LEO SATELLITE COMMUNICATION SYSTEMS AND METHODS
A low earth orbit (LEO) satellite including a processor, a memory, and a communication sub-system. The communication sub-system including: an antenna array and a reconfigurable digital logic processing device. The processor dynamically reconfigures the reconfigurable digital logic processing device to amplify or attenuate transmissions received from one or more directions of interest, or to amplify or attenuate signals transmitted by the antenna array in one or more directions of interest according to the orbital schedule of the LEO satellite.
Embodiments relate to communication systems and methods. In particular, embodiments relate to systems and methods for low earth orbit (LEO) satellite communication with remote terrestrial communication systems.
BACKGROUNDPositioning sensors in remote environments may provide beneficial information in various economic or environmental contexts. For example, in a remote mining operation, information from sensors positioned in remotely located machinery may be beneficial for managing and improving the remote mining operation. Similarly, for a remotely located farm, information from various sensors positioned on livestock or sensors positioned on the ground may be beneficial in managing and planning operations at the remotely located farm.
Access to information from remote environments presents several technical challenges. In remote environments, there may be significant connectivity and power supply issues. Prior sensor networks and gateways may not provide reliable and rich access to information generated by sensors positioned in remote environments because of a lack of connectivity and power. If connectivity is possible, for example via a satellite uplink, then the current and anticipated future cost of using such an uplink is typically prohibitively high for many sensor deployment scenarios. A satellite uplink using a LEO satellite may often have significant limitations of bandwidth and may have limited time windows over which communication is feasible. Further, the size, power supply and thermal dissipation limitation in LEO satellites present additional challenges for communication systems on board the LEO satellite.
It is desired to address or ameliorate one or more shortcomings or disadvantages of prior satellite communication techniques for LEO nano- or micro-satellites, or to at least provide a useful alternative thereto.
Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each claim of this application.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
SUMMARYSome embodiments relate to a low earth orbit (LEO) satellite, the LEO satellite comprising:
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- a microsatellite or nanosatellite chassis housing or carrying at least one processor, a memory accessible to the at least one processor, the memory storing an orbital schedule of the LEO satellite, and a communication sub-system accessible to the at least one processor; the communication sub-system comprising:
- an antenna array comprising two or more antenna elements;
- a reconfigurable digital logic processing device in communication with the antenna array;
- wherein the at least one processor is in communication with the reconfigurable digital logic processing device, and
- wherein the at least one processor is configured to dynamically reconfigure the reconfigurable digital logic processing device to perform directional beamforming based on the orbital schedule by applying different transfer functions to signals simultaneously received or transmitted by multiple antenna elements of the antenna array over time.
The microsatellite or nanosatellite chassis may carry the antenna array on any one of the faces of the chassis. The microsatellite or nanosatellite chassis may carry or house the processor, memory and the reconfigurable digital logic processing device as one of its payload components.
A transfer function defines the mathematical operations performed on one or more signals received by the antenna array. The mathematical operations of a transfer function may include mathematical operations to amplify a part of a received signal and/or mathematical operations to attenuate a part of a received signal, for example.
The directional beamforming may be performed using all antenna elements of the antenna array simultaneously. The at least one processor may be further configured to dynamically reconfigure the reconfigurable digital logic processing device to perform directional beam-nulling based on the orbital schedule by applying different transfer functions to signals received and/or transmitted by multiple antenna elements of the antenna array over time.
The directional beamforming and/or beam-nulling may be performed simultaneously across multiple frequency channels. The directional beamforming and/or beam-nulling may be performed simultaneously in multiple different directions.
The antenna array may be a linear array. The antenna array may be disposed along one side of the chassis. The antenna array may be disposed to substantially cover a minor face of the chassis. Each of the antenna elements may include a patch antenna. The antenna array may include at least four antenna elements. Each patch antenna may include a corrugated radiator.
Some embodiments relate to a low earth orbit (LEO) satellite, the LEO satellite comprising: a chassis housing at least one processor, a memory accessible to the at least one processor, the memory storing an orbital schedule of the LEO satellite, and a communication sub-system accessible to the at least one processor; the communication sub-system comprising:
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- an antenna array comprising two or more antenna elements;
- a reconfigurable digital logic processing device in communication with the antenna array;
- wherein the at least one processor is in communication with the reconfigurable digital logic processing device, and
- wherein the at least one processor is configured to dynamically reconfigure the reconfigurable digital logic processing device to: process signals received by the antenna array to amplify transmissions received from one or more directions of interest according to an orbital schedule of the LEO satellite, or amplify signals to be transmitted by the antenna array in or more directions of interest for transmission according to the orbital schedule of the LEO satellite; and
the LEO satellite has a mass in the range of 1 kg to 100 kg.
In some embodiments, the chassis has a CubeSat structure and a size from 1 CubeSat unit to 50 CubeSat units, or from 3 CubeSat units to 6, 12, 16 or 24 CubeSat units.
In some embodiments, the chassis comprises a major face, a minor face, the major face having a greater surface area than the minor face; and the antenna array is provided on at least a part of the minor face.
In some embodiments, the at least one processor dynamically reconfigures the reconfigurable digital logic processing device to process the signals received by the antenna array to attenuate transmissions received from one or more directions not of interest according to the orbital schedule of the LEO satellite, or attenuate signals transmitted by the antenna array in one or more directions not of interest for transmission according to the orbital schedule of the LEO satellite.
In some embodiments, the orbital schedule data comprises one or more antenna array configuration records, each antenna array configuration record comprising:
an ephemeris record indicating a scheduled position or a portion of a flight path of the LEO satellite in orbit at different times over a period of time; and
array factor coefficients associated with each of the two or more antenna elements defined in relation to the ephemeris record.
The array factor coefficients define the mathematical operations of the transfer function applied to the signals received or transmitted by the antenna array.
In some embodiments, each array factor coefficient is a complex weight comprising a real coefficient value and an imaginary coefficient value.
In some embodiments, the at least one processor dynamically reconfigures the reconfigurable digital logic processing device to process the signals received by the antenna array or amplify signals transmitted by the antenna array based on the scheduled position of the LEO satellite and the array factor coefficients as defined in the antenna array configuration record associated with the scheduled position of the LEO satellite.
In some embodiments, the antenna array is a patch antenna array.
The LEO satellite of some embodiments further comprises an analog to digital converter for pre-processing signals before processing by the reconfigurable digital logic processing device. The LEO satellite of some embodiments further comprises a digital to analog converter for processing signals generated by the reconfigurable digital logic processing device for transmission by the antenna array.
The LEO satellite of some embodiments further comprises a signal channeliser for channelising signals before processing by the reconfigurable digital logic processing device. Channelisation allows transmission or reception of multiple messages or multiple series of messages simultaneously or nearly simultaneously over a common radio frequency range/band. Channelisation allows further scaling of the communication between the LEO satellite and remote terrestrial communication systems.
In some embodiments, the at least one processor dynamically reconfigures the reconfigurable digital logic processing device to enable the transmission of signals from the antenna array in one or more directions of interest for transmission according to the orbital schedule data.
In some embodiments, the reconfigurable digital logic processing device comprises a Field Programmable Gate Array (FPGA).
In some embodiments, the LEO satellite receives signals from multiple directions of interest. The at least one processor is configured to dynamically reconfigure the reconfigurable digital logic processing device to level amplitudes of signals received from the more than one directions of interest.
In some embodiments, the LEO satellite transmits signals to multiple directions of interest. The at least one processor is configured to dynamically reconfigure the reconfigurable digital logic processing device to level amplitudes of signals transmitted to the multiple directions of interest.
