An apparatus for controlling the gain and phase of an input signal input to a power amplifier comprises a gain control loop configured to control the gain of the input signal based on power levels of the input signal and an amplified signal output by the power amplifier, to obtain a predetermined gain of the amplified signal, and a phase control loop configured to obtain an error signal related to a phase difference between a first signal derived from the input and a second signal derived from the amplified signal, and control the phase based on the error signal, to obtain a predetermined phase of the amplified signal. The phase control loop delays the first signal such that the delayed first signal and the second signal used to obtain the error signal correspond to the same part of the input signal. The apparatus may be included in a satellite.
An apparatus for controlling the gain and phase of an input signal input to a power amplifier comprises a gain control loop configured to control the gain of the input signal based on power levels of the input signal and an amplified signal output by the power amplifier, to obtain a predetermined gain of the amplified signal, and a phase control loop configured to obtain an error signal related to a phase difference between a first signal derived from the input and a second signal derived from the amplified signal, and control the phase based on the error signal, to obtain a predetermined phase of the amplified signal. The phase control loop delays the first signal such that the delayed first signal and the second signal used to obtain the error signal correspond to the same part of the input signal. The apparatus may be included in a satellite.
A satellite antenna arrangement for a satellite communication system comprising: a reflector for producing a far field pattern with near-zero field strength at a predetermined location to reject unwanted signals from said predetermined location or minimize signal power transmitted to said predetermined location, the reflector having a surface comprising a stepped profile arranged to generate the near-zero field strength in the predetermined location. The stepped profile may comprise a radial step. The location of the near-zero field strength can be steered by moving the reflector or by adjusting the amplitude and phase of an additional beam that covers substantially the same region as the main beam reflected by the reflector.
H01Q 1/28 - Adaptation for use in or on aircraft, missiles, satellites, or balloons
H01Q 15/16 - Reflecting surfacesEquivalent structures curved in two dimensions, e.g. paraboloidal
H01Q 19/10 - Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces
An apparatus for controlling the gain and phase of an input signal input to a power amplifier comprises a gain control loop configured to control the gain of the input signal based on power levels of the input signal and an amplified signal output by the power amplifier, to obtain a predetermined gain of the amplified signal, and a phase control loop configured to obtain an error signal related to a phase difference between a first signal derived from the input and a second signal derived from the amplified signal, and control the phase based on the error signal, to obtain a predetermined phase of the amplified signal. The phase control loop delays the first signal, such that the delayed first signal and the second signal used to obtain the error signal correspond to the same part of the input signal. The apparatus may be included in a satellite.
A reflector antenna includes a dual-band waveguide feed and a splashplate support arranged to define a space between the waveguide feed aperture and the splashplate. The dual-band waveguide feed is configured to receive an input signal in a first transmission mode, to convert a transmission mode of an upper frequency band from a first transmission mode to a mixed transmission mode including the first transmission mode and a second transmission mode. The supporting portion can be spaced apart from the aperture of the waveguide feed, and may have a thickness corresponding to half a wavelength of a beam emitted from the aperture.
H01Q 13/00 - Waveguide horns or mouths Slot antennas Leaky-waveguide antennas Equivalent structures causing radiation along the transmission path of a guided wave
H01Q 19/13 - Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces wherein the surfaces are concave the primary radiating source being a single radiating element, e.g. a dipole, a slot, a waveguide termination
H01Q 13/20 - Non-resonant leaky-waveguide or transmission-line antennas Equivalent structures causing radiation along the transmission path of a guided wave
H01Q 19/19 - Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces having two or more spaced reflecting surfaces comprising one main concave reflecting surface associated with an auxiliary reflecting surface
An article comprises a carbon fibre reinforced plastic (CFRP) substrate, a buffer layer disposed adjacent the substrate, the buffer layer comprising a poly(para-xylylene) polymer; and a moisture barrier coating disposed adjacent the buffer layer.
An ion accelerator comprises: an inner magnet (10) having a channel (34) extending through it in an axial direction; an outer magnet (12) extending around the inner magnet (10), the magnets having like polarities so as to produce a magnetic field having two locations of zero magnetic field strength. The locations are spaced apart in the axial direction; and an anode (38) and a cathode (36) are arranged to generate an electrical potential difference between the locations.
There is provided a filter network arrangement comprising a filter network; and one or more correction networks, wherein the one or more correction networks is arranged to substantially equalise the passband gain and group delay of the filter network arrangement. Given an appropriate Q for the one or more correction networks, a polynomial for the one or more correction networks can be found that equalises both the passband gain and group delay and the one or more correction networks can be synthesised from the polynomial.
A phased array antenna for providing a radiation pattern having at least one communication beam, includes a plurality of antenna elements, each with an antenna element signal having a phase relationship and an amplitude relationship to the other element signals; a digital signal processing arrangement providing a digital beamforming network; and an analog beamforming network arranged to reduce exposure of the digital signal processing arrangement to an interfering signal. Analog beamforming weights are selected to generate a null in the radiation pattern in a direction corresponding to the interfering signal.
H04L 1/02 - Arrangements for detecting or preventing errors in the information received by diversity reception
H01Q 3/40 - Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elementsArrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the distribution of energy across a radiating aperture varying the phase by electrical means with phasing matrix
H04B 7/08 - Diversity systemsMulti-antenna systems, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
H01Q 3/26 - Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elementsArrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the distribution of energy across a radiating aperture
10.
REFLECTOR ANTENNA INCLUDING DUAL BAND SPLASHPLATE SUPPORT
A reflector antenna includes a dual-band waveguide feed and a splashplate support arranged to define a space between the waveguide feed aperture and the splashplate. The dual-band waveguide feed is configured to receive an input signal in a first transmission mode, the input signal including a plurality of frequencies arranged into upper and lower frequency bands, and includes means for converting a transmission mode of the upper frequency band from a first transmission mode to a mixed transmission mode including the first transmission mode and a second transmission mode. The supporting portion can be spaced apart from the aperture of the waveguide feed, and may have a thickness corresponding to half a wavelength of a beam emitted from the aperture. The shape of the supporting portion may preferably correspond to a shape of the beam wavefront after it has been reflected from the splashplate. A satellite including the reflector antenna is also disclosed.
H01Q 13/20 - Non-resonant leaky-waveguide or transmission-line antennas Equivalent structures causing radiation along the transmission path of a guided wave
H01Q 19/19 - Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces having two or more spaced reflecting surfaces comprising one main concave reflecting surface associated with an auxiliary reflecting surface
11.
REFLECTOR ANTENNA INCLUDING DUAL BAND SPLASHPLATE SUPPORT
A reflector antenna includes a dual-band waveguide feed and a splashplate support arranged to define a space between the waveguide feed aperture and the splashplate. The dual-band waveguide feed is configured to receive an input signal in a first transmission mode, the input signal including a plurality of frequencies arranged into upper and lower frequency bands, and includes means for converting a transmission mode of the upper frequency band from a first transmission mode to a mixed transmission mode including the first transmission mode and a second transmission mode. The supporting portion can be spaced apart from the aperture of the waveguide feed, and may have a thickness corresponding to half a wavelength of a beam emitted from the aperture. The shape of the supporting portion may preferably correspond to a shape of the beam wavefront after it has been reflected from the splashplate. A satellite including the reflector antenna is also disclosed.
