Selenia Industrie Elettroniche Associate S.p.a.

Università Degli Studi Di Roma "tor Vergata"

Other

Selex Sistemi Integrati S.p.a.

Selenia Spazio S.p.a.

Univeristà Degli Studi Di Roma “tor Vergata”

Universta' Degli Studi Di Roma &ldquo;tor Vergata&rdquo;

Gaspare Galati

Selenia-industrie Elettrotechniche Associate S.p.a.

Selex Es S.p.a.

Ennio Giaccari

Giacinto Losquadro

Stefano Gelli

Egidio D'Addio

Emilio Giuseppe Piracci

Paolo Lombardi

Simone Bartolini

Mario Orsini

Mauro Leonardi

Fabrizio Fiori

Giovanni Jacovitti

The present invention relates to a system for locating non-cooperating objects by means of a random or pseudo-random noisy type waveform generator, an amplifier, of said waveforms and an antenna which radiates them towards the object, which object generates an electromagnetic echo which is detected by a passive subsystem of antennas and receivers. The time delay and Doppler shift values are determined in the latter subsystem and in turn forwarded from encoding and modulating blocks to a central processor which estimates the position and the speed of the object. The passive subsystem receives, through a transmission channel or storage element, the reference signal which represents the transmitted noisy type waveform and uses it for calculating the bi-dimensional cross correlation (ambiguity function), which permits to estimate the time delay and the Doppler shift.

Locating system based on noisy type waveforms

The present invention relates to a detecting device for detecting an SSR signal having a characteristic structure. The detecting device comprises filtering means matched to the characteristic structure of the SSR signal, and means for maintaining a false-alarm rate at a substantially constant value. The characteristic structure of the SSR signal comprises either a preamble or an initial pulse and a final pulse separated by a fixed dwell time. The means for maintaining a false-alarm rate at a substantially constant value comprise computing means configured to compute a detection threshold on the basis of a signal supplied by the filtering means, and decision means configured to detect the SSR signal on the basis of the detection threshold and of the signal supplied by the filtering means.

Reply detection in a secondary surveillance radar

A system able to locate and identify aircraft and vehicles based on the reception and processing, with novel means and methods, of signals emitted by the transponder of the secondary surveillance radar, shortly SSR. The system has a number of fixed stations distributed in the area of interest, e.g. in the airport area; any signal (the well known SSR reply/squitter) transmitted by the on-board transponder is received by four or more stations and the measurement of three or more differences of times of arrival (TOA) permits the reconstruction of the position of the transponder in spite of the fact that the transmission time is unknown. Suitable algorithms based on optimal estimation enhance both the accuracy of TOA measurements and the accuracy of the reconstructed position. The effects of possible overlapping of signal in time are avoided or mitigated by multiple source separation techniques based on least squares algebraic processing.

High precision surveillance system by means of multilateration of secondary surveillance radar (SSR) signals

Cooperating mobiles (ground vehicles, aircraft) are located and identified by Multilateration and Automatic Dependent Surveillance-Broadcast (ADS-B) techniques using the frequency band and the format of the Secondary Surveillance Radar (SSR) signals in high traffic situations. Standard messages, transmitted by the mobile on the downlink channel, i.e. to a set of fixed receiving stations, and including the identification code, permit the location of the mobile by multiple time measurements (Multilateration) from a subset of the set of fixed receiving stations; when the message contains the position (GPS and, later, Galileo datum) the mobile may be located with the ADS-B when in view even of a few stations or of a single station. In order to overcome the problem that arises with high traffic, i.e. the superimposition of signals, called garbling.

High-capacity location and identification system for cooperating mobiles with frequency agile and time division transponder device on board

A super resolution processor/receiver to discriminate superimposed secondary surveillance radar (Mode S, Mode A/C) replies and squitter that uses frequency-domain analysis to suppress interference between replies. In particular, the processor/receiver uses a spectral super-resolution method to estimate carriers of reply signals (every reply has a carrier that could be slightly different from the others). These frequency analyses, applied with particular timing referring to the signal that effectively carried the information, allow to estimate the information on SSR Mode S/Mode A/C replies.

