Abstract: The present disclosure is directed to a system and method for measuring small frequency differences between two signals quickly and with high precision. In particular examples, an offset between two clock signals on a satellite can be accurately determined in a time period enabling rapid clock synchronization useful in position, navigation, and tracking (PNT) and satellite communications applications. The system and method may also be implemented in constellation of cooperative satellites or other space-borne and high-altitude assets, wherein a plurality of such assets are accurately time-synchronized and more accurate ensemble average calculations are enabled using two-way time transfer (TWTT) protocols. A particular application presently disclosed measurement and correction of very small frequency differences between an atomic clock signal and a tunable clock signal.

Abstract: A wireless device determines a biased wireless device position and a receiver clock error for a plurality of satellites, the biased wireless device position and the receiver clock error being associated with a biased ambiguity. The wireless device calculates, upon determining the biased wireless device position and the receiver clock error, the biased ambiguity for each of the plurality of satellites. The wireless device applies the biased ambiguity to a carrier phase measurement for each of the plurality of satellites, the carrier phase measurement being associated with the receiver clock error and an absolute location of the wireless device. The wireless device determines, upon applying the biased ambiguity to the carrier phase measurement for each of the plurality of satellites, the absolute location of the wireless device based on the biased ambiguity for all of the plurality of satellites.

Abstract: The system is configured to generate a display of a tagging interface. The tagging interface may include a stitching selector. In response to a user selection of (1) a destination element that includes a first name identifier, (2) a source element that includes at least one of the plurality of pixels such that at least one of the plurality of pixels corresponding to longitude-time points comprising a second name identifier, and (3) the stitching selector, the system can be configured to indicate that the source element comprises the first name identifier.

Abstract: An apparatus includes multiple patch antenna elements configured to transmit multiple electromagnetic beams in multiple beam directions. The apparatus also includes multiple inputs each configured to receive one of multiple input signals, where each input signal is associated with one of the electromagnetic beams. The apparatus further includes multiple phase-tapered splitters each configured to receive one of the input signals, divide the received input signal into a set of sub-signals, and provide a phase taper that adjusts phases of at least some of the sub-signals in the set of sub-signals. Different phase tapers are associated with different ones of the beam directions. In addition, the apparatus includes multiple 90° hybrid transformers each configured to receive sub-signals associated with different ones of the input signals, isolate the received sub-signals from each other, and provide the isolated sub-signals to one of the patch antenna elements.

Abstract: In certain embodiments, an apparatus includes a switch matrix and frequency band isolation circuitry. The switch matrix is configured to receive, at an input port, an electrical signal, which corresponds to a transmission signal received at antennas of an antenna array. The transmission signal corresponds to a transmission spatial sector of the array. The electrical signal includes first and second signal portions in first and second frequency bands, respectively, the electrical signal having been generated from an optical signal that corresponds to the transmission signal. The switch matrix is configured to direct, via an output port and in accordance with a control signal, the electrical signal to a first of multiple signal conversion paths.

Abstract: A method for piloting from bypass in a network with open wireless channels is disclosed. The method includes: 1) selecting a terminal station as a reference in open wireless channels, and sending a pilot signal, in which all or some frequency bands of open wireless channels occupied by the pilot signal are pilot frequency bands, and the proportion of power of the pilot signal to the total power of the pilot frequency bands is 0.1‰-5%; 2) spreading the pilot signal with a spread spectrum code when it is transmitted, and then superimposing on a communication signal in the pilot frequency bands in a low power spectrum signal mode similar with noise; and 3) providing pilot, carrier wave and clock synchronization, standard timing and indication information for network construction and mutual communication of multiple types of terminal stations in channels by the pilot signal.

Abstract: A multiple wideband antenna or broadband antenna using the concepts of cellular clusters integrated into a dual polarity antenna panel. These panels integrate a free space optic capability to transmit and receive high-bandwidth communications and provide an option for communication transport of information from the base of the tower to the antenna. This antenna also integrates the capability to provide command and control using the cellular guard bands created between each cellular block to support Unmanned Aerial Systems or free space optics connection.

Abstract: A satellite communication system and method for resizing an outroute carrier from a gateway to a terminal population including determining, at the gateway, an insufficiency based on an Uplink Power Control (ULPC) function in conjunction with an Adaptive Coding and Modulation (ACM) function failing to maintain the outroute carrier in operation; and downsizing, at the gateway based on the insufficiency, the outroute carrier by decreasing a symbol rate of the outroute carrier from the gateway while maintaining the aggregate carrier output power level to increase an outroute carrier margin, where the insufficiency is based on a fade. The outroute carrier may be upsized when the insufficiency expires or is reduced.