H01Q 13/20 - Non-resonant leaky-waveguide or transmission-line antennas Equivalent structures causing radiation along the transmission path of a guided wave
H01Q 19/19 - Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces having two or more spaced reflecting surfaces comprising one main concave reflecting surface associated with an auxiliary reflecting surface
An apparatus for controlling the gain and phase of an input signal input to a power amplifier comprises a gain control loop configured to control the gain of the input signal based on power levels of the input signal and an amplified signal output by the power amplifier, to obtain a predetermined gain of the amplified signal, and a phase control loop configured to obtain an error signal related to a phase difference between a first signal derived from the input and a second signal derived from the amplified signal, and control the phase based on the error signal, to obtain a predetermined phase of the amplified signal. The phase control loop is arranged to delay the first signal before obtaining the error signal, such that the delayed first signal and the second signal used to obtain the error signal correspond to the same part of the input signal. The gain control loop may compare a power of a third signal derived from the input signal and a power of a fourth signal derived from the amplified signal. The third and fourth signals may be output by first and second couplers, which may have coupling factors that are selected such that the third and fourth signals have the same power level when the amplified signal has the predetermined gain. The current gain and phase of the amplified signal may be dependent on an operational history of the power amplifier, which may be a GaN power amplifier, and the apparatus and power amplifier may be included in a satellite. In another embodiment, a satellite includes a power amplifier control system that uses a feed-forward control loop to control both the gain and phase of a signal input to the power amplifier.
A device for guiding and absorbing electromagnetic radiation, the device comprising: absorbing means for absorbing the electromagnetic radiation; and a coupled to the absorbing means for guiding the electromagnetic radiation to the absorbing means, wherein the waveguide and the absorbing means are formed from a structure comprising a first cladding layer, a second cladding layer over the first cladding layer, and a quantum-well layer between the first and second cladding layers, the quantum-well layer being formed of a material having a different composition to the first and second cladding layers, wherein the thickness and the composition of the quantum-well layer is optimised to provide an acceptable level of absorption of electromagnetic radiation in the waveguide while providing an appropriate band gap for absorption of the electromagnetic radiation in the absorbing means.
G02B 6/293 - Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
A device comprising: a substrate (110); a plurality of resonators (130) on the substrate, each of the resonators of the plurality of resonators being resonant at a predetermined wavelength of electromagnetic radiation and at least some of the resonators being arranged to operate in different resonance orders; a waveguide (120) on the substrate, the waveguide being coupled to the plurality of resonators for guiding the electromagnetic radiation to the plurality of resonators, wherein the resonance order of each resonator along the waveguide is optimised to maximise the coupling of light into the resonators.
G02B 6/293 - Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
An apparatus for controlling the gain and phase of an input signal input to a power amplifier comprises a gain control loop configured to control the gain of the input signal based on power levels of the input signal and an amplified signal output by the power amplifier, to obtain a predetermined gain of the amplified signal, and a phase control loop configured to obtain an error signal related to a phase difference between a first signal derived from the input and a second signal derived from the amplified signal, and control the phase based on the error signal, to obtain a predetermined phase of the amplified signal. The phase control loop is arranged to delay the first signal before obtaining the error signal, such that the delayed first signal and the second signal used to obtain the error signal correspond to the same part of the input signal. The gain control loop may compare a power of a third signal derived from the input signal and a power of a fourth signal derived from the amplified signal. The third and fourth signals may be output by first and second couplers, which may have coupling factors that are selected such that the third and fourth signals have the same power level when the amplified signal has the predetermined gain. The current gain and phase of the amplified signal may be dependent on an operational history of the power amplifier, which may be a GaN power amplifier, and the apparatus and power amplifier may be included in a satellite. In another embodiment, a satellite includes a power amplifier control system that uses a feed-forward control loop to control both the gain and phase of a signal input to the power amplifier.
The present application relates to relates to a control system for maintaining linearity of a power amplifier. Apparatus for controlling the gain and phase of the input signal comprises a gain control loop configured to control the gain of the input signal based on power levels of the input signal and an amplified signal output, to obtain a predetermined gain of the amplified signal, and a phase control loop configured to obtain an error signal related to a phase difference between a first signal derived from the input and a second signal derived from the amplified signal, and control the phase based on the error signal, to obtain a predetermined phase of the amplified signal. The first signal is delayed before obtaining the error signal, such that the delayed first signal and the second signal used to obtain the. error signal correspond to the same part of the input signal.
A spectrometer comprises a substrate and a waveguide on the substrate, the waveguide including an elongate part and a tapered input for guiding electromagnetic radiation to the elongate part. The tapered input includes an input end for receiving the electromagnetic radiation and an output end coupled to the elongate part, the input end being wider than the output end. The spectrometer may further comprise a plurality of resonators coupled to the elongate part of the waveguide.
G02B 6/122 - Basic optical elements, e.g. light-guiding paths
G02B 6/293 - Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
A structure for guiding electromagnetic radiation, comprising: a substrate (230); a waveguide (220) provided on the substrate and having a first end (220a) for receiving electromagnetic radiation and a second end (220b); and an anti-reflection region (270) provided at the second end (220b) of the waveguide on the substrate, the length and the width of the anti-reflection region being optimised to suppress back reflection of radiation that reaches the second end.
G02B 6/293 - Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
G02B 6/42 - Coupling light guides with opto-electronic elements
A device for detecting electromagnetic radiation comprises a waveguide and at least one resonator on a substrate, and a low-refractive index region between each resonator and the substrate. The low-refractive index region has a lower refractive index than a material of the resonator. The low-refractive index region may be annular, and may have a width corresponding to a width of a region in which electromagnetic radiation is concentrated in a whispering-gallery resonant mode. The low-refractive index region may be an air gap between the substrate and the resonator. The device may be a spectrometer for detecting a plurality of predetermined wavelengths of electromagnetic radiation.
G02B 6/122 - Basic optical elements, e.g. light-guiding paths
G02B 6/293 - Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
20.
APPARATUS AND METHOD FOR USE IN A SPACEWIRE-BASED NETWORK
An apparatus for use in a SpaceWire-based network is configured to send and receive data packets, and process data included in a received data packet. A header of the received data packet is stored in a buffer whilst the data is being processed, a processed data packet including the stored header and the processed data is generated, and the processed data packet is transmitted. The header of the received data packet may be modified, and the modified header attached to the processed data to generate the processed data packet. A boundary between header and data fields of the received data packet may be identified based on a predefined marker. When the data packet is received via a first port, the processed data packet may be transmitted via the first port, or may be transmitted via a second port. The second port may be selected from a plurality of available ports based on address information in the header of the received data packet.
A test arrangement includes a multi-port test interface having a first waveguide coupled to a plurality of second waveguides. The first waveguide is arranged to propagate an input signal and each of the second waveguides is arranged to output the input signal, providing a plurality of test signals to be supplied to a communications apparatus. Such a test interface may also be used to output respective channel signals in a multiplexed signal received from a communications apparatus. The test interface permits the provision and/or monitoring of a large number of channel signals without separate respective connections to the communications apparatus. This may be particularly useful where tests are performed in a constrained space and/or where repeated access to the apparatus is impractical, e.g. in a vacuum chamber. The simultaneous provision of many channel signals may allow evaluation of co-channel interference.
An apparatus for aligning non-synchronous input data streams received in the apparatus, the apparatus comprising an analogue to digital converter arrangement for digitising the data streams into a plurality of sequences of samples; and a synchronisation processing arrangement for generating alignment pulses for each sequence of the plurality of sequences of samples, for arranging each sequence of samples with respect to the alignment pulses for the sequence and for synchronisation the delivery of said plurality of sequences of samples to a common processor with respect to the respective alignment pulses. The synchronisation processing arrangement may comprise a processing chain for each antenna feed of said plurality of antenna feeds and each processing chain may comprise an alignment pulse generator for generating an alignment pulse for the sequence of samples corresponding to the processing chain. The input data streams may be received by a plurality of antenna feeds.
An apparatus for aligning non-synchronous input data streams received in the apparatus, the apparatus comprising an analogue to digital converter arrangement for digitising the data streams into a plurality of sequences of samples; and a synchronisation processing arrangement for generating alignment pulses for each sequence of the plurality of sequences of samples, for arranging each sequence of samples with respect to the alignment pulses for the sequence and for synchronisation the delivery of said plurality of sequences of samples to a common processor with respect to the respective alignment pulses. The synchronisation processing arrangement may comprise a processing chain for each antenna feed of said plurality of antenna feeds and each processing chain may comprise an alignment pulse generator for generating an alignment pulse for the sequence of samples corresponding to the processing chain. The input data streams may be received by a plurality of antenna feeds.
