Patent Description:
The present disclosure relates to a manpack or portable VSAT satellite communications terminal, including antenna, modem, and supporting equipment.

Communications satellites provide connectivity around the globe across a number of frequency bands and services to fixed, mobile, permanent, and temporary sites. The VSAT (Very Small Aperture Terminal) class of service that is provided in the X, Ku, and Ka frequency bands is used in civil, commercial, and defense applications that require global connectivity and high bandwidths from moderate aperture sizes. Alternate, lower frequency bands (UHF, L-, S-, C-) services apply to uses requiring much lower bandwidth, unless extremely large antennas can be used.

Communicating with a satellite requires a terminal, which includes an antenna, modem, and associated amplifiers, mixers, and other RF or microwave components. Terminals are differentiated primarily by the antenna, and whether the antenna is fixed or steerable, mechanical or electronic.

For defense and civil applications where intermittent and on-the-fly communications are required in remote locations, a particular class of terminals known as "manpack" are designed to be easily transported, assembled, operated, and disassembled by a very small group of individuals. Manpack terminals can be regarded as a subset of the class of Comms-on-the-Halt antennas, but specifically those that can be transported by one or two individuals on foot. Weight, power consumption, volume, and ease of use are key differentiators for this market segment. In particular, the ability to travel with an antenna on an aircraft in hand or checked luggage is highly regarded.

For VSAT frequencies, parabolic reflector antennas are almost universal among manpack solutions. The most common approach is a parabolic dish that is broken down into pieces that clip together to form the right shape, with a central collapsible frame holding the feed antenna, subreflector, amplifiers, modem, batteries, and other equipment. See e.g., Hawkeye III Lite, <NUM> Tri-band VSAT, www. The size and the weight determine whether the terminal is regarded as a manpack or a larger flyaway terminal that is intended for truck or plane transport rather than for individuals. There are varieties that are an inflatable sphere that contains the reflector and the feed. See e.g., Expeditionary SATCOM, Cubic, www. Some models have automatic motor-driven pointing, others require a skilled or semi-skilled user to align the reflector with the desired satellite. Fully integrated pre-staged and preconfigured modems are very common, since the end-users are interested in rapid setup and breakdown of communications without the need for configuration and complex wiring or setup.

Flat panel antennas (see e.g., Paradigm Communications Swarm <NUM> (<NUM>) Flat Panel Ka-Band Satellite Terminal, Digisat International, Inc. ) are an alternative to parabolic reflectors as a fundamental antenna for SATCOM terminals. These terminals can be smaller and, in some cases, lighter than parabolic antennas, but typically are not used for very large aperture sizes and performance applications.

Typical phased array or electronically-steered antennas are rarely used in manpack configurations primarily due to the high power consumption relative to the performance, as well as the limitation on aperture size imposed on a single-piece antenna designed to be manportable. In other applications, phased arrays have many benefits, including the capability of near-instant steering and tracking with higher reliability, due to a lack of moving parts. Getting high performance requires large aperture sizes, which also scales the power requirements.

<CIT> discloses an apparatus, system and method for phased array antenna communications. A phased array antenna tile includes a plurality of antenna elements. A beamformer module is integrated into the phased array antenna tile. The beamformer module is electrically coupled to each antenna element to process directional signals for the plurality of antenna elements. A plurality of cascadable connection points are disposed along a perimeter of the phased array antenna tile for connecting the phased array antenna tile to one or more additional phased array antenna tiles.

The invention comprises field-assembled satellite communications terminal having the features of claim <NUM>.

Further advantageous features are defined in the dependent claims.

The field-assembled electronically-steered phased array for VSAT satellite communications may include a set of independent, identical, self-contained aperture blocks. The aperture blocks may snap together mechanically or magnetically in the field with limited or no exposed contacts, and self-configure and calibrate to form a single phased array or otherwise electrically-steered antenna aperture. Each block may include control, power supply, antenna segment, signal processing, and may be configured to interface so that any combination of blocks, from a single block up to a large, unspecified number, can be tiled together to form a functioning satcom terminal. Different implementations may include integrated modem and batteries, or have a single externally-connected block that provides those and other capabilities for the assembled terminal as a whole.

The overall antenna aperture having the combination of the antenna apertures from each of the assembled aperture blocks has gain and performance corresponding to its size - the more blocks, the more antenna gain, and the higher the achievable performance. In the field, as many blocks as are available are combined on-the-fly to form a functioning communications terminal with automatic configuration, satellite tracking, and connection initialization, which can then be instantly disassembled and distributed for transport, decentralizing the communications capability within a group of individuals compared to the conventional case of a single individual carrying the communications equipment. Each individual block is lightweight and easily transported. This system can be used as a manpack or flyaway terminal, with the number of modules allocated determining the overall performance.

The accompanying drawings are incorporated in and constitute a part of this specification. It is to be understood that the drawings illustrate only some examples of the disclosure and other examples or combinations of various examples that are not specifically illustrated in the figures may still fall within the scope of this disclosure. Examples will now be described with additional detail through the use of the drawings, in which:
This disclosure comprises a field-assembled satellite communications terminal intended for manpack or flyaway applications where portability, ease of use, and robustness are critically important, though other applications can also be provided. As shown in <FIG>, the satellite communications terminal <NUM> includes a plurality of interconnected discrete aperture blocks <NUM>, including a first block 103a, second block 103b, third block 103c, and fourth block 103d, though any suitable number of blocks <NUM> can be utilized. Generally, each discrete block <NUM> in an array <NUM> is identical, interconnected with its neighbors in a modular fashion with potential rotations between adjacent blocks to form a larger, interconnected array of blocks of an arbitrary size to form a satellite communications terminal, from a single block to a large number of blocks. Each modular block can operate independently if appropriately connected to power and local data communications channel (i.e., ethernet, modem) with the end user, but the more modular blocks are interconnected, the greater the capability of the combined terminal. In this illustration, each block <NUM> is substantially square or rectangular, with four sides having edges, and an aperture <NUM> arranged at the center of the block <NUM>; different block shapes are also possible.

One key feature of the disclosure is that the discrete, modular blocks <NUM> are assembled into a terminal <NUM> on-demand by the end user in the field (e.g., at the point of use, without a requirement for specialty tools or training), that the combined blocks then self-calibrate and initialize themselves to communicate with a satellite no matter how many blocks are in use. The signals received from the satellite and transmitted to the satellite from each aperture block are transferred between blocks as digitized waveforms having digital samples of the waveform either at the RF frequency or at an Intermediate Frequency (IF) or at baseband, to reduce the DSP requirements. This is different from other phased arrays described as composed of modular subarrays that are assembled into an array, but are assembled and calibrated in the factory or during installation on a mobile platform, and are not repeatedly disassembled and reassembled into a functional terminal in varying numbers and configurations by the end user. Self-calibration to correct for time-dependent changes to thermal or frequency response is common in existing phased arrays, but this standard capability (also called Built-In Test [BIT]) does not support the terminal's continued operation after being disassembled into component modules, transported, and reassembled in potentially different shapes and configurations when next required. The exchange of digitally sampled waveform data simplifies the calibration process, since the digital communications removes the sensitivity to phase and magnitude variations in each block connection that would differ with each assembly. Once digitized, the waveforms can be transferred between the modular, field-assembled blocks without distortion or signal loss.

