbiting systems (circular above the Van Allen belts); and (3) highly eccentric orbiting systems (perigee below and apogee above the Van Allen belts). It is shown that the cost

Relationships between the gain-beamwidth product, commonly used to predict antenna gain, and edge taper, sidelobe level, and 3-dB beamwidth are presented for an antenna reflector illuminated by a truncated Gaussian beam. Expressions are first derived for the spill-over efficiency, aperture efficiency, phase-error efficiency and overall antenna efficiency as functions of the edge taper, and for the loss in gain for a front-fed reflector due to blocking by the feed structure. Equations for the 3-dB beamwidth and the first sidelobe level are then obtained in terms of the taper and antenna geometry, and the gain-beamwidth product, defined as the product of the maximum gain with the square of the beamwidth, is calculated for offset and front-fed antennas in the presence and absence of phase errors. It is noted that maximum gain is achieved for a taper between 10 and 12 dB, while the best beam efficiency occurs when the taper is between 12 and 17 dB. Typical efficiencies calculated for offset and front-fed antennas are finally compared with those measured for Intelsat-V, ECS, OTS and ISPM.

IEE802.15.4 technology is widely deployed to monitor environmental changes without being tethered off of a wired network. In order to have good performance and no loss of information or alarm an accurate planning of indoor radio systems is required. It means to characterize the propagation channel. Moreover to know the behavior of the WSN channel model or RFID technologies allows to localize the positions of the sensors through techniques range or time to arrival based of the radio signals. Starting from experimental data obtained in two typical indoor environments we show the parameters, obtained by fitting, concerning One Slope (OS) and Multi-Wall (MW) models with reference to the office like environment. Differently from the standard MW model indicated in the literature, we include losses due to doors and different kind of wall that may lead to significant contributions to the overall attenuation. The developed channel model MW is used in a computer simulator in order to evaluate...

A radio communication system comprising a transmitter (4) and a receiver (5); wherein the transmitter (4) is configured to: - generate or receive digital symbols having symbol rate associated with a given period corresponding symbol; - generate, each S generated / received digital symbols a: respective multimode digital signal having a time duration preset shorter than S times the symbol period, which is sampled at a higher rate predefined sampling rate symbols. and carrying said S digital symbols via a plurality of harmonic modes orthogonal comprising - a primary mode that is a real harmonic mode and transports P of said S digital symbols, and - one or more secondary modes that carry other SP digital symbols , each secondary mode harmonically complex time-shifted by half of the symbol period relative to the main mode; and - transmitting a radio frequency signal that carries a sequence of digital signals generated multimode; where S is an integer greater than three and P is an integ...

Mobile ad hoc networks (MANETs) are characterized by their intrinsic capability to be set up without needing any kind of infrastructure, allowing a high degree of flexibility both at technological level and at application and service level. For this reason they are particularly useful in environment where no fixed network infrastructure is available. For example, they are well suitable for emergency application, when fixed telecommunication infrastructures, whereas present, can be seriously damaged or destroyed. Satellite networks also work without terrestrial infrastructure, excluding one gateway localized inside the footprint, and are easy to be set up too. For the same reasons also satellites can be fruitfully be utilized in case of emergency. Nevertheless, these two technologies are not in competition, as they might appear, but absolutely complementary. In fact, ad hoc mobile networks are characterized by very small terminals, low consumption, limited capacity per user terminals...

ABSTRACT The paper deals with the opportunity to introduce “Not strictly TEM waves” Synthetic detection Method (NTSM), consisting in a Three Axis Digital Beam Processing (3ADBP), to enhance the performances of radio telescope and sensor systems. Current Radio Telescopes generally use the classic 3D “TEM waves” approximation Detection Method, which consists in a linear tomography process (Single or Dual axis beam forming processing) neglecting the small z component. The Synthetic FEED ARRAY three axis Sensor SYSTEM is an innovative technique using a synthetic detection of the generic “NOT strictly TEM Waves radiation coming from the Cosmo, which processes longitudinal component of Angular Momentum too. Than the simultaneous extraction from radiation of both the linear and quadratic information component, may reduce the complexity to reconstruct the Early Universe in the different requested scales. This next order approximation detection of the observed cosmologic processes, may improve the efficacy of the statistical numerical model used to elaborate the same information acquired. The present work focuses on detection of such waves at carrier frequencies in the bands ranging from LF to MMW. The work shows in further detail the new generation of on line programmable and reconfigurable Mixed Signal ASIC technology that made possible the innovative Synthetic Sensor. Furthermore the paper shows the ability of such technique to increase the Radio Telescope Array Antenna performances.

The proposed multimission configuration reduces the number of reflectors present on the spacecraft and their related supporting structure (masts, booms) and at the same time divides the feed system from the reflector system for possible maintenance and/or payload substitution. This implies: An antenna system that is split into two parts: (1) the reflector with the platform (2) the feed subsystem with the payload. Reuse of the same reflector at different frequencies (to achieve this, the reflector system will use additional components, i.e., frequency sensitive subreflectors (FSS)). In case of in-orbit refurbishment or maintenance, the reflector system may remain in orbit with the platform. The presence of the FSS allows separation of the focal position sufficiently for the multiple-contoured beam applications required by future missions. There are two of these reflectors (one for TX function, one for RV deployed) on the east and west sides of the spacecraft, and the solar panels are on the north and south sides. The payloads are aligned along the yaw axis. Apart from the size, this configuration looks like a conventional spacecraft.