Abstract: Embodiments provide in-flight configuration of satellite pathways to flexibly service terra-link and cross-link traffic in a constellation of non-processed satellites, for example, to facilitate flexible forward-channel and return-channel capacity in a satellite communications system. For example, each satellite in the constellation can include one or more dynamically configurable pathway, and switching and/or beamforming can be used to configure each pathway to be a forward-channel pathway or a return-channel pathway in each of a number of timeslots according to a pathway configuration schedule. At least some of the pathways can be further selectively configured, in each timeslot, to carry “terra-link” traffic to and/or from terrestrial terminals and “cross-link” traffic to and/or from one or more other satellites of the constellation.

Abstract: Time-synchronization of a space-system having a plurality of satellites. During a first period, a first satellite of the plurality of satellites is designated as a master satellite. A clock of the master satellite is configured to provide time and frequency to remaining satellites of the plurality of satellites and the remaining satellites are designated as slave satellites. During a second period, a second satellite of the slave satellites is designated as the master satellite based on a performance indicator and the first satellite is designated as a slave satellite. During the first period and the second period, clocks of the slave satellites are crosslinked with a clock of the master satellite using time transfer. At least one satellite during the first period and the second period, delivers time data having the time and the frequency generated by a clock of the at least one satellite.

Abstract: Techniques and mechanisms to transmit signals with an antenna array. In an embodiment, a first signal is received at a first input of the first antenna while a second signal is received at a second input of the second antenna. A difference in phase differentials—the phase differentials each between the first signal and the second signal—results from propagation of the first signal and the second signal in the antenna array and from a difference between respective configurations of the first antenna and the second antenna. Each of the first antenna and the second antenna has respective emitters distributed along the length thereof. In another embodiment, the first antenna and the second antenna have different respective dielectric structures or different respective distributions of emitters.

Abstract: Technology for a desktop signal booster is disclosed. The desktop signal booster can include one or more amplification and filtering signal paths configured to amplify and filter a cellular signal for a wireless device. The desktop signal booster can include wireless charging circuitry configured to wirelessly charge the wireless device when the wireless device is placed within a selected distance from the desktop signal booster.

Abstract: A system for providing mobile interactive satellite services includes a satellite operable to communicate with mobile units, a terrestrial base transceiver station operable to communicate with mobile units, and a ground station in communication with the satellite and the terrestrial base transceiver station to provide mobile interactive satellite services. The mobile interactive satellite services include a multicast component and an interactive component such that the ground station provides both the multicast component and the interactive component using the satellite, with the terrestrial base transceiver station used to provide an ancillary terrestrial component. A device for communicating with a mobile interactive satellite service system includes an antenna, a transceiver coupled to the antenna and operable to communicate with a mobile interactive satellite service system, a user input device, an output device, a processor unit, and a network interface.

Abstract: A non-geostationary satellite system and method for weather and climate monitoring, communications applications, scientific research, and similar tasks. The satellite system provides global coverage using a constellation of six satellites in two orthogonal, 24 sidereal hour orbits (geosynchronous) with inclinations of 70° to 90°, and eccentricities of 0.275-0.45. By placing three of the satellites in a first orbit with an apogee over the north pole, and three of the satellites in a second, orthogonal orbit with an apogee over the south pole, global coverage may be obtained. As well, the satellites in these orbits avoid most of the Van Allen Belts.

Abstract: Apparatuses, methods, and systems are described for a receiver of signals from one or more satellite navigational systems to detect and/or eliminate impaired satellites/signals and/or “false positives” from the set of satellites being estimated/acquired. One method includes acquiring coarse position, time, and frequency values for each of a plurality of satellites from one or more satellite navigational systems and then selecting a set of satellites based on whether one or more of their corresponding acquired coarse values are within a minimum range. An intersection point of the position domain correlograms generated from vectors of each satellite in the selected set is determined and, using that intersection point, satellites/signals are eliminated from the selected set of satellites.

Abstract: Example methods and systems of deploying a constellation of spacecraft are described. An example method includes releasing a cluster of spacecraft from a launch vehicle at a first orbit, separating spacecraft in the cluster of spacecraft from each other to minimize overlap of visibility periods from a ground station, and raising each of the spacecraft as separated simultaneously in a synchronized ascent to a respective final orbit. An example system includes a cluster of spacecraft in orbit at a first orbit, and a ground station in communication with spacecraft of the cluster of spacecraft when the spacecraft of the cluster are visible to the ground station. The ground station commands each spacecraft to separate from each other and to raise in altitude as separated simultaneously in a synchronized ascent to a respective final orbit.

