Abstract: GNSS receivers and systems within such receivers use improvements to reduce memory usage while providing sufficient processing resources to receive and acquire and track E5 band GNSS signals directly (without attempting in one embodiment to receive L1 GNSS signals). Other aspects are also described.

Abstract: The present invention provides an antenna array which includes a structure in the form of a hexagonal pyramid with a flat top surface/facet. According to preferred aspects, the pedestal support of the present invention preferably further includes six side facets which are preferably disposed 60 degrees from each other. Preferably, each side facet preferably supports a patch antenna and the top facet supports a top/zenith antenna. According to a preferred embodiment, the azimuth antennas may be offset from the ground plane by an angle between 20 and 60 degrees. The zenith antenna is preferably substantially parallel to the ground plane.

Abstract: A heat dissipation system for an antenna assembly for a vehicle is disclosed that provides enhanced heat removal attributes and that provides heat transfer from various components to a heat sink through different heat transfer flow paths to reduce the transfer of heat from high heat producing components to heat sensitive components. Improved heat insulation components can be added to maximize the thermal isolation between heat producing components and to prevent heat transferred from the vehicle into the antenna assembly.

Abstract: The present invention provides a data transmission method, apparatus and system. The method includes: in a detection period, receiving a first pilot signal sent by an unmanned aerial vehicle (UAV), the first pilot signal being a downlink signal obtained by modulating a useful signal at a preset candidate frequency, and the preset candidate frequency including a frequency in a same frequency band and/or different frequency bands; determining a downlink operating frequency from the preset candidate frequency according to the first pilot signal; sending a first feedback signal to the UAV, the first feedback signal including information about the downlink operating frequency; and receiving downlink data sent by the UAV and modulated at the downlink operating frequency.

Abstract: Certain aspects of the present disclosure generally relate to wireless communication. In some aspects, a base station may transmit beam information associated with a set of cells detected by the base station, wherein the beam information is transmitted to a target base station; and receive, based at least in part on transmitting the beam information to the target base station, one or more random access messages, wherein the one or more random access messages are transmitted by one or more other base stations, wherein the one or more other base stations are associated with one or more cells included in the set of cells detected by the base station. Numerous other aspects are provided.

Abstract: A device and method for registering devices on advanced networks as well as providing operative communications between a legacy device and a advanced network. The legacy device may contain data, such as sensor data, which is being collected on a network outside the communication range/abilities of the legacy device. An intermediary device may receive the data via a first communication scheme and send the device to a server collecting the data via a second communication scheme.

Abstract: A system and method of the disclosure relates to satellite tracking. The system may comprise a tracking receiver that includes a first analog-to-digital (A/D) converter coupled between a sum input and a digital signal processor (DSP), a second A/D converter coupled between a difference input and the DSP, and a calibration output coupled to the sum input and coupled to the difference input. The first A/D converter may convert an signal received at the sum input into a sum digital signal, and provide the sum digital signal to the DSP. The second A/D converter may convert an signal received at the difference input into a difference digital signal, and provide the difference digital signal to the DSP. The tracking receiver may generate an calibration signal and provide the calibration signal through the calibration output.

Abstract: A system and a method for transmitting information from a synthetic aperture radar satellite to a client receiver. In one aspect, the synthetic aperture radar satellite includes a processing unit configured to form information from a previously measured synthetic aperture radar raw data stored in a data storage; a modulator configured to modulate the information to a synthetic aperture radar transmission signal; a transmitter for transmitting the modulated synthetic aperture radar transmission signal. The processing unit is configured to demodulate a received echo signal of the modulated synthetic aperture radar transmission signal to form and store a synthetic aperture radar raw data in the data storage. The client receiver includes an antenna for receiving the transmitted modulated synthetic aperture radar transmission signal; and a demodulator configured to demodulate the received transmitted modulated synthetic aperture radar transmission signal to obtain the information.

Abstract: Effects of communications blockages can be mitigated. A wireless communication transmitter comprises a processor and a memory. The memory stores instructions executable by the processor to, upon receiving a current data packet in a sequence of data packets, wirelessly transmit a burst to a second computer. The burst includes the current data packet and a previous data packet in the sequence.