Apparatus for a spaceborne or aerial platform, comprising a frequency demultiplexer for frequency demultiplexing a signal corresponding to a range line or an azimuth line of SAR data, and comprising information about a plurality of target points, into a plurality of frequency channels, and compression means for performing compression on each frequency channel, each frequency channel signal comprising information about the same target points. The frequency demultiplexer and the compression means are implemented in hardware. The apparatus may be used for either or both of the range compression and the azimuth compression of a SAR arrangement on board a spaceborne or aerial platform and the SAR arrangement may generate a plurality of sub-images corresponding to the frequency channels from the SAR raw data. The sub-images may be combined by averaging in order to reduce the volume of memory required to store the SAR data.
A plasma thruster includes a plasma chamber having first and second axial ends, the first of which is open, an anode located at the second axial end, and a cathode. The cathode and anode are arranged to produce an electric field having at least a component in the axial direction of the thruster. A magnet system including a plurality of magnets is spaced around the thruster axis, each magnet having its north and south poles spaced around the axis.
A receiver is configured to receive signals wirelessly from a plurality of pseudolites, each signal including information defining a pseudolite from which the signal was transmitted. The receiver is configured to determine an estimated location based on which combination of two or more pseudolites the receiver is currently within range of. The receiver may determine the estimated location independently of a time taken for each one of the signals to reach the receiver from the two or more pseudolites. The signals may be formatted according to a global navigation satellite system GNSS specification.
G01S 19/11 - Cooperating elementsInteraction or communication between different cooperating elements or between cooperating elements and receivers providing dedicated supplementary positioning signals wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters
G01S 5/14 - Determining absolute distances from a plurality of spaced points of known location
G01S 5/02 - Position-fixing by co-ordinating two or more direction or position-line determinationsPosition-fixing by co-ordinating two or more distance determinations using radio waves
G01S 19/48 - Determining position by combining or switching between position solutions derived from the satellite radio beacon positioning system and position solutions derived from a further system
A receiving device for receiving a satellite broadcast is disclosed which includes a receiver for receiving a sustaining satellite beam and a controller for switching the receiver to receive a high power content beam in response to a determination that the high power content beam can be received by the receiving device. A communication satellite can transmit the high power content beam to different geographical areas at different times. The sustaining beam allows the receiving device to remain synchronized with the communication satellite when the high power content beam is directed elsewhere. The sustaining beam may be a lower power beam. The determination that the high power content beam can be received may be performed based on information in the sustaining beam.
H04N 21/235 - Processing of additional data, e.g. scrambling of additional data or processing content descriptors
H04H 40/90 - Arrangements characterised by circuits or components specially adapted for receiving specially adapted for broadcast systems covered by groups specially adapted for satellite broadcast receiving
H04H 20/74 - Wireless systems of satellite networks
28.
SYSTEM FOR THE RECOVERY, STORAGE AND UTILISATION OF ATMOSPHERIC GAS FOR USE AS A VEHICLE PROPELLANT
A system (1) for the recovery and management of atmospheric gas for use as a vehicle propellant. The system comprises a compressor (6, 8, 10) configured to draw in and compress atmospheric gas and first (2) and second (4) storage tanks configured to store liquefied atmospheric gas from the compressor. Each storage has an inlet duct (14a, 14b) for the supply of liquefied atmospheric gas thereto. The inlet duct of the first storage tank is fluidly connected to the compressor. The second storage tank has a heater (20) operable to heat liquefied atmospheric gas therein to convert it to a high pressure gas. The second storage tank includes an outlet duct (22) fluidly coupled to the first storage tank for supplying high pressure gas to the first storage tank. A control valve (24) is provided in said outlet duct. The first storage tank includes an outlet duct (36) for the flow of liquid out of the first storage tank under pressure provided by the gas from the second storage tank. The invention also provides a vehicle propulsion system including such a system for the recovery and management of atmospheric gas for use as a vehicle propellant in combination with a main lift thruster unit and a plurality of reaction control thrusters, and also a planetary surface explorer vehicle including such a propulsion system.
A phased array antenna for providing a radiation pattern comprising at least one communication beam, the antenna comprising a plurality of antenna elements, each antenna element having an antenna element signal having a phase relationship and an amplitude relationship to the other element signals; a digital signal processing arrangement providing a digital beamforming network; and an analogue beamforming network arranged to reduce exposure of the digital signal processing arrangementto an interfering signal, the analogue beamforming network being configured to apply analogue beamforming weights selected to generate a null in the radiation pattern in a direction corresponding to the interfering signal to signals received from said antenna elements and the digital beamforming network being configured to apply digital beamforming weights for each of said at least one communication beams to signals received from said analogue beamforming network such that the composite radiation pattern of the antenna provides said at least one communication beams. The elements may be partitioned into subarrays, the analogue beamforming network applying beamformingweights to each antenna element within a subarray and the digital beamforming network applying beamforming weights to eachsubarray.
H01Q 3/26 - Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elementsArrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the distribution of energy across a radiating aperture
H01Q 3/40 - Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elementsArrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the distribution of energy across a radiating aperture varying the phase by electrical means with phasing matrix
A phased array antenna for providing a radiation pattern comprising at least one communication beam, the antenna comprising a plurality of antenna elements, each antenna element having an antenna element signal having a phase relationship and an amplitude relationship to the other element signals; a digital signal processing arrangement providing a digital beamforming network; and an analogue beamforming network arranged to reduce exposure of the digital signal processing arrangement to an interfering signal, the analogue beamforming network being configured to apply analogue beamforming weights selected to generate a null in the radiation pattern in a direction corresponding to the interfering signal to signals received from said antenna elements and the digital beamforming network being configured to apply digital beamforming weights for each of said at least one communication beams to signals received from said analogue beamforming network such that the composite radiation pattern of the antenna provides said at least one communication beams. The elements may be partitioned into subarrays, the analogue beamforming network applying beamforming weights to each antenna element within a subarray and the digital beamforming network applying beamforming weights to each subarray.
H01Q 3/26 - Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elementsArrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the distribution of energy across a radiating aperture
H01Q 3/40 - Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elementsArrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the distribution of energy across a radiating aperture varying the phase by electrical means with phasing matrix
A plasma thruster comprises a plasma chamber having first and second axial ends, the first of which is open, an anode located at the second axial end, and a cathode. The cathode and anode are arranged to produce an electric field having at least a component in the axial direction of the thruster. A magnet system comprising a plurality of magnets is spaced around the thruster axis, each magnet having its north and south poles spaced around the axis.
According to the present invention, there is provided an apparatus (300) comprising a hybrid network (301, 302) comprising at least one hybrid coupler, and a plurality of circulators (303, 304, 305, 306), each circulator having a first port connected to the hybrid network (301, 302), 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 (301, 302) via the first port, and to direct a signal received from the hybrid network (301, 302) towards the third port.
A multi-band filter (10) comprising: an input manifold (12); an output manifold (18); and a plurality of filters (13, 14, 15, 16) connected in parallel between the input manifold (12) and output manifold (18). Each filter is directly coupled to a said input manifold and a said output manifold. The filters have a first section proximal to the input manifold which is coupled to the input manifold and a second section proximal to the output manifold which is coupled to the output manifold.
A connector includes an outer connection element and an inner connection element. One of the outer connection element and inner connection element includes a plurality of fingers extending at an angle relative to a longitudinal axis of the connector.
H01R 24/40 - Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure having concentrically or coaxially arranged contacts specially adapted for high frequency
H01R 43/16 - Apparatus or processes specially adapted for manufacturing, assembling, maintaining, or repairing of line connectors or current collectors or for joining electric conductors for manufacturing contact members, e.g. by punching and by bending
H01R 13/03 - Contact members characterised by the material, e.g. plating or coating materials
A multi-band filter is disclosed which includes an input manifold; an output manifold; and a plurality of filters connected in parallel between the input manifold and output manifold. The filters have a first section proximal to the input manifold which is matched to the input manifold and a second section proximal to the output manifold which is matched to the output manifold.