The LEO satellite of some embodiments further comprises one or more variable gain amplifiers (VGAs) in communication with the at least one processor, wherein when the LEO satellite receives signals from multiple directions of interest, the at least one processor configures the one or more VGAs to level amplitudes of signals received from the more than one directions of interest.
The antenna array of some embodiments comprises four or more antenna elements.
Some embodiments relate to a method of communication between at least one LEO satellite and a plurality of terrestrial gateway devices in communication with a plurality of terrestrial sensor devices, the method comprising:
based on the orbital schedule data, the at least one processor dynamically reconfiguring the reconfigurable digital logic processing device to process signals received by the antenna array or to generate and transmit signals through the antenna array;
the antenna array receiving transmissions and making the received transmissions available to the reconfigurable digital logic processing device;
the reconfigurable digital logic processing device processing the received signals to amplify a subset of the received signals corresponding to signals transmitted by one or more of the plurality of terrestrial gateway devices, or
the reconfigurable digital logic processing device feeding to the antenna array signals for transmission in one or more transmission directions corresponding to respective locations of one or more of the plurality of terrestrial gateway devices.
In some embodiments, the method further comprises the communication sub-system processing the amplified subset of received signals to decode information encoded in the subset of received signals.
In some embodiments, the method further comprises the reconfigurable digital logic processing device processing the received signals to attenuate a second subset of the received signals corresponding to signals not of interest received by the antenna array. The received signals corresponding to signals not of interest may relate to known sources of noise or undesirable signals, such as signals originating from terrestrial sources or other satellites.
In some embodiments, the method further comprises the at least one processor dynamically reconfiguring the reconfigurable digital logic processing device to enable the transmission of signals from the antenna array in one or more directions of interest for transmission according to the orbital schedule data.
Some embodiments relate to a method for providing a satellite communication service, comprising providing a LEO satellite of any one of the embodiments as a payload to a satellite launch vehicle.
The method of some embodiments further comprises launching the satellite launch vehicle configured to release the LEO satellite in an orbit.
Described embodiments generally relate to LEO satellites for communication. Particular embodiments relate to communication systems for LEO satellite communications. LEO satellites comprise satellites that orbit the earth at an altitude of 2000 km or less. LEO satellites have an orbital period (time to complete an orbit around the earth) of 128 minutes or less, sometimes closer to 90 minutes. The lower altitude and short orbital period of an LEO satellite give it a field of view that is both small in terms of the area of earth covered and the duration of coverage of a particular area. Accordingly, there is a need to make communications between LEO satellites and terrestrial communication systems more efficient to best utilise the limited field of view and the short duration of the field of view over a certain terrestrial area. For example, data gathering by the LEO satellite from terrestrial systems must be performed in around 240 seconds or less from the moment the LEO satellite is in view of the target terrestrial systems that it is scheduled to communicate with. Further, the frequency spectrum available for the communications between LEO satellites and terrestrial communication systems is also limited. The limited frequency spectrum adds further constraints on the communications between LEO satellites and terrestrial communication systems, amplifying the need for efficiency in the communications.
To increase the data gathering capability of the LEO satellite according to embodiments described herein (as compared to conventional LEO satellites), the LEO satellite communication subsystem of the present disclosure uses digital beamforming to form multiple digital beams simultaneously directed in different terrestrial directions to receive and/or transmit data. Some embodiments utilise three or more digital beams formed simultaneously. Such multiple digital beams are formed by a phased antenna array in some embodiments. The multiple digital beams are generally oriented perpendicularly to the flight direction, in azimuth, of the LEO satellite. This allows the creation of terrestrially directed data funnels on each lateral side of the LEO satellite for efficient communication.
Embodiments leverage particular filtering or beamforming signal processing techniques to enable efficient communications between an LEO satellite and terrestrial communication systems. Various embodiments relate to communication systems for satellites, such as LEO satellites, where the communication systems comprise an antenna array and a reconfigurable digital logic processing device (for example a Field Programmable Gate Array (FPGA)). The reconfigurable digital logic processing device is configured to dynamically receive or transmit signals according to the changing position of the LEO satellite in orbit while taking into account the relative position of terrestrial communication systems on earth. The relative position of terrestrial communication systems on earth may be encoded into schedule data stored in a memory of LEO satellite, for example.
In other words, the reconfigurable digital logic processing device allows multiple beams to be formed to transmit and/or receive data in a first set of directions and to then change its configuration to transmit and/or receive data in a second set of directions as the LEO satellite progresses along its orbital path. Such configuration changes can be made up to 20-40 times during each full orbit period around the earth, for example.
The terrestrial communication systems of the embodiments may comprise gateway devices described in PCT Application No. PCT/AU2019/050429 filed 9 May 2019 and titled “Remote LPWAN gateway with backhaul over a high-latency communication system” the contents of which are hereby incorporated by reference. Such gateway devices may have limited uplink power and so efficient communication with the LEO satellite is important in order to be able to conserve power and maximise data transmission.
LEO satellites orbit the earth at an altitude of 2000 km or less. Launching satellites involves significant costs and the costs of launching are significantly higher for LEO satellites with greater mass. Accordingly, the mass of a LEO satellite is often limited by the costs of launching the LEO satellite into orbit. LEO satellites are often powered by solar cells backed by one or more batteries. Because of the mass limitation on satellites, the capacity to generate power by the solar cells is also limited. The availability of solar power is also constrained by the position of the satellite in its orbit and the exposure to solar power available to the satellite as it orbits the earth. This in turn limits the power available to the various electronic components of the LEO satellite. The power limitations impose restrictions on the nature and number of electronic components that may be incorporated in a LEO satellite.
LEO satellites of some embodiments may comprise a chassis for housing the various electronic and communication components of the LEO satellite. The chassis may enable the efficient utilisation of space and efficient thermal dissipation. In some embodiments, the chassis may be in the form of a CubeSat. A CubeSat comprises a structural framework that comprises one or more cubic structural units. Each cubic structural unit may be in the form of a cube with approximate dimensions of 10 cm×10 cm×10 cm. Various cubic structural units may be aggregated to form a CubeSat structure for the LEO Satellite 110. The size of a CubeSat structure may be represented by the number of cubic structural units comprised in the CubeS at. For example, a CubeSat comprising two cubic structural units may be described as a 2U CubeSat unit satellite.
LEO satellites also have a limited capacity to radiate thermal power to cool down the various components of the satellite that generate heat. Some embodiments may comprise a 6 CubeSat units (6U) LEO satellite (a satellite with dimensions of around 10×20×30 cm or around 12×24×36 cm) structural design and/or framework. The 6 CubeSat unit LEO satellite may receive on average 50-60 W of power per orbit from its solar cell array. Average per-orbit thermal dissipation capability may be approximately 40-45 W. In example embodiments, a 6U nanosatellite operating in S-band frequencies may have a linear array of four antennae. Such an array allows the formation of 4 independent digital beams in azimuth. This gives the potential to double the data gathering capability of LEO satellites when compared with conventional LEO satellites that do not use digital beam-forming. If the antenna array included 8 antenna elements, then such an array could potentially quadruple the data gathering capacity relative to conventional LEO satellites. This is because the antenna array according to embodiments described herein can allow multiple beams to be formed with the same frequency simultaneously.
