Abstract: A hybrid network is disclosed having at least one hybrid coupler, and a plurality of circulators, each circulator having a first port connected to the hybrid network, and further having a second port and a third port. Each circulator is arranged to direct a signal received via the second port to the hybrid network via the first port, and to direct a signal received from the hybrid network towards the third port.

Abstract: In order to maintain isolation of signals within a multiport amplifier of a communications satellite and to reduce cross-talk components, by monitoring communications signals passing through the multiport amplifier, output signals of the multiport amplifier are sensed and downconverted to baseband, and applied to an emulator mechanism of the multiport amplifier. The emulator mechanism comprises a reverse matrix of the multiport amplifier, which recovers the input signals of the multiport amplifier together with cross-talk components, and a digital signal processor which carries out a frequency analysis of the cross-talk components by means of an FFT, and employs a digital model of the multiport amplifier to determine the state of the multiport amplifier which gives rise to such cross-talk components. The digital signal processor may be located at a ground station to which communication is made via a telemetry link.

Abstract: A hybrid network is disclosed having at least one hybrid coupler, and a plurality of circulators, each circulator having a first port connected to the hybrid network, and further having a second port and a third port. Each circulator is arranged to direct a signal received via the second port to the hybrid network via the first port, and to direct a signal received from the hybrid network towards the third port.

Abstract: For selectively routing downlink frequency channels to downlink beams of a communications satellite, the inherent routing functionality of a normal bandwidth multiport amplifier (MPA) is exploited in conjunction with the grouped channel filter characteristics of an output multiplexer (OMUX). In this arrangement the guard bands inherent in the OMUX mitigate the poor inter-port isolation inherent in the MPA so that two low performance elements in combination can be used to achieve an improved performance at system level.

Abstract: The invention provides a method and apparatus for applying test signals to a multiport amplifier (MPA) and a method, apparatus and system for determining parameter adjustments for an MPA. Applying test signals to an MPA is performed so as to provide an output signal indicative of parameter adjustments for the MPA, the multiport amplifier arrangement comprising an input network, an amplifier unit and an output network, where the method includes providing a test signal directly to a point in the multiport amplifier arrangement between an output of the input network and an input of the amplifier unit.

Abstract: In order to maintain isolation of signals within a multiport amplifier of a communications satellite and to reduce cross-talk components, by monitoring communications signals passing through the multiport amplifier, output signals of the multiport amplifier are sensed and downconverted to baseband, and applied to an emulator mechanism of the multiport amplifier. The emulator mechanism comprises a reverse matrix of the multiport amplifier, which recovers the input signals of the multiport amplifier together with cross-talk components, and a digital signal processor which carries out a frequency analysis of the cross-talk components by means of an EFT, and employs a digital model of the multiport amplifier to determine the state of the multiport amplifier which gives rise to such cross-talk components. The digital signal processor may be located at a ground station to which communication is made via a telemetry link.

Abstract: For selectively routing downlink frequency channels to downlink beams of a communications satellite, the inherent routing functionality of a normal bandwidth multiport amplifier (MPA) is exploited in conjunction with the grouped channel filter characteristics of an output multiplexer (OMUX). In this arrangement the guard bands inherent in the OMUX mitigate the poor inter-port isolation inherent in the MPA so that two low performance elements in combination can be used to achieve an improved performance at system level.

Abstract: The invention provides a method and apparatus for applying test signals to a multiport amplifier (MPA) and a method, apparatus and system for determining parameter adjustments for an MPA. Applying test signals to an MPA is performed so as to provide an output signal indicative of parameter adjustments for the MPA, the multiport amplifier arrangement comprising an input network, an amplifier unit and an output network, where the method includes providing a test signal directly to a point in the multiport amplifier arrangement between an output of the input network and an input of the amplifier unit.