Abstract: A GNSS receiver includes an antenna receiving GNSS signals from a plurality of GNSS satellites; a plurality of channels, each channel processing a single GNSS signal from a single GNSS satellite, and outputting a pseudo-phase of a signal carrier frequency of the single GNSS signal; a block for solving the navigation task based on the pseudo-phases of multiple GNSS signals; each channel including a detector of shadowing of the corresponding GNSS signal; each channel including a weight calculator specifying a relative weight of the single GNSS signal in solving of the navigation task; and each channel including a circuit for recovering a tracking of the shadowed GNSS signal once the shadowing ends. The recovering includes generating guiding indications that enable reducing a time to re-acquire the shadowed GNSS signal.

Abstract: A GNSS receiver includes an antenna receiving GNSS signals from a plurality of GNSS satellites; a plurality of channels, each channel processing a single GNSS signal from a single GNSS satellite, and outputting a pseudo-phase of a signal carrier frequency of the single GNSS signal; a block for solving the navigation task based on the pseudo-phases of multiple GNSS signals; each channel including a detector of shadowing of the corresponding GNSS signal; each channel including a weight calculator specifying a relative weight of the single GNSS signal in solving of the navigation task; and each channel including a circuit for recovering a tracking of the shadowed GNSS signal once the shadowing ends. The recovering includes generating guiding indications that enable reducing a time to re-acquire the shadowed GNSS signal.

Abstract: The effects of shock and vibration on a navigation receiver processing satellite signals received from global navigation satellites are reduced by controlling the frequency and the phase of the individual numerically controlled oscillator in each individual satellite channel. The frequency is controlled by an individual frequency control signal based on individual correlation signals generated in an individual satellite channel. The phase is controlled by a common phase control signal or a combination of a common phase control signal and an individual phase control signal. The common phase control signal is based on all the correlation signals generated in all the satellite channels processed by a separate common broadband quartz loop (SCBQL). An individual phase control signal is based on the individual correlation signals generated in an individual satellite channel.

Abstract: A navigation receiver processes signals transmitted by global navigation satellites and received by a set of antenna units. Each antenna unit is connected to a separate input port of an antenna multiplexer switch. Satellite signals received from each antenna unit are consecutively switched to the input of a common radiofrequency processing module. A common signal correlator generates a common in-phase correlation signal from the satellite signals received from all the antenna units. The common in-phase correlation signal is processed by a data processing module to demodulate information symbols from the received satellite signals. The common in-phase correlation signal is also processed by phase-lock loops and delay-lock loops to generate carrier phases and code delays from the received satellite signals. Embodiments are described in which, along with the common in-phase correlation signal, common functional blocks or hardware are used to process the satellite signals received from all the antenna units.

Abstract: Base data received at a rover receiver is extrapolated to a rover measurement time referenced to a clock in the rover receiver. The base data comprises a plurality of base parameters, such as pseudo-ranges and full phases, calculated at base epochs from data received from navigation satellites. Base data is decomposed into a computed component, a common component, and an information component. Only the information component is extrapolated, thereby increasing the extrapolation time interval (during which base data are missing) over which an acceptable accuracy in determination of rover coordinates may be provided. The extrapolated base data is calculated by adding the computed component updated to the rover measurement time, the information component extrapolated to the rover measurement time, and the common component. A second-order recursive digital filter is used to generate the extrapolation function.

Abstract: The effects of shock and vibration on a navigation receiver processing satellite signals received from global navigation satellites are reduced by controlling the frequency and the phase of the individual numerically controlled oscillator in each individual satellite channel. The frequency is controlled by an individual frequency control signal based on individual correlation signals generated in an individual satellite channel. The phase is controlled by a common phase control signal or a combination of a common phase control signal and an individual phase control signal. The common phase control signal is based on all the correlation signals generated in all the satellite channels processed by a separate common broadband quartz loop (SCBQL). An individual phase control signal is based on the individual correlation signals generated in an individual satellite channel.

Abstract: A navigation receiver processes signals transmitted by global navigation satellites and received by a set of antenna units. Each antenna unit is connected to a separate input port of an antenna multiplexer switch. Satellite signals received from each antenna unit are consecutively switched to the input of a common radiofrequency processing module. A common signal correlator generates a common in-phase correlation signal from the satellite signals received from all the antenna units. The common in-phase correlation signal is processed by a data processing module to demodulate information symbols from the received satellite signals. The common in-phase correlation signal is also processed by phase-lock loops and delay-lock loops to generate carrier phases and code delays from the received satellite signals. Embodiments are described in which, along with the common in-phase correlation signal, common functional blocks or hardware are used to process the satellite signals received from all the antenna units.