In some embodiments, the various power-consuming components may be turned on or off to manage the overall consumption of power and the need for thermal dissipation by the satellite. LEO satellites may keep track of their position using a GPS signal receiver 119 fitted on the LEO satellite. In some embodiments, LEO satellites may comprise an orbit propagator program provided in a memory on the LEO satellite. The orbit propagator program may be executable by a processor on board the LEO satellite to determine a position of the LEO satellite at any instance of time, with information regarding acceleration and initial velocity. Using the position information available, the LEO satellite may adaptively turn on or off the various power-consuming components to manage the overall consumption of power and the need for thermal dissipation by the satellite. Some embodiments may comprise a LEO satellite of a size from 1 CubeSat units to 50 CubeSat units. Some embodiments may comprise a LEO satellite of a size from 3 CubeS at units to 48 CubeS at units. For example, the size may be 3U, 4U, 5U, 6U, 8U, 9U, 10U, 12U, 16U, 20U, 24U, 32U, or 48U.
The various components within the LEO satellite may have different requirements for thermal dissipation. Some components may generate more heat in comparison to the rest of the components. In some embodiments, the components generating more heat may be located closer to the chassis (i.e. an outer frame) of the LEO satellite to improve thermal dissipation. Components requiring a lower rate of thermal dissipation may be placed away from the chassis. In some embodiments, thermal straps may be used to improve thermal dissipation. Thermal straps may assist in conducting heating from within the LEO Satellite to its chassis. In particular, components positioned away from the chassis may be provided with heat straps to conduct heat away from the components.
The mass of the LEO satellite of various embodiments may be within a range of 1 kg to 100 kg, 10 kg to 50 kg, or 10 kg to 100 kg, for example. The mass of the LEO satellite of various embodiments may be within a range of 10 kg to 30 kg, for example. Example masses further include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49 and 50 kg. A satellite with a mass between 10 kg to 100 kg may be referred to as a microsatellite. A satellite with a mass between 1 kg to 10 kg may be referred to as a nanosatellite.
Spatial filtering as described herein comprises signal processing techniques for focusing the reception or transmission of a wireless signal arriving from or directed to a particular direction of interest or multiple directions of interest simultaneously, such as a terrestrial area of around 100 km2 or more. For example, the terrestrial area may be around 200 km2. The field of view of the LEO satellite according to described embodiments can be logically segmented into sub-areas, where each sub-area is serviced by one of the multiple beams as described herein. Spatial filtering may also comprise processing received wireless signals to attenuate signals not of interest received from a particular direction (beam nulling). Spatial filtering may also comprise attenuating signals transmitted in one or more directions not of interest. Spatial filtering may provide the LEO satellite the capability to avoid interference with other communication systems and meet any regulatory requirements associated with the operation of the LEO Satellite. Spatial filtering relies on processing signals received by or transmitted by an antenna array in a specific manner to impose constructive or destructive interference or a combination of both constructive and destructive interference to the signals depending on the needs of the communication system at a particular time and location. The combination of constructive and destructive signal interference may be a linear combination resulting from the arrangement of the phased linear antenna array.
The focused spatial filtering is configured to amplify signals from some directions and/or attenuate signals from other directions. For the amplification of received or transmitted signals, the spatial filtering acts to shape the gain of the antenna in selected directions to resemble a “beam” in directions of relatively high gain. This spatial filtering for amplification can therefore also be referred to as beam-forming. For the attenuation of received or transmitted signals, the spatial filtering acts to shape the gain of the antenna array in selected directions to have a signal attenuation effect in the directions of particularly unwanted (i.e. undesirably interferential) ground emitter or receiver signals. This spatial filtering for attenuation can therefore also be referred to as beam-nulling.
Embodiments rely on communication protocols that are designed for low power consumption. The terrestrial communication systems transmitting signals to the LEO satellite may be located in remote locations where power supply or availability thereof may be limited. The communication protocols employed by the terrestrial communication systems may be specifically selected to reduce the power consumption in transmission, reception and processing of the signals in the LEO satellite. Such communication protocols include, for example, spread spectrum based protocols, including chirp spread spectrum based protocols such as LoRa™ (Long Range).
The remote terrestrial communication system 120 comprises a sensor device network 122 that may be configured to wirelessly communicate with a terrestrial gateway 121, for example. The sensor device network 122 may comprise several or many sensor devices located in a remote area where conventional communication networks, such as the internet or cellular networks, may not be available, for example. Such remote areas may include mines, remote agricultural land, remote scientific research stations, for example. The sensor devices may be configured to sense various environmental conditions, the status of machinery or may be used to track the movement of cattle, for example. The sensor devices network 122 may extend over an area of approximately 700 km2, for example. The terrestrial gateway device 121 receives and stores information transmitted by the sensor devices of the sensor device network 122. The terrestrial gateway device 121 also serves as an information relay device between devices in the sensor device network 122 and the LEO satellite 110.
The LEO Satellite 110 comprises a communication system comprising an antenna array 117, a radio frequency front end 115, a digital logic processing device 114, a processor 112, a memory 113 in communication with the processor 112, and a data handling subsystem 116. The LEO satellite 110 also comprises a power management subsystem 111.
The antenna array 117 comprises two or more antenna elements, each antenna element being an independent antenna capable of receiving or transmitting or both receiving and transmitting radio waves or signals. The multiple antenna elements enable spatial filtering capabilities of the communication system of the LEO satellite 110.
The LEO satellite 110 also comprises a radio frequency front end 115 that performs pre-processing of signals received by the antenna array 117 or processing of signals provided to the antenna array 117 for transmission. The processing may comprise conversion of analogue signals to digital signals or vice versa, channelization of signals, and selection or rejection of particular frequency bands of signals, for example.
The reconfigurable digital logic processing device 114 comprises a matrix of configurable logic blocks (CLBs) connected via programmable interconnects. The reconfigurable digital logic processing device 114 may be dynamically reprogrammed to provide desired application or functionality required to provide a communication service through the communication system 100. The CLBs may be reconfigured to implement various digital logic processing capabilities. The CLBs may be configured to operate in cooperation with each other by appropriately programming the interconnects to implement complex logical operations. Advantageously, the reconfigurable digital logic processing device 114 may be reconfigured dynamically to account for changes in the location of the LEO satellite during orbit and consequential changes in the need for spatial filtering to be performed by the communication system of the LEO satellite. In some embodiments, the reconfigurable digital logic processing device 114 may be or include a field-programmable gate array (FPGA).
The LEO satellite 110 also comprises at least one processor 112 that is in communication with a memory 113 and the reconfigurable digital logic processing device 114. The processor 112 has the capability to reconfigure the reconfigurable digital logic processing device 114 according to instructions and data stored in the memory 113. In some embodiments, the LEO satellite 110 may receive commands or instructions from ground station 130 over the link 170. The commands may include instructions to reconfigure the reconfigurable digital logic processing device 114 to meet changing communication requirements between the LEO satellite 110 and one or more remote terrestrial communication systems 120. The capability to reconfigure the reconfigurable digital logic processing device 114 while the LEO satellite 110 is in orbit provides significant flexibility in providing a satellite communication service using described embodiments.