A method of manufacturing a connector (10; 60) comprising forming an outer connection element (20) or inner connection element (90) having fingers (22, 92). The fingers (22, 92) are deformed to an angle to a longitudinal axis. The connection element (90) is heat treated with the fingers (22, 92) restrained at the angle to the longitudinal axis such that the fingers (22, 92) are permanently deformed to extend at the angle to the longitudinal axis.
H01R 24/40 - Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure having concentrically or coaxially arranged contacts specially adapted for high frequency
37.
A METHOD OF MANUFACTURING A CONNECTOR, AND A CONNECTOR
A method of manufacturing a connector (10; 60) comprising forming an outer connection element (20) or inner connection element (90) having fingers (22, 92). The fingers (22, 92) are deformed to an angle to a longitudinal axis. The connection element (90) is heat treated with the fingers (22, 92) restrained at the angle to the longitudinal axis such that the fingers (22, 92) are permanently deformed to extend at the angle to the longitudinal axis.
H01R 24/40 - Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure having concentrically or coaxially arranged contacts specially adapted for high frequency
A multi-band filter (10) comprising: an input manifold (12); an output manifold (18); and a plurality of filters (13, 14, 15, 16) connected in parallel between the input manifold (12) and output manifold (18). Each filter is directly coupled to a said input manifold and a said output manifold. The filters have a first section proximal to the input manifold which is coupled to the input manifold and a second section proximal to the output manifold which is coupled to the output manifold.
According to the present invention, there is provided an output multiplexer OMUX comprising a plurality of hybrid-coupled filters. Each hybrid-coupled filter may be arranged to receive a first signal and a second signal via first and second input ports respectively, and output the first signal and the second signal via first and second output ports respectively, and the hybrid-coupled filters may be connected to combine a plurality of said first signals into a first multiplexed signal and combine a plurality of said second signals into a second multiplexed signal.
A satellite communication system comprises: - at least one base station (1); - at least one satellite (2) which can be brought into communication connection with the base station (1) for data transmission; and - a plurality of receivers (32) adapted to receive signals transmitted from the satellite (2); - wherein the communication system is designed to transmit data in at least one uplink data stream (U) from the base station (1) to the satellite (2) with a first data transmission rate and to transmit data in at least one downlink data stream (D) from the satellite (2) to the receivers (32) with a second data transmission rate; - wherein the first data transmission rate is lower than the second data transmission rate and - wherein the satellite (2) is provided with a data storage means (22) adapted to store the data transmitted from the base station (1) to the satellite (2) and to supply the data provided for the transmission to the receivers (32).
The present invention relates to a pseudo-noise generator comprising a plurality of pseudo-random number generators and an averaging unit. The averaging unit is arranged to receive a plurality of pseudo-random numbers from the plurality of pseudo-random number generators, calculate a mean value of the plurality of pseudo-random numbers, and output said mean value as a digital pseudo-noise signal.
A waveguide is provided that comprises an elongate dielectric inner region, and an electrically conducting outer region spaced apart from the dielectric inner region. The dielectric inner region may be arranged to be flexible, and in some examples may be formed from powdered dielectric contained in a polymer tube or matrix, or in other examples may be formed from a plurality of segments. In some examples of the waveguide, each segment may be formed to have lenticular end faces, and may be formed from sintered BaTi4O9.
A receiver (10) is configured to authenticate received satellite signals (12) having a carrier wave carrying positioning data. The receiver comprises a processor arrangement configured to analyse the carrier wave to determine an apparent acceleration between the satellite and receiver. The processor arrangement is also configured to compare the apparent acceleration between the satellite and receiver with a threshold value to determine if the satellite signal is authentic.
A telecommunications satellite payload processing system having one or more identical generic integrated processor modules is provided. The number of integrated processor modules can be selected in accordance with the antenna and bandwidth characteristics of a specified mission uplink and downlink in relation to the characteristics of the integrated processor module.
An apparatus comprising: a first transceiver for communicating with a set-top box via a first network corresponding to a short-range network; a second transceiver for communicating with a geostationary communication satellite in a second network, the first transceiver being configured to receive information corresponding to a request from said set-top box related to broadcast content, and said second transceiver being configured to transmit a message corresponding to said request to said geostationary communication satellite. The set-top box may comprise a receiver for receiving broadcast content; a transceiver for communicating data, through a short-range network, to a terminal, said terminal being in communication with a content management centre via a geostationary satellite; and an input interface for receiving instructions from a user, the input interface being configured to receive a user input associated with broadcast content, and the transceiver being configured to transmit said user input to said terminal for onward transmission to the content management centre.
A terminal for communicating with a communication satellite A terminal comprising: a first transceiver for communicating with at least one device in a short range network; a second transceiver for communicating with a geostationary communication satellite in a network deploying a plurality of forward channels for the communication satellite to transmit data to said terminal and a plurality of return channels for the terminal to transmit data to said communication satellite, the second transceiver being configured to transmit data from said at least one device in one of said plurality of return channels. The at least one device may comprise a plurality of utility meters and other sensors. A large system comprising a plurality of the terminals, a communication satellite and a data authority may provide a system for collecting utility meter readings across a geographical region.
A positioning system (1) comprising one or more transmitters configured to transmit transmissions including positioning data, wherein the system is configured to synchronise the transmission with a reference time. The transmissions are formed using a repeating pseudorandom number (PRN) code comprising a plurality of chips. The system (1) is configured to determine a timing bias (44;54) between the first transmission and the reference time. The system (1) is configured to change the number of chips in one or more of said transmissions such that the timing bias of a subsequent pseudorandom number (PRN) code is reduced.
G01S 1/00 - Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmittersReceivers co-operating therewith
G01S 5/02 - Position-fixing by co-ordinating two or more direction or position-line determinationsPosition-fixing by co-ordinating two or more distance determinations using radio waves
An antenna feed assembly is provided which includes at least two elongate feed chains lying adjacent one another. Each feed chain is adapted to transmit or receive electromagnetic radiation between itself and the antenna along a longitudinal feed axis thereof via a transmit/receive element. The feed chains are held in fixed lateral relationship to one another by first and second mountings spaced apart axially of the feed chains. The transmit/receive elements extend axially from the first mounting towards the antenna and the second mounting is positioned on a side of the first mounting remote from the antenna. The first mounting has a lower coefficient of thermal expansion in the lateral direction than the second mounting whereby translational movement of each transmit/receive element in the lateral direction owing to temperature change of the assembly will be reduced.
H01Q 19/195 - Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces having two or more spaced reflecting surfaces comprising one main concave reflecting surface associated with an auxiliary reflecting surface wherein a reflecting surface acts also as a polarisation filter or a polarising device
An extendable structure (100) which may be used in space-based applications, for example forming the body of a telescope. The structure is movable between a stowed configuration and an extended configuration, and comprises a plurality of walls (401,402,403,404) arranged to give a polygonal cross-section in the extended configuration. Each wall comprises a plurality of repeating units (2501,2502) which are connected by a plurality of hinges. Each repeating unit itself comprises a plurality of sections (101,102,103,104,105,106) connected by a plurality of hinges (109,110,111,112,113,114). The plurality of hinges may comprise tape-spring hinges.
B64G 1/22 - Parts of, or equipment specially adapted for fitting in or to, cosmonautic vehicles
E04B 1/344 - Structures characterised by movable, separable, or collapsible parts, e.g. for transport with hinged parts
E04H 12/18 - TowersMasts or polesChimney stacksWater-towersMethods of erecting such structures movable or with movable sections, e.g. rotatable or telescopic
50.