Abstract: Disclosed is a system and method for processing signals received from different global navigation satellite systems. The receiver includes a number of universal digital channels. The universal digital channel can be used to receive and process different code signals of each of the three navigation satellite systems GPS, GLONASS, and GALILEO. The universal digital channels have the same structure. Each of them can be tuned to receive different signals. The core of the universal digital channel is a code generator and a universal strobe generator.

Abstract: Disclosed is a method for determining coordinates of a mobile rover. The method includes determining a vector of one-shot code coordinates of the mobile rover. The method also includes determining a vector of phase increments by determining full phase differences for each navigation satellite in a plurality of navigation satellites in view at a discrete time interval (called a time epoch) and at a previous time epoch in a plurality of time epochs. A vector of radial range increments is determined from the full phase differences. A vector of rover phase coordinate increments is also determined using the vector of radial range increments. The vector of one-shot code coordinates and the vector of rover phase coordinate increments are then filtered to determine, at each time epoch, smoothed code coordinates of the mobile rover. Measured phase increments are cleared up from abnormal measurements.

Abstract: Base data received at a rover receiver is extrapolated to a rover measurement time referenced to a clock in the rover receiver. The base data comprises a plurality of base parameters, such as pseudo-ranges and full phases, calculated at base epochs from data received from navigation satellites. Base data is decomposed into a computed component, a common component, and an information component. Only the information component is extrapolated, thereby increasing the extrapolation time interval (during which base data are missing) over which an acceptable accuracy in determination of rover coordinates may be provided. The extrapolated base data is calculated by adding the computed component updated to the rover measurement time, the information component extrapolated to the rover measurement time, and the common component. A second-order recursive digital filter is used to generate the extrapolation function.

Abstract: Disclosed is a method and apparatus for determining the relative position of a mobile unit that moves from an initial location to a plurality of successive positions. The mobile unit receives signals from a plurality of navigation satellites and tracks the carrier phases of the signals during movement. For each of the received signals, carrier phase increments are calculated over a plurality of epochs. Anomalous carrier phase increments are determined and eliminated from further calculations. The non-eliminated carrier phase increments are then used to calculate coordinate increments for each of the time epochs. If, after elimination, the remaining number of carrier-phase increments is less than a threshold for a particular epoch, then coordinate increments for the particular epoch may be extrapolated using data from prior epochs. In various embodiments, least squares method and Kalman filtering may be used to calculate the coordinate increments.

Abstract: Disclosed is an adaptive receiver configured to receive signals from satellite navigation systems to determine receiver coordinates and configured to use a co-op tracking system to evaluate full phases of carrier phases for N navigation satellites in view. The adaptive receiver includes channels with autonomous wideband phase lock loops (PLLs) in a guiding status. The wideband PLLs are configured to track phases of carrier signals from satellites having high SNR and configured to produce control codes for target designations of varying carrier frequency. The adaptive receiver also includes channels with narrow-band PLLs in a guided status. The narrow-band PLLs can track phases of carrier signals of satellites with low SNR and are configured to use target designations from the wideband PLLs in guiding status and a prediction of frequency change caused by satellite movement. The adaptive receiver also includes channels with open PLLs in a standby mode.

Abstract: Disclosed is a method for determining coordinates of a mobile rover. The method includes determining a vector of one-shot code coordinates of the mobile rover. The method also includes determining a vector of phase increments by determining full phase differences for each navigation satellite in a plurality of navigation satellites in view at a discrete time interval (called a time epoch) and at a previous time epoch in a plurality of time epochs. A vector of radial range increments is determined from the full phase differences. A vector of rover phase coordinate increments is also determined using the vector of radial range increments. The vector of one-shot code coordinates and the vector of rover phase coordinate increments are then filtered to determine, at each time epoch, smoothed code coordinates of the mobile rover. Measured phase increments are cleared up from abnormal measurements.