A key feature of each block <NUM> is the phased array or other electrically-steered antenna aperture <NUM>, which is recessed inside of but at the top of the block <NUM> such that it can radiate freely into the upper hemisphere. When the blocks are interconnected for operation in the field, the antenna aperture <NUM> of each block <NUM> are enabled and operate together to form a larger, combined or aggregate antenna aperture, with gain and overall antenna performance commensurate with the size of the combined or aggregate antenna aperture. A variable number of blocks <NUM> can be assembled into an array. The blocks are interconnected through communications and power transfer ports <NUM>, which also provide for mechanical alignment & orientation between the blocks <NUM>. The ports constrain adjacent blocks to be coplanar (to within mechanical tolerances) and oriented with their normal axes in the same direction, such that all antenna apertures <NUM> are coplanar to within mechanical tolerances and facing in the same direction, so that they may all communicate with the same targets. In this way, a single aperture block <NUM> may connect to additional blocks 103a and 103b via the ports <NUM>. In the embodiment shown, the port <NUM> is located at the center of each side edge of the block <NUM>. The housing or outer case of each block <NUM> should be sealed and proofed against environmental conditions experienced outdoors (moisture, dust, sand, mud, etc.). The housing includes the RF-transparent radome above the antenna aperture <NUM> The ports <NUM> are formed in the block housing in a manner to prevent moisture or contaminant ingress.

The terminal <NUM> can be designed to operate at any frequency band, but the preferred implementation is for one of the common VSAT frequency bands of X-band, Ku-band, and the military and commercial Ka-band. To increase operational flexibility, operation across multiple bands in the same aperture is highly desirable - for example, a single terminal that would operate across the X and Ku, or Ku and Ka bands.

Each block should be capable of both transmitting and receiving satellite signals through the antenna aperture <NUM>, either in switched half-duplex mode, or simultaneous full-duplex through separate subsets of the antenna for transmit and receive, or a shared aperture. Although it would be possible to have separate aperture blocks <NUM> that either transmit or receive and construct a terminal <NUM> from both, that would place more constraints on the assembly of the blocks to form a functioning terminal, since the right proportion and arrangement is required.

An antenna aperture <NUM> that supports multiple transmit and receive beams simultaneously is highly desirable, since the terminal <NUM> as a whole could then support multiple beams to allow connections to multiple satellites simultaneously. This is desirable to allow more resilient communications through multiple ground gateways or to selectively route communications through two different networks with different bandwidth or latency or data security characteristics. In addition, the new constellations of NGSO (Non-Geostationary Orbit) satellites, including those in LEO (Low-Earth Orbit), MEO (Medium-Earth Orbit) and HEO (Highly-Elliptical Orbit), are benefited by terminals with multiple beams from the same aperture that can allow seamless make-before-break handovers.

The interconnection ports <NUM> between aperture blocks <NUM> are used for all data and power transfer between the different blocks. Although multiple methods of implementation are possible, including conventional ports, plugs, headers, and/or cables, any solution that involves exposed contacts or holes is susceptible to damage or becoming inoperable due to dirt, grease, moisture, or any number of environmental contaminants or conditions. For this reason, one embodiment of the disclosure uses short-range high-speed wireless links for data and inductive coupling for bulk power transfer, as illustrated in <FIG>, where a magnified view from the side <FIG> and top <FIG> are demonstrated.

In all cases, the implementations of the interconnection ports <NUM> must be symmetric across the geometric center line to allow for identical ports on neighboring blocks <NUM> to interface. For example, a single power transformer coil <NUM> should be centered within the port <NUM>, while posts <NUM> and holes <NUM> intended to interface with each other from neighboring blocks should be symmetric about the centerline.

In one embodiment, the outer cases or housings of the aperture blocks <NUM> are sealed, with no holes or perforations. For alignment, the ports <NUM> (including power and data transfer capability) include alignment features that are formed by symmetric alignment and mounting holes <NUM> and posts <NUM> that align the aperture blocks <NUM> as they are brought together.

In one embodiment, as shown in <FIG>, <FIG>, the holes <NUM> of the ports 107a are recessed inward from the side edge of the block <NUM>. The holes <NUM> have a first side wall <NUM>, a second side wall <NUM>, and a bottom surface <NUM> formed between the first and second side walls <NUM>, <NUM>. The side walls <NUM>, <NUM> can be angled to be tapered outward so that the opening at the top of the hole <NUM> is larger than the bottom <NUM> of the hole <NUM>, to allow simple alignment between the blocks <NUM>. As best shown in <FIG>, the hole can be circular or oval in shape, but can also take on other shapes, such as substantially square or rectangular.

The posts <NUM> have a mirrored geometry to the holes <NUM>, to allow the posts of one block 103a to engage with the holes of a second block 103b, and vice versa. The posts <NUM> project outward from the side edge of the block <NUM>. The posts <NUM> have a first side wall <NUM>, a second side wall <NUM>, and a top surface <NUM> formed between the first and second side walls <NUM>, <NUM>. The posts <NUM> form a base at the side edge of the block <NUM>. The side walls <NUM>, <NUM> can be angled to be tapered upward so that the top surface <NUM> is smaller than the base. As best shown in <FIG>, the post <NUM> can be circular or oval in shape, matching the shape of the hole <NUM>.

The holes <NUM> and posts <NUM> are angled and shaped so that the holes <NUM> and posts <NUM> slidably interconnect and mate with the respective posts <NUM> and holes <NUM> of a neighboring aperture block <NUM>, as shown in <FIG>. Thus, for example, the side walls <NUM>, <NUM> of the hole <NUM> slidably receive the side walls <NUM>, <NUM> of a neighboring mating block post <NUM>. When fully mated, the top surface <NUM> of the post <NUM> contacts with the bottom surface <NUM> of the hole <NUM>, supporting either direct electrical engagement of contacts, inductive coupling between power-transmission transformer coils, and/or wireless data transmission via adjacent transceivers within the holes <NUM> and posts <NUM> respectively.

As further shown in <FIG>, the second side wall <NUM> of the hole <NUM> can be continuous with the first side wall <NUM> of the post <NUM>. Accordingly, the post <NUM> of one block can slide along the first side wall <NUM> of a neighboring block and along the second side wall <NUM> of the hole <NUM> to be received in the hole <NUM>. In another embodiment shown in <FIG>, the hole <NUM> and post <NUM> can be separated slightly to form a bridge <NUM> therebetween.

Powerful magnets 209a and 209b are aligned with appropriate polarization within the holes <NUM> and posts <NUM> to hold the modules together. In addition, electronic components, such as short-range high-frequency communications components such as microchips 207a, 207b (see e.g., Keyssa technology, www. com, © <NUM> Keyssa, Inc. ) are mounted in each of the holes <NUM> and posts <NUM>, passing traffic wirelessly between two aperture blocks <NUM> via the ports <NUM>.