Abstract: The present invention relates to satellite systems and more particularly, to the provision of a satellite system and method for communications applications, with global coverage. An optimal method of providing global broadband connectivity has been discovered which uses two different LEO constellations with inter-satellite links among the satellites in each constellation, and inter-satellite links between the constellations. The first constellation is deployed in a polar LEO orbit with a preferred inclination of 99.5 degrees and a preferred altitude of 1000 km. The second constellation is deployed in an inclined LEO orbit with a preferred inclination of 37.4 degrees and a preferred altitude of 1250 km.

Abstract: The satellite system for navigation and/or geodesy according to the invention is provided with a plurality of MEO satellites, each comprising a dedicated clock, which are arranged in a distributed manner on orbital planes and orbit the Earth, wherein a plurality of MEO satellites, particularly eight, are located in each orbital plane. The satellite system according to the invention is further provided with a plurality of LEO satellites and/or a plurality of ground stations. Each MEO satellite comprises two optical terminals for bidirectional transmission of optical free-beam signals by use of lasers with the respectively first and/or second MEO satellite orbiting ahead in the same orbital plane and with the first and/or second MEO satellite orbiting behind. By use of the optical free-beam signals, the clocks of the MEO satellites are synchronized with each other for each orbital plane at an orbital plane time applicable to this orbital plane.

Abstract: The present invention relates to method for ultrasonic inspection of a test object, comprising the steps of defining a coordinate system of the test object; selecting, relative to the coordinate system of the test object, at least two positions of a test area; positioning a respective ultrasonic measuring device at the at least two positions within the test area; transmitting, an ultrasonic wave pattern into the test object; receiving an ultrasonic wave pattern signal; acquiring an ultrasonic reference wave pattern signal for a reference area of a reference object, and comparing the received ultrasonic wave pattern signal from the test object with the acquired ultrasonic reference wave pattern signal of the reference object for detecting a defect in the test object.

Abstract: Disclosed is a method of identifying location information of a signal source, the method including: identifying, at a first position, first position information and first posture information of an UAV equipped with a linear array antenna; identifying, after identifying a first measured azimuth between the signal source and the antenna at the first position, a first corrected azimuth; identifying, at at least one second position, at least one piece of second position information and at least one of second posture information of the UAV; identifying, after identifying at least one second measured azimuth between the signal source and the antenna at the at least one second position, at least one second corrected azimuth; and estimating the location information of the signal source by using the first position information, the first posture information, the first corrected azimuth, the second position information, the second posture information, and the second corrected azimuth.

Abstract: A wireless access point device includes a main frame, a transmission assembly, an antenna module and a fixing assembly. The main frame includes a casing and a first connection portion connected to the casing. The transmission assembly is disposed in an internal space of the casing and provided with a signal transceiving element. The antenna module includes a waveguide, a second connection portion and a positioning recess. The second connection portion is disposed on the waveguide and detachably connected to the first connection portion to be coupled to the signal transceiving element. The positioning recess is formed on the second connection portion. The fixing assembly is movably disposed on the first connection portion. The antenna module is thereby fixed on the casing, when the second connection portion and the first connection portion are fixed through the fixing assembly removably inserting into the positioning recess.

Abstract: A method and system for analysis of a facility may include providing an emulation host system, generating a pristine circuit model on the emulation host system, inserting a first hardware trojan model, emulating operation of the golden circuit model, and emulating operation of the first hardware trojan model, and determine a set of machine-learning models, detecting the presence of an unknown trojan as a function of the set of machine learning models and using the same to authenticate the integrity of a GPS signal.

Abstract: Various embodiments of the present technology generally relate to Global Navigation Satellite Systems (GNSS). More specifically, the embodiments of the present technology relate to a smart antenna module resistant to Radio Frequency Interference (RFI) saturation for dual-frequency GNSS receivers. In some embodiments, a dynamically configured antenna module architecture can be for a dual-band (or multi-frequency) GNSS receiver that can adapt to different RFI conditions by performing corresponding working modes. For example, some embodiments of the smart antenna can measure (e.g., using a power detector) the power of an incoming multi-frequency signal to determine when the multifrequency signal is saturated. Then, using control logic the smart antenna can determine which frequency in the multi-frequency signal is usable and isolate (e.g. using radio frequency components) a frequency that is not saturated. A position estimate can then be generated based on the isolated multi-frequency signal.

Abstract: A maintenance operation support device includes a procedure information outputter configured to output procedure information representing an operation procedure of maintenance operations for a facility, the procedure information being obtained by combining action definition information for defining actions of a setting tool that adjusts or sets the facility and operation definition information for defining operations to be instructed to a maintenance operator who performs the maintenance operations for the facility.