Abstract: A method and apparatus for estimating the changing frequency of a signal received by a satellite receiver from, illustratively, positioning system satellites is disclosed that enables a more accurate measurement of the change in frequency of that signal due to movement of the satellite receiver relative to those satellites. The system includes a PLL having a numerically controlled oscillator (NCO) and a filter of frequency estimates (FFE). In operation, an analog signal is received at the satellite receiver and the PLL tracks the changing signal frequency and outputs non-smoothed frequency estimates into the FFE. The FFE then smoothes noise in the signal to produce a more accurate smoothed frequency estimate of the input signal. Comparing multiple estimates over time allows Doppler shift of the signal frequency received by the satellite receiver to be calculated more precisely, thus resulting in more accurate satellite receiver velocity vector determinations and, hence, position measurements.

Abstract: Disclosed is a method and apparatus for determining the relative position of a mobile unit that moves from an initial location to a plurality of successive positions. The mobile unit receives signals from a plurality of navigation satellites and tracks the carrier phases of the signals during movement. For each of the received signals, carrier phase increments are calculated over a plurality of epochs. Anomalous carrier phase increments are determined and eliminated from further calculations. The non-eliminated carrier phase increments are then used to calculate coordinate increments for each of the time epochs. If, after elimination, the remaining number of carrier-phase increments is less than a threshold for a particular epoch, then coordinate increments for the particular epoch may be extrapolated using data from prior epochs. In various embodiments, least squares method and Kalman filtering may be used to calculate the coordinate increments.

Abstract: Disclosed is a method and apparatus for multipath mitigation using an antenna array. An antenna array made up of a plurality of antennas is used to receive satellite signals from satellites. Various configurations of antenna arrays is disclosed, including a linear vertical antenna array and a horizontal antenna array in which the antenna elements are located in a horizontal plane. A switch sequentially connects each of the antenna outputs to a single processing path to generate a common additive signal. The common additive signal is provided to satellite channel processors, each of which processes the signals from an associated satellite. A phase shift correction signal associated with each of the antennas is generated and synchronously applied to a carrier phase reference signal. A blocking signal may be applied to the satellite channel processors in order to block the processing of signals from an unwanted satellite.

Abstract: A method and apparatus for detecting and correcting anomalous measurements in a satellite navigation receiver is disclosed. Anomalous measurements are detected using the redundancy of observed satellite signals, or by analyzing the relationship between phase measurements at two frequencies when using dual frequency receivers. Upon determination that an anomalous measurement exists, the particular channel on which the anomalous measurement has occurred is determined. In addition, the extent of the anomalous measurement is estimated to produce an estimated error value. This information may then be used by the satellite navigation receiver in order to increase the accuracy of a navigation task.

Abstract: A receiver of a radio frequency signal having a pseudo-random noise (PRN) code, and techniques of processing such a signal that are especially adapted for ranging applications. A signal corresponding to the PRN code is locally generated and used for decoding the received signal in a manner to reduce ranging errors that can result when multipath (delayed) versions of the radio frequency signal are also present. A significant application of the receiver and signal processing techniques of the present invention is in a Global Positioning System (GPS), wherein a number of such signals from several satellites are simultaneously received and processed in order to obtain information of the position, movement, or the like, of the receiver. A delay locked loop (DLL) correlator, provided in each of the receiver's multiple processing channels, locks onto a line of sight signal from one of the satellites with the effect of any multipath signal(s) being significantly reduced.

Abstract: A receiver of a radio frequency signal having a pseudo-random noise (PRN) code modulated on a carrier, and techniques of processing such a signal that are especially adapted for ranging applications. Such an application is in a global positioning system (GPS or GLONASS) receiver. Both of the receiver DLL code and PLL carrier loops include a loop component that senses an error in its main loop caused by the presence of a multipath signal. The main loop is continuously adjusted by this sensed error, thereby causing the loop to track more precisely and minimize the effect of the multipath signal. The result is a more accurate range measurement.

Abstract: A receiver of a radio frequency signal having a pseudo-random noise (PRN) code, and techniques of processing such a signal that are especially adapted for ranging applications. A signal corresponding to the PRN code is locally generated and used for decoding the received signal in a manner to reduce ranging errors that can result when multipath (delayed) versions of the radio frequency signal are also present. A significant application of the receiver and signal processing techniques of the present invention is in a Global Positioning System (GPS), wherein a number of such signals from several satellites are simultaneously received and processed in order to obtain information of the position, movement, or the like, of the receiver. A delay locked loop (DLL) correlator, provided in each of the receiver's multiple processing channels, locks onto a line of sight signal from one of the satellites with the effect of any multipath signal(s) being significantly reduced.