As shown in the embodiment of <FIG>, a first magnet 209a is mounted at the center of the interior surface (i.e., inside the hole, internal to the block body) of the bottom <NUM> of the hole <NUM>, such as recessed in the bottom <NUM> of the hole <NUM> and substantially flush with the bottom surface <NUM> of the hole <NUM>. And a first electronic device or component 207a is mounted just to the side of the first magnet 209a at the interior surface of the bottom <NUM> of the hole <NUM>, such as recessed in the bottom <NUM> of the hole <NUM> and substantially flush with the bottom surface <NUM> of the hole <NUM>. And, a second magnet 209b is mounted at the center of and recessed within the outside surface of the top <NUM> of the post <NUM> to be substantially flush with the top surface. And a second electronic component 207b is mounted just to the side of the second magnet 209b and recessed within the outside surface of the top <NUM> of the post <NUM> to be substantially flush with the top surface.

The first and second magnets 209a, 209b attract each other. Accordingly, as the post <NUM> is being slidably received by the hole <NUM>, the magnets 209a, 209b exert an attractive magnetic force that draws the post <NUM> fully into the hole <NUM> to fully engage the neighboring blocks with one another and to maintain the engagement of the neighboring blocks. In addition, a user can pull the neighboring blocks apart, if desired.

The first and second electronic components 207a, 207b are positioned to align with a respective mating component 207b, 207a of the neighboring block. Once the neighboring blocks are fully engaged, the first and second electronic component 207a, 207b are aligned with each other and communicate via a short-range wireless channel, such as via ultra-wideband transceivers or inductive or capacitive coupling without electrical contact. In one embodiment, the magnet 209a and/or the electronic component 207a can be recessed at the outside surface of the hole <NUM> to be substantially flush with the inside surface of the hole <NUM>. The magnets 209a, 209b can also be located internal to the block body and exert a magnetic force that extends through the block body into the hole or through the post top.

Depending on the capability of the chip <NUM>, each of these chips may pass bidirectional traffic, or may transmit data in only one direction, with data transmitted through the hole <NUM> and received through the post <NUM>, or vice versa. When the two aperture blocks <NUM> are aligned and interfaced via the holes <NUM> and posts <NUM>, the magnets <NUM> hold them together with the appropriate tolerances such that the communications chips are correctly aligned for proper operation. The magnets <NUM> and communications microchips <NUM> are inside the hermetically sealed block case or housing, and are not visible from outside the aperture block. The magnetic coupling and data transfer are accomplished through the magnetically- and RF-transparent (polymer) housing, or through RF- and magnetically-transparent windows within a nontransparent housing. The ports <NUM> coexist within the sealed case or housing of the aperture block <NUM> with the aperture <NUM>. The data to be exchanged includes low-speed control, calibration, and health information, as well as the high-speed digitized waveform data for each receive and transmit beam to be carried by the terminal <NUM>.

A power transfer mechanism <NUM>, such as an inductive coupling loop or transformer is used to transfer power between the blocks <NUM> forming the terminal <NUM>. Power transfer between aperture blocks <NUM> allows for embedded batteries to be charged from a single external power connection, or for operational power to be provided to the entire array in the case where no batteries are included in each aperture block. The mechanism <NUM> can be an open coil of wire or a wire-wrapped ferrite core in linear or half-circle configuration to increase the transfer efficiency of the coil. The use of wireless communications and wireless power transfer between blocks increases the power requirements of the array over and above the direct needs of the terminal; optimizing the power transfer efficiency as much as possible is important for minimizing the power consumption as much as possible, increasing the battery life or decreasing the number of batteries required. In the embodiment shown, the power transfer mechanism <NUM> can be mounted to the bridge <NUM> between the hole <NUM> and the post <NUM>.

As alternate alignment features instead of magnets <NUM> (<FIG>), mechanical devices can be provided at each hole <NUM> and post <NUM> that removably and reliably connect the hole <NUM> and post <NUM> with the post <NUM> and hole <NUM> of a neighboring block, and at the same time provide an electronic connection between the electronic components 207a, 207b. For example, one embodiment of the interconnection port 107b is shown in <FIG> (side view) and <NUM>(d) (top view). In this implementation, one or more posts <NUM> replace the post <NUM> and one or more slots <NUM> replace the hole <NUM> and are configured to mechanically register the locations of the neighboring aperture blocks <NUM>, and allow for a flexible clip <NUM> in one aperture block to removably connect with a mating slot <NUM> in the other aperture block. As shown, the posts <NUM> can be spaced apart from the slots <NUM>, for example at opposite ends of the block <NUM> and separated by other components at the side edge or surface of the block, such as light sources <NUM> and/or receivers <NUM>. In the embodiment of <FIG>, two posts <NUM> and two slots <NUM> are shown, though any suitable number can be provided. Whereas in the embodiment of <FIG>, the hole <NUM> and post <NUM> are adjacent to one another at a same area at the side edge or surface of the block <NUM> without components located at the surface therebetween (it is noted that the power transfer <NUM> is recessed at or beneath the surface). Though the posts and slots are shown at facing edges of the block <NUM>, they can be at a positioned anywhere on the block such as at the top and/or bottom surface. In yet another embodiment, one or more of the light sources <NUM> and/or light receivers <NUM> can be positioned to the outside of the respective post <NUM> and/or hole <NUM>.

In one example embodiment, a mating feature such as a catch or button <NUM>, can be integrated with the mating slot <NUM> and used to engage and disengage the mechanical clip <NUM> and allow the two aperture blocks <NUM> to be removably connected and disconnected. The use of mechanical clips <NUM> may be preferable over magnets <NUM>, as the structure can be made more robust and rigid when connected and protecting against accidental disconnection, but requiring more effort to connect and disconnect. The use of mechanical clips increases the rigidity of the assembled terminal <NUM>, and (for example) might allow the assembled terminal <NUM> composed of a number of aperture blocks <NUM> to be placed such that it is supported only from the edges, such as when tilted at an angle by resting on a stand or rock, thus increasing the operational flexibility of the terminal.

In this implementation, a PCB-integrated ferrite transformer coil 205b is used to transfer power in either direction between the two aperture blocks, preferably a ferrite pot core to contain the fields of the transformer and increase efficiency. A PCB-integrated planar ferrite core that uses traces on the PCB for the field windings of the transformer is a good solution, since the resulting transformer can have a very low profile and minimize the size and mass required for a given power transfer. Circuitry integrated into the interconnection port 107b would monitor the transformer and indicate when a neighboring block was installed and available to deliver or receive power. The circuitry would then configure the interconnection port <NUM> to either receive power, deliver power, or neither through the transformer depending on the requirements of the system.

