Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Improvement to satellite telecommunication systems using SS-TDMA (Satellite Switch Time Domain Multiple Access) technique equipped with on board regenerative repeaters consisting of: 1. Transmitting from ground to the satellite a signal (CM) with high frequency stability and in harmonic relationship with digital data rate by modulating the carrier sent by a beacon station for fine tracking of on-board antennas. The signal (CM) being synchronized to the plesiochronous clock (CPL) common to all ground stations is used for: a. on board bit re-synchronization of the data stream after demodulation and re-generation on board of the asynchronous data arriving at the satellite; b. synchronization of reference words related to start of frames sent by the satellite. 2. Modulating the signal CM with digital signals, to be used as high speed telecommand which operate in a totally independent way of the telecommand system usually adopted for satellite control.