533 results about "Satellite constellation" patented technology

A method and apparatus for mitigating communications interference between satellite communications systems in different orbits is disclosed. The method comprises the steps of evaluating a geometrical relationship between a second ground station and the satellites in the second satellite constellation, and directing communications between the second ground station and the second satellite according to the evaluated geometrical relationship. In one embodiment communications are handed over from a first satellite to another satellite when the first satellite is no longer at the highest elevation angle of visible satellites. In another embodiment, handover occurs when the first satellite drops below a minimum elevation angle.

A method and apparatus for mitigating communications interference between satellite communications systems in different orbits is disclosed. The method comprises the steps of evaluating a geometrical relationship between a second ground station and the satellites in the second satellite constellation, and directing communications between the second ground station and the second satellite according to the evaluated geometrical relationship. In one embodiment communications are handed over from a first satellite to another satellite when the first satellite is no longer at the highest elevation angle of visible satellites. In another embodiment, handover occurs when the first satellite drops below a minimum elevation angle.

A system and method for assisting an integrated GPS / wireless terminal unit in acquiring one or more GPS satellite signals from the GPS satellite constellation. The invention includes a method for narrowing the PN-code phase search. That is, by accounting for the variables in geographic location and time delay relative to GPS time, the systems and methods of the present invention generate a narrow code-phase search range that enables the terminal unit to more quickly acquire and track the necessary GPS satellites, and thereby more quickly provide accurate position information to a requesting entity.

This invention describes a means for acquiring GPS P / Y code under jamming conditions. It improves jam resistance by augmenting a component of the GPS signal with one from a different satellite system, such as a low earth orbiting (LEO) satellite. The preferred embodiment of this invention employs the Iridium LEO satellite constellation broadcasting in a 10 MHz wide band about 1,621 MHz. A low-cost, integrated Iridium receiver coupled to the GPS receiver employs a single antenna that is capable of receiving both the GPS and Iridium signals together.

A communications system and method are disclosed that may include a constellation of satellites operating in a substantially equatorial, non-geostationary orbit; a plurality of ground stations configured to communicate with the satellites, at least one given ground station of the ground stations lacking a wired connection to any global communications network; and at least one gateway station coupled to a global communications network and to at least one said satellite, wherein each satellite includes at least one antenna having a steerable beam, the antenna being controllable to continuously direct a concentrated spot beam toward the given ground station.

The invention discloses a kind of underwater GPS allocation and navigation system and method without high stable frequency scale. The system is made up of GPS satellite constellation, four or more GPS floating marks, underwater navigation transceiver, data control centre, sea level wireless communication loop and hydroacoustics communication loop. The method is: when the object underwater needed to be located, the underwater navigation transceiver sends out hydroacoustics localization signal to the GPS floating mark, the floating mark transmits the hydroacoustics localization signal, the GPS signal and the posture calibration data wirelessly to the data control centre, and the data are processed with the difference signal, works out the position and time sending out the localization signal of the underwater object, the position and time data are transmitted to the underwater navigation transceiver by the hydroacoustics communication system, it can carry on navigation or time service. The invention can be applied to underwater object tracing, underwater localization and navigation, underwater precise timer service, measuring project control and project structure sample, it needs no high stable frequency scale.

Routing methods are provided for IP-based Iridium like LEO polar satellite constellation network for finding a Manhattan path between a source node and a destination node. The routing methods can include identification of congested inter satellite links (ISLs). By selecting and using uncongested alternative paths, an original routing process can be converted into sub-routing processes each in a small scale of a Manhattan path region. Quality of Service (QoS) requirements such as delays and jitters can be incorporated into the routing methods, which leads to efficient routing and enhanced QoS-performance over the satellite constellation network. The disclosed routing methods can be suitable for real-time routing / rerouting applications under dynamic network conditions.

A satellite network constellation employs a technique for multicasting packets through the network according to the present invention. The network comprises plural satellites in plural orbital planes with each satellite equipped with a plurality of high-speed point-to-point full duplex radio links for inter-satellite communications. A node intending to send a multicast packet to a multicast group or a set of destination satellite nodes initially sends the packet to the orbital planes that include the group members. Once reaching the plane, in-plane routing techniques are used to forward the packet to the intended group members. If there are broken or disabled links, an alternative path is taken to forward the packet without disrupting the functioning links.