In the embodiment of <FIG>, data transfer is accomplished through optical devices. One or more high-speed light sources <NUM> are excited by circuitry to carry a signal in one aperture block <NUM>, the resulting light would then be received by a matching and aligned one or more light receivers <NUM> in the other aperture block. In this implementation 107b, light sources <NUM> and receivers <NUM> replace the high-speed data interfaces 207a, b within the port <NUM> for transferring data between blocks <NUM>. Each aperture block would have both light sources <NUM> and light receivers <NUM> to both send and receive data, respectively, through the interconnection port 107b. An example implementation would use an LED <NUM> coupled to a corresponding light pipe or light guide <NUM> to drive the light source <NUM>, and a photodiode or phototransistor sensor <NUM> coupled to a corresponding light pipe or light guide <NUM> to detect the light received by the light receiver <NUM>. In this case, the light guides <NUM>, <NUM> would be used to couple the light from the LED <NUM> and sensor <NUM> to the source <NUM> and receiver <NUM> while the LED <NUM> and sensor <NUM> are installed on a printed circuit board <NUM> internal to the aperture block <NUM>. Stated otherwise, the light sources <NUM> and light receivers <NUM> can be positioned at the end surface of the block, and the LED <NUM> and phototransistor <NUM> can be located within the block and connected by guides <NUM>, <NUM>, respectively. With a high-speed LED <NUM> and photodiode <NUM>, high data transmission rates can be achieved, with additional pairs of sources <NUM> and sensors <NUM> added to support even higher rates as might be required for broad instantaneous bandwidths or multiple simultaneous beams. The outer surfaces of the light guides <NUM>, <NUM> must be at least relatively clean in order to transfer light, but the surface design of the sources and sensors <NUM>, <NUM> can be designed to avoid trapping dirt or other contaminants so that the surface can be quickly cleaned.

In another embodiment, the interconnection port 107c is shown from the side in <FIG> and the top in <FIG>. In this implementation, alignment features such as pegs <NUM> and slots <NUM> are configured to mechanically register the locations of the neighboring aperture blocks <NUM>. Embedded recesses <NUM> in the housing are then included to allow an external retaining clip or snap to be installed to hold the neighboring blocks <NUM> together. The benefits of an external clip are the ease of installation and the tension that it can withstand when connected can be controlled better.

In this implementation, electrical contacts <NUM> are used in each interconnection port 107c for power transfer between the aperture blocks. The benefits of direct electrical contacts are increased power transfer efficiency over a transformer-based approach and therefore reduced overall power draw and reduced heating, as well as increased design simplicity and reduced cost. However, exposed contacts must be protected from moisture and contaminants, and this can be performed with an integrated cover, such as a flexible silicone lid <NUM> over the port <NUM> that can be removed for installation and replaced for storage and transport. Similar to the power transfer, data signals may be carried by electrical contacts <NUM>, <NUM>, with the same benefits and costs. In this implementation 107c, plugs <NUM> and sockets <NUM> replace the high-speed data interfaces <NUM> a, b within the port <NUM> for transferring data between blocks <NUM>.

The different options discussed for the alignment and mechanical mounting between aperture blocks <NUM>, power transfer between blocks <NUM>, and data transfer between blocks may be applied in different combinations, and not only those illustrated as examples here.

<FIG> illustrates one embodiment of the functionality and subcomponents of the aperture block <NUM>, including any of the implementations shown in <FIG> or <FIG>. The general aperture block <NUM> contains a plurality of interconnection ports <NUM>, where they would be geometrically located around the perimeter of the block where appropriate interconnect to neighboring blocks <NUM> of the terminal <NUM>. The physical arrangement of blocks <NUM> may be a uniform arrangement with all blocks identically arranged (as would be the case with squares) or may involve rotations with only some ports <NUM> of some blocks able to interconnect with specific ports 107n on neighboring blocks <NUM>.

The physical user interface on each block has a plurality of input buttons <NUM> and indicator lights <NUM>, located where both would be physically accessible while the array is connected and operational. The location could be on one or more of the sides, or the front or rear face of the aperture block, depending on the application and installation case. Multiple sets of input buttons <NUM> and lights <NUM> could be located around the aperture block <NUM> to allow for easy access in different arrangements and orientations. Control and configuration of the blocks <NUM> and the terminal <NUM> overall is performed primarily using external control (such as a software application running on an end-user device, or the modem, or a virtual control panel running as a web application hosted on the terminal) rather than the physical interface <NUM> and <NUM>, which can be used for simple activity such as power-on and power-down.

The data to/from the interconnection ports <NUM>, n, p through the high-speed data interfaces <NUM> and the user interface <NUM>, <NUM> are both directly connected via transmission lines <NUM> and <NUM>, respectively, to the communications controller <NUM>, which might be implemented as a microcontroller or similar device responsible for managing the data entering and leaving the block <NUM>. The power transfer mechanism <NUM> of the interconnection ports <NUM> are connected to and controlled by the power manager <NUM>, which controls the flow of power between blocks <NUM> via power line <NUM>, manages and charges the batteries <NUM> (while power is supplied from one of the ports <NUM>,n,p) via the unregulated supply lines <NUM>, as well as supplies regulated power from the batteries <NUM> to the rest of the block electronic components via power lines <NUM>. The power manager may use data transferred between blocks via <NUM> to change the flow of power through the power transfer mechanism <NUM>.

The Antenna aperture <NUM> is a segment of a phased array or other variety of electrically-steered antenna (ESA) selected for power efficiency and ability to operate in discrete blocks that receives and generates the satellite signals <NUM>. This might be, for example, a conventional patch antenna phased array in a rectangular, triangular, or irregular grid, an array based on digital or analog beamforming and phase shifting, or an array based on liquid crystal or other tunable material. The block <NUM> can utilize any electrically-steered antenna, but is especially useful with antenna having reduced power consumption, such as in <CIT>, the entire content of which is hereby incorporated by reference. The benefits of this system for a conventional phased array antenna include that the aperture can be broken into smaller pieces and is therefore more transportable and yields more flexibility in applications since larger or smaller apertures can be constructed and operated on-demand.

The state and operation of the ESA is controlled via control signals <NUM> by the antenna control logic <NUM> running on the data processor <NUM> (e.g., implemented as a FPGA (Field-Programmable Gate Array) or SoC (System on Chip)). The RF or IF signals <NUM> (which may be digital or analog signals) to/from the aperture <NUM> are passed to the DSP processor <NUM>, which performs filtering, processing, time and phase shifting, and data combinations on the received and transmitted signals, including combining the signals with data from neighboring blocks <NUM> through the interconnections ports <NUM> and communications processor <NUM>. The processed data <NUM> is then passed to the data processor <NUM>, which works with the data depending on the configuration of the array. The overall combination of components in the block is novel to a single aperture block, along with the combinations such that multiple blocks are combined and operate jointly is novel.

The data processor <NUM> works very closely with the orchestration processor <NUM> to control the operation and state of the array. The data processor <NUM> handles the real-time signal processing and control operations, while the orchestration processor <NUM> is the primary controller of the block, and manages the communications flow <NUM>, <NUM> from block <NUM> to block, decides power allocation between blocks and components of a block, configures the data processor <NUM> via <NUM>, manages and integrates the sensor data <NUM> from the Inertial Navigation Unit <NUM> and GNSS receiver <NUM>, stores and retrieves configuration data <NUM> from memory <NUM>, coordinates behavior and operation with the orchestration controllers <NUM> of other interconnected blocks <NUM>, and ultimately controls the user interface and configuration through the data ports <NUM> or on-board interface <NUM>, <NUM>. The GNSS antenna <NUM> receives GNSS signals (i.e., GPS) <NUM> and passes those signals to the GNSS receiver <NUM>, which provides position and time data to the orchestration processor <NUM> that runs the antenna controller and sets the pointing direction of the terminal to a given satellite based on the terminal's location and orientation.