Filtering communications channels within telecommunications satellites
A method is disclosed for filtering communications channels in a telecommunications satellite to remove large unwanted interfering signals, which includes monitoring channels of an uplink signal by stepping across a channel with a first analog agile filter having a narrow bandwidth in relation to the channel, and at each step monitoring the signal within the channel step, in order to determine the presence of interfering signals, and configuring a second analog agile filter having an adjustable band stop function to block the interfering signals. The uplink signal has first and second signal paths for the uplink signal, and the method includes demultiplexing the channels of the uplink signal onto separate lines in the first path, carrying out the band stop function within the second signal path, and replacing with the remaining filtered part of the channel, by a switching operation, the demultiplexed version of the channel.
A receiving device for receiving a satellite broadcast comprising: a receiver for receiving a sustaining satellite beam; and a controller for switching the receiver to receive a high power content beam in response to a determination that the high power content beam can be received by the receiving device. A communication satellite transmits the high power content beam to different geographical areas at different times. The sustaining beam allows the receiving device to remain synchronised with the communication satellite when the high power content beam is directed elsewhere. The sustaining beam may be a lower power beam. The determination that the high power content beam can be received may be performed based on information in the sustaining beam. Alternatively or additionally, the determination that the high power content beam can be received may be made by monitoring the signal strength of a frequency associated with the high power content beam.
H04H 20/74 - Wireless systems of satellite networks
H04H 40/90 - Arrangements characterised by circuits or components specially adapted for receiving specially adapted for broadcast systems covered by groups specially adapted for satellite broadcast receiving
52.
Filtering communications channels within telecommunications satellites
A variable bandwidth filter for use in filtering signal channels in a telecommunication satellite between uplink and downlink beams, and having a reduced amount of phase noise, includes a first mixer for translating the frequency of an input signal by a first predetermined frequency value, a first filter for defining one edge of the variable bandwidth, a second mixer for translating the frequency of the input signal by a second predetermined frequency value, a second filter for defining another edge of the variable bandwidth, and further mixer for translating the frequency of the input signal by a further predetermined frequency value, and wherein first and second local oscillator frequencies are applied to the first mixer, the second mixer and the further mixer such that each frequency translation of the input signal in one direction has a counterpart translation of corresponding value in the opposite direction.
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.
A radar system for forming a scanning receive beam from signals received by a phased array (4) having a plurality of sub arrays (6), comprises a plurality of phase units (8) each configured to receive a said signal from one or more sub arrays. Each phase unit (8) comprises a waveform generator (18) configured to generate an analogue waveform having a frequency corresponding to a time-varying phase shift. Each waveform generator (18) is arranged to digitally generate the analogue waveform, and output a comparison of the received signal with the waveform, incorporating the time-varying phase shift. The system further comprises a combining unit (10) configured to combine the outputs from the plurality of phase units (8) to form a scanning receive beam.
G01S 13/90 - Radar or analogous systems, specially adapted for specific applications for mapping or imaging using synthetic aperture techniques
H01Q 3/38 - Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elementsArrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the distribution of energy across a radiating aperture varying the phase by electrical means with variable phase-shifters the phase-shifters being digital
A radar system is disclosed for forming a scanning receive beam from signals received by a phased array having a plurality of sub arrays. An exemplary radar system includes a plurality of phase units each configured to receive a signal from one or more sub arrays. Each phase unit includes a waveform generator configured to generate an analog waveform having a frequency corresponding to a time-varying phase shift. Each waveform generator is arranged to digitally generate the analog waveform, and output a comparison of the received signal with the waveform, incorporating the time-varying phase shift. The system further includes a combining unit configured to combine the outputs from the plurality of phase units to form a scanning receive beam.
H01Q 3/30 - Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elementsArrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the distribution of energy across a radiating aperture varying the phase
G01S 13/00 - Systems using the reflection or reradiation of radio waves, e.g. radar systemsAnalogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
H01Q 3/00 - Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
56.
Satellite beam-pointing error correction in digital beam-forming architecture
A digital method of determining and correcting beam-pointing for a communications spacecraft that has a digital beam-forming architecture for defining multiple spot transmit and receive beams, the antenna system of the spacecraft including a receive antenna (DRA, AFR) having antenna elements providing respective antenna element signals, and wherein at least one of the uplink signals to the spacecraft includes a beacon signal, and wherein the method comprises digitally weighting components of said beacon signal present in antenna element signals, combining such weighted beacon signal components such as to derive beam-pointing error signals, and employing the error signals to adjust beam-forming weight values of the receive antenna, in order to adjust the pointing direction of at least one signal beam. The digital weights for the beacon signal define difference radiation patterns for x, y axes of the antenna which vary rapidly in a range corresponding to the pointing errors most commonly occurring.
An apparatus for a satellite communication system is provided, the apparatus comprises: means for monitoring a plurality of frequency channels demultiplexed from a signal comprising one or more carriers; means for identifying at least one frequency channel of the plurality of frequency channels comprising interference; and means for removing the identified at least one frequency channel before the one or more carriers are reformed. By removing the frequency channels comprising interference, the signal-to-noise ratio of a carrier can be improved. Also, if the interference occurs within a carrier, the carrier is usable as long as the removed frequency channels are considerably narrower than the carrier.
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.
H04B 1/38 - Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
H04W 4/00 - Services specially adapted for wireless communication networksFacilities therefor
H04J 3/04 - Distributors combined with modulators or demodulators
There is provided an apparatus for a satellite communication system comprising: a processor to determine at least one out of a phase offset for a frequency channel of a plurality of frequency channels demultiplexed from a carrier to compensate for group delay variation within the carrier and a gain offset for the frequency channel to compensate for gain variation within the carrier, wherein the processor is further configured to apply the at least one out of the determined phase offset and gain offset to the frequency channel before the carrier is reformed from said plurality of frequency channels. The invention therefore provides a way of digitally compensating for any undesired gain and group delay introduced by, for example, analogue components such as filters in the satellite communication system.
The invention relates to active interference suppression in a satellite communication system, particularly but not exclusively to an apparatus and method for using active interference suppression in order to suppress co-channel interference between user signals in the communication system. The communication system includes a receive or transmit antenna having a plurality of antenna elements, each antenna element associated with a respective antenna element signal. The method includes the steps of calculating complex weighting values for one or more of a plurality of beam signals, adjusting the beam signals in accordance with the calculated complex weighting values and cancelling co-channel interference in at least one of the beam signals using the one or more adjusted derived beam signals to provide an interference suppressed output signal. The complex weighting values can be calculated based on a constant modulus algorithm.
There is provided an apparatus for a satellite communication system comprising: means for determining at least one out of a phase offset for a frequency channel of a plurality of frequency channels demultiplexed from a carrier to compensate for group delay variation within the carrier and a gain offset for the frequency channel to compensate for gain variation within the carrier; and means for applying the determined at least one out of a phase offset and a gain offset to the frequency channel before the carrier is reformed from said plurality of frequency channels. The invention therefore provides a way of digitally compensating for any undesired gain and group delay introduced by, for example, analogue components such as filters in the satellite communication system.
There is provided an apparatus for a satellite communication system comprising: means for determining at least one out of a phase offset for a frequency channel of a plurality of frequency channels demultiplexed from a carrier to compensate for group delay variation within the carrier and a gain offset for the frequency channel to compensate for gain variation within the carrier; and means for applying the determined at least one out of a phase offset and a gain offset to the frequency channel before the carrier is reformed from said plurality of frequency channels. The invention therefore provides a way of digitally compensating for any undesired gain and group delay introduced by, for example, analogue components such as filters in the satellite communication system.
A method of tuning a multiport amplifier and a multiport amplifier are provided. The multiport amplifier comprises an even number of microwave power amplifiers arranged in parallel, a series of input ports and a series of output ports, the input ports being connected to the amplifiers by a series of input hybrids and the output ports being connected to the amplifiers by a series of output hybrids, whereby an input signal at any given input port is amplified by all amplifiers, and then recombined into an output signal at a given output port. The method includes the steps of matching each amplifier in a pair of adjacent amplifiers to the other to an extent which is greater than matching between non paired amplifiers while still being able to ensure acceptable signal isolation between all output ports. This method of tuning results in an MPA well suited to the requirements of certain frequency re-use schemes and which has a significantly reduced set-up and test time.