A satellite clock error is determined for each navigation satellite based on the pseudo-range code measurements, the carrier phase measurements, and broadcast satellite clock errors provided by a receiver network. Differences are determined between the computed satellite clock errors and the broadcast clock errors for each satellite. For each constellation, a clock reference satellite is selected from among the navigation satellites, where the clock reference satellite has the median value of clock error difference for that satellite constellation. A correction is determined for the broadcast clock error by applying a function of the reference satellite's clock error to the broadcast clock error for each satellite in the one or more constellations.

A method and apparatus for monitoring a configuration of satellites to maintain integrity of LTO information in a GNSS receiver of a GNSS or other positioning system is described. The method may include obtaining broadcast ephemeris transmitted from at least one satellite of a constellation of satellites; comparing the broadcast ephemeris to long-term-orbit information available to a global-navigation-satellite receiver; and causing the global-navigation-satellite receiver to not use the long-term-orbit information when the long-term-orbit information does not correspond to the broadcast ephemeris.

<heading lvl="0">Abstract of Disclosure< / heading> A method and apparatus for locating mobile device over a broad coverage area using a wireless communications link that may have large and unknown latency. The apparatus comprises at least one mobile device, a reference network, a position server, a wireless carrier, and a location requester. The mobile device is in communication with the wireless carrier and receives global positioning system (GPS) signals from a plurality of satellites in the GPS satellite constellation. The reference network is coupled to the position server and provides GPS data. The mobile receiver receives GPS signals, performs rudimentary signal processing and transmits the processed signals to the wireless carrier. The wireless carrier passes the signals on to the position server. The position server processes the mobile receiver's GPS data and the reference network ephemeris data to identify the location of the mobile receiver. The location is sent to the location requester.

A method and apparatus for operating a satellite system including different satellites that may belong to different types of satellite constellations. In some implementations, the satellite system may include a LEO satellite constellation and one or more non-LEO satellite constellations that can be used to increase the forward link capacity of the LEO satellite constellation, for example, by allowing an LEO satellite to offload at least some of its forward link traffic to one of the non-LEO satellites. The user terminals can dynamically switch forward link communications between a LEO satellite and a non-LEO satellite while maintaining a return link connection with the LEO satellite.

An indoor GPS repeater unit comprising a directional receive aerial for receiving GPS signals from one or more satellites in a preselected area of the sky, a transmitting aerial for transmitting the received GPS signals; and, RF amplification means for enhancing the received GPS signals before transmitting into an indoor area is disclosed. One or more such GPS repeater units are used to reproduce the satellite constellation within buildings or underground to provide GPS coverage in these environments.

A global navigation system includes a first navigation receiver located in a rover and a second navigation receiver located in a base station. Single differences of measurements of satellite signals received at the two receivers are calculated and compared to single differences derived from an observation model. Anomalous measurements are detected and removed prior to performing computations for determining the output position of the rover and resolving integer ambiguities. Detection criteria are based on the residuals between the calculated and the derived single differences. For resolving integer ambiguities, computations based on Cholessky information Kalman filters and Householder transformations are advantageously applied. Changes in the state of the satellite constellation from one epoch to another are included in the computations.

A configuration for a satellite constellation has a plurality of planes, each plane including a plurality of satellites therein, at least some of the planes situated at a different altitude than other of the planes. In some embodiments, all planes contain the same number of satellites; in some other embodiments, at least one plane includes a different number of satellites than the other planes in the constellation. In some embodiments, the satellites in each plane are evenly spaced.

A time reference system for generating a time reference from signals produced by a global navigation satellite constellation has a satellite signal receiver to receive and down-convert code-modulated signals from a plurality of satellites and a correlator to track and decode the down-converted signals to provide signals containing partial pseudo-range measurements for respective satellites. A data processing arrangement receives assistance data from an external source and performs data-bit synchronisation in which bit edges of a low frequency data bit stream carried by the received satellite signals are identified, to perform a preliminary position-velocity-time solution to provide an approximate time reference, and to perform auto-correlation of pre-selected data sequences in the data stream to resolve time ambiguities thereby to compute a precise time reference signal in weak received signal conditions. The pre-selected data sequences may be the repeated data preamble in the GPS navigation message constituted by the data stream.