The data processor <NUM> is implemented using reconfigurable hardware (such as an FPGA) so that the functionality and features of each block can be modified by software. When a terminal <NUM> is assembled and in operation, one of the constituent blocks <NUM> will be selected automatically to be the master or primary block from which the other slave or secondary blocks will be controlled, one will be selected to act as the modem, one will be selected to act as the antenna control unit (ACU), and so forth for the functions for which only one instance is needed. In some cases, a single block may act in multiple roles simultaneously. Any block <NUM> that is not selected to act in a special way acts as a standard block, which optionally receives data comprising digital samples of a received waveform from neighboring aperture blocks from its ports <NUM>, processes that digitally sampled waveform data along with the digitally processed waveform data <NUM> to produce a combined sampled signal from its own DSP processor <NUM>, and forwards the combined digitally processed waveform data from the current block <NUM> as well as the neighboring blocks to another port <NUM>.

Data received by the antenna apertures <NUM> is summed together in a distributed fashion by all of the aperture blocks <NUM> before being routed and combined in turn by neighboring blocks <NUM> until the final, total data representing the satellite signal received by the entire terminal <NUM> reaches the specific block <NUM> acting as the modem (or holding the interface to the external modem). Each of the blocks <NUM> is capable of acting as any of the roles by loading a respective FPGA or software image <NUM> from the image storage <NUM>, which contains images for all of the features and functionality that is required. Some functionality <NUM>, which is the control logic for the aperture <NUM>, is included in every aperture block <NUM>, where the remaining unallocated capacity <NUM> on the data processor <NUM> is configured dynamically in each block at array setup time based on the needs of the terminal. The unallocated capacity <NUM> is used to implement the control processes on the primary block, the modem functionality, and the antenna control unit (ACU) functionality on the selected aperture blocks <NUM>.

Although <FIG> shows a large number of features and subcomponents included in the aperture block <NUM>, there is the option for some to be regarded as optional or only be included in different variants of the aperture block to save costs. For example, some modules could contain the battery unit <NUM>, others the FPGA processing block <NUM>, and others the GNSS receiver <NUM>; then, as long as at least one aperture block in the array contained each of the required features, the array would function. This would reduce the cost of each block by reducing the installed components, but would multiply the number of aperture block variants and increase the risk of missing an essential element when assembling a terminal, reducing the flexibility of the installation and configuration. For this reason, the preferred embodiment is for each aperture block to contain all illustrated features and functionality, so that the aperture blocks <NUM> are interchangeable, and any combination of blocks can be used to form a functioning terminal.

Accordingly, <FIG> shows a fully self-contained implementation with batteries and a controller embedded so that there are no single points of failure. <FIG> shows a simplified option that requires dedicated external hardware (controller, modem, power), but reduces the cost, weight, power of the antenna overall. Thus, <FIG> shows an alternate implementation of the functionality and subcomponents of the aperture block <NUM>, where components that would only be required in a single block <NUM> of the terminal are removed to an external user interface block <NUM>, modem & antenna controller block <NUM>, and external battery pack 315z. In this alternate implementation, features such as the battery <NUM>, physical user interface <NUM>, <NUM>, Inertial Navigation Unit <NUM> and GNSS receiver <NUM> are omitted from the terminal block <NUM> and instead installed externally. In this way, the cost of the aperture blocks is reduced, since only one aperture block <NUM> in an array requires a user interface or GNSS receiver, for example.

The external user interface block <NUM> then connects to an aperture block <NUM> via an interconnection port <NUM> (transferring power via <NUM> and control and digitally sampled waveforms via <NUM>) in the same way as two aperture blocks <NUM> might be connected. A communications controller or processor 311z receives and transmits over lines 307z signals from / to the port 107z, and also interfaces over lines 305z with the user interface components 301z, 303z. An orchestration processor 339z receives input 341z from the IMU 343z and GNSS receiver 345z, which operates with a similar antenna 347z and GNSS signals <NUM> as when installed in the aperture block <NUM>. The GNSS receiver 345z, IMU 343z, and user interface 301z and 303z must be directly attached to an aperture block <NUM> to ensure that the position and motion data is directly relevant to the antenna aperture for calibration purposes.

Additional processing capacity 325z for the modem functionality running via a data processor 329z and an overall power supply 313z may be optionally connected via a cable <NUM> to another block <NUM> that could be suitable for carrying in a backpack or other convenient method. An external or integrated high-capacity battery pack 315z would also be available to be carried in a similar convenient fashion.

The benefit of this alternate implementation as illustrated in <FIG> over that illustrated in <FIG> is that the mass and cost of the aperture block <NUM> is reduced due to common functionality being included in a single external block <NUM>, rather than in every aperture block <NUM>. That, in turn, enables use of a traditional phased array or other electronically-steered antenna (such as a lens array antenna) to be used in a manpack configuration. A separate user interface 301z, 303z also allows controlling the assembled antenna <NUM> from further away. It is noted that any one or more of the operational components <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> can be a processing device, such as a processor, controller or ASIC. The components <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> can be separate or combined into one or more integrated processing devices. Any combination of <NUM>, <NUM>, <NUM> may be carried by a single individual in a backpack or other container, with other items <NUM>, <NUM>, <NUM> being carried by others, and the terminal assembled when required.

<FIG> demonstrates how the aperture blocks <NUM> interconnect via their ports <NUM> to form a representative terminal <NUM>, with associated accessories <NUM>, <NUM>, <NUM>, <NUM>, <NUM> connected using the same ports <NUM>. One of the blocks <NUM> may be selected jointly by the orchestration processors during startup to be the primary block <NUM>, based on a set of criteria that might include proximity to the other blocks and relevant accessories to minimize the complexity of data transfer within the array, battery levels, etc. Or, an external user interface block <NUM> with associated modem block <NUM> may be connected.

The ports <NUM> can be viewed as having multiple internal connections or data streams, as shown in the magnified view of the transferred signals <NUM>, which can be communicated for example via the interface <NUM>. The ports <NUM> can pass power <NUM> bidirectionally, in response to the commands issued by the orchestration processor <NUM> and power controller <NUM> of each of the blocks, under the command of the orchestration processor <NUM> of the primary block <NUM>. For example, if external power <NUM> is being supplied by a power accessory <NUM>, then the availability of that accessory will be reported to the primary block <NUM>, which will then coordinate power transfers from the external power accessory <NUM> through to the rest of the connected blocks <NUM>.

