Abstract: The present invention provides a receiver including an RF circuit, a correlator and a signal delay estimator. The RF circuit is configured to receive a first satellite signal and a second satellite signal to generate a first base-band signal and a second base-band signal, respectively. The correlator is configured to use a first local signal to integrate with the first base-band signal to generate a first correlation result, and to use a second local signal to integrate with the second base-band signal to generate a second correlation result. The signal delay estimator is coupled to the correlator, and is configured to use the second correlation result to compensate the first correlation result to generate a compensated first correlation result, and determine a signal delay of the first satellite signal according to the compensated first correlation result.

Abstract: A system for generating a 3D reflective surface map includes a positioning system, one or more antennas co-located with the positioning system, and a processing system. The positioning system calculates a position estimate. The one or more antennas co-located with the positioning system are configured to receive at least one reflected global navigation satellite system (GNSS) signal associated with a respective GNSS satellite and wherein a pseudo-range to the GNSS satellite is determined based on the reflected GNSS signal. The processing system is configured to receive the position estimate and the pseudo-ranges calculated with respect to each reflected GNSS signal, wherein the processing system maps a reflective surface based on the calculated pseudo-range provided by the reflected GNSS signals, the position estimate, angle-of-arrival of each reflected GNSS signal, and known satellite location of each respective GNSS satellite.

Abstract: A baggage keeping system includes a passenger tag, a first baggage tag, a second baggage tag, a reader and a management device. The three tags have RFID, which wirelessly transmits information about the passenger or baggage. The passenger tag is given to the passenger, the first baggage tag is stored in the baggage inaccessibly by a third party and the second baggage tag is attached to the outside of the baggage. The reader reads information about the passenger or baggage from three tags at boarding the departure-side airport and at arriving the arrival-side airport. The management device registers the information about the passenger and baggage, wirelessly received from the reader, compares the wirelessly received the information, determines whether the information about the passenger and baggage matches each other or not, and when they match, are the genuine baggage and the genuine owner.

Abstract: This problem has been addressed before, but the way of doing so is flawed and incomplete. Only larger objects can be tracked, neglecting items such as glasses, TV remotes, and headphones. Some also solely use Bluetooth tracking, which can be quick and precise, but is unreliable. Items lost far away from people with Bluetooth active their phone cannot be found using this method. This is not an option for most small, easily misplaced items. Various embodiments of the device (in one case using the name SeekR) allow for tracking of all these difficult-to-keep-track-of items. The device's small size allows it to attach to all of these items that existing solutions cannot, e.g., on the frame of glasses, e.g., the bridge, temple and/or temple tips.

Abstract: A GPS filter-setting method comprises collecting, by a GPS filter-setting server, terminal information of a user terminal and GPS signal receiving environment information, setting, by the GPS filter-setting server, a filtering parameter used to filter an invalid GPS signal in the user terminal based on the collected terminal information of the user terminal and the GPS signal receiving environment information and transmitting, by the GPS filter-setting server, the set filtering parameter to the user terminal.

Abstract: Methods and systems for tracking the location of an object. The method includes assigning a unique first device identifier, associating the first device with an object, and storing the unique identifier in a location server. The method also includes receiving, at the location server, data indicating a projected travel path for the object and data comprising spatial, temporal, and contextual data elements. The method also includes determining, based on two or more of the received spatial, temporal, and contextual data elements, the availability of second devices in the vicinity of the projected travel path for the object. The method also includes transmitting, as a function of the determined availability of the second devices in the vicinity of the projected travel path for the object, a command to modify a transmission property of the first device.