A telecommunications satellite having a phased array antenna, wherein the beam-forming function within the phased array is simplified by partitioning it into two stages, in which the sub-array stage relates to a fixed, or infrequently changed, set of overlapping sub-arrays and the main stage provides the main pattern reconfiguration, typically in the form of multiple reconfigurable spot beams within a defined coverage region. The key advantage lies in the significant reduction in number of second stage beam-forming control points (at which independent amplitude and phase is applied) when compared with a conventional phased array (where amplitude and phase control is applied for each element of the array). The sub-array stage beam-forming may be implemented in analogue technology. The main beam-former may be implemented in digital technology, where the key processing functions of A/D or D/A conversion, frequency (de)multiplexing and digital beam-forming all scale with the number of control points.
H01Q 3/00 - Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
There is provided an apparatus for calibrating a multi-beam satellite system comprising a beam forming network providing a plurality of signal paths, the apparatus comprising a calibration processor for determining the phase and amplitude shift of a test path of the plurality of signal paths by correlating a calibration tone extracted from the test path with a reference calibration signal, the calibration processor being configured to determine the phase and amplitude shifts of the test path for at least two calibration tones of at least two different frequencies. The apparatus also comprises means for applying a correction based on the determined phase and amplitude shift to the test path in the beam forming network. The two calibration tones of at least two different frequencies may be calibration tones injected at two different frequencies but also calibration tones translated into two different frequencies by the beam forming network. The invention allows a phase and amplitude shift for any path through the beam forming network to be calculated for any frequency in an operational frequency range of the multi-beam satellite system and corrections to be applied to form or interpret the required downlink or uplink beams of the multi-beam satellite system.
There is provided an apparatus for calibrating a multi-beam satellite system comprising a beam forming network providing a plurality of signal paths, the apparatus comprising a calibration processor for determining the phase and amplitude shift of a test path relative to a reference path, the calibration processor being configured to determine the phase and amplitude shifts of the test path relative to the reference path for at least two calibration tones of at least two different frequencies to allow a phase and amplitude offset of the test path for a signal of any frequency within an operational frequency range of the multi-beam satellite system to be calculated.
H01Q 3/00 - Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
Feedback loops are used within a Multiport Amplifier (MPA) of a communications satellite to maintain phase and amplitude tracking and hence isolation and combining performance. at Ku and Ka-bands, for which there is increasing interest in MPA applications, and where wavelengths are short and maintenance of phase/amplitude tracking becomes highly challenging. Feedback loops are located at strategic points within the MPA Output Network (ONET) to detect tracking errors and provide compensation. Errors are detected through power measurements at “null points”, with zero power corresponding to accurate tracking. The feedback loops adjust the MPA phase/gains such that the levels at these points are maintained at zero. The scheme operates with a pilot signal for measurement of nulls, injected at one of the MPA inputs.
H04B 1/00 - Details of transmission systems, not covered by a single one of groups Details of transmission systems not characterised by the medium used for transmission
H04B 7/00 - Radio transmission systems, i.e. using radiation field
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. The method of determining parameter adjustments for a multiport amplifier arrangement includes receiving first and second output signals associated with an output of the multiport amplifier arrangement, the first output signal corresponding to a first signal path through the multiport amplifier arrangement and the second output signal corresponding to a second signal path through the multiport amplifier arrangement and determining parameter adjustments based on the first and second output signals.
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. The method of determining parameter adjustments for a multiport amplifier arrangement includes receiving first and second output signals associated with an output of the multiport amplifier arrangement, the first output signal corresponding to a first signal path through the multiport amplifier arrangement and the second output signal corresponding to a second signal path through the multiport amplifier arrangement and determining parameter adjustments based on the first and second output signals.
The invention provides a content broadcasting system comprising a communications satellite and a satellite control arrangement for controlling the communications satellite to transmit a satellite broadcast signal. The satellite control arrangement is arranged to control the satellite to transmit the satellite broadcast signal to a first geographical area during a first time interval and to transmit the satellite broadcast signal to a second geographical area during a second time interval. The broadcast signal is not transmitted to the first geographical area during at least the second time interval and the broadcast signal is not transmitted to the second geographical area during at least the first time interval. This enables broadcast content to be provided to a large geographical area, while increasing the radio frequency spectrum efficiency of the system and minimising the continuous power consumption of the satellite required for the broadcast.
The invention relates to active interference suppression in a satellite communication system, particularly but not exclusively to an apparatus and method for using active interference suppression in order to suppress co-channel interference be-tween user signals in the communication system. The communication system includes a receive or transmit antenna having a plu-rality of antenna elements, each antenna element associated with a respective antenna element signal. The method includes the steps of calculating complex weighting values for one or more of a plurality of beam signals, adjusting the beam signals in accor-dance with the calculated complex weighting values and cancelling co-channel interference in at least one of the beam signals us-ing the one or more adjusted derived beam signals to provide an interference suppressed output signal. The complex weighting values can be calculated based on a constant modulus algorithm.
The invention relates to active interference suppression in a satellite communication system, particularly but not exclusively to an apparatus and method for using active interference suppression in order to suppress co-channel interference between user signals in the communication system. The communication system includes a receive or transmit antenna having a plurality of antenna elements, each antenna element associated with a respective antenna element signal. The method includes the steps of calculating complex weighting values for one or more of a plurality of beam signals, adjusting the beam signals in accordance with the calculated complex weighting values and cancelling co-channel interference in at least one of the beam signals using the one or more adjusted derived beam signals to provide an interference suppressed output signal. The complex weighting values can be calculated based on a constant modulus algorithm.
A reflector (8) for a reflector antenna is provided for producing a far field pattern with near-zero field strength at a predetermined position, the reflector having a surface comprising a stepped profile for generating the near-zero field strength. The stepped profile may comprise a radial step. The location of the near-zero field strength can be steered by moving the reflector only or by adjusting the amplitude and phase of an additional beam, produced by a further radiator (16), that covers substantially the same region as the main beam reflected by the reflector.
H01Q 1/28 - Adaptation for use in or on aircraft, missiles, satellites, or balloons
H01Q 15/16 - Reflecting surfacesEquivalent structures curved in two dimensions, e.g. paraboloidal
H01Q 19/10 - Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces
H01Q 25/00 - Antennas or antenna systems providing at least two radiating patterns
H01Q 3/26 - Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elementsArrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the distribution of energy across a radiating aperture
H01Q 3/02 - Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical movement of antenna or antenna system as a whole
An apparatus for an antenna system comprising one or more blades for splitting the electromagnetic field received by an antenna into a plurality of sections corresponding to separate beams and redirecting said plurality of sections for detection by a plurality of detectors. The apparatus may comprise a plurality of blades for splitting the field into successively smaller and smaller portions. The plurality of detectors can be positioned outside the focal region of the antenna system. If the dimensions of the detectors are required to be relatively large, the system can then detect more closely packed beams than if the detectors had been positioned in the focal region. The apparatus may further comprise focusing means for focusing the sections of the field onto another blade or a detector. There is also provided an antenna system comprising a plurality of feed horns for producing a plurality of beams; and a plurality of elements for redirecting said beams towards a focal region of the antenna system so as to form a group of closely packed beams for transmission by the antenna system.
H01Q 15/00 - Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
H01Q 19/19 - Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces having two or more spaced reflecting surfaces comprising one main concave reflecting surface associated with an auxiliary reflecting surface
75.
MODULAR DIGITAL PROCESSING SYSTEM FOR TELECOMMUNICATIONS SATELLITE PAYLOADS
A telecommunications satellite payload processing system comprising one or more identical generic integrated processor modules 10 is provided. The number of integrated processor modules 10 is selected in accordance with the antenna and bandwidth characteristics of a specified mission uplink 36, 50 and downlink 40, 52 in relation to the characteristics of the integrated processor module 10.