Multiple parallel data streams are supported by the interconnection ports <NUM>, specifically the communications devices <NUM>. These may be carried over separate physical channels, contacts, or communications chips, or may be multiplexed into one or more underlying physical data streams. Low-speed command and control signals <NUM> are used for orchestration and low-rate communication and control throughout the array using a CAN (Controller-Area Network) or similar. A management <NUM>/<NUM>/<NUM> ethernet network <NUM> or similar with dynamic routing within the connected elements is used for higher-speed communications and control, including beam-pointing instructions from the antenna control unit, modem command and control signals internal or external to the terminal, and management, programming, and configuration of the terminal and individual blocks from an external computer. A user data <NUM>/<NUM>/<NUM> ethernet link <NUM> carries the user traffic from the modem through the array to one or more accessories for access by the user, such as a local wireless access card <NUM> with a wifi or Bluetooth antenna <NUM>, an ethernet adapter accessory <NUM> to connect to an external ethernet network <NUM>, or an adapter <NUM> to connect via USB or other connection to an external computer, radio, or other device <NUM>.

Finally, a high-speed synchronized packet line <NUM> carrying the sampled RF signal data <NUM> to and from the antenna apertures <NUM> and DSP processors <NUM> in the attached blocks <NUM>, or out of the terminal altogether through a modem port <NUM> to pass the digital data (potentially converted to an L-band IF signal) to an external modem <NUM> (which may be desirable in some use cases).

This flexible architecture allows terminals to be customized in size and applications by connecting different accessories. Depending on the desired applications and use cases, the functionality of some of the accessories could be integrated into the modules <NUM> themselves under sealed covers (i.e., enclosed by a module housing); for example, providing a single ethernet port on each module that would provide external connectivity for the management and data networks, power via power over ethernet for charging, and interconnection to a computer. Whether using a separate accessory <NUM>, <NUM>, <NUM>, <NUM>, <NUM> through the sealed magnet-mount data ports <NUM> or including the functionality in the aperture block <NUM> itself depends on the use cases and requirements for the terminal system as a whole. Additional accessory types are also possible, including data storage, external batteries, chargers for external devices to make use of the batteries internal to the aperture blocks <NUM>, etc..

An implementation of this disclosure places a number of constraints on the shape and size of the aperture blocks <NUM>. The larger the blocks <NUM>, the fewer are required to be interconnected to achieve a given communications performance, but the individual blocks are bulkier and heavier, thus complicating transport. Smaller blocks <NUM> require more blocks to be interconnected, increasing the time taken to assemble and disassemble, but might allow more blocks to be distributed to more individuals within a group to distribute the transport, thus making some level of communications available to more individuals within the group, no matter how separated they might become or into which subgroups they are separated at a moment in time. The shape of the blocks should be such that they may be tiled or tessellated in arbitrary numbers to form arbitrarily large or small arrays. Because there will be gaps, even small, between the antenna apertures <NUM>, supporting aperiodic tilings or rotationally-symmetric rather than translationally-symmetric tilings of aperture blocks are desirable. Aperiodic and asymmetric tilings are preferred since periodic or symmetric structures can possess undesirable characteristics in the sidelobes of the resulting overall antenna beam.

<FIG> shows three possible implementation shapes for an aperture block <NUM>, namely a triangular block 103x in <FIG>, a square block 103y in <FIG>, <FIG>, and a hexagonal block 103z in <FIG>. Many triangular configurations are possible, but a particularly desirable option is the triangle of which five triangular blocks <NUM> form a regular pentagon, with interior angles of the triangular block <NUM> of <NUM>, <NUM>, and <NUM> degrees. This specific triangle tiles into a regular polygon with no reflectional symmetries, and can be tiled into a large number of different irregular polygons and other shapes with primarily rotational symmetry. This is highly desirable compared to the periodic arrays that are achievable when using the square 103y or hexagonal 103z options. Triangles that form regular polygons with a small, odd number of sides are more likely to produce desirable tilings or tesselations than others (such as equilateral triangles that naturally form regular hexagons with six sides). Another option is irregular pentagons, of which there are <NUM> families that are capable of tiling the plane with a single shape (see Wolchover, Pentagon Tiling Proof Solves Century-Old Math Problem); however, the more complex the shape, the more challenging for the end user to tile into an appropriate and workable array. Other shapes are also possible, including the options that allow for multiple shapes of aperture blocks to be tiled together.

In the case where the shape of the aperture block <NUM> has multiple edge lengths (like the triangle 103x), then the interconnection ports <NUM> in the long and short edges can have different sizes or orientations to ensure that the blocks can only be assembled in a compliant way.

Rather than a conventional phased array or electrically-steered antenna, the antenna aperture <NUM> can be implemented using a lens array as described in <CIT>, which is especially useful for lenses that are substantially flat (e.g., non-spherical) to form a phased array. <FIG> demonstrates how an array of transmit <NUM> and receive <NUM> lenses might be tiled within a triangular aperture block <NUM>. The lenses <NUM>, <NUM> are shown as being circular, but can be hexagonal (as in <CIT>) or any other suitable shape and size. The ratio of transmit to receive lenses can be varied to adjust the overall array performance. The aperture <NUM> could also be implemented by combined receive and transmit lenses supporting either full- or half-duplex operation to optimize the gain of the terminal <NUM> in either mode for a given number of blocks. The benefits of the lens array over a conventional array antenna is that the power consumption and heat generation is lower, which is critical for a battery-operated application, and the component count is much reduced.

In addition, capabilities for simple extension to multiple beam operation for NGSO are included. <FIG> then illustrates how these blocks can be tiled together to form arrays of a single <NUM> (<FIG>), five <NUM> (<FIG>), ten <NUM> (<FIG>), and twenty <NUM> (<FIG>) aperture blocks.

To demonstrate the level of flexibility to work with an arbitrary number of aperture blocks, <FIG> demonstrates array terminals composed of <NUM>-<NUM> elements <NUM>-<NUM>, and <NUM> elements <NUM>. These are representative tilings - other arrangements area possible and acceptable. In general, the denser the tiling the more practical. The benefit of supporting many tilings with different shapes is that any number of elements <NUM> may be combined to form the terminal <NUM>, and they may be combined in many ways, simplifying assembly; as long as the module can fit, it can be installed and function.

<FIG> shows a representative terminal <NUM> assembled from five triangular aperture blocks 103x assembled in a regular pentagon. Three accessories are shown assembled on the device - a power adapter <NUM>, a data cable <NUM>, and a local wireless adapter <NUM>. This is one of many potential configurations that is achievable using the blocks and accessories described previously (e.g., with the angles <NUM>, <NUM>, and <NUM> degrees). For clarity, the accessories, such as adapter <NUM>, cable <NUM> and adapter <NUM>, are on the outside of the triangular block <NUM> housing, such as coupled to the block <NUM> at the port <NUM>; though in other embodiments the accessory can be integral with the block <NUM>.

<FIG> shows another embodiment of the terminal assembly <NUM> that connects five triangular aperture blocks 103x to an external user interface block <NUM>, which is connected via a cable <NUM> to the modem block <NUM> and external battery 315z. The modem block <NUM> and external battery 315z are shown superimposed on a backpack to illustrate that those components need not be unpacked in order to connect them to the antenna array <NUM>, easing quick setup and breakdown of the system.