Memory 113 comprises orbital schedule data 118 relating to the LEO satellite 110. Orbital schedule data 118 includes data relating to the scheduled position of the LEO satellite 110 over time with respect to the earth and the various remote terrestrial communication systems 120 as the LEO satellite 110 traverses its orbit. The orbital schedule data 118 also comprises antenna array configuration records that reference an ephemeris record (stored in memory 113) indicating a scheduled position of the LEO satellite 110 in orbit over a period of time, together with array factor coefficients or weights associated with each antenna element defined in relation to the ephemeris record. The array factor coefficients or weights associated with each antenna element (at a particular time) define the mathematical operations to be performed by the reconfigurable digital logic processing device 114 to process the signals received by each antenna element or process signals provided to each antenna element for transmission. The array factor coefficients or weights are complex numbers comprising a real coefficient and an imaginary coefficient. The mathematical operations performed by the reconfigurable digital logic processing device 114 using the array factor coefficients or weights are explained further below with reference to
The at least one processor 112 is configured to execute software program code stored in memory 113 to periodically check the current scheduled orbital position and/or the actual determined orbital position of the LEO satellite 110 and then access the orbital schedule data associated with the current (determined) orbital position to determine the array factor coefficients to be provided to the reconfigurable digital logic processing device 114 for signal transmission and/or reception over a next (succeeding) time period. The resetting of the array factor coefficients (and thus redirection of digitally formed beams or nulled beams) can happen frequently according to the ephemeris data corresponding to the determined position of the LEO satellite 110. This means that, during a pass of the LEO satellite 110 over a particular terrestrial area, the array factor coefficients can be reset multiple times in a pass-over period (e.g. 200-250 seconds, optionally around 240 seconds) while the LEO satellite is in range of that particular area. Resetting the array factor coefficients multiple times in a pass-over period for a particular area causes the one or multiple formed or nulled beams of the LEO satellite 110 to be angularly adjusted to account for the satellite movement relative to the particular area. This allows the formed or nulled beams of the satellite to be adjusted to better track and target the particular terrestrial area for improved communication efficiency. In some embodiments, the array factor coefficients can be set according to the ephemeris data for a pass over a known terrestrial area (containing a field of target devices for communication) and the array factor coefficients are maintained for a scheduled time (e.g. the entire pass-over period for that target terrestrial area) while the digitally formed or nulled beams pass over that area. The array factor coefficients can then be reset according to the ephemeris data for the next target terrestrial area that the LEO satellite is scheduled to pass over.
Ground station 130 is a terrestrial radio station designed for receiving and transmitting signals or radio waves from each of the LEO satellites 110. Ground station 130 comprises suitable antennas to communicate with the LEO satellites 110 and suitable network interface components to convey data received from the LEO satellites 110 to a network 150. Network 150 may be or include a data network, such as the Internet, over which the client device 140 may receive or access the data received by the ground station 130. The client device 140 may be a computer server or an end user computing device such as a desktop, laptop, smartphone or tablet, for example.
Signals received by each antenna element pass through a band pass filter 210 that removes signals received at frequencies that are not of interest for the LEO satellite 110. In some embodiments, the band pass filter may allow signals of frequencies between about 2170 MHz and about 2200 MHz to pass through, for example. Subsequently, the received signals pass through a radio frequency (RF) amplifier 220. The RF amplifier front-end may provide a total gain in the range of 40 to 60 dB, for example, as additional amplification can be provided in the Intermediary Frequency (IF) stage (228 to 242). The RF amplifier in combination with other components (including the input filter) processing the RF signal may have a noise figure lower than 2 dB from the antenna port, for example.
The radio frequency amplifier 220 increases the sensitivity of the receiver by amplifying weak signals without contaminating them with noise so that they can stay above the noise level in succeeding stages. The RF front end 115 comprises a local oscillator 280 that generates a local RF signal at an offset from the signal received by the antenna array 117. The local RF signal in some embodiments may have a frequency in the range of 1000 to 1200 MHz, for example.
In some embodiments, the local RF signal may have a frequency in C-band (4.5-6 GHz) or in Ku-band (13 to 14.5 GHz) or in Ka-band (27.5 to 31 GHz), for example.
A splitter 280 splits the local RF signal into four different split local RF signals. Each of the split local RF signals are mixed with the signals received by each of the antenna array elements by mixers 225 to generate a mixed phase and amplitude synchronous intermediate frequency signal (MIF1) for all the array elements 117a to 117n. The MIF1 signal may have a range of frequencies between 750 to 950 MHz, for example. The MIF1 frequency has a lower frequency than the frequency of the signal received by the antenna array 117 and is more conveniently processed by the rest of the components of the RF front end 115. The components necessary to process signals at lower frequencies are less sophisticated, less expensive and often more power efficient. Further, the antenna array 117 may receive signals at different frequencies. Converting the various signals received by the antenna array 117 to the MIF1 signals simplifies the processing of all the received signals by the rest of the components of the RF front end 115.
The MIF1 signal is subsequently passed through band pass filters 230 to generate an intermediate frequency signal (IF1). In some embodiments, the band pass filter 230 may retain signals within the frequency range of 900 MHz to 930 MHz, for example. In some embodiments, a signal conditioning unit, such as muRata™ SF2098H, may be used to implement the band pass filters 230. The IF1 signal subsequently passes through variable gain amplifiers 240. The antenna array 117 may receive signals from multiple remote terrestrial communication systems 120 simultaneously. The strength of the signals received by the antenna array 117 from two remote terrestrial communication systems 120 may vary significantly. Significant differences in signal strength may make numerical operations over the received signals infeasible or complicated for the reconfigurable digital logic processing device 114. The variable gain amplifiers 240 perform the function of signal levelling based on the commands or signals received from an automatic gain control loop 270. The automatic gain control loop 270 receives feedback from the reconfigurable digital logic processing device 114 regarding the strength of the received signals. The automatic gain control loop 270 working in combination with the variable gain amplifiers 240 maintains a suitable signal amplitude, despite variation of the signal amplitude of the IF1 signal.
In embodiments wherein the signals received by the antenna array 117 are dominated by noise, the RF front end 115 may be implemented with fixed gain (without variable gain amplifiers 240). In noise dominated received RF signals, the power level of transmissions by remote terrestrial communication system 120 may be similar to the power level of the noise component in the noise dominated received RF signal. Accordingly variable gain amplifiers 240 may not be necessary in processing noise dominated received RF signals as they may not meaningfully separate the noise component from the transmissions by remote terrestrial communication system 120. Similar signal levelling operations may be performed on signals transmitted by the LEO Satellite 110 in multiple directions of interest. Levelling of the signals transmitted by the LEO Satellite 110 in multiple directions of interest may be performed by the reconfigurable digital logic processing device 114 generating a signal provided to the RF front end 115 for transmission by the antenna array 117.
After the variable gain amplification, the signal IF1 passes through baluns 250. The baluns 250 convert the unbalanced signal UBIF1 to a balanced signal BIF1 suitable for downstream transmission and processing by the rest of the RF front end 115. The BIF1 signal is subsequently processed by an analogue to digital converter 255 to convert the analogue signals into a digital signal DIF2 suitable for processing by the reconfigurable digital logic processing device 114. The DIF2 signals may be 12-bit digital signals in some embodiments.
As illustrated in
Blocks 222, 228, 232, 242 labelled “att.pad” in
The RF front end 115 may also process signals generated by the reconfigurable digital logic processing device 114 to enable transmission of the signals by the antenna array 117. The RF front end 115 may control a feeder signal provided to the antenna array 117 based on the signals provided by the reconfigurable digital logic processing device 114. Based on the feeder signal provided to the antenna array 117, the antenna array 117 may transmit signals in a pattern comprising one or more beams based on constructive and/or destructive interference of the radio frequency transmission. The directivity or direction of the one or more beams may be controlled by the signal provided by the reconfigurable digital logic processing device 114. The directivity or direction of the one or more beams may be controlled to correspond to the location of one or more remote terrestrial communication systems 120, thereby enhancing the quality of signals received by the remote terrestrial communication systems 120. In this way, multiple transmission beams can be simultaneously created and directed in multiple different terrestrial target directions.