The feasibility of extending the Inmarsat coverage to the polar caps is discussed, and possible configurations are examined. These are (1) low-altitude orbiting systems (below the Van Allen belts); (2) high-altitude orbiting systems (circular above the Van Allen belts); and (3) highly eccentric orbiting systems (perigee below and apogee above the Van Allen belts). It is shown that the cost

The design approach and trade-offs in the development of the TDMA terminal and satellite network control processor (SNCP) for operation in the Italsat SSS/TDMA network are addressed. Among the TDMA terminal design issues discussed are clock synchronization, frame and burst timing, bus architecture, high-speed front-end, terrestrial interface ports, and processor. Network-management design concepts are considered, and two types of traffic

ABSTRACT The paper deals with a possible use of the feed array present in a large antenna system, as a layer for measuring the antenna performance with a self-test procedure and a possible way to correct residual errors of the Antenna geometry and of the antenna distortions. Focus has been concentrated on a few key critical elements of a possible feed array metrology program. In particular, a preliminary contribution to the design and development of the feed array from one side, and the subsystem dedicated to antenna distortion monitoring and control from the other, have been chosen as the first areas of investigation. Scalability and flexibility principles and synergic approach with other coexistent technologies have been assumed of paramount importance to ensure ease of integrated operation and therefore allowing in principle increased performance and efficiency. The concept is based on the use of an existing feed array grid to measure antenna distortion with respect to the nominal configuration. Measured data are then processed to develop a multilayer strategy to control the mechanical movable devices (when existing) and to adjust the residual fine errors through a software controlled phase adjustment of the existing phase shifter The signal from the feed array is converted passing through a FPGA/ASIC level to digital data channels. The kind of those typically used for the scientific experiments. One additional channel is used for monitoring the antenna distortion status. These data are processed to define the best correction strategy, based on a software managed control system capable of operating at three different levels of the antenna system: reflector rotation layer, sub reflector rotation and translation layer (assuming the possibility of controlling a Stewart machine), phase shifter of the phased array layer. The project is at present in the design phase, a few elements necessary for a sound software design of the control subsystem have been developed at a technological demonstrator level while the ASIC board for generating the digital data stream has been fully developed. A prototype for control accurately the position of the sub-reflector up to a diameter of 5 meters (similar to the sub reflector size of a large antenna) using a Stewart mechanism is being planned. The selection strategy of the correction modes will depend on the dynamics of the phased array (i.e. the available bits of the A/D conversion). The reaction time allowed for the correction, depending on the error type and the inertia of the sub systems. Typically, the compensation can be divided among all the adjusting elements.

The Italsat multibeam is a preoperational system aimed at investigating innovative technologies onboard a satellite and at anticipating the characteristics and the performance of an operational digital satellite telecommunication network integrated into the national terrestrial network. Laboratory tests were carried on and field trials are in progress in order to verify extensively the expected performance of the in orbit multibeam

The authors describe the ITALSAT satellite network, which will operate with an onboard base band switching matrix. They describe the main features of the system architecture, satellite terminal, and control center and the overall preoperational network performance. The satellite network interfaces the terrestrial network with three types of traffic: trunk, split and DAMA (demand-assigned multiaccess). The digital streams carry voice

The results of a preliminary study of an advanced configuration for a multimission multifrequency GEO spacecraft to be launched by the Ariane IV are presented. The multiple use of the platform requires multiple antennas and thereby redesign of the antenna booms, increases in the platform weight, long feeders from the electronics units to the antenna system, and upgraded control and

The propagation package mounted on the ITALSAT consisted of three beacon transmitters at 20, 40, and 50 GHz. The main characteristics of the equipment are described. Preliminary measurements have been performed with the aim of testing the performance of the satellite in orbit and to acquire information about the propagation of the 40- and 50-GHz bands through the atmosphere. The authors report on the most significant results obtained during the in-orbit-testing activity pertaining to the propagation payloads. These results demonstrate that the measured effective isotropically radiated power (EIRP) value significantly exceeded the specification value. The attenuation observed when some clouds crossed the antenna beam appeared to exceed significantly the values suggested by the CCIR for the same type of clouds

A description is given of two antenna standards that were assessed to be capable of assuring the required service quality and availability. Both antennas have an offset configuration with three reflectors. The main reflector is a paraboloid which is realized with carbon-fiber multilayered materials. The two shaped metallic subreflectors and a specially designed feed system incorporating a frequency selective surface

The main objective of the described investigation was the optimization of the synthesized circular reflector surface with respect to the minimum gain within coverage in the two frequency bands and versus the steering angle. The surface synthesis, the analysis of the reflector, and the optimization procedures were conducted with the aid of a set of computer programs based upon mathematical models of the reflector and of the source. The adopted reflector illumination makes it possible to obtain very low sidelobes. Attention is given to the general characteristics of the feed horn, aspects of steering center positioning, the design parameters of the antenna, and a design description. The main phases of the computer program are related to the synthesis of the reflector central section and an analysis of the radiation characteristics of the reflector.