Abstract: A transceiver receives linearly polarized signals from two geostationary satellites. The transceiver includes a first and second waveguide to form two receiving beam patterns with a maximum gain in angular directions different from each other. At one end of each waveguide, two receiving elements orthogonal to each other are provided. Four converting units convert, using a common local oscillator, the carrier frequency of the four signal components received from the two pairs of receiving elements into an intermediate frequency. A combining unit linearly combines the converted signal components, based on weights representing phase shifting and/or amplification of signal components. A weight input unit receives the weights to be used in the combining unit.

Abstract: A system for estimating a spacecraft (6) position is disclosed. It includes receiving stations (4) for receiving signals transmitted from the spacecraft (6) and a processing station (2) for receiving data from the receiving stations (4). Each receiving station (4) records, during a recording window (8), the signals transmitted from the spacecraft (6) and transmits, to the processing station (2), data representing the recorded signals during the recording window (8). The recording windows (8) associated with each of the receiving stations (4) are offset and/or of different size with respect to each other. The processing station (2) correlates the recorded signals to estimate the distance difference between the spacecraft (6) and each of a plurality of receiving stations and to estimate the spacecraft (6) position. A method, a receiving station (4), a processing station (2) and a computer program are also disclosed.

Abstract: A transceiver (2) receives linearly polarized signals (4) from two geo-stationary satellites (6). The transceiver (2) includes a first and second waveguide (8) to form two receiving beam patterns with a maximum gain in angular directions different from each other. At one end of each waveguide (8), two receiving elements (12) orthogonal to each other are provided. Four converting units (14) convert, using a common local oscillator (16), the carrier frequency of the four signal components received from the two pairs of receiving elements (12) into an intermediate frequency. A combining unit (20) linearly combines the converted signal components, based on weights representing phase shifting and/or amplification of signal components. A weight input unit (18) receives the weights to be used in the combining unit (20).

Abstract: The invention refers to a location method and location apparatus for determining the location of a stationary satellite receiver having a stationary satellite antenna by means of ranging packets within satellite payload signals.

Abstract: The invention refers to a satellite communications system with a mobile user terminal. In order to provide a satellite communications system which enables communication with a mobile user terminal via conventional communication satellites on any area of interest on earth, a quasi-geostationary satellite is operated in an inclined orbit and sends a spread downlink signal s? (t) to said area of interest on earth to be received and despreaded by a mobile user terminal.

Abstract: A ranging system determines ranging information of a spacecraft carrying a component of a communication channel. In order to provide a ranging system for determining ranging information of a satellite carrying a transponder as well as to provide a method thereof which yield a sufficient accuracy without causing further costs when narrow spot beams by the transponder are used, a ranging system includes a plurality of receiving stations at different locations on earth, wherein each receiving station is arranged for receiving a reference signal from the component; a synchronization unit for providing a synchronized time base between the plurality of receiving stations; a calculation unit for calculating the ranging information in accordance with the propagation time of each received reference signal and with the synchronized time base; wherein at least one receiving station includes a correlation receiver for receiving the reference signal.

Abstract: The invention refers to a system for distributing data from a transmission station to a plurality of user stations over a transmission channel having a predetermined bandwidth. In order to provide internet services to the end user via a single direct-to-home satellite transmission channel, the transmission channel comprises a contents channel and an announcement channel, wherein the transmission station transmits over the contents channel a data subset within a certain period and transmits over the announcement channel an index of future data subsets to be transmitted, and wherein a user profile is stored in each user station characterizing the relative importance of topics of interest to the user and wherein the user station downloads data subsets from the transmission channel in accordance with the quality of matching between the index of the announcement channel and the user profile.

Abstract: The invention refers to a method and an apparatus for determining characteristics of components of a communication channel.

Abstract: The method according to the invention allows to determine the yaw angle of a satellite from the reading of two different sensors measuring the roll and/or pitch angles, provided that the reference point of the two sensors are not identical. A description is given basically for geostationary satellites but the method can be applied directly to satellites which are stationary with respect to any star. The method can be employed for circular and non-circular orbits.