Abstract: A GNSS (Global Navigation Satellite System) receiver apparatus includes a bank of correlators configured to receive in-phase and quadrature versions of a received signal. A code numerical controlled oscillator is configured to determine a code frequency. A GNSS pseudo random noise sequence generator is configured to generate a pseudo random noise sequence at the code frequency set by the code numerical controlled oscillator. A GNSS pseudo random noise delayed sequence generator includes a first shift register and a second shift register. Taps of the shift registers are selectable as a punctual replica, an early replica and a delayed replica of the pseudo random noise sequence. An enable circuit is configured to generate an enable signal coupled to an enable input of the flip-flops, the enable signal operating at a selectable enable frequency.

Abstract: A system and method for determining a layout of a wireless communication network in a terrain. The wireless communication network includes multiple wireless communication devices each arranged to communicate wirelessly with one or more external communication devices. The method includes obtaining a modelled terrain of the terrain in which the wireless communication devices of the wireless communication network can be arranged. The modelled terrain includes a first type of area in which external communication devices can be located, and a second type of area representing obstacles arranged to affect communication between the wireless communication devices and the external communication device. The method also includes determining, based on a criteria, respective installation locations of the wireless communication devices in the modelled terrain so as to determine a layout of the wireless communication network in the terrain.

Abstract: A positioning device receives positioning signals from multiple positioning satellites respectively provided by multiple positioning systems, selects one or more use systems to be used in a positioning calculation processing among the multiple positioning systems based on a determination of whether a surrounding environment is an environment in which a multipath is likely to occur, and performs the positioning calculation processing by using the positioning signals from the positioning satellites provided by the positioning systems selected as the use systems.

Abstract: A positioning device receives multiple positioning signals respectively transmitted from multiple positioning satellites, changes a condition of the positioning satellites to be used in a positioning calculation processing based on a determination of whether a surrounding environment is an environment in which a multipath is likely to occur, and performs the positioning calculation processing by using the positioning signals from the positioning satellites that satisfy the condition.

Abstract: The present invention provides a method of performing a position measurement on the basis of a signal from a global navigation satellite system (GNSS). The method includes: receiving initial position information; estimating an initial value of a multipath error through a measurement of the GNSS signal on the basis of the received initial position information; estimating a multipath error from the initial value of the multipath error on the basis of a change in the measurement; removing the estimated multipath error from the measurement of the GNSS signal; and performing the position measurement on the basis of the GNSS measurement from which the multipath error is removed.

Abstract: Systems, methods and apparatuses for multipath mitigation in global navigation satellite system (GNSS) receivers are described. One method includes modifying the locally generated code in the GNSS receiver bit by bit in order to reduce offset peaks in the autocorrelation when receiving the satellite generated code signal. Such modified local codes may be pre-computed and stored or otherwise provided during reception. Moreover, the GNSS receiver may select whether or not to use the modified local code or the standard local code based on a selection criteria. Furthermore, multiple modified version of the same local code may be generated and/or stored in order to provide differing performance levels.

Abstract: A method and a receiving node for determining Time Of Arrival (TOA) for a radio signal received from a transmitting node in a wireless network. The receiving node detects the received radio signal by cross-correlating the received radio signal with a predefined reference signal transmitted by the transmitting node, to obtain a Cross-Correlated Function (CCF). The receiving node then estimates a set of candidate TOAs for respective signal components of the cross-correlated signal, and determines a final TOA for the received radio signal based on the set of candidate TOAs.

Abstract: A method for detecting a multipath effect in a GNSS receiver which is designed to receive different signals from a GNSS satellite and includes a parameter which is determined from directly received signals and has a substantially constant target value, including the steps receiving at least two mutually independent signals; determining a current parameter value from at least the first and the second signal; evaluating the parameter value in relation to the target value, and detecting a multipath effect when the parameter value has a deviation (?K) which deviates from the already known target value.

Abstract: A method includes: obtaining an azimuth and a signal parameter value of each preset satellite of M preset satellites when a mobile terminal is at a first location. The M preset satellites are sorted according to the values of their azimuths and N satellite combinations are obtained from those satellites that are consecutively arranged and have signal parameter values less than preset values. In response to determining that a ratio of the quantity of the preset satellites in the first satellite combination to M is less than a first threshold, the positioning mode of the mobile terminal is set to an outdoor positioning mode. In response to determining that a ratio of the quantity of the preset satellites in the first satellite combination to M is greater than a second threshold, the positioning mode is set to an indoor positioning mode.