Super-resolution processor/receiver to discriminate superimposed secondary surveillance radar (SSR) replies and squitter

Device for angle measurement for inclusion within a monopulse amplitude comparison radar receiver for particular application within secondary radars. In essence it consists of a log (.SIGMA.) signal comparator (9) against a detection threshold, which is meant to enable further processing; of two-analog-numerical converters (10, 11), a codes (12), receiving outputs .SIGMA. and .DELTA. from converters above, which provides the calculation of target azimuth.

Angle measurement device for amplitude monopulse receivers

A radar system for primary and secondary airspace surveillance, and especially for the detection and tracking of moving targets, consisting of a number of elementary satellites connected to nonrigid structures and of a main satellite, which performs accurate measurement of the position and altitude of elementary satellites and real-time adaptive combination of radar signals coming from them, so as to provide a large-phased array operating in the microwave band. This system overcomes the limitations on dimensioned large space-bound antennae found in the literature, minimizing the incidence and effects of undesired echoes and interference and assuring high detection accuracy. The fact that the elementary satellites are all the same (modular) makes possible gradual assembly of the system with possible expansion in time and assures particularly high operating availability.

Distributed-array radar system comprising an array of interconnected

Device for the identification of undesirable echoes in radar systems

A digital MTD processor interposed between a coherent video detector and a signal extractor of a surveillance radar comprises a plurality of Doppler filters connected in parallel to the video-detector output, including a zero filter, working into respective modulus extractors connected by way of respective threshold circuits to a common OR gate. Each threshold circuit includes a fixed-threshold comparator and an adaptive-threshold comparator with inputs connected in parallel to the output of the associated modulus extractor, either of these comparators being connectable to the OR gate via a switch controlled with the aid of a rain-clutter map so that the adaptive threshold is used only during exploration of regions with heavy rain. A ground-clutter map, which can be updated on the basis of level measurements performed on the output of the zero filter, controls the selective loading of each Doppler filter with one of three preselected sets of weights depending on the intensity of the ground clutter in the region being explored. Where ground clutter is heavy, the threshold circuit of the zero filter may be cut off from the OR gate. Both the fixed and the adaptive thresholds can be incremented in response to a command from the signal extractor generated upon the occurrence of an excessive number of false alarms.

Adaptive MTD digital processor for surveillance radar

A device for suppressing second-time-around echoes from far-out clutter in an MTI pulse radar lies in shunt with a digital signal processor connected to the receiver output of the radar whose transmitter includes a power oscillator maintaining phase coherence only for the duration of an outgoing pulse. In order to minimize the occurrence of blind speeds, the oscillator is triggered for different pulse-repetition frequencies of predetermined values in alternate scanning intervals each lasting for an antenna rotation by half a beamwidth. Echoes from a group of radar pulses emitted in one interval are accumulated and then compared in magnitude with accumulated echoes from another such group emitted in an adjoining interval. If these magnitudes--relatively adjusted to compensate for the different numbers of pulses per group--are substantially equal over a sequence of antenna revolutions, they are classified as due to second-time-around clutter echoes and the output signal of the processor is eliminated for the corresponding scanning intervals.

Suppressor of second-time-around clutter echoes for MTI pulse radar

A receiving section of a surveillance radar equipped with a power oscillator in its transmitting section comprises several registers for the storage of values, perferably in complex digital form, representing the starting phase of a continuous wave at the instant of transmission of an outgoing pulse, these values being used thereafter to establish coherence with an incoming echo pulse at a time when the power oscillator is no longer able to do so on account of unavoidable frequency drifts or because of intervention of a new recurrence period. Thus, the stored values permit the correct detection of targets at the far end of the range and/or the cancellation of second-time-around clutter echoes. The continuous wave may be generated by a coherent oscillator, phase-locked during each recurrence period by the outgoing pulse, or a separate crystal-controlled oscillator of highly stable frequency.

System for suppressing unwanted long-range and/or second-time-around

Disclosed is a method for the suppression by complex conjugate cancellation of unwanted radar echoes caused both by obstacles stationary with respect to the radar transmitter as well as obstacles having a relative speed with respect to the radar transmitter. Cancellation is achieved by the use of a conventional type cancelling operator with at one input a constant weight equal to 1 and at the other input a weight variable in such a way as to make the frequency response of the cancelling operator equal to zero instant-by-instant for a Doppler frequency equal to the average frequency of the unwanted echoes.

Growing community of inventors

Rome, Italy

Gaspare Galati