Abstract: A system comprises a ground hub and a mobile airborne platform hovering over or close to a coverage area on or near the earth surface. A bistatic radar receiver on the airborne platform includes a first antenna system to capture reflected radiofrequency signals originated from a satellite via reflected paths from the coverage area; and a second antenna system to transmit the reflected radiofrequency signals to the ground hub via a feeder link. At the ground hub, a multibeam antenna system receives the reflected radiofrequency signals and captures radiation signals directly from the satellite via a direct path; and a remote beam forming network remotely forms receiving beams for the first antenna system. A remote radar processing center includes a cross-correlator to receive the reflected radiofrequency signals and the radiation signals as two input signal streams, perform cross-correlations between the two input signal streams, and output an output signal stream.

Abstract: A system includes a ground hub and a mobile airborne platform hovering over or close to a coverage area on or near the earth surface. The mobile airborne platform comprises a bistatic radar receiver including an antenna system to capture first radiofrequency signals originated from a first satellite and second radiofrequency signals originated from a second satellite, via direct paths and via reflected paths from the coverage area. The mobile airborne platform transmits the captured first and second radiofrequency signals to a ground hub via a feeder link. The ground hub includes a remote beam forming network to remotely form receiving beams for the antenna system of the bistatic radar receiver to capture the first and second radiofrequency signals, and a remote radar processing center to transform the captured first and second radiofrequency signals into a first and a second two-dimensional radiofrequency image, respectively.

Abstract: Techniques and mechanisms to transmit signals with an antenna array. In an embodiment, a first signal is received at a first input of the first antenna while a second signal is received at a second input of the second antenna. A difference in phase differentials—the phase differentials each between the first signal and the second signal—results from propagation of the first signal and the second signal in the antenna array and from a difference between respective configurations of the first antenna and the second antenna. Each of the first antenna and the second antenna has respective emitters distributed along the length thereof. In another embodiment, the first antenna and the second antenna have different respective dielectric structures or different respective distributions of emitters.

Abstract: A communication apparatus has a receiver that is capable of receiving an alternating phase signal and a tuned circuit whose input is adjusted to be capable of receiving the alternating phase signal. The communication apparatus can be used with both wireless and wired communication links and provide enable faster data rates, greater immunity to noise, increased bandwidth/spectrum efficiency and/or other benefits. Applications include but are not limited to: cell phones, smartphones (e.g., iPhone, BlackBerry, etc.), wireless Internet, local area networks (e.g., WiFi type applications), wide area networks (e.g., WiMAX type applications), personal digital assistants, computers, Internet service providers and communications satellites.

Abstract: A hub terminal and remote client communicate via a target satellite in an inclined geosynchronous orbit. As the target satellite ascends or descends away from the geostationary arc, the signal strength of the uplink channel is increased without increasing the level of interference with geostationary satellites. The increased angular separation from geostationary satellites also decreases downlink interference. The resulting increase in signal strength permits adjustment of the modulation and coding parameters to increase spectral efficiency. The antenna gain pattern is modeled based on antenna characteristics and the model may be supplemented with measurements of a signal relayed by other satellites. The method permits intermittent communication with an inclined satellite sharing a geostationary slot with a station-kept satellite, or from locations where the geostationary arc is blocked, or while using disadvantaged antennas that would be impractical for use with geostationary satellites.

Abstract: A method of movement mode determination comprising measurement of vehicle's position and orientation and calculation of movement parameters, a compass on the vehicle, is azimuthally oriented along the prevailing and is mostly used movement direction (“forward” direction), a movement vector measurement unit, is used for measuring the azimuth of movement vector. A calculation unit being used for measuring an angle between vehicle movement vector azimuth measured by the movement vector measurement unit and vehicle azimuth measured by the compass fixed on the vehicle; movement is regarded as “backward” if the calculated angle is greater than 90 degrees, and “forward” if the calculated angle is smaller than 90 degrees. Also, an apparatus for movement direction determination includes a compass and a computation unit and further comprises a movement vector measurement unit for determining vehicle movement azimuth and connected through a signal connection to the computation unit.