A telecommunications satellite payload processing system comprising one or more identical generic integrated processor modules 10 is provided. The number of integrated processor modules 10 is selected in accordance with the antenna and bandwidth characteristics of a specified mission uplink 36, 50 and downlink 40, 52 in relation to the characteristics of the integrated processor module 10.
An antenna feed assembly (15) is provided which includes at least two elongate feed chains (1, 2) lying adjacent one another. Each feed chain is adapted to transmit or receive electromagnetic radiation between itself and the antenna (34) along a longitudinal feed axis (3, 4) thereof via a transmit/receive element (7). The feed chains (1, 2) are held in fixed lateral relationship to one another by first and second mountings (5, 6) spaced apart axially of the feed chains. The transmit/receive elements (7, 8) extend axially from the first mounting (5) towards the antenna and the second mounting (6) is positioned on a side of the first mounting (5) remote from the antenna. The first mounting (5) has a lower coefficient of thermal expansion in the lateral direction than the second mounting (6) whereby translational movement of each transmit/receive element (7, 8) in the lateral direction owing to temperature change of the assembly (15) will be reduced.
H01Q 1/28 - Adaptation for use in or on aircraft, missiles, satellites, or balloons
H01Q 19/17 - Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces wherein the surfaces are concave the primary radiating source comprising two or more radiating elements
H01Q 25/00 - Antennas or antenna systems providing at least two radiating patterns
F16L 3/237 - Supports for pipes, cables or protective tubing, e.g. hangers, holders, clamps, cleats, clips, brackets specially adapted for supporting a number of parallel pipes at intervals for two pipes
The invention provides a communication system and method of communication. The communication system includes a satellite transmitter arranged to transmit a first signal to be received within a predefined geographical area by a satellite receiver, and a terrestrial transmitter arranged to transmit a second signal to be received within the predefined geographical area by a terrestrial receiver. The first and second signals share a common radio frequency band and the system is arranged such that the first signal is received at an antenna associated with the satellite receiver at a first angle from the horizontal, the first angle being greater than a second angle from the horizontal at which the second signal is received at the antenna. This enables the satellite receiver to distinguish the first signal from the second signal. The terrestrial transmitter and receiver are also arranged to operate a multiple-input and multiple-output MIMO system enabling the terrestrial receiver to distinguish the second signal from the first signal.
A variable bandwidth filter for use in filtering signal channels in a telecommunication satellite between uplink and downlink beams, and having a reduced amount of phase noise, comprises a first mixer for translating the frequency of an input signal by a first predetermined frequency value, a first filter for defining one edge of said variable bandwidth, a second mixer for translating the frequency of the input signal by a second predetermined frequency value, a second filter for defining another edge of said variable bandwidth, and further mixer means for translating the frequency of the input signal by a further predetermined frequency value, and wherein first and second local oscillator frequencies are applied to the first mixer, the second mixer and the further mixer means such that each frequency translation of the input signal in one direction has a counterpart translation of corresponding value in the opposite direction.
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.
A means of filtering communications channels in a telecommunications satellite to remove large unwanted interfering signals, comprising monitoring channels of an uplink signal by stepping across a channel with a first analog agile filter having a narrow bandwidth in relation to the channel, and at each step monitoring the signal within the channel step, in order to determine the presence of interfering signals, and configuring a second analog agile filter having an adjustable band stop function to block the interfering signals. The uplink signal has first and second signal paths for said uplink signal, and including demultiplexing the channels of said uplink signal onto separate lines in said first path, carrying out the band stop function within the second signal path, and replacing with the remaining filtered part of the channel, by means of a switching operation, the demultiplexed version of the channel.
A method of operating synthetic aperture radar in a low PRF mode, comprising generating a stream of radar pulses, imposing onto said stream a predetermined modulation of the Pulse Repetition Frequency (PRF), directing said stream to a target area, and processing received pulses, comprising separating the received pulses as a sequence of sets, and superposing received radar pulses of said sets, whereby to enhance the central received lobe and to attenuate side lobes.
G01S 13/00 - Systems using the reflection or reradiation of radio waves, e.g. radar systemsAnalogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
A telecommunications satellite having a phased array antenna, wherein the beam-forming function within the phased array is simplified by partitioning it into two stages, in which the sub-array stage relates to a fixed, or infrequently changed,set of overlapping sub-arrays and the main stage provides the main pattern reconfiguration, typically in the form of multiple reconfigurable spot beams within a defined coverage region. The key advantage lies in the significant reduction in number of second stage beam--forming control points (at which independent amplitude and phase is applied) when compared with a conventional phased array (where amplitude and phase control is applied for each element of the array). The sub-array stage beam-forming may be implemented in analogue technology. The main beam-former may be implemented in digital technology, where the key processing functions of A/D or D/A conversion, frequency (de)multiplexing and digital beam-forming all scale with the number of control points.
H01Q 1/28 - Adaptation for use in or on aircraft, missiles, satellites, or balloons
H01Q 3/26 - Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elementsArrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the distribution of energy across a radiating aperture
A telecommunications satellite having a phased array antenna, wherein the beam-forming function within the phased array is simplified by partitioning it into two stages, in which the sub-array stage relates to a fixed, or infrequently changed,set of overlapping sub-arrays and the main stage provides the main pattern reconfiguration, typically in the form of multiple reconfigurable spot beams within a defined coverage region. The key advantage lies in the significant reduction in number of second stage beam-forming control points (at which independent amplitude and phase is applied) when compared with a conventional phased array (where amplitude and phase control is applied for each element of the array). The sub-array stage beam-forming may be implemented in analogue technology. The main beam-former may be implemented in digital technology, where the key processing functions of A/D or D/A conversion, frequency (de)multiplexing and digital beam-forming all scale with the number of control points.
H01Q 1/28 - Adaptation for use in or on aircraft, missiles, satellites, or balloons
H01Q 3/26 - Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elementsArrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the distribution of energy across a radiating aperture
An embedded test system is provided where asynchronous communications links are used to pass the boundary scan information by the use of a network router to a boundary scan adapter(54, 60) associated with each component to be tested. This approach enables the system components themselves to facilitate the implementation of a chain-free boundary scan architecture as opposed to a traditional boundary scan bridge approach thus reducing component count and simplifying system design. Thus boundary scan tests can still be performed even after one or more components have been disabled, configured in functional mode or have failed. The same commanding sequence can be applied irrespective of the network topology or the component count since the routing of the boundary scan information is the responsibility of the network routing functionality. This testing method is independent of the underlying functionality of the target hardware or its individual components. The invention also provides for a hybrid solution to adapt boundary scan compatible COTS component so that they can be used within a chainless boundary scan architecture.
A method and system of supporting and testing equipment distant from the support system are provided. The method includes the steps of forming a communications link between the equipment and the support system, using the support system to measure performance of the equipment and to provide a set of performance data, providing library data relating to the equipment, comparing the performance data with the library data and analysing the compared data whereby to provide a performance diagnosis of the equipment, all in a substantially continuousreal time operation.
The invention relates to the implementation of a digital signal processor that is required to process a large number of narrowband analogue input or output signals. Analogue processing is performed to combine multiple analogue signals together (with non-overlapping frequency bands) into a composite signal which is fed to a single analogue to digital converter. These signals come from different sources and would in a conventional implementation use individual converters. Analogue signal processing is used outside of the digital signal processor and digital processing is used inside to enable the original analogue signals to be reconstructed in the digital domain in the same format as if individual converters have been used. A similar technique can be applied to digital to analogue conversion interfaceswhere a digital combining operation is performed to combine digital sub-band signals into a single composite signal, prior to input to a single digital-to-analogue(DAC) converter for conversion to the analogue domain and subsequently to an analogue splitter device for separation into a plurality of analogue signals.Hence, the technique can be implemented in both transmitter and receiver systems.