A system for sensing aircraft and other objects uses bistatic radar with spread-spectrum signals transmitted from remotely located sources such as aircraft flying at very high altitudes or from a satellite constellation. A bistatic spread spectrum radar system using a satellite constellation can be integrated with a communications system and / or with a system using long baseline radar interferometry to validate the digital terrain elevation database. The reliability and safety of TCAS and ADS-B are improved by using the signals transmitted from a TCAS or ADS-B unit as a radar transmitter with a receiver used to receive reflections. Aircraft and other objects using spread spectrum radar are detected by using two separate receiving systems. Cross-Correlation between the outputs of the two receiving systems reveals whether a noise signal is produced by the receiving systems themselves or is coming from the outside.

A wireless tank monitoring system for remotely monitoring a plurality of storage tanks is provided. This tank monitoring system utilizes wireless communication from individual tank level monitors to a single SatComm Gateway. The SatComm Gateway then utilizes a low-Earth Orbit satellite constellation to transmit information to a central data collection center. The data collection center then provides access to this information to clients. These clients also have the capability of controlling individual monitors via the bi-directional communications path through the satellite link to the SatComm Gateway to the individual monitors. The SatComm Gateway packages the information from each of the monitors to optimize the communications through the satellite link to decrease the cost of transmission. Intrinsic safety is provided by each of the individual tank level monitors.

A scalable satellite data communication system that provides incremental global broadband services using Earth-fixed cells may begin with a limited satellite deployment that initially serves a limited number of Earth-fixed cells. The system has the flexibility to incrementally increase the number of Earth-fixed cells that are served, with minimal constraints on the relative locations of the cells on the Earth, by adding satellites of potentially greater complexity to the system. Backward compatibility with existing user terminals is achieved by maintaining the same satellite communication interface as with the already-deployed satellite constellation. Continuous and / or non-continuous service may be provided to selected Earth-fixed cells. Scheduled non-continuous service is particularly advantageous for bulk data transport services. Satellites may use simple mechanically-steered antennas. Communication links may be handed from one satellite to another when one satellite moves out of range and is no longer able to cover a selected Earth-fixed cell.

The invention discloses a low-orbit satellite constellation system cell switching method and device based on ephemeris information. The method comprises the steps of enabling a mobile terminal to receive the signal intensity of a service satellite; judging a switching triggering moment, then predicting a subsatellite point position of a low-orbit satellite according to a received satellite ephemeris parameter; calculating a coverage satellite set of the switching triggering moment according to the predicted subsatellite point position; and comparing a mobile terminal with a beam feature pointset of all beams of each satellite in the coverage satellite set to obtain an adjacent cell list. The mobile terminal calculates the visual time of each beam in the neighbor cell list, screens out thebeams of which the visual time is less than a beam visual time threshold, selects the beam with the maximum switching weight in the screened neighbor cell list as a target beam, and finally sends a request of switching to the target beam to a source beam. The method has the characteristics that the beam cell switching reliability is improved; the ping-pong switching probability is reduced; the number of system control signaling is reduced; and the network efficiency is improved.

A system for remotely tracking, monitoring and messaging vessels (14) utilizing a global positioning system satellite constellation, having a transceiver located on the vessel to be tracked and monitored, a monitoring center located remote from the vessel, a communications means allowing the bi-directional communication between the transceiver and the monitoring center, a communications means allowing the uni-directional communication from the global positioning system satellite constellation to the transceiver, sensors on the on-board systems of the vessel, a communications means allowing communication between the sensors and the transceiver, an input / output means for messaging, and a communications means allowing communication between the input / output means and the transceiver.

The invention provides a double-deck satellite load balancing method based on link cost conversion. According to the method, on the basis of the virtual topology strategy of a satellite, low earth orbit (LEO) layer link cost conversion and layered flow division are conducted on a topology snapshoot. Thus, by means of predictability and periodicity of constellation running of the satellite, system running time is divided into a plurality of same time periods, each time period is divided into n gaps tp, and link overload judgment is conducted on an inter-satellite link in each time gap. Congestion grading is conducted on a global coverage area, cost regulation and route optimization are conducted in cooperation with the real-time flow of the LEO satellite link when the link is congested, and therefore flow of the whole network is balanced. On this basis, reasonable route selection is conducted on transmission service with different qualities of service (QoS) in cooperation with the MEO layer satellite network, and the throughput of the whole network is improved while the requirement for the high priority service time delay is met.