Abstract: Methods and apparatuses for a receiver of signals from one or more satellite navigational systems to detect and/or eliminate impaired satellites from the set of estimated/acquired satellites in view are described. One method includes acquiring coarse position, time, and frequency values for each of a plurality of satellites from one or more satellite navigational systems, the plurality of satellites being those currently estimated to be in view of the receiver; determining whether one or more of the acquired coarse values are within a minimum range; and if it is determined that the one or more acquired coarse values are within the minimum range: determining a pseudo-true peak of a position domain correlogram comprising Line of Sight (LOS) vectors of each of the plurality of satellites; and identifying any satellite whose cross-correlation peak is beyond a maximum distance from the pseudo-true peak as an impaired satellite.

Abstract: The invention relates to an online charging method for always on IP connectivity in a communication system, the method comprises a Diameter router receiving an online charging request from a Diameter client, wherein the online charging request includes subscriber information; the Diameter router finding a corresponding online charging system in a subscriber index database based on the subscriber information; sending a successful acknowledge to the Diameter client and generating a ticket file when the corresponding online charging system does not exist in the subscriber index database or the corresponding online charging system is not available, wherein the successful acknowledge includes a dummy quota specified by the Diameter router; and the ticket file processor reading the ticket file based on a scheduled timing and generating a first online charging event request and sending the first online charging event request to the Diameter router when the corresponding online charging system exists in the subscribe

Abstract: Various embodiments implement apparatuses and methods for conversion of radio frequency (RF) signals to intermediate frequency (IF) signals. More particularly, some embodiments are directed toward down conversion of RF signals to IF signals in a multi-band radio receiver, such as a satellite receiver, using a single oscillator for different frequency bands. For example, some of the apparatuses and methods presented are suitable for integration into monolithic RF integrated circuits in low-cost satellite receivers for home entertainment use.

Abstract: A method of movement mode determination comprising measurement of vehicle's position and orientation and calculation of movement parameters, a compass on the vehicle, is azimuthally oriented along the prevailing and is mostly used movement direction (“forward” direction), a movement vector measurement unit, is used for measuring the azimuth of movement vector. A calculation unit being used for measuring an angle between vehicle movement vector azimuth measured by the movement vector measurement unit and vehicle azimuth measured by the compass fixed on the vehicle; movement is regarded as ‘backward” if the calculated angle is greater than 90 degrees, and “forward” if the calculated angle is smaller than 90 degrees. Also, an apparatus for movement direction determination includes a compass and a computation unit and further comprises a movement vector measurement unit for determining vehicle movement azimuth and connected through a signal connection to the computation unit.

Abstract: Some demonstrative embodiments include devices, systems and/or methods of communicating during a Contention-Based-Access-Period (CBAP). For example, a device may include a wireless communication station to transmit a wireless communication transmission over a wireless communication medium upon determining that the wireless communication medium is idle for a predefined time period within a contention-based-access period (CBAP), if a scheduling element allocating the CBAP includes an indication of an identity of the wireless communication station in a predefined field.

Abstract: Spacecraft payload orientation steering is provided for an orbiting spacecraft in motion along an orbit track around a celestial body, the orbit track having a nominal inclination with respect to an equatorial orbit, a substantial eccentricity, and a drift angle with respect to the nominal inclination. Coordinates of an optimal payload target location as a function of a spacecraft position along the orbit track are determined, the target location being on the surface of the celestial body and having a substantial motion with respect to the surface and with respect to a spacecraft nadir. A payload of the spacecraft is substantially aligned with the determined coordinates by steering the satellite body to correct for at least one of the inclination drift angle, and the eccentricity, thereby adjusting the spacecraft orientation as a function of the spacecraft position along the orbit track.

Abstract: A conical region in space with a base at a geosynchronous distance from the earth and the apex of the cone at a point on the ground may be termed a space needle. A multiplicity of small satellites in elliptical orbits located within such a space needle may establish timing of their radio frequency (RF) transmissions forming what may be termed a needle beam downlink having an apparent origin that may be thousands of kilometers to the North or South of a Kepler geosynchronous satellite parking orbit. A noise-like RF signal may be transmitted synchronously from multiple transmitters in space forming a spatially distributed spread spectrum RF needle beam. Applying the method of space-based needle beams to a multiplicity of transmitters on the ground, a network of ground stations may form a ground-based needle beam uplink that may be pointed a given satellite at a given time.

Abstract: Disclosed herein is a tracking system configured to track a product and/or an activity. The tracking system comprises a tracing device and a verification server. The tracing device is coupled with the verification server by means of communication means configured to allow exchange of data between the tracing device and the verification server. The tracing device is coupled with a first satellite localization receiver which is configured to receive signals from a satellite localization system, process the received signals to obtain satellite localization observables, and compute locations based on the satellite localization observables. The tracing device is configured to acquire from the first satellite localization receiver positioning data. The tracing device is further configured to provide the verification server with the positioning data and the satellite localization observable acquired from the satellite localization receiver.