<FIG> illustrates the operation flowchart of the terminal <NUM>. Beginning with a request <NUM> for a terminal to be deployed, a terminal is first configured <NUM>. A plurality of aperture blocks <NUM> and any associated accessories (including external user interface <NUM> or modem blocks <NUM>) are jointly inspected, optionally have their batteries (if any) charged, and configured <NUM> with the same satellite, modem, and operational settings and any required credentials to be able to connect to provisioned capacity on the network. Once a set of blocks are configured appropriately before departing to the field, then any combination or subset of the blocks <NUM> may be combined to form an operational terminal. Then, the blocks with any allocated accessories are distributed <NUM> to the end users.

In the field, when the end users have a need to communicate <NUM>, the terminal is assembled and setup <NUM>. First, the blocks and necessary accessories must be unpacked and assembled <NUM> into an array, with the documentation illustrating preferred arrangements, to form a single connected unit on the ground or other flat surface. Here, one or more of the blocks <NUM> are physically connected together by connecting the mating posts and holes to form a continuous block assembly, and optionally attaching an accessory to one or more of the blocks.

When the blocks <NUM> are assembled and all accessories connected, step <NUM>, the end user then presses <NUM> the power button <NUM> on any one of the connected units. This triggers the coordination phase <NUM> of the setup process, in which the set of connected blocks <NUM> jointly communicate by means of the ad-hoc mesh network of port connections in which they are assembled to identify the number, orientation, and geometry of connected blocks, identify any of the connected accessories, and select one of the blocks to be the primary block <NUM>. The primary block is selected based on configurable metrics such as proximity to the modem, central position within the array, or battery charge level. This process is performed on each block <NUM> by the orchestration processor <NUM>. Temporary addresses for each block <NUM> are mutually determined according to their locations within the array to facilitate communications. For example and with reference to <FIG>, block 103x might be chosen as the primary block of the array <NUM>. In this case, addresses might then be determined in a breadth-first traversal manner through all connected ports <NUM> of each connected block in the array <NUM>. The primary block would be assigned address <NUM>, the blocks (if any) attached to each of the ports then assigned addresses <NUM>, <NUM>, <NUM>. In array <NUM>, only addresses <NUM> and <NUM> are used for the blocks to the left and right respectively. The remaining blocks would be addressed in the same manner. Command and control signals can then be sent and received between blocks that are not directly connected through messages being forwarded by intervening aperture blocks. The status of this process and any faults are reported via the status indicators <NUM>.

After the primary block is selected, it then takes control (run specifically by the orchestration processor <NUM>) over the communications and configuration of the array in the calibration and initialization phase <NUM>. Based on the geometry and orientation information determined earlier, the primary block <NUM> establishes power, signal, and data routing paths throughout the array, simplifying the mesh network topology to a defined set of connections. The terminal as a whole <NUM> then self-calibrates under the control of the primary block <NUM>, loading calibration coefficients from storage and performing self-checks to confirm that all connections are secure. Each block computes the relative orientation and offset distance to its neighbors independently, and the terminal under the control of the primary block <NUM> uses a consensus approach to compare the calculations by different blocks <NUM> to arrive at a single value for each interface in the terminal <NUM>. The computed orientation and offset are then used by the calibration routines to correct the phase settings for each block to ensure accurate beamforming by the array as a whole.

A block or blocks are selected to act as the antenna control unit (ACU) and the modem, unless an external modem accessory <NUM> or external modem block <NUM> and external user interface <NUM> are installed, in which case the digitized waveforms or signals are routed to/from the external modem accessory or external modem block. The location and overall orientation of the terminal relative to the earth and the satellite is determined using the INU <NUM> and GNSS sensors <NUM> on one or more of the connected blocks under the control of the orchestration processor <NUM> of the primary block <NUM>, and at least one beam is formed to connect to at least one satellite, based on the configuration data loaded during the configuration phase <NUM>.

A beam is implemented as a bidirectional stream of digital waveform samples containing the transmitted and received signals, where the signals to be transmitted are distributed to all of the aperture blocks <NUM> for the appropriate magnitude and phase offsets to be applied before being transmitted by each respective aperture <NUM>, and the received signals are aggregated from all of the apertures <NUM> in the aperture blocks <NUM> and combined to a single sampled waveform from the terminal as a whole and provided to the modem. Once the satellite link is established, which starts with a receive-only connection being established to locate the target satellite and confirm that the expected signal is received from the satellite before enabling the transmit link, any external data accessories are activated, and the terminal <NUM> enters <NUM> the operation phase <NUM>. The status of this process and any faults are reported via the status indicators <NUM>.

In the operation phase, step <NUM>, bidirectional data is transferred, at step <NUM>, over the satellite links through the combined aperture formed from all of the interconnected apertures <NUM> in each block <NUM> of the block assembly. In this phase, both transmitted and received waveforms are continually streamed through the array between the satellite and the modem, subject to any implementation requirements for half-duplex operation. The beam or beams continue to track the satellites, step <NUM>, and report feedback to the users, step <NUM>, via the physical user interface <NUM> or via a data link <NUM>, <NUM>, <NUM> to an end user device. Tracking data and command and control signals from the primary block <NUM> continue to be transferred between the blocks to update beam pointing directions, power levels, calibration settings, and other operational information of use to the individual blocks within the terminal <NUM>. This process continues while the terminal <NUM> remains in operation. Terminal status is reported via the status indicators <NUM> as well as over the data links to the end user device. The terminal will continually monitor the received signal from the satellite to use for tracking purposes. If the received signal is lost, then the transmit beam must be immediately disabled until the received signal can be reacquired, as is standard in SATCOM terminal operation.

Shutdown of the terminal is triggered <NUM> either by the user issuing a command through a data link, pressing the power button <NUM> on the interface of any one of the connected aperture blocks <NUM>, or breaking any one of the connections between blocks by starting to disassemble the terminal <NUM>. The primary block <NUM> then instantly disables <NUM> the transmit function of all of the blocks <NUM>, and then powers down the entire system. The user then disassembles and stores <NUM> the aperture blocks <NUM> for transport. As necessary to re-start communications <NUM>, the process repeats starting with the setup phase <NUM>.

If new modules <NUM> are added to a terminal <NUM> in the operation state <NUM>, the terminal can either automatically revert back to the setup phase <NUM> to reconfigure for the larger size, or wait for the user to request the setup and recalibration process to begin.

This disclosure demonstrates a good configuration for a manpack SATCOM terminal. It is highly modular, with completely interchangeable components. Failure of any one component does not prevent the terminal from operating, instead only a single element is removed. Assembly in the field comprises removing the tiles from a backpack or other carry-case, placing them all facing the sky with a view of the desired satellite in a moderately-level location, and snapping them together. For operation with a LEO constellation, no knowledge of satellite location is needed - just a clear view of the sky. Assembly can be accomplished within short minutes. The ports <NUM> are keyed so that they will only connect if they are supposed to connect, with the apertures facing the same direction (up) and all edges of triangles (for example) aligned with like edges. With integrated batteries, there is no need to find power in order to operate the terminals, and the battery capacity can be scaled up and down to meet application requirements. As environmentally sealed units with integrated, sealed housings that incorporate the RF-transparent radome above the aperture, they are well-suited for operation in dirty environments. The ports themselves are large enough to be easily cleaned or washed of gross debris, and the system is not sensitive to grit, dust, and dirt on the surfaces.