A new approach for designing satellite constellations whereby each satellite follows a common ground track is being proposed for performing high-precision change detection imagery for long periods of time. By precisely prescribing the orbital parameters, i.e., the relationship between the right ascension of the ascending nodes (RAAN) and the phase angle difference between successive satellites, for example, sharpened change detection images may be taken from successive satellites in the constellation without the need to process out blurring by any special image re-working software. The relationship between the orbital parameters of the satellites is precisely tuned to the earth's rotation rate for the altitude of the satellites. A reduction in the total satellite count is achievable due to tiling the satellite coverage in near optimal arrangements. Such high-precision change detection imaging by successive satellites in orbit around the earth is at least useful in the detection of underground facilities activities and the detection of slow moving objects.

A low cost and low profile antenna for commercial use, either in a fixed or mobile condition is disclosed. The antenna has a generally flat circular plate that rotates to seam the azimuth direction. A plurality of radiation elements are positioned on the surface of the circular plate. The received signals are multiplexed, digitally converted, digitally beamformed, and then transferred to a digital receiver.

A satellite constellation has a plurality of satellites. Each of the satellites has an RF ground link for communicating with a ground station and an optical link for communication with at least one of the plurality of satellites. Each of the satellites has a reconfigurable optical transmitter for sending and receiving data streams. Each reconfigurable optical transmitter has a first optical carrier associated therewith and a reconfigurable optical receiver. The plurality of satellites is arranged to have a first subset of satellites. The first subset of satellites is configured to communicate. The plurality of satellites is reconfigured to have a second subset of satellites having at least one different satellites than that of said first subset. The second subset supercedes the first subset. The second subset of satellites is configured to communicate. Various subset around the globe may form local area networks. The local area networks are preferably optically coupled to form a wide area network.

The invention belongs to the field of satellite communication technologies and particularly relates to a ground station system and a method for avoiding collinear interference with a geostationary satellite. The system comprises a ground station located at one position of the earth and a non-geostationary satellite constellation connected to the ground station, wherein the ground station traces one satellite in the non-geostationary satellite constellation through controlling antenna beam and establishes a communication link with the satellite; when a connecting line between the ground station and one non-geostationary satellite points at the geostationary satellite, the ground station adjusts the beam direction and selects another non-geostationary satellite in the different direction in view to communicate, so that the collinear interference with the geostationary satellite is avoided. According to the ground station system and the method, the restriction that shutdown of the non-geostationary satellite is needed or the transmitting power of the non-geostationary satellite is greatly reduced when the collinear interference occurs is avoided, and the satellite communication of the ground station keeps continuous, so that the availability and the message capacity of the non-geostationary satellite constellation are improved and the same frequency coexistence of the non-geostationary satellite and the geostationary satellite is realized.

Systems and methods are provided to determine launch parameters of satellites of a satellite constellation that provides optimized performance of the satellite constellation over the service lifetime of the satellite constellation. The launch parameters may be determined by considering perturbing accelerations of one or more of the satellites for the purposes of optimizing the launch parameters of the satellites of the satellite constellation. The systems and methods may include heuristic optimization and high-fidelity astrodynamic modeling methodologies.

The disclosed technology relates to systems and methods for tasking satellite constellations. A method is disclosed herein for receiving, from a resource database of a satellite control system, knowledge data corresponding to a plurality of components associated with a satellite constellation communications system. The plurality of components can include one or more satellites associated with a constellation. The method includes processing the knowledge data according to at least one received mission objective. Processing the knowledge data can include determining a status of at least one satellite in the constellation. The method includes scheduling the satellite control system based at least in part on the received mission objective and the processed knowledge data; initiating communication with the at least one satellite in the constellation according to the scheduling; receiving updated status information for at least one component of the plurality of components; and storing, in the resource database, the updated status information.