In some embodiments, the LEO satellite 110 may comprise a separate reconfigurable digital logic processing device and a separate RF front end, both dedicated to transmission beamforming. In some embodiments, the reconfigurable digital logic processing device 114 and RF front end 115 may be configured to perform both transmission and reception beamforming. In some embodiments, there may be a common reconfigurable digital logic processing device 114 performing both transmission and reception beamforming and two separate RF front ends, one dedicated for transmission beamforming and another dedicated for reception beamforming.
The beamformed signals are then processed by a beam levelling block 330. Each beamformed signal is expected to have been received from a particular remote terrestrial communication system 120. Depending on the relative location of the remote terrestrial communication system 120 with respect to the LEO satellite 110, the signal received from the various remote terrestrial communication systems 120 may have different amplitude levels. The beam levelling blocks 330 perform the function of levelling the amplitude levels across the various beams corresponding to signals generated by different remote terrestrial communication systems 120. The beam levelling blocks 330 may perform beam levelling by dynamically adjusting a multiplication coefficient applied to the beamformed signals. Signal levelling through the beam levelling blocks 330 may be used alone or if necessary may be applied in combination with the signal levelling performed by the variable gain amplifiers 240 described with reference to
After beam levelling, the levelled beam signals are processed by beam base band down-conversion blocks 340. The beam base band down-conversion blocks 340 convert the levelled beamformed signals to a lower frequency signal at a lower sampling rate to meet the requirements of downstream signal processing components. The downstream signal processing components may include components that expect a spread spectrum modulated digital signal, for example a signal according to the LoRa™ protocol. In some embodiments, the beam base band down-conversion blocks 340 may generated a LoRa™ based signal 370 as output.
The reconfigurable digital logic processing device 114 also comprises diodes 305 and low pass filters 308 corresponding to each input point 301, 302, 303 and 304. In some embodiments, the low pass filters 308 pass signals with a frequency lower than 1 kHz or lower than 10 kHz, for example. The low pass filters 308 are configured to have a cut-off frequency significantly lower than the lowest frequency of the signals received or transmitted by the antenna array 117. In some embodiments, the low pass filters 308 may have a cut off frequency of around 5-6 kHz. The signals processed by the low pass filters 308 are added using a summing block 360 and a summed signal 365 is generated. The summed signal serves as an input to drive the automatic gain control loop 270 of
Processing blocks 470 and 475 define the mathematical operations that are performed on the signals received at inputs 401 and 402. The mathematical operations are performed by appropriately configuring the logical blocks and the interconnects of the reconfigurable logic processing device 114. For example, processing block 470 implements the operations in complex numbers:
I1A=IAnt.1(t).ICoef1A−QAnt.1(t)QCoef1A
Q1A=IAnt.1(t).QCoef1A+QAnt.1(t).ICoef1A
In the above mathematical operations, IAnt.1(t) is a function corresponding to I component of the signal received by antennal element Ant.1 that corresponds to the input at 401. Similarly QAnt.1(t) is a function corresponding to Q component of the signal received by antennal element Ant.1 that corresponds to the input at 402. ICoef1A and QCoef1A are coefficients that control the result of the mathematical operation on the received signals. Processing block 470 performs similar operations of the signals 401 and 402 using the coefficients ICoef1B and QCoef1B. The rest of the processing blocks within the beamforming block 320 perform similar operations to the rest of the signals received at inputs 403 to 408 using a distinct set of coefficients stored in memory 113. These coefficients may also be described as weights corresponding to each antenna element.
Each antenna element has at least 4 coefficients or weights labelled ICoef1A, QCoef1A, ICoef1B and QCoef1B These coefficients or weight are dynamic and are varied by the beamforming block 320 on instructions from the processor 112. The processor 112 varies these coefficients based on the orbital schedule data 118 and information regarding a current position of the LEO satellite 110. In some embodiments, the LEO satellite 110 may receive command instructions from ground station 130 over the communication link 170. The command instructions may comprise instructions to the processor 112 to vary the coefficients depending on a change in the needs from the communication system 100. The change in communication needs may include the addition or removal of particular remote terrestrial communication systems 120 to the communication schedule. The change in the communication needs may also include identification of a source of interference or noise along certain parts of the LEO path and implementing beam nulling at appropriate times or time periods along the LEO path to address the source of interference or noise.
The orbital schedule data 118 includes antenna array configuration records. Each antenna array configuration record comprises an ephemeris record or an ephemeris zone record and weights or coefficients associated with each antenna array element in relation to the ephemeris record. The ephemeris record defines a zone or part of the orbit of the LEO satellite 110. Given a current position of the LEO satellite 110, the processor 112 is able to determine which ephemeris record the current position of the satellite corresponds to. After determining the ephemeris record that the current position of the satellite corresponds to, the processor 112 retrieves the weights or coefficients associated with each antenna array element in relation to the ephemeris record. The processor 112 subsequently reconfigures the coefficients of the beamforming block 320 based on the retrieved weights. Once the weights or coefficients of the beamforming block 320 are reconfigured, the reconfigurable digital logic processing device 114 processes the signals received by the antenna array 117 to best amplify the signals transmitted by the one or more remote terrestrial communication systems 120 that are part of the communication system 100 and currently fall within the field of view of the antenna array 117 of the LEO satellite 110.
Processing block 470 processes the input signals 401 and 402 to generate output signals 409 and 410. The output signals produced by the various mathematical operations illustrated in
The reconfigurable digital logic processing device 114 may similarly comprise transmission beamforming blocks that generate a signal provided to the RF front end 115 based on transmission beamforming coefficients or weights stored in the memory 113 to enable transmission beamforming using the antenna array 117.
The RF front end 500 comprises a series of band pass filters 501, 504, 507, 517 and 522. In some embodiments, the band pass filters 501, 504 and 507 may pass signals with a frequency from 1980 MHz to 2010 Mhz with a loss of 0.7 dB, for example. In some embodiments, the band pass filters 501, 504 and 507 may be implemented using a muRata SF2234E-1 filter, for example. In some embodiments, the band pass filters 517 and 522 may pass signals with a frequency from 938 MHz to 902 Mhz with a loss of 3 dB. In some embodiments, the band pass filters 517 and 522 may be implemented using a muRata SF2098H filter, for example.
The RF front end 500 comprises a series of amplifiers 502, 505, 508, 510, 515, 520 and 526. In some embodiments, amplifiers 502, 505, 508 and 510 may have a gain of 20 dB, a noise figure of 0.7 dB, an output intercept point (OIP3) of 17.5 dBm, for example. In some embodiments, amplifiers 515 and 520 may have a gain of 23 dB, a noise figure of 0.7 dB, an output intercept point (OIP3) of 17.5 dBm, for example. In some embodiments, amplifier 526 may have a gain of 22 dB, a noise figure of 1.5 dB, an output intercept point (OIP3) of 28 dBm, and an OP1 dB gain compression parameter value of 18 dBm, for example. In some embodiments, amplifiers 502, 505, 508, 510, 515 and 526 may operate at 3V, using a 6 mA current and drain 20 mW of power, for example.
The RF front end 500 comprises variable gain amplifiers 518 and 523. The variable gain amplifiers 518 and 523 may have a variable gain value from −23 dB to 17 dB, a noise figure of 5 dB (including attenuator insertion loss), and an OIP3 value of 34 dBm, for example. The variable gain amplifiers 518 and 523 may operate on 5V, using 110 mA current and drain 550 mW power, for example. In some embodiments, the variable gain amplifiers 518 and 523 may be implemented using a Maxim Integrated MAX2092 variable gain amplifier, for example.