Abstract: Techniques provided herein are directed toward using a camera, such as a forward-facing camera, to identify non-line-of-sight (NLoS) satellites in a satellite positioning system. In particular, successive images captured by the camera of the vehicle can be used to create a three-dimensional (3-D) skyline model of one or more objects that may be obstructing the view of a satellite (from the perspective of the vehicle). Accordingly, this allows for the determination of NLoS satellites and exclusion of data from the NLoS satellites in the determination of the location of the vehicle. Techniques may further include providing the determined location of the vehicle.

Abstract: A tracking system can provide intervention notifications to a user to notify the user that a tracking device is potentially lost or is in a predicted state. The tracking system may notify the user that a tracking device is potentially lost or in a predicted state based on a number of factors, including: a proximity of a tracking device to other tracking devices or a user's mobile device, a movement of a tracking device to more than a threshold distance away from a mobile device or other tracking devices, a location of a tracking device relative to a geographic location or to geographic boundaries, a usage or movement behavior of the tracking device, a usage or movement behavior of a user or owner of a tracking device, information received from an external source, or information received from sensors within the tracking device or a user's mobile.

Abstract: The present technology relates to a reception device that can realize low power consumption. The reception device comprises an RF unit, a demodulating unit, and a control unit. The RF unit includes a filtering unit, an amplifying unit, and an A/D converter. The filtering unit allows an IF signal to pass within a predetermined band. The IF signal is acquired by mixing a reception signal received from a positioning satellite with a local oscillation signal generated by a local oscillation unit to perform frequency conversion of the reception signal into an intermediate frequency. The amplifying unit amplifies the IF signal with a predetermined amplification factor. The A/D converter converts the IF signal from an analog signal into a digital signal. The demodulating unit demodulates the digital signal. Based on the demodulation, the control unit controls an operation of the RF unit. The present technology is applicable to a GNSS receiver.

Abstract: GNSS receivers and methods of determining a current receiver state of a GNSS receiver are provided. The method includes receiving positioning signals from a plurality of satellites; generating a plurality of correlation grids from the received positioning signals, where each correlation grid is associated with a respective one of the plurality of satellites; estimating a probability distribution of the current receiver state from the plurality of correlation grids; and determining a maximum likelihood estimate of the current receiver state from the estimated probability distribution.

Abstract: Apparatuses, systems, and methods for mitigating the effects of null zones on the measurements of Global Navigation Satellite System (GNSS) receivers are described. In one aspect, a GNSS receiver calculates both a filtered value of an integrated and summed value for a punctual correlator of a satellite signal (“the calculated filtered punctual correlator value”) and an average of integrated and summed correlator values for a plurality of noise/offset correlators of the satellite signal (“the calculated average noise/offset correlator value”). The GNSS receiver then calculates a signal energy loss parameter ESL of the satellite signal using the calculated filtered punctual correlator value and the calculated average noise/offset correlator value and processes the satellite signal measurement based at least on the signal energy loss parameter ESL and a predetermined threshold ThSL presently corresponding to the punctual and noise/offset correlators of the satellite signal.

Abstract: One embodiment of the invention provides a receiver for use in a navigation system comprising multiple transmitters. Each transmitter transmits a positioning signal comprising a pseudo-random noise (PRN) sequence corresponding to the respective transmitter. The receiver comprises a code module for supplying multiple PRN sequences corresponding to the respective multiple transmitters; and a correlator for correlating the PRN sequences supplied by the code module with an incoming signal. The multiple PRN sequences are based on a single Sidelnikov/Lempel/Cohn/Eastman (SLCE) generative sequence uSLCE, and each of said multiple PRN sequences, denoted ui satisfies the equation: ui=uSLCE?TiuSLCE, where ? indicates element by element binary XOR addition, and Ti indicates a cyclic shift of i chips.