Abstract: Disclosed herein are system, method, and computer program product embodiments for detecting spoofing of a navigation device. A plurality of anti-spoofing techniques are provided. The plurality of anti-spoofing techniques detect interference with data provided by one or more navigation devices for a plurality of threat situations. Positioning, timing and frequency characteristics associated with the one or more navigation devices are analyzed in order to identify a threat situation among the plurality of threat situations. Based on the identified threat situation one or more of the anti-spoofing techniques are executed. The one or more anti-spoofing techniques can be executed in parallel in order to provide various anti-spoofing detection techniques at the same time.

Abstract: A system for managing a time reference includes a real-time clock, an interface, and a processor. The real-time clock store an RTC time. The interface is configured to receive a GPS time and a cellular time. The processor is configured to: indicate to start a time-speed adjustment loop; determine a true time based at least in part on the GPS time and the cellular time; determine an error between the true time and the RTC time; determine an RTC speed calibration adjustment based at least in part on the error; and adjust the real-time clock speed based at least in part on the RTC speed calibration adjustment.

Abstract: An apparatus includes a cross-link phased array and a communication-link phased array. The cross-link phased array and the communication-link phased array are integrated into a single array. The cross-link phased array and communication-link phased array comprise a multi-beam phased array. The cross-link phased array provides communication between multiple space vehicles and the communication-link phased array provides communication between the satellite and the ground GPS system.

Abstract: Examples disclosed herein relate to an antenna system. The antenna system has a transceiver unit adapted to receive a composite communication signal, wherein the composite communication signal is a mix of multiple individual communication signals transmitted at different frequencies, a radiating structure comprising multiple subarrays of radiating elements, each subarray responsive to a different frequency, and an antenna controller adapted to map each communication signal to a user equipment and adjust an electrical parameter of the radiating elements within each subarray so as to direct each individual communication signal in the composite communication signal to a corresponding user equipment.

Abstract: A system of architecture, apparatus and calibration method is invented for high-power flexible-polarization payload for satellite communications. The system comprises onboard phase-tracked apparatus, flexible polarization mechanism, and in-orbit calibration method. The power combining and polarization performance of the phase-tracked payload is monitored on ground by measuring the cross-polarization discrimination (XPD) and/or axial ratio (AR). The high performance over the life is achieved by optimization of the XPD or AR on ground and adjusting complex gain of the transponders. The high-power flexible-polarization in-orbit-calibration payload may be applied but not limited to UHF, L, S, C, X, Ku and Ka-band high power satellite systems.

Abstract: A system and method are described for distributed antenna wireless communications.

Abstract: Methods and systems for amplifying signals are provided. Embodiments include a three-to-one multiplexer, a multiband RF variable gain amplifier (VGA), a multiband power amplifier driver (PAD), and a one-to three multiplexer. The three-to-one multiplexer receives three input signals from an RF frequency source and outputs an output signal corresponding one input signal. The multiband RF VGA receives the output signal of the three-to-one multiplexer, provides a first level of amplification to the signal received from the three-to-one multiplexer, and outputs an amplified version of the signal. The multiband PAD receives the signal output by the multiband RF variable gain amplifier and provides a second level of amplification to the signal and outputs an amplified version of the signal. The one-to-three multiplexer receives a signal output by the multiband PAD produces three output signals that correspond to each of the three input signals.

Abstract: A heat dissipation system for an antenna assembly for a vehicle is disclosed that provides enhanced heat removal attributes and that provides heat transfer from various components to a heat sink through different heat transfer flow paths to reduce the transfer of heat from high heat producing components to heat sensitive components. Improved heat insulation components can be added to maximize the thermal isolation between heat producing components and to prevent heat transferred from the vehicle into the antenna assembly.

Abstract: An anti-collision radar device includes a radar mount for fixation to an outer peripheral side of a powerless trailer carriage, and a radar mounted in the radar mount for sensing vehicles coming from left and right sides. The radar mount defines a reference surface. The radar has a sensing surface. The extending direction of the sensing surface is intersected with the extending direction of the reference surface so that a predetermined angle of 30° to 50° is defined therebetween. Thus, the anti-collision radar device can expand the radar sensing range and reduce the visual field blind spot of the driver of the car, thereby ensuring the safety of the car when towing the powerless trailer carriage.