The RF front end 500 comprises attenuator pads 503, 506, 509, 511, 516, 519, 521 and 524. In some embodiments, the attenuator pads 503, 506, 509, 511, 516, 519, 521 and 524 may each have a loss value of 3 dB, for example. The RF front end 500 comprises baluns 512, 514 and 527. The RF front end 500 comprises a frequency mixer 513. In some embodiments, the frequency mixer 513 has a gain of 1 dB, a noise factor of 12 dB and OIP3 of 22 dBm, for example. In some embodiments, the frequency mixer 513 may operate at 3.3V, using 95 mA current and drain 320 mW power, for example. The RF front end 500 comprises an analog to digital signal converter 528. In some embodiments, the analog to digital signal converter 528 may operate at a power level of 4 dBm, for example.
The reconfigurable digital logic processing device 114, when incorporating the coefficients of table 1, processes the signals received by the antenna array according to a transfer function graphically represented by the graph 600 of
The reconfigurable digital logic processing device 114 when incorporating the coefficients of table 2 processes the signals received by the antenna array according to the array factor in graph 700 of
The reconfigurable digital logic processing device 114 when incorporating the coefficients of table 3 processes the signals received by the antenna array according to the array factor in graph 800 of
The reconfigurable digital logic processing device 114 when incorporating the coefficients of table 4 processes the signals received by the antenna array according to the array factor in graph 900 of
The array factor graph 900 of
The reconfigurable digital logic processing device 114 when incorporating the coefficients of table 5 processes the signals received by the antenna array according to the array factor in graph 1000 of
In some embodiments, the antenna array 117 or 1100 may be a patch antenna array suitable for positioning or mounting on a flat surface. Each element of the antenna array may be a patch of metal mounted on a larger sheet of metal 1190 serving as a ground plane for the antenna array. In other embodiments, the antenna array 117 or 1100 may include multiple ones of other forms of radiating element, such as a whip radiating element or a horn radiating element, for example. However, the antenna elements of the antenna array 117 or 1100 are not configured to move relative to each other, nor does the antenna array rely on a diversity setup.
The microstrip hybrid network may create two ports, one Right Hand Circular Polarised (RHCP) port and another Left Hand Circular Polarised (LHCP) port. Accordingly, some embodiments use left hand or right hand circular polarisation of transmissions. Incorporation of left hand or right hand circular polarisation of transmissions allows for a simultaneous transmission of two independent signals, a first signal using the RHCP port and a second signal using the LHCP port. The two simultaneously transmitted signals comprise oscillations in planes orthogonal to each other, as opposed to oscillation in a singularly polarised transmission. Circularly polarised transmissions are more robust in response to problems associated with signal reflection or lack of a clear line of sight to a transmission target.
The phased antenna array of various embodiments disclosed herein is advantageously suited to the creation of multiple simultaneous transmit or receive beams (or to beam nullification) in multiple directions. This increases the communication efficiency of the LEO satellite 110.
In embodiments related to a 6U CubeSat, spatial limitations on the 6U selected satellite chassis platform resulted in the need to fit the antenna array into a maximum of 310×90×14 mm3 volume on one side of the satellite body.
In order to perform array beam scanning, the radiating elements in the array should not be arbitrarily separated, but should have a separation distance as a function of the array beam scan angular range. If the antenna element to antenna element spacing is too large, grating lobes (which are a sort of parasitic radiation lobe) can appear in the antenna radiation patterns. Such grating lobes can be detrimental to the performance of the antenna system by reducing signal transmission efficiency which can ultimately negatively affect the performance of the whole satellite.
In some embodiments based on a 6U chassis, a 75 mm (centre to centre) antenna element to antenna element separation may be used for communication in S-band frequencies. The adjacent edges of adjacent antenna elements may be separated by about 3 mm to about 5 mm, for example. Antenna accommodation on the satellite can be more of a performance limiting factor than the RF performance (i.e. avoiding grating lobes) in some embodiments. The desired RF performance of the antenna array can be maintained in receive mode with an antenna element to antenna element spacing of 78 mm without significant changes, if the spatial accommodation of the antenna array on the satellite allows for such antenna element to antenna element spacing.
As a general rule, the performance of a patch antenna is reduced in terms of bandwidth when the element is small, and/or extremely low profile. To achieve the RF performance desired for satellite communication functionality of 6U satellite embodiments as described herein but with an element that could fit into an array cell with a maximum length of 75 mm, lengthwise compression or surface variation of patch radiators of the antenna elements may be employed.
A wave or corrugation may be formed in the surface and cross sectional profile of the patch radiators to increase their RF electrical lengths while maintaining the reduced mechanical length. The waving or corrugation of the patch surface allows a physical patch size reduction of a few percent, but this may be sufficient to allow the desired RF performance within the constrained physical space of the CubeSat chassis.
However, the wave or corrugation patterning of the patch surface may introduce manufacturing challenges as it is not suitable for conventional machining of patch antenna radiators. According to some embodiments, 3D printing of the patch antenna in Aluminium with the wave or corrugation patterning can be used for the manufacturing of the patch antenna. However, 3D printing of the wavy or corrugated patches is challenging because of the shape and nature of the patch antenna and the physical constraints of 3D printing machines.
In some embodiments, the antenna array 117 or 1100 is positioned on the first minor face 1820, leaving the first major face 1810 and the second major face available for positioning of solar cells. Alternatively, or in addition, the antenna array 117 or 1100 may be disposed on the second minor face. The antenna array 117 or 1100 may extend across multiple CubeSat units, for example, and may extend across substantially the whole length of the first minor face 1820 and/or the second minor face.
Since the first and second major faces have the greatest surface area, positioning the antenna array 117 or 1100 on the first minor face 1820 and/or the second minor face allows for larger generation of solar power for use within the LEO satellite. In some embodiments, the antenna array 117 or 1100 may be positioned on the first and/or second major face to accommodate an antenna array larger in an area than the first minor face 1820 and/or second minor face. In some embodiments, the antenna array 117 or 1100 may include array portions disposed on the first side face 1830 and/or second side face. The at least one processor 112 is configured to control orientation mechanisms of the LEO satellite 110 to consistently adopt an orientation that points the antenna array 117 or 1100 toward the centre of the earth.
At 2012, the processor 112 determines array factor coefficients based on the satellite position determined at 2010. The array factor coefficients may be retrieved from memory 113 storing orbital schedule data 118. The array factor coefficients may be suitable for allowing transmission or reception beamforming operations.
At 2014, the processor 112 reconfigures the reconfigurable digital logic processing device 114 using the array factor coefficients determined at 2012. The schematic diagram of
The orbital schedule data 118 of the LEO satellite 110 may comprise the flight path coordinates as exemplified in table 6 above. Ephemeris records stored in memory 118 indicating a scheduled position or a portion of a flight path of the LEO satellite 110 may also include the flight path coordinates as exemplified in table 6 above.
At 2016, the antenna array 117 may receive signals. The received signals are processed by the RF front end 115 and made available to the digital logic processing device 114. At 2018, the digital logic processing device 114 processes the signals received by the antenna array 115 to amplify a subset of received signals corresponding to terrestrial communication system 120. At 2018, the digital logic processing device 114 may also simultaneously attenuate signals that are not of interest or signals corresponding to known sources of noise. At 2020, the amplified subset of signals determined at 2018 are processed to determine information encoded in the signals received at 2016 by the antenna array 117. Step 2020 may be performed in its entirety by the digital logic processing device 114 or the processor 112. In some embodiments, step 2020 may be performed by the digital logic processing device 114 and the processor 112 in coordination with each other. The decoded information may be stored in memory 113. When the LEO satellite 110 establishes communication with ground station 130, the decoded information may be transmitted to the ground station 130 over the radio communication link 170 to be made available to client device 140.