Abstract: Disclosed are a multipath selection method and device, and a storage medium. The method includes that: a correlation sequence between a received signal and a local reference signal is acquired by means of a correlation calculation method; a power spectrum of the correlation sequence and an average noise power of the received signal are acquired; according to the average noise power of the received signal, the power spectrum of the correlation sequence is divided into at least one first multipath component area and a second multipath component area according to a pre-set dividing rule; the at least one first multipath component area is searched according to a pre-set first noise threshold, so as to acquire a valid multipath component signal in the at least one first multipath component area; and the second multipath component area is searched according to a pre-set second noise threshold, so as to acquire a valid multipath component signal in the second multipath component area.

Abstract: Described is a technology by which GPS-capable devices work with a cloud service to receive satellite visibility-related data. The satellite visibility-related data may be used to determine a location, and/or to abort a search for satellites. The cloud service may use crowd data from other GPS-capable devices. In one aspect, line-of-sight satellites are differentiated from other satellites, and used to determine which satellite signals are more trustworthy. Reflected signals also may be determined.

Abstract: A test installation for simulating multiple reflections of GNSS signals, the installation including a top screen that is semitransparent in a radio frequency portion of the electromagnetic spectrum, wherein the top screen is substantially dome-shaped; a bottom screen that is reflective in the radio frequency portion of the electromagnetic spectrum; the top semitransparent screen over the bottom reflecting screen; and a GNSS antenna connected to a receiver and located between the top screen and the bottom screen.

Abstract: A mobile device adjusts the extents to which it depends on various satellites to estimate its global position based on the predicted probability for each such satellite that a ray extending from that satellite to the mobile device is obstructed by a building. The mobile device can predict the probabilities of building obstructions based on a digital model of the environment in which the mobile device is estimated to be. The mobile device weights the extent of uncertainty for each satellite's global positioning data based on the predicted probability of obstruction for that satellite. Using these weighted uncertainties, the mobile device selects the extents to which it relies on each satellite's global positioning data when estimating the mobile device's current global position.

Abstract: A navigation receiver operably coupled to an antenna can determine location by receiving and processing radiofrequency navigation signals from global navigation satellites. The navigation receiver includes a quartz crystal oscillator that serves as a reference frequency source for a local oscillator signal that is mixed with the radiofrequency navigation signals to generate intermediate signals at intermediate frequencies lower than the radiofrequencies. In particular applications, the quartz crystal oscillator and the antenna are subjected to vibration and shock. A shift in the frequency or phase of the intermediate signals can result, and performance of phase-lock loops can degrade. Performance is improved with a phase-lock loop that processes a combination of individual channel control signals and common control signals.

Abstract: An attenuated satellite positioning system (SPS) signal is acquired using long integration over multiple navigation data bits. To produce a stable internal clock signal to perform the long integration, an external clock signal is received from a highly stable source, such as a wireless communication base station or a nearby femtocell. An internal oscillator is driven at a desired frequency that is aligned with the scaled frequency of the external clock signal to produce the stable internal clock signal. The SPS signal is received and integrated for an extended period using the internal clock signal. Predicted SPS data may be received from an external source and used to perform coherent integration. Alternatively, non-coherent integration may be performed. Additionally, a motion sensor may be used to determine if there is motion relative to the external clock source or to compensate for Doppler errors in the external clock signal due to motion.

Abstract: Various embodiments are disclosed for providing timing tracking loops in a communication system. A communication system includes a delay locked loop (DLL) comprising a maximum region detector configured to identify a target channel profile comprising at least a portion of the multipath signals based on the timing information, the maximum region detector further configured to apply a weight vector to each channel tap in the target channel profile and determine a tap with a maximum power level relative to remaining channel taps in the channel profile. The system further comprises a window timing loop (WTL) adjuster configured to track a position of a channel estimation window (CEW) within an observation window corresponding to the maximum channel energy level, where the maximum channel energy level corresponds to the sum of the energy of all the taps for a given window.