Abstract: Methods and systems are described for providing end-to-end beamforming. For example, end-to-end beamforming systems include end-to-end relays and ground networks to provide communications to user terminals located in user beam coverage areas. The ground segment can include geographically distributed access nodes and a central processing system. Return uplink signals, transmitted from the user terminals, have multipath induced by a plurality of receive/transmit signal paths in the end to end relay and are relayed to the ground network. The ground network, using beamformers, recovers user data streams transmitted by the user terminals from return downlink signals. The ground network, using beamformers generates forward uplink signals from appropriately weighted combinations of user data streams that, after relay by the end-end-end relay, produce forward downlink signals that combine to form user beams.

Abstract: Provided is a control device for controlling flight vehicles, including a replacement control unit for controlling replacement of a first flight vehicle covering a target area on the ground by a cell in a first frequency band with a second flight vehicle, in which the replacement control unit is for controlling the replacement such that, after the second flight vehicle moves to a location corresponding to a location of the first flight vehicle, the first flight vehicle continues using one part of a frequency band in the first frequency band and stops using a remaining part of the frequency band, and also the second flight vehicle forms a cell in a frequency band excluding the one part of the frequency band but including the remaining part of the frequency band, which overlaps with the cell formed by the first flight vehicle, and the first flight vehicle stops forming the cell.

Abstract: The subject method for delivering power to a moving target wirelessly via electromagnetic time reversal can find applications in wireless electrical transmission to portable devices, wireless heating of portable devices, novel wirelessly powered accelerometers, hyperthermic treatment of cancers, and many other applications. The subject non-linear time reversed electromagnetic waves based wireless power transmission (WPT) system targets either a single linear or non-linear object where a selective targeting between two diodes has been demonstrated simultaneously with different degrees of non-linearity in a three-dimensional ray-chaotic billiard model. A dual-purpose rectenna with harmonic generation for wireless power transfer by non-linear time-reversal has been designed for the subject system using the Schottky diode.

Abstract: A multiple wideband antenna or broadband antenna includes 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 improved communication transport of information from the base of the tower to the antenna minimizing the number of cables required to support the antenna. This antenna's also will integrate 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. This antenna will provide several methods of employment, including military operations, commercial cellular operations, unmanned systems communication requirements, the Internet of Things, and the future of autonomous vehicles or robotics.

Abstract: Empirically modulated antenna systems and related methods are disclosed herein. An empirically modulated antenna system includes an antenna and a controller programmed to control the antenna. The antenna includes a plurality of discrete scattering elements arranged in a one- or two-dimensional arrangement. A method includes modulating operational states of at least a portion of a plurality of discrete scattering elements of the antenna in a plurality of different modulation patterns. The plurality of different modulation patterns includes different permutations of the discrete scattering elements operating in different operational states. The method also includes evaluating a performance parameter of the antenna responsive to the plurality of different empirical one- or two-dimensional modulation patterns. The method further includes operating the antenna in one of the plurality of different one- or two-dimensional empirical modulation patterns selected based, at least in part, on the performance parameter.

Abstract: Several examples of a navigation disruption device and methods of using the same are described herein that use real-time, low-cost computation to generate conflicting/competing signals to actual Global Navigation Satellite System (GNSS) signals. For example, the novel, hand-held navigation disruption devices described herein (1) generate signals from a simulated satellite constellation, wherein the signals from the simulated satellite constellation conflict/compete with signals from one or more actual satellite constellations, and (2) transmit the signals from the simulated satellite constellation(s) towards an unmanned vehicle. The signals from the simulated satellite constellation(s) cause the unmanned vehicle to compute an incorrect position, which in turn disrupts its ability to navigate and operate effectively.

Abstract: Implementations are directed to remote data aggregation, data management, and data visualization of field data from remote field site locations. Actions can include generating, by one or more sensors, the field data, each sensor of the one or more sensors being responsive to field site activity, transmitting, through a regional network, the field data to a back-end system, processing, by the back-end system, the field data to provide visualization data, transmitting the visualization data to one or more mobile computing devices, and providing a computer-executable application for execution on a mobile computing device, the computer-executable application processing the visualization data to provide data visualizations.