Abstract: An electronic device 1 receives ephemeris information from a GPS satellite at intermittent timings TE1, TE2, and TE3 and stores the received information in its memory. In addition, the electronic device 1 receives time information at intermittent timings TC1, TC2, TC3, and TC4, and corrects a clocked time based on the received time information. Then, at positioning timing T1, the electronic device 1 captures a transmission signal from the GPS satellite while synchronizing timing with the GPS satellite based on the clocked time, and performs positioning based on the captured transmission signal and the ephemeris information stored in the memory.

Abstract: A satellite communication system designed to communicate with wireless communication devices (WCDs) by use of a mosaic pattern of signal beams uses multiple beams to augment the communication with individual WCDs. In addition to communication with a WCD through a primary beam for that WCD, adjacent beams are used, but with signals utilizing circuit parameters assigned to the primary beam. The signals from a given WCD are relayed in a backhaul, either as an aggregate signal processed by the satellite, or as backhaul communication signals to be combined or separated on the ground.

Abstract: The present invention provides a method and apparatus for determining the transmit location of an emitter using a single geostationary satellite. In an embodiment, a signal is received at a ground station from the emitter and relayed by the geostationary satellite. The signal is received at the ground station at a plurality of time instances and has a plurality of observed frequencies, one for each time instance. A plurality of lines of position are determining based on the plurality of observed frequencies. The transmit location of the emitter is determined based on at least one intersection among the plurality of lines of position.

Abstract: Technology is generally described for computing paths between geographical localities. The technology can receive a request for a path between two or more geographical localities, and compute a path based at least on a popularity rating of intermediate geographical localities.

Abstract: A global communication satellite system includes at least three communication satellites. Each communication satellite is disposed in a geostationary orbit about the Earth. Each communication satellite also includes a feed horn array having at least 4,000 feed horns with each feed horn capable of transmitting at least one radio frequency (RF) signal. The feed horn array produces a plurality of spot beams with each spot beam corresponding to a spot beam area on the surface of the Earth. Each spot beam area has a generally circular shape with a diameter less than 150 miles. Furthermore, each spot beam area overlaps with a plurality of other spot beams areas such that plurality of spot beams provide saturation coverage of all populated land areas of the Earth.

Abstract: A system includes a central controller to transmit a plurality of synchronization codes through a transmission medium and a plurality of satellite controllers, each satellite controller configured to recognize one or more synchronization codes of the plurality of synchronization codes, each satellite controller comprising a synchronous clock signal generator to generate a synchronous clock signal each time the satellite controller recognizes the one or more synchronization codes of the plurality of synchronization codes.

Abstract: Embodiments related to cross-talk mitigation are described and depicted.

Abstract: Disclosed is a system for positioning a terrestrial user. The system includes navigation satellites placed in medium altitude orbits, management satellites placed in high orbits, able to manage the navigation satellites and communicate with the Earth. The management satellites can include a set of at least three management satellites each placed in a high orbit, having a plane that is inclined with respect to the plane of the terrestrial equator and cuts the equator along a diametral straight intersection line with respect to the Earth. Two external diametral straight intersection lines can form an angle of longitude of at least 90 degrees.

Abstract: A method and apparatus for providing a sequence of location data points to a mapping device. A cellular mobile station uses GPS satellite signals to compute its varying location over time and outputs the location as data points in a sequence to the mapping device. If the mobile station loses satellite communication, it transitions the output sequence to a static state in which the location data points are a substantial repetition of the last location that the mobile station determined from satellite signals. Further, when the mobile station detects that it has entered into a new cellular coverage area, it obtains satellite assistance data from its cellular carrier network and uses the data to renew satellite communication. The mobile station may then transition the sequence back to a dynamic state, with location data points determined over time based on received satellite signals.

Abstract: A global communication satellite system includes at least three communication satellites. Each communication satellite is disposed in a geostationary orbit about the Earth. Each communication satellite also includes a feed horn array having at least 4,000 feed horns with each feed horn capable of transmitting at least one radio frequency (RF) signal. The feed horn array produces a plurality of spot beams with each spot beam corresponding to a spot beam area on the surface of the Earth. Each spot beam area has a generally circular shape with a diameter less than 150 miles. Furthermore, each spot beam area overlaps with a plurality of other spot beams areas such that plurality of spot beams provide saturation coverage of all populated land areas of the Earth.