Abstract: A mobile device adjusts the extents to which it depends on various satellites to estimate its global position based on the predicted probability for each such satellite that a ray extending from that satellite to the mobile device is obstructed by a building. The mobile device can predict the probabilities of building obstructions based on a digital model of the environment in which the mobile device is estimated to be. The mobile device weights the extent of uncertainty for each satellite's global positioning data based on the predicted probability of obstruction for that satellite. Using these weighted uncertainties, the mobile device selects the extents to which it relies on each satellite's global positioning data when estimating the mobile device's current global position.

Abstract: A method and a receiver for receiving positioning signals are disclosed. The positioning signals are received from a plurality of first sources in a first frequency range and from a plurality of second sources in a second frequency range different from the first frequency range. The receiver is switched between the first and second frequency ranges to receive the positioning signals, and the receiver obtains time offset information about a time taken to switch the receiver between the first and second frequency ranges, by obtaining a solution to a set of simultaneous equations based on combined navigation data for the first and second sources.

Abstract: An object of the present invention is to provide a positioning device which can more reliably and frequently correct a own vehicle position earlier, reliably detect an error matching state or a straying state earlier and correct the position to a correct position. The positioning device according to the present invention includes a GPS receiver, a GPS position calculating unit which calculates pseudo distances to the GPS satellites based on the transmission signals, and calculates a re-calculated GPS position which is the own vehicle position based on the pseudo distances, and a multipath influence evaluating unit which evaluates a multipath influence on the GPS position based on a difference between the GPS position calculated by the GPS receiver and the re-calculated GPS position calculated by the GPS position calculating unit.

Abstract: An object is to provide in a positioning device of a moving body such as a vehicle, a technique which can modify a built-in clock error of a moving body to increase accuracy of a velocity. The positioning device includes a built-in clock error estimating unit which estimates a built-in clock error of the vehicle as a built-in clock error based on a difference between a delta range and a calculated range rate, and a range rate estimating unit which estimates a vehicle stop range rate based on position and velocity of GPS satellite based on transmission signal and a vehicle position, and modifies a calculated range rate, based on the built-in clock error. Further, the positioning device includes an own vehicle velocity calculating unit which calculates own vehicle velocities in three axial directions which form an orthogonal coordinate system, based on a navigation matrix, the vehicle stop range rate and the modified calculated range rate.

Abstract: Systems, methods and devices for improving the accuracy of GNSS data are provided. Specifically, embodiments of the invention can advantageously use sensor input to improve the accuracy of position fixes. The use of physical 5 sensors in navigation systems is deemed particularly advantageous, especially where altitude data derived from the pressure sensor is calibrated with and/or blended with GNSS altitude data.

Abstract: A method and apparatus for estimating and compensating for a broad class of non-Gaussian sensor and process noise. In one example, a coded filter combines a dynamic state estimator (for example, a Kalman filter) and a non-linear estimator to provide approximations of the non-Gaussian process and sensor noise associated with a dynamic system. These approximations are used by the dynamic state estimator to correct sensor measurements or to alter the dynamic model governing evolution of the system state. Examples of coded filters leverage compressive sensing techniques in combination with error models based on concepts of compressibility and the application of efficient convex optimization processes.

Abstract: The invention, in some embodiments, relates to the field of global navigation satellite systems, and more particularly to the field of methods and devices for identifying whether a satellite in a global navigation satellite system has a line of sight to a specific global navigation satellite system receiver (LOS satellite) or does not have a line of sight to the global navigation satellite system receiver (NLOS satellite).