H04B 7/08 - Diversity systemsMulti-antenna systems, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
a control ASIC for receiving an input power signal of the RF amplifier for providing a voltage control signal to the EPC to determine the value of the DC voltage, the control ASIC addressing an EEPROM holding a collection of control words that define output values of a control output signal for varying values of said input power, such that the value of the DC voltage to the power output stage is varied so as to control the gain compression of the RF amplifier for varying values of input power in order to maintain constant amplifier linearity.
Feedback loops are used within a Multiport Amplifier (MPA) of a Communications satellite to maintain phase and amplitude tracking and hence isolation and combining performance, at Ku and Ka-bands, for which there is increasing interest in MPA applications, and where wavelengths are short and maintenance of phase/amplitude tracking becomes highly challenging. Feedback loops are located at strategic points within the MPA Output Network (ONET) to detect tracking errors and provide compensation. Errors are detected through power measurements at 'null points', with zero power corresponding to accurate tracking. The feedback loops adjust the MPA phase/gains such that the levels at these points are maintained at zero. The scheme operates with a pilot signal for measurement of nulls, injected at one of the MPA inputs.
H03F 3/60 - Amplifiers in which coupling networks have distributed constants, e.g. with waveguide resonators
H03F 1/06 - Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in discharge-tube amplifiers to raise the efficiency of amplifying modulated radio frequency wavesModifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in discharge-tube amplifiers to raise the efficiency of amplifiers acting also as modulators
H03F 3/68 - Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics
H03F 1/34 - Negative-feedback-circuit arrangements with or without positive feedback
H03F 1/32 - Modifications of amplifiers to reduce non-linear distortion
A method of tuning a multiport amplifier and a multiport amplifier are provided. The multiport amplifier comprises an even number of microwave power amplifiers (A1-A8) arranged in parallel, a series of input ports (p1-p8) and a series of output ports (q1-q8), the input ports being connected to the amplifiers by a series of input hybrids (A-M) and the output ports being connected to the amplifiers by a series of output hybrids (A-M), whereby an input signal at any given input port is amplified by all amplifiers, and then recombined into an output signal at a given output port. The method includes the steps of matching each amplifier in a pair of adjacent amplifiers to the other to an extent which is greater than matching between non paired amplifiers while still being able to ensure acceptable signal isolation between all output ports. This method of tuning results in an MPA well suited to the requirements of certain frequency re-use schemes and which has a significantly reduced set-up and test time.
A beamforming system that can be used for both receive and transmit beamforming is provided. The system receives samples of a number of signals, each sample containing a band of frequencies and routes all sampled signals associated with the same beamformed frequency band to a predetermined processing block. A predetermined number of the routed sampled signals are selected sequentially according to predetermined criteria, weighted and accumulated to form a composite signal. Individual signals are then selected from the composite signal and routed to an appropriate output. The system uses a much smaller number of weighting functions than conventionally required, with processing for a single frequency being performed in the same processing block. This reduces the complexity of beamforming processing substantially and simplifies frequency reuse. In addition a single DSP design that works for both transmit and receive beamforming can be implemented.
H04M 1/00 - Substation equipment, e.g. for use by subscribers
H04B 1/38 - Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
H04L 25/49 - Transmitting circuitsReceiving circuits using code conversion at the transmitterTransmitting circuitsReceiving circuits using predistortionTransmitting circuitsReceiving circuits using insertion of idle bits for obtaining a desired frequency spectrumTransmitting circuitsReceiving circuits using three or more amplitude levels
92.
ROUTING OF DOWNLINK CHANNELS IN A COMMUNICATIONS SATELLITE
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 inthe MPA so thattwo low performance elements in combination can be used to achieve an improved performance at system level.
A digital method of determining and correcting beam-pointing for a communications spacecraft that has a digital beam-forming architecture for defining multiple spot transmit and receive beams, the antenna system of the spacecraft including a receive antenna (DRA, AFR) having antenna elements providing respective antenna element signals, and wherein at least one of the uplink signals to the spacecraft includes a beacon signal, and wherein the method comprises digitally weighting components of said beacon signal present in antenna element signals, combining such weighted beacon signal components such as to derive beam-pointing error signals, and employing the error signals to adjust beam-forming weight values of the receive antenna, in order to adjust the pointing direction of at least one signal beam.The digital weights for the beacon signal define difference radiation patterns for x, y axes of the antenna which vary rapidly in a range corresponding to the pointing errors most commonly occurring.
H04B 7/06 - Diversity systemsMulti-antenna systems, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
H04B 7/08 - Diversity systemsMulti-antenna systems, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
A digital method of determining and correcting beam-pointing for a communications spacecraft that has a digital beam-forming architecture for defining multiple spot transmit and receive beams, the antenna system of the spacecraft including a receive antenna (DRA, AFR) having antenna elements providing respective antenna element signals, and wherein at least one of the uplink signals to the spacecraft includes a beacon signal, and wherein the method comprises digitally weighting components of said beacon signal present in antenna element signals, combining such weighted beacon signal components such as to derive beam-pointing error signals, and employing the error signals to adjust beam-forming weight values of the receive antenna, in order to adjust the pointing direction of at least one signal beam.The digital weights for the beacon signal define difference radiation patterns for x, y axes of the antenna which vary rapidly in a range corresponding to the pointing errors most commonly occurring.
H04B 7/06 - Diversity systemsMulti-antenna systems, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
H04B 7/08 - Diversity systemsMulti-antenna systems, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
A thermal control film for use in spacecraft having a multi-layer interference filter adapted to exhibit high reflectivity to solar radiation, low absorptivity across the microwave spectrum and high emissivity in the far infra-red. The film is free from metal and extends over the active face of an antenna carried by the spacecraft. Such a film exhibits the desired thermo-optical properties for a thermal control radiator surface and can be used over the active face of a communications or radar antenna without disrupting the RF signal.
G02B 1/04 - Optical elements characterised by the material of which they are madeOptical coatings for optical elements made of organic materials, e.g. plastics
B32B 7/02 - Physical, chemical or physicochemical properties
A beamforming system that can be used for both receive and transmit beamforming is provided. The system receives samples of a number of signals, each sample containing a band of frequencies and routes all sampled signals associated with the same beamformed frequency band to a predetermined processing block. A predetermined number of the routed sampled signals are selected sequentially according to predetermined criteria, weighted and accumulated to form a composite signal. Individual signals are then selected from the composite signal and routed to an appropriate output. The system uses a much smaller number of weighting functions than conventionally required, with processing for a single frequency being performed in the same processing block. This reduces the complexity of beamforming processing substantially and simplifies frequency reuse. In addition a single DSP design that works for both transmit and receive beamforming can be implemented.
H04B 7/06 - Diversity systemsMulti-antenna systems, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
A phased array antenna for a telecommunications satellite, that is deployable from a retracted condition to a deployed condition when the satellite is on-station, comprising a base member of hexagonal form, and a plurality of deployable antenna panels stacked one on top of the other on the base member in the retracted condition, each antenna panel being connected to a respective side edge region of the base by means of a respective back flap hinge, and the hinges having pivot points that are offset relative to one another, such that the antenna panels can be hinged sequentially one after the other from the stick to a position in which each panel is adjacent a respective base side edge region to provide an extended flat two-dimensional area when deployed.
H01Q 1/28 - Adaptation for use in or on aircraft, missiles, satellites, or balloons
H01Q 3/02 - Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical movement of antenna or antenna system as a whole
A method and apparatus for obtaining, while on a spacecraft, a random number and hence a secure cryptographic key. The method includes the steps of providing, on the spacecraft, a device capable of producing random information when subject to random space phenomena, obtaining the random information and producing a random number therefrom and using an algorithm to establish the secure key. The apparatus includes a random access memory (RAM) which experiences bit-flips when struck by radiation such as cosmic rays. Changes in the RAM bits are propagated using a linear feedback shift register.
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