Abstract: Data from GPS satellites within the field of view of a ground station are retransmitted to LEO satellites, such as Iridium satellites, and cross-linked if necessary before being transmitted to a user. The user is then able to combine the fed-forward data with data received directly from GPS satellites in order to resolve errors due to interference or jamming. Iridium and data aiding thus provides a means for extending GPS performance under a variety of data-impaired conditions because it can provide certain aiding information over its data link in real time.

Abstract: According to the invention, navigation satellites (1) are at least partially managed by at least three management satellites (3.1 to 3.3) positioned on high orbits inclined in relation to the equator (E). Said high orbits intersect the equatorial plane along intersecting diametrical straight lines (5.1 to 5.3), such that the two outer intersecting diametrical lines (5.2, 5.3) form therebetween an angle of longitude (2?) that is at least equal to 90°.

Abstract: A method of using a bistatic passive radar system for tracking a plurality of targets utilizing transmitted radar signals from at least one satellite platform in a geosynchronous orbit with the earth, a radar receiver capturing signals from a reflection of the transmitted radar signals from each target, tracking a position of each target over time, and a processing method for computation of a fire control solution of each target.

Abstract: A system for receiving a satellite digital radio signal, the system comprising: a repeater having a unibody housing and an antenna disposed within the housing, the antenna being configured for receiving the satellite digital radio signal; a repeater circuit for receiving the satellite digital radio signal of the antenna, the repeater circuit being configured to condition and re-transmit the satellite digital radio signal as a first signal containing audio data capable of being transmitted through electrical wiring; a satellite digital radio signal receiver having a receiver circuit being configured to receive the first signal; and wherein the receiver circuit receives the first signal from a power cable of the satellite digital radio signal receiver.

Abstract: A satellite system for broadband communication with a plurality of remote locations in a geography is described. The satellite system utilizes a plurality of service spot beams distributed over the geography in a fixed pattern and a plurality of return spot beams distributed over the geography, wherein the service spot beams and the return spot beams use overlapping frequencies.

Abstract: A communication system for supporting communications with a target market area. The system includes one or more solar-powered aircraft maintained in, or successively passing through, flight stations or flight patterns around the market area. Each of the aircraft targets limited beamwidth communication antennas on a substantial portion of the target market area. The control system is configured to fly selective flight patterns depending on the aircraft characteristics and the flight conditions. The flight patterns may emphasize high-power-generation patterns such as flying away from the sun for aircraft with wing-mounted solar cells.

Abstract: A system includes a central controller to transmit a plurality of synchronization codes through a transmission medium and a plurality of satellite controllers, each satellite controller configured to recognize one or more synchronization codes of the plurality of synchronization codes, each satellite controller comprising a synchronous clock signal generator to generate a synchronous clock signal each time the satellite controller recognizes the one or more synchronization codes of the plurality of synchronization codes.

Abstract: A bistatic passive radar system for tracking at least one target utilizing means for transmitting radar signals from at least one satellite platform in a geosynchronous orbit with the earth, means for receiving radar signals from a reflection from each target, means for tracking a position of each target over time, and means for computation of a fire control solution of each target.

Abstract: A system and method for providing assistance to a position receiver in a location network consisting of a Global Navigation Satellite System (GNSS) and a synchronized network of positioning-unit devices is disclosed. A positioning-unit device observes the time and frequency of received Global Navigation Satellite System (GNSS) signals relative to the synchronized network of positioning-unit devices. These time and frequency observations are modulated, as assistance data, onto the positioning signals that are broadcast by the positioning-unit devices. A position receiver demodulates the assistance data and analyzes the positioning signals. The position receiver then searches for Global Navigation Satellite System (GNSS) signals in a range responsive to the assistance data and the analysis of the received positioning signals.

Abstract: According to one embodiment of the invention, a stationkeeping method for a geostationary satellite includes determining a gravitational force of the sun on the satellite at a beginning of a stationkeeping operation and a gravitational force of the moon on the satellite at the beginning of the stationkeeping operation. An initial inclination vector of the satellite is determined at the beginning of the stationkeeping operation that accounts for a first set of one or more perturbations affecting the orbit of the satellite. A maneuver strategy is determined to correct for a second set of one or more perturbations affecting the orbit of the satellite without accounting for the first set of one or more perturbations affecting the orbit of the satellite. Finally, a maneuver is performed on the satellite according to the maneuver strategy.