Abstract: A method comprises generating a respective code-carrier difference for each of a plurality of satellite vehicle and signal frequency combinations, wherein the code-carrier difference is based on a code range and a carrier range. The method also comprises filtering the respective code-carrier difference for an unknown bias and random noise; determining whether multipath is present for each of the plurality of satellite vehicle and signal frequency combinations based on the respective filtered code-carrier difference; and computing a position solution based on trust placed in respective measurements from each of the plurality of satellite vehicle and signal frequency combinations, the trust based on whether multipath is present for the respective satellite vehicle and signal frequency combination.

Abstract: A method for calibrating spatial errors induced by phase biases having a detrimental effect on the measurements of phase differences of radio signals received by three unaligned receiving antennas of a vehicle. An inter-satellite angular deviation of a pair of satellites is estimated in two different ways: on the basis of the respective positions of the vehicle and of the satellites to obtain a theoretical inter-satellite angular deviation; and on the basis of the respective directions of incidence of the satellites relative to the vehicle, which are determined from phase measurements, to obtain an estimated inter-satellite angular deviation. The space errors are estimated on the basis of said theoretical and estimated inter-satellite angular deviations. Also, a method and system for estimating the attitude of a vehicle, in particular a spacecraft.

Abstract: A positioning system operates by first determining that a user is pedestrian, and then estimating a speed of the user. Having tracked a first signal from one radio transmitter whose position is known, the system attempts to detect additional signals from the one transmitter, in a search space such that the first signal and the or each additional signal are consistent with the estimated speed of the user and with one or more of the signals having been reflected off a reflector in the vicinity of the user. One or more detected additional signals from the one transmitter are then tracked, and candidate measurements, derived from the first signal and the one or more detected additional signals, are provided for use when estimating the position and/or velocity of the user.

Abstract: The invention, in some embodiments, relates to the field of global navigation satellite systems, and more particularly to the field of methods and devices for identifying whether a satellite in a global navigation satellite system has a line of sight to a specific global navigation satellite system receiver (LOS satellite) or does not have a line of sight to the global navigation satellite system receiver (NLOS satellite).

Abstract: A method, system, and apparatus are disclosed for multipath isolation through the combined use of antenna diversity and frequency diversity. In particular, the present disclosure utilizes antenna diversity and frequency diversity to combat the deleterious effects of reflected signals on the positioning accuracy of satellite navigation systems. In at least one embodiment, the present disclosure uses two antennas and two frequencies for operation with a satellite navigation system. The present disclosure segregates the antennas and frequencies into two classes: references and monitors. The reference measurements are used for estimating the state of the vehicle, and the monitor measurements are used to detect faults that might degrade the reference estimation. Thus, the present disclosure enables an improvement in the positioning error experienced by roving users in downtown and indoor environments.

Abstract: A navigation receiver mounted on a moving vehicle receives navigation signals transmitted from global navigation satellites. The navigation signals are separated into direct navigation signals, navigation signals reflected from an object, and navigation signals reflected from an environmental surface. The signal separation is based on algorithms including various combinations of signal strength, change in signal strength, delay time, spectral width, change in spectral width, and user-defined thresholds. The navigation signals reflected from an environmental surface are eliminated from further processing. The position of the navigation receiver is calculated based on the direct navigation signals. The object is detected, and the position of the object is calculated, based on the navigation signals reflected from the object. If the object is determined to lie in the path of the moving vehicle, a command can be generated to avoid collision between the moving vehicle and the object.

Abstract: 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 Cholesky 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.

Abstract: A method includes estimating a position of a receiver, aboard a moving object, on the basis of the navigation signals emitted by satellites received by an antenna in an antenna array placed on the moving object, and using a three-dimensional geographical map to deduce, geometrically, on the basis of the position of the receiver and of a ray casting starting from the receiver, the number of paths reflected on walls of buildings present in a scene corresponding to an environment surrounding the receiver. The determined number of reflected paths is used to initialize an algorithm for estimating angles of arrival of multi-paths to deduce therefrom angles of arrival of the paths reflected on the walls before reaching the receiver. Optionally, the method can comprise making it possible to bound the distance information error due to a multi-path to render the estimation of direction of arrival of the signals more efficacious.