Steps 2022, 2024 and 2026 correspond to steps for transmission of information from the LEO satellite 110 to a remote terrestrial communication system 120. At 2022, the processor 112 retrieves the information/payload to be transmitted from memory 113. The retrieved information/payload is made available to the reconfigurable digital logic processing device 114. At 2024, the reconfigurable digital logic processing device 114 processes the information/payload to generate a feed signal for the antenna array 117. The generated feed signal is determined based on the array factor coefficients used to dynamically reconfigure the digital logic processing device 114 to allow transmission beam forming in a desired direction of interest for transmission corresponding to the remote terrestrial communication system 120 or ground station 130. The feed signal is made available to the antenna array 117 through the RF front end 115. At step 2026, the antenna array 117 transmits the signal based on the feed signal generated by the reconfigurable digital logic processing device 114.
The method 2000 as performed by the various components of the LEO satellite 110 may be continuously or repeatedly performed at regular intervals. After completion of step 2020 or after completion of the step 2026, the method 2000 may continue at step 2010 by determining a change in the position of the satellite followed by the rest of the steps of the method 2000 as described.
Some embodiments relate to installation in and/or on a microsatellite or nanosatellite chassis or housing: at least one processor, a memory accessible to the at least one processor, the memory storing an orbital schedule of a LEO satellite, and a communication sub-system accessible to the at least one processor. The communication sub-system comprises: an antenna array comprising two or more antenna elements; and a reconfigurable digital logic processing device in communication with the antenna array. The at least one processor is in communication with the reconfigurable digital logic processing device, and the at least one processor is configured to dynamically reconfigure the reconfigurable digital logic processing device to perform directional beamforming based on the orbital schedule by applying different transfer functions to signals simultaneously received or transmitted by multiple antenna elements of the antenna array over time. The installation of the communication subsystem and other components as described may form an early part of the step 2102 of providing described above.
Some embodiments relate to a method for providing a satellite communication service, comprising providing a LEO satellite of any one of the embodiments as a payload to a satellite launch vehicle.
Some embodiments relate to a method for providing a satellite communication service, comprising launching the satellite launch vehicle configured to release the LEO satellite of any one of the embodiments for travel in a low earth orbit.
It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.
Claims
1. A low earth orbit (LEO) satellite, the LEO satellite comprising:
- a microsatellite or nanosatellite chassis housing at least one processor, a memory accessible to the at least one processor, the memory storing an orbital schedule of the LEO satellite, and a communication sub-system accessible to the at least one processor; the communication sub-system comprising:
- an antenna array comprising two or more antenna elements;
- a reconfigurable digital logic processing device in communication with the antenna array;
- wherein the at least one processor is in communication with the reconfigurable digital logic processing device, and
- wherein the at least one processor is configured to dynamically reconfigure the reconfigurable digital logic processing device to perform directional beamforming based on the orbital schedule by applying different transfer functions to signals simultaneously received or transmitted by multiple antenna elements of the antenna array over time.
2. The LEO satellite of claim 1, wherein the antenna array is a linear array.
3. The LEO satellite of claim 1, wherein the directional beamforming is performed using all antenna elements of the antenna array simultaneously.
4. The LEO satellite of claim 1, wherein the at least one processor is further configured to dynamically reconfigure the reconfigurable digital logic processing device to perform directional beam-nulling based on the orbital schedule by applying different transfer functions to signals received and transmitted by multiple antenna elements of the antenna array over time.
5. The LEO satellite of claim 4, wherein the directional beamforming and/or beam-nulling is performed simultaneously across multiple frequency channels.
6. The LEO satellite of claim 4, wherein the directional beamforming and/or beam-nulling is performed simultaneously in multiple different directions.
7. The LEO satellite of claim 1, wherein the antenna array is disposed along one side of the chassis.
8. The LEO satellite of claim 1, wherein the antenna array is disposed to substantially cover a minor face of the chassis.
9. The LEO satellite of claim 1, wherein each of the antenna elements includes a patch antenna.
10. The LEO satellite of claim 1, wherein the antenna array includes at least four antenna elements.
11. A low earth orbit (LEO) satellite, the LEO satellite comprising:
- a chassis housing at least one processor, a memory accessible to the at least one processor, the memory storing an orbital schedule of the LEO satellite, and a communication sub-system accessible to the at least one processor; the communication sub-system comprising:
- an antenna array comprising two or more antenna elements;
- a reconfigurable digital logic processing device in communication with the antenna array;
- wherein the at least one processor is in communication with the reconfigurable digital logic processing device, and
- wherein the at least one processor is configured to dynamically reconfigure the reconfigurable digital logic processing device to: process signals received by the antenna array to amplify transmissions received from one or more directions of interest according to an orbital schedule of the LEO satellite, or amplify signals to be transmitted by the antenna array in one or more directions of interest for transmission according to the orbital schedule of the LEO satellite; and
- the LEO satellite has a mass in the range of 1 kg to 100 kg.
12. The LEO satellite of claim 1, wherein the LEO satellite has a mass in the range of 10 kg to 50 kg.
13. The LEO satellite of claim 1, wherein the chassis has a CubeSat structure and a size from 1 CubeSat unit to 50 CubeSat units.
14. The LEO satellite of claim 12, wherein the chassis has a CubeSat structure and a size from 3 CubeSat units to 24 CubeSat units.
15. The LEO satellite of claim 1, wherein the chassis comprises a major face, a minor face, the major face having a greater surface area than the minor face; and
- the antenna array is provided on at least a part of the minor face.
16. The LEO satellite of claim 1, wherein the at least one processor dynamically reconfigures the reconfigurable digital logic processing device to:
- process the signals received by the antenna array to attenuate transmissions received from one or more directions not of interest according to the orbital schedule of the LEO satellite, or
- attenuate signals to be transmitted by the antenna array in one or more directions not of interest for transmission according to the orbital schedule of the LEO satellite.
17. The LEO satellite of claim 1, wherein the orbital schedule data comprises one or more antenna array configuration records, each antenna array configuration record comprising:
- an ephemeris record indicating a scheduled position of the LEO satellite in orbit over a period of time; and
- array factor coefficients associated with each of the two or more antenna elements defined in relation to the ephemeris record.
18. The LEO satellite of claim 17, wherein each array factor coefficient is a complex number weight comprising a real coefficient value and an imaginary coefficient value.
19. The LEO satellite of claim 17, wherein the at least one processor dynamically reconfigures the reconfigurable digital logic processing device to process the signals received by the antenna array or amplify signals transmitted by the antenna array based on the scheduled position of the LEO satellite and the array factor coefficients as defined in the antenna array configuration record associated with the scheduled position of the LEO satellite.
20. The LEO satellite of claim 11, wherein the antenna array is a patch antenna array.
21. The LEO satellite of claim 1, further comprising an analog to digital converter for pre-processing signals before processing by the reconfigurable digital logic processing device.
22. The LEO satellite of claim 1, further comprising a digital to analog converter for processing signals generated by the reconfigurable digital logic processing device for transmission by the antenna array.
23. The LEO satellite of claim 1, further comprising a signal channeliser for channelising signals before processing by the reconfigurable digital logic processing device.