Abstract: Approaches for efficient broadcast of satellite ephemeris information or data in NGSO satellite systems, based on Keplerian parametric models of the satellite orbits, are provided. Keplerian orbit parameters are utilized (e.g., parametric orbit models) for improved efficiency in broadcast of ephemeris data over use of point-wise vectors. The linear change and harmonic variations in Keplerian orbit parameters are accounted for, for example, based on the specification of the linear and harmonic terms, increasing accuracy and extending duration of validity of the orbit parameters. Data compression is employed by (i) differential encoding of orbital parameters, and (ii) exploiting the correlation between the harmonic (Fourier) coefficients model of the orbit parameters.

Abstract: Methods and systems are described for providing end-to-end beamforming. For example, end-to-end beamforming systems include end-to-end relays and ground networks to provide communications to user terminals located in user beam coverage areas. The ground segment can include geographically distributed access nodes and a central processing system. Return uplink signals, transmitted from the user terminals, have multipath induced by a plurality of receive/transmit signal paths in the end to end relay and are relayed to the ground network. The ground network, using beamformers, recovers user data streams transmitted by the user terminals from return downlink signals. The ground network, using beamformers generates forward uplink signals from appropriately weighted combinations of user data streams that, after relay by the end-end-end relay, produce forward downlink signals that combine to form user beams.

Abstract: Certain implementations of the disclosed technology may include systems and methods for reducing noise in dual-frequency GNSS signal observation. The method can include: receiving, at a GNSS receiver, a first signal and a second signal. At least the second signal includes noise. The first signal is characterized by a first carrier frequency, and the second signal is characterized by a second carrier frequency. The method includes: down converting, sampling, cross-correlating, accumulating, determining ambiguous instantaneous phases, determining non-ambiguous instantaneous phases, producing normalized non-ambiguous instantaneous first phase samples, constructing a normalized first counter rotation phasor, generating a counter-rotated second observable, applying a low pass filter to remove noise; and outputting the filtered second observable.

Abstract: This system and method provides for a plurality of satellite ground stations, distributed across some geographic region, and for these regions in turn to be scalable to cover large regions, including across the Earth or in orbit with planets or other celestial bodies using a combination of low-orbit satellites, terrestrial participant devices, and cloud-based communications. The invention in its simplest form is intended to solve the short temporal window problem inherent to the scenario where a single base or ground station is trying to track and communicate with a low-end OSAT or even a cube-satellite.

Abstract: Methods and systems are disclosed for user recognition and express for an automobile. For one example, a data processing system for an automobile includes a database, a user capture device, and a computer. The database stores at least an image of a user of the automobile. The user capture device captures at least an image of the user. The computer is coupled to the database and the user capture device. The computer allows the user access to the automobile if the user is authenticated as a valid user by determining if stored image of the user match the captured image of the user. The facial features can include two-dimensional (2D) or three-dimensional (3D) images including facial features. The computer allows the user access to the automobile and controls of the automobile if the user is authenticated as a valid user. The computer can also deny the user access to the automobile and controls of the automobile if the user is not authenticated as a valid user.

Abstract: A wireless communication system includes frequency reuse between terminals in common coverage regions using a multiple satellite architecture with spatial diversity. Different terminals may be associated with different ones of the satellites such that a common frequency can be reused by the different terminals. A gateway may communicate with a first satellite using a feeder beam having an overlapping geographic coverage region with a user beam used for communication between a set of user terminals and a second satellite. Spatial diversity is provided between the satellites, and the feeder beam and the user beam operate at common frequencies within the overlapping coverage region. In this manner, the bandwidth of both satellites at the common coverage region is used to increase the available capacity.

Abstract: A vehicle includes: an antenna; a polarization adjuster configured to change a first polarized wave emitted through the antenna; and a controller configured to receive a wireless signal from a portable user device through the antenna, to identify a second polarized wave emitted from the portable user device based on the wireless signal, and to control the polarization adjuster such that the first polarized wave matches the second polarized wave.

Abstract: Example communication stations and methods for transmitting on a random access channel (RACH) in wireless networks are disclosed herein. An example method for transmitting on an enhanced RACH by a device such that an initial access burst is received in a single time slot by a wireless network involves determining a timing advance, the timing advance being associated with a serving cell. The example method also involves transmitting, using the determined timing advance, the initial access burst, on the enhanced RACH, that includes at least one of an identifier or user data.

Abstract: 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.