Abstract: A method for mitigating the effects of multipath errors in GNSS devices is provided. Signals from GNSS satellites are received. Image data from an image sensor is received. Orientation data from an orientation sensor is received. The orientation data describes the orientation of the image sensor. Obstruction data is determined based on the image data. The obstruction data includes an obstruction region that indicates the sky in that region is obstructed by a structure. Based on the orientation data, obstruction data, and GNSS satellite location data, the position of GNSS satellites with respect to the obstruction region is determined. The location of the GNSS device is determined based on signals from some of the GNSS satellites and the position of GNSS satellites with respect to the obstruction region.

Abstract: Embodiments of the invention involve providing assistance data to a global position and navigation receiver, for example topographical data, such that the receiver can decide on a specific action depending on that data. The topographical data may include one or both of geographical data and architectural data. Geographical data may include information about natural formations, such as hills, valleys, forests, etc. Architectural data may include manmade formations, such as streets, buildings, bridges, etc. The receiver may then interpret and decide on a course of action for controlling the receiver base on the assistance data.

Abstract: A method for reducing multipath when determining a location of a stationary or near stationary position, includes receiving a signal from an antenna moving continuously with respect to the stationary or near stationary position, the signal including a multipath component, processing the received signal including the multipath component, wherein multipath error in the received signal is reduced during the processing and determining a location of the stationary or near stationary position based on the processed received signal with the multipath error reduced.

Abstract: A method for reducing multipath when determining a location of a stationary or near stationary position, includes receiving a signal from an antenna moving continuously with respect to the stationary or near stationary position, the signal including a multipath component, processing the received signal including the multipath component, wherein multipath error in the received signal is reduced during the processing and determining a location of the stationary or near stationary position based on the processed received signal with the multipath error reduced.

Abstract: A GPS receiver for tracking a GPS signal. The receiver generates a mixed GPS signal by mixing the GPS signal with an oscillator signal, generates a first correlation signal by correlating the mixed GPS signal with a reference signal, and generates a filtered GPS signal from the GPS signal. The receiver also generates a filtered reference signal from the reference signal, generates a second correlation signal by correlating the filtered GPS signal with the filtered reference signal, and a generates a combined correlation signal by combining the first correlation signal with the second correlation signal. The receiver tracks the GPS signal by adjusting the phase of the oscillator signal based on the combined correlation signal.

Abstract: A method, system, and apparatus are disclosed for multipath isolation through the combined use of antenna diversity and frequency diversity. In particular, the present disclosure utilizes antenna diversity and frequency diversity to combat the deleterious effects of reflected signals on the positioning accuracy of satellite navigation systems. In at least one embodiment, the present disclosure uses two antennas and two frequencies for operation with a satellite navigation system. The present disclosure segregates the antennas and frequencies into two classes: references and monitors. The reference measurements are used for estimating the state of the vehicle, and the monitor measurements are used to detect faults that might degrade the reference estimation. Thus, the present disclosure enables an improvement in the positioning error experienced by roving users in downtown and indoor environments.

Abstract: A system implements a location based service, and comprises a satellite navigation receiver implementing a position tracking function for providing the location of a user of the service. An analogue RF receiver receives satellite signals and performs at least a frequency downconversion. Correlation and decoding functions are applied to the downconverted signals for deriving location information from detected specific satellite signals. The system further comprises a server for receiving samples of the downconverted signals, and for verifying the samples are consistent with the expected satellite signals at that time and location. The invention provides a counter measure for detecting the counterfeiting of, or tampering with, the satellite signals at the receiver. A check can be made that the received satellite signals correspond to those which are expected at that location and time.