Assembling more aperture blocks <NUM> together increases the aperture area; the triangular preferred shape 103x creates an irregular, non-periodic tiling that is preferred from the perspective of the aperture. This terminal <NUM> is suitable for both large and small throughput applications - more blocks <NUM> are used to generate more throughput, since both more RF power as well as aperture area and gain are available for both transmit and receive modes.

Electrical steering of the beams is necessary to allow for both high antenna gain as well as no moving parts. Without electrical steering, the aperture would need to be physically oriented towards the satellite either by the user or by actuators, which is undesirable and removes the key benefits of this terminal. The beam direction is determined by the orchestration controller <NUM>, with the specific settings for the aperture <NUM> determined by the beam controller processor <NUM>. Each beam is electronically scanned in the way that is appropriate for the type of antenna aperture <NUM> that is used to implement the antenna. For example, a phased array of patch antennas would have a phase and magnitude setting on each patch antenna that would be configured by the beam controller <NUM> to produce a beam in the desired direction, subject to calibration coefficients for the specific aperture block.

When an array <NUM> is assembled of multiple aperture blocks <NUM>, the alignment features built into the interconnection ports <NUM> will ensure that blocks are connected in acceptable fashions. However, the achievable mechanical tolerances on assembly may not allow for sufficiently repeatable and exact alignment (relative position and orientation) of neighboring aperture blocks <NUM> that the aperture array could reliably form beams without self-calibration.

Calibration of the array before operation would be intended to correct for relative position and orientation offsets between the aperture blocks <NUM> forming the array <NUM>, as well as phase differences and mismatches in the interconnections <NUM> themselves. This process must be automatic in order for this system to operate, since the array is intended to be assembled and disassembled in the field without external equipment.

One solution is to have each of the aperture blocks independently lock onto a strong signal, and measure the differences in the received signals from each block as a way to compute the phase corrections for each block to accurately form beams. This can be done by transmitting test signals from one or more blocks, or by listening to a known satellite signal.

This method may be improved if the relative positions and orientations of the aperture blocks can be estimated to a high degree of accuracy prior to evaluating the signals in the RF domain. <FIG> illustrates a measurement method for characterizing jointly the relative position and orientation offset between two aperture blocks <NUM>. A sensor <NUM> can be integrated into an interconnection port <NUM>, and can interface in operation with a second identical sensor 1101b. The sensor <NUM> includes a single optical or light transmitter <NUM> that is coupled through the housing by a light guide <NUM> to a transmit port <NUM>. The light transmitter <NUM> can be an infrared, UV, or visible light LED or laser diode.

The sensor includes a corresponding receive port <NUM> with three light receivers <NUM> and corresponding light guides <NUM>. The receivers <NUM> can be photodiodes or phototransistors. The receive port can have a generally recessed hemispherical shape, with the three light guides spaced in an equidistant pattern across the surface.

The light transmitter is driven by a signal generator <NUM> that would create a high-frequency signal, where the desired position measurement precision would be no more than <NUM> degree of phase at the nominal frequency. For example, to measure distances on the order of <NUM>, a signal with maximum frequency content <NUM> might be selected, since the <NUM> wavelength at <NUM> yields a light propagation distance of less than <NUM> for <NUM> deg of phase shift. Multiple sinusoidal tones or other signals might be overlayed to allow for more precision on the absolute distance measurements allowed by the sensor <NUM>.

The Light sensors generate signals corresponding to the light generated by the opposite sensor 1101b. The three received signals are compared to the output of the signal generator and relative time delays / phase shifts measured by comparators <NUM>, which can be implemented by phase-locked-loops or similar circuits. The measured time offsets and/or phase shifts would then be read by a processor <NUM> to compare the relative time delays between the three signals, and therefor the three distances between the transmitter 1103b and the receivers <NUM>. The processor <NUM> also adjusts the signal generator <NUM> to match the received signal and convert the two different systems into a single loop. If multiple tones are created by the generators <NUM>, then filters or frequency diplexers may be used to separate the different tones and compare phases separately in separate comparators <NUM>, or unified comparators could operate on the aggregate signals.

As this process continues in both associated sensors <NUM>, 1101b, both sensors generate measurements of the phase offset and therefore relative distances between the transmitters <NUM>, 1103b and the receivers <NUM>, 1105b. The arrangement and spacing of the transmitters and receivers <NUM>, <NUM> on one sensor <NUM> are known, and are then used to compute with the path length differences / measured relative distances the relative position <NUM> and orientations <NUM>, 1109b of the two aperture blocks. This method uses processing techniques similar to those used for interferometers, and relies on the base time delays in the light guides and processing chain being known to allow their influence to be removed from the position calculations. This position and relative orientation can then be used by the orchestration processors <NUM> of the blocks <NUM> to calibrate the arrays and support the beamforming control calculations to set phase weights for each individual aperture <NUM>.

It is noted that the figures show the ports <NUM> on all sides of each block. However, the ports <NUM> can be provided on fewer than all sides of each block. In addition, though one example of the port <NUM> is shown, any suitable port can be utilized and the blocks can electronically and / or mechanically couple together in any suitable manner.

It is noted that the drawings may illustrate, and the description and claims may use geometric or relational terms, such as side, edge, top, bottom, planar, coplanar, parallel, perpendicular, rectangular, square, triangular, circular, polygon, pentagon, equilateral triangle, irregular polygon, etc. These terms are not intended to limit the disclosure and, in general, are used for convenience to facilitate the description based on the examples shown in the figures. In addition, the geometric or relational terms may not be exact. For instance, walls may not be exactly perpendicular or parallel to one another because of, for example, roughness of surfaces, tolerances allowed in manufacturing, etc., but may still be considered to be perpendicular or parallel.

Claim 1:
A field-assembled satellite communications terminal (<NUM>), comprising:
a. a plurality of discrete, modular aperture blocks (<NUM>), each aperture block comprising:
i. an electrically steered antenna aperture (<NUM>);
ii. a plurality of interconnection ports (<NUM>) for power and data communications between the plurality of aperture blocks, said plurality of interconnection ports (<NUM>) being removably connectable; and
b. a signal processing system (<NUM>) configured to receive, process and generate signals to and from the antenna apertures (<NUM>),
c. wherein the aperture blocks (<NUM>) are removably connectable to each other;
characterised by:
the aperture blocks (<NUM>) are arranged to self-configure to form a combined electrically-steered antenna, and
a controller (<NUM>) within each of the plurality of aperture blocks (<NUM>) configured to automatically measure a relative distance and orientation between each block and each of its adjacent connected blocks to calibrate the combined electrically-steered antenna.