Abstract: A device of piloting sensors for a rotary wing aircraft having at least two IMU inertial modules, at least two GNSS receivers having respective first fault detection and exclusion modules for detecting and excluding failures and covering distinct GNSS satellite navigation systems, at least two second FDE modules, at least two hybridizing platforms, and at least one third FDE module. The FDE modules enable signals that are of integrity and/or signals that are erroneous to be detected so as to exclude each GNSS system that is defective. In addition, each hybridizing platform makes it possible to determine a hybridized ground speed in order to delivering a ground speed for said aircraft that is accurate and of integrity.

Abstract: An antenna assembly comprising a base, a modem, a top lid and a housing is disclosed herein. The base is composed of an aluminum material. The modem is disposed on the base. The top lid is for the base, and the top lid comprises at least one antenna element disposed on an exterior surface. The housing covers the top lid and base. The top lid acts as an electro-magnetic barrier for the modem. A communication cable is connected to the modem at one end and extending to and connected to a vehicle internal router with a vehicle modem at the other end.

Abstract: Systems and methods for maintaining synchronization of repeater networks with Global Positioning System (GPS) signals using phase locked loops (PLLs) and based on generation of predicted control words for controlling local oscillator frequencies is described. The predicted control words can be generated based on performing a linear fit of control words generated over a predetermined duration of time. Phase locked loops with additional false GPS pulse identification and GPS signal loss compensation circuitry can enforce a false pulse count threshold and/or an error threshold. The additional circuitry and prediction of control words can overcome errors in GPS receiver outputs and maintain accuracy of signal timings across single frequency networks using inexpensive local oscillators.

Abstract: At a receiver in a short-range wireless system having a plurality of channels and a plurality of receiving antennas, an angle-of-arrival of a signal is determined by receiving, at at least two antennas, the signal on one of the channels, determining a phase difference between the signal as received at those antennas, removing a local oscillator phase from the phase difference to provide an adjusted phase difference, and determining, from the adjusted phase difference, the angle-of-arrival. Removing the local oscillator phase includes estimating a local oscillator phase for each channel to be used for all antennas, or determining an angle using multi-channel combining, and for each channel, using that angle to determine a channel local oscillator phase, or, for a given channel, identifying, as the local oscillator phase, a phase that minimizes the sum, over all antennas, of squares of phase differences between the given channel and a neighboring channel.

Abstract: An apparatus for matching probe measurements to a path in a geographic location includes a receiver, a window manager, a location generator, a path calculator, and an output. The receiver is configured to receive a stream of probe measurements. The window manager is configured to fill a window with the measurements, to select an additional measurement from the stream, and to select an oldest measurement in the window. The location generator is configured to generate candidate locations for the measurements in the window and the additional measurement. The path calculator is configured to match the oldest measurement to a candidate location. The output is configured to output a path-matched probe measurement based on the oldest measurement and the candidate location matched to the oldest measurement.

Abstract: Systems for communicating data through a satellite are disclosed. The systems generally include a terrestrial radio, such as a chirp spread spectrum modulator. The terrestrial radio is configured to uplink data to one or more satellites. The one or more satellites are configured to receive the data from the terrestrial radio. In addition, the systems include terrestrial receivers, such as one or more chirp spread spectrum receivers, positioned at ground level, which are configured to receive the data from the one or more satellites.

Abstract: Satellite navigation receivers are provided herein. In certain embodiments, a satellite navigation receiver correlates a received RF navigational signal from a satellite with a replica code generated by the receiver. Additionally, errors due to multipath are mitigated by identifying the location of the peak values of the correlation function obtained when the replica code is aligned with the received RF navigational signal. Thus, the peak correlation value is detected by sweeping the user replica code in delay in place of a closed loop early/late discriminator. Moreover, multiple copies of the receiver generated replica codes with different time offsets can be used to perform the acquisition in parallel. This advantageously reduces the amount of acquisition time to align the replica code and provides averaging to improve the accuracy in detecting the delay location of the peak correlation value.

Abstract: A system and method for HF positioning characterizes the undulations of the ionosphere in real-time to determine the refraction altitude of a specific HF frequency at a specific time of day at a specific position. The system accounts for the seasonal (summer, winter) and daily (daylight, night, grey-line transition) variations of the ionosphere determining a highly accurate timing error relative to a timing reference. The system employs a novel approach that is capable of passively and accurately determining a position anywhere in the world without use of a GNSS signal receiving known-time transmissions of narrow band HF timing signals refracted via ionospheric skywave.