24. The LEO satellite of claim 1, wherein the reconfigurable digital logic processing device comprises a Field Programmable Gate Array (FPGA).
25. The LEO satellite of claim 1, wherein when the LEO satellite receives signals from more than one directions of interest, the at least one processor dynamically reconfigures the reconfigurable digital logic processing device to level amplitudes of signals received from the more than one directions of interest.
26. The LEO satellite of claim 1, wherein when the LEO satellite transmits signals to multiple directions of interest, the at least one processor dynamically reconfigures the reconfigurable digital logic processing device to level amplitudes of signals transmitted to the multiple directions of interest.
27. The LEO satellite of claim 1, further comprising one or more variable gain amplifiers (VGAs) in communication with the at least one processor,
- wherein when the LEO satellite receives signals from more than one directions of interest, the at least one processor configures the one or more VGAs to level amplitudes of signals received from the more than one directions of interest.
28. The LEO satellite of claim 11, wherein the antenna array comprises four or more antenna elements.
29. In a satellite communication system comprising:
- at least one LEO satellite of claim 1; and
- a plurality of terrestrial gateway devices, each terrestrial gateway device in communication with a plurality of terrestrial sensor devices;
- a method of communication between the at least one LEO satellite and the plurality of terrestrial gateway devices comprising:
- based on the orbital schedule data, the at least one processor dynamically reconfiguring the reconfigurable digital logic processing device to process signals received by the antenna array or to generate and transmit signals through the antenna array;
- the antenna array receiving signals and making the received signals available to the reconfigurable digital logic processing device;
- the reconfigurable digital logic processing device processing the received signals to amplify a subset of the received signals corresponding to signals transmitted by one or more of the plurality of terrestrial gateway devices, or
- the reconfigurable digital logic processing device making available to the antenna array signals for transmission in one or more transmission directions corresponding to respective locations of one or more of the plurality of terrestrial gateway devices.
30. The method of claim 29, further comprising the communication sub-system processing the amplified subset of received signals to decode information encoded in the subset of received signals.
31. The method of claim 29, further comprising the reconfigurable digital logic processing device processing the received signals to attenuate a second subset of the received signals corresponding to signals not of interest received by the antenna array.
32. A method for providing a satellite communication service, comprising:
- providing a LEO satellite of claim 1 as a payload to a satellite launch vehicle.
33. A method for providing a satellite communication service, comprising launching a satellite launch vehicle configured to release the LEO satellite of claim 1 for travel in a low earth orbit.
34. The LEO satellite of claim 11, wherein the LEO satellite has a mass in the range of 10 kg to 50 kg.
35. The LEO satellite of claim 11, wherein the chassis has a CubeSat structure and a size from 1 CubeSat unit to 50 CubeSat units.
36. The LEO satellite of claim 34, wherein the chassis has a CubeSat structure and a size from 3 CubeSat units to 24 CubeSat units.
37. The LEO satellite of claim 11, wherein the chassis comprises a major face, a minor face, the major face having a greater surface area than the minor face; and
- the antenna array is provided on at least a part of the minor face.
38. The LEO satellite of claim 11, wherein the at least one processor dynamically reconfigures the reconfigurable digital logic processing device to:
- process the signals received by the antenna array to attenuate transmissions received from one or more directions not of interest according to the orbital schedule of the LEO satellite, or
- attenuate signals to be transmitted by the antenna array in one or more directions not of interest for transmission according to the orbital schedule of the LEO satellite.
39. The LEO satellite of claim 11, wherein the orbital schedule data comprises one or more antenna array configuration records, each antenna array configuration record comprising:
- an ephemeris record indicating a scheduled position of the LEO satellite in orbit over a period of time; and
- array factor coefficients associated with each of the two or more antenna elements defined in relation to the ephemeris record.
40. The LEO satellite of claim 39, wherein each array factor coefficient is a complex number weight comprising a real coefficient value and an imaginary coefficient value.
41. The LEO satellite of claim 39, wherein the at least one processor dynamically reconfigures the reconfigurable digital logic processing device to process the signals received by the antenna array or amplify signals transmitted by the antenna array based on the scheduled position of the LEO satellite and the array factor coefficients as defined in the antenna array configuration record associated with the scheduled position of the LEO satellite.
42. The LEO satellite of claim 11, further comprising an analog to digital converter for pre-processing signals before processing by the reconfigurable digital logic processing device.
43. The LEO satellite of claim 11, further comprising a digital to analog converter for processing signals generated by the reconfigurable digital logic processing device for transmission by the antenna array.
44. The LEO satellite of claim 11, further comprising a signal channeliser for channelising signals before processing by the reconfigurable digital logic processing device.
45. The LEO satellite of claim 11, wherein the reconfigurable digital logic processing device comprises a Field Programmable Gate Array (FPGA).
46. The LEO satellite of claim 11, wherein when the LEO satellite receives signals from more than one directions of interest, the at least one processor dynamically reconfigures the reconfigurable digital logic processing device to level amplitudes of signals received from the more than one directions of interest.
47. The LEO satellite of claim 11, wherein when the LEO satellite transmits signals to multiple directions of interest, the at least one processor dynamically reconfigures the reconfigurable digital logic processing device to level amplitudes of signals transmitted to the multiple directions of interest.
48. The LEO satellite of claim 11, further comprising one or more variable gain amplifiers (VGAs) in communication with the at least one processor,
- wherein when the LEO satellite receives signals from more than one directions of interest, the at least one processor configures the one or more VGAs to level amplitudes of signals received from the more than one directions of interest.
49. The LEO satellite of claim 11, wherein the LEO satellite is a microsatellite.
50. A method of communication between at least one LEO satellite and a plurality of terrestrial gateway devices in a satellite communication system, the satellite communication system comprising:
- at least one LEO satellite of claim 11; and
- one or more terrestrial gateway devices;
- the method of communication between the at least one LEO satellite and the one or more terrestrial gateway devices comprising:
- based on the orbital schedule data, the at least one processor dynamically reconfiguring the reconfigurable digital logic processing device to process signals received by the antenna array or to generate and transmit signals through the antenna array;
- the antenna array receiving signals and making the received signals available to the reconfigurable digital logic processing device;
- the reconfigurable digital logic processing device processing the received signals to amplify a subset of the received signals corresponding to signals transmitted by at least one of the one or more terrestrial gateway devices, or
- the reconfigurable digital logic processing device making available to the antenna array signals for transmission in one or more transmission directions corresponding to respective locations of at least one of the one or more terrestrial gateway devices.
51. The method of claim 50, further comprising the communication sub-system processing the amplified subset of received signals to decode information encoded in the subset of received signals.
52. The method of claim 50, further comprising the reconfigurable digital logic processing device processing the received signals to attenuate a second subset of the received signals corresponding to signals not of interest received by the antenna array.
53. A method for providing a satellite communication service, comprising:
- providing a LEO satellite of claim 11 as a payload to a satellite launch vehicle.
54. A method for providing a satellite communication service, comprising launching a satellite launch vehicle configured to release the LEO satellite of claim 11 for travel in a low earth orbit.
Type: Application
Filed: Apr 30, 2021
Publication Date: Jun 8, 2023
Inventors: Flavia Tata NARDINI (Semaphore Park, South Australia), Matthew James PEARSON (Semaphore Park, South Australia), Yan BRAND (Quebec), Sabooh AJAZ (Croydon Park, South Australia), Lawrence TREVOR (North Adelaide, South Australia), Abdullah SEAD (Parkside, South Australia)
Application Number: 17/997,713