Selenia Spazio S.p.a.

Alenia Spazio S.p.a.

Giorgio Perrotta

Giacinto Losquadro

A satellite telecommunications and remote sensing system including a plurality of satellites arranged above the Earth in short-period elliptical sun-synchronous orbits which have the following Keplerian parameters: an orbit inclination of 116.6.degree. on an equatorial plane of the Earth, a daily rotation of a nodal line of 0.9863.degree., an orbital period selected such that N orbital periods fit into M sidereal days, any desired argument of perigee and any desired value of the right ascension of the ascending node.

Satellite telecommunications and remote sensing system based on the use

An integrated antenna system for signal error tracking and correction capable of performing a mechanical conical scan. The mechanical conical scan imposes a modulation upon a received RF signal. This modulation is in turn imposed on an AGC circuit in the receiver of the antenna system, which modulates the AGC signal of the receiver in accord with the modulation imposed on the RF signal by the conical scan. This modulated AGC signal is compared in a detector circuit to a reference sinusoidal signal generated by a local oscillator in the system. This detector circuit outputs an error signal which is added to a reference sinusoidal signal which in combination drive an actuator. This actuator is responsible for imparting nutative motion to the antenna, for the purposes of producing the conical scan pattern. The error detection and correction which result from the conical scan and the error detection circuitry, are capable of operating at multiple RF frequencies and modulation schemes, since the error signal of the system is generated by a modulated AGC signal as opposed to the modulated RF signal itself.

Satellite antenna tracking system

A fine tracking radio frequency sensor system capable of locating ground beacons within an angular field which is substantially larger than -3dB antennae beamwidth beams, to be used preferably on board artificial telecommunication satellites equipped with single or multiple beam antennae.

Antenna tracking system using sequential lobing

A digital signal to be transmitted (TXSG) is encoded through an external code device (EXCD); digital signal TXSG' so obtained (with a bit rate greater than TXSG) is used to modulate, through modulator MOD 1, a transmission carrier later amplified by transmitter TEQ 1 and radiated by antenna ANT1. The RF carrier sent by the transmitter is received by an intermediate transponder through antenna ANT2, receiver REQ2 and demodulator DEM1, which reconstitutes signal TXSG', save for transmission errors. The signal so received is once again encoded by internal coder INCD, obtaining a new digital signal TXSG', which has a bit rate even higher than TXSG'. This TXSG' signal is then used to modulate a second RF carrier by means of MOD2 modulator. The resulting signal is amplified by TEQ2 and radiated by antenna ANT3. The RF signal sent by the transponder is received by the receiver terminal through ANT4 and, through receiver (REQ2) and demodulation (DEM2) units, a RXSG' signal is rebuilt, coinciding, save for transmission errors, with signal TXSG'. Such signal is decoded by internal decoder INDC, thereby obtaining a signal RXSG' which, save for transmission errors, coincides with signal TXSG'. This last signal is decoded by external decoder EXDC so as to rebuild signal RXSG which, save for transmission errors, coincides with transmitted signal TXSG.

Growing community of inventors

Rome, Italy

Giorgio Perrotta