Abstract: Approaches for detecting and/or rejecting fraudulent positioning system signals at one or more positioning system receivers. The receivers may establish a time search window that may be maintained beyond a time in which a fraudulent signal is expected to move away from an authentic signal a sufficient amount so as to fall outside the time search window. Various approaches are described for updating the time signal at the receiver to maintain accuracy without acquiescing to the introduced bias of a fraudulent signal. Also, an approach for evaluation of candidate signals for consistency at one or more stationary receivers is described. Also, approaches for collective evaluation of signals provided from networked receivers are described to provide sentry receivers operative to detect and alert the presence of a fraudulent signal.

Abstract: Determination of one or more timing (phase) and/or frequency corrections to be made to a local time base of a receiver device to synchronize the local time base with the time of GPS or other highly accurate time base. Timing packets from one or more grandmaster devices whose time bases are substantially the same as that of GPS or the like and/or positioning system signals (e.g., GPS signals) directly from a positioning system are received and manipulated to determine the timing and/or frequency corrections. The corrected time base may be used to assist in acquiring such positioning signals to allow for higher accuracy correction and/or for downstream communication operation. The present utilities are advantageous such as when a sufficient number of channels (e.g., four) from the receiver device to positioning system satellites are unavailable to synchronize the local time base to the GPS or other accurate time base.

Abstract: Wave based signals such as radio transmissions are susceptible to frequency alterations caused by the relative movement between a transmitter and a receiver. In a satellite context, the radio signals emitted by a satellite based transmitter may take on a frequency higher or lower than the actual frequency at which they are generated depending on whether the satellite is moving toward or away from the receiver, respectively. By calculating the theoretical frequency shift (Doppler shift) that should occur if a signal travels directly from a satellite to a receiver, the actual frequency of the signal as received can be used to determine if the signal's integrity is sufficient or if it has been compromised by some sort of interference or malfunction.

Abstract: Determination of one or more timing (phase) and/or frequency corrections to be made to a local time base of a receiver device to synchronize the local time base with the time of GPS or other highly accurate time base. Timing packets from one or more grandmaster devices whose time bases are substantially the same as that of GPS or the like and/or positioning system signals (e.g., GPS signals) directly from a positioning system are received and manipulated to determine the timing and/or frequency corrections. The corrected time base may be used to assist in acquiring such positioning signals to allow for higher accuracy correction and/or for downstream communication operation. The present utilities are advantageous such as when a sufficient number of channels (e.g., four) from the receiver device to positioning system satellites are unavailable to synchronize the local time base to the GPS or other accurate time base.

Abstract: Location of a device within a monitored environment with compromised communication with ranging communication nodes. Specifically, an intermediate device previously located by communication with ranging communication nodes is provided to provide a ranging signal to a device to be located. The device to be located may in turn use a ranging signal received from communication with the previously located device and one or more ranging communication nodes to resolve a location.

Abstract: Positioning, navigation, and timing (“PNT”) signals, such as those used in GNSS or LORAN systems, may be vulnerable to spoofing attacks. To generate trustworthy time and location data at a receiver, one must at least reduce the likelihood of or be capable of detecting spoofing attacks. Embodiments of the present invention, as presented herein, provide solutions for detecting spoofing of PNT signals. Various aspects incorporated into the described embodiments which assist in detecting spoofing attacks may include but are not limited to: monitoring the SNR of received PNT signals of a first modality and switching over to an alternate PNT modality when an anomaly is detected, comparing data associated with signals of multiple PNT modalities to identify a discrepancy indicative of spoofing on one of the multiple PNT modalities, and implementing a security regime to prevent spoofers from being able to produce perceivably authentic, but corrupt, replica signals of a PNT modality.

Abstract: Location of a device within a monitored environment with compromised communication with ranging communication nodes. Specifically, an intermediate device previously located by communication with ranging communication nodes is provided to provide a ranging signal to a device to be located. The device to be located may in turn use a ranging signal received from communication with the previously located device and one or more ranging communication nodes to resolve a location.

Abstract: The present disclosure is directed to utilities (methods, systems, apparatuses) associated with improving the signal-to-noise ratio of a wireless signal at a receiver. It is known in the art to correlate a received signal with a replica signal generated at the receiver to improve reception. However, the inventors have determined that correlation using a replica signal which is not completely accurate may be detrimental. An improved method of correlation disclosed herein includes identifying data bits which are predictable and performing correlation with respect to those data bits while ignoring data bits which are identified as unpredictable. This method may have particular advantages in the case of receivers having attenuated reception (e.g., indoors) after losing a data connection used for receipt of assistance data.

Abstract: Determination of a signal loss profile relative to a receiver based on measured signal power of a sounding signal from a sounding transmitter having a known signal power in free space relative to the receiver. The signal loss profile may include a plurality of signal loss values corresponding to a plurality of received sounding signals at the receiver. In an embodiment, the sounding signal may comprise a GNSS navigational signal (e.g., a GPS signal). The signal loss profile may be used to extrapolate signal loss for a transmitter collocated with the receiver. In turn, the signal loss profile may be used in conjunction with a shared spectrum system to model a signal propagation from the collocated transmitter when determining allocation of a shared spectrum resource of the shared spectrum system.

Abstract: Data bandwidth reduction in positioning system signals. Specifically, a first, relatively easily acquired signal may be analyzed to determine if and/or to what extent to decimate a second signal. The second signal may comprise a higher encoded data rate (e.g., a chip rate). In turn, decimation of the second signal based on characteristics of the first signal may allow for more efficient processing of the second signal.

Abstract: A GNSS cooperative receiver system that can be utilized when one or more GNSS receivers is in a compromised position where it cannot receive direct signals from a sufficient number of GNSS satellites. This may in the interior of an office building or multi-dwelling unit, which may be in the vicinity of other tall buildings. The receivers determine their relative positions from one of various ranging techniques, and then with this relative position information, pseudoranges, and correlation values from the various GNSS receivers, the best GNSS solution can be determined for the group of cooperative receivers. This could include two or more receivers in a group. There also related techniques for one receiver to be a designated, remote anchor for other GNSS receivers that need such assistance.

Abstract: An approach to joint processing of GNSS signals to determine a receiver location and common mode bias associated with grouped records corresponding to GNSS signals. In this regard, a receiver may acquire signals from a GNSS space vehicle over a relatively long period of time. In turn, records corresponding to received signals may be stored and grouped. The grouping of records may be based on assumptions of a common-mode bias for certain records (e.g., records acquired within a given duration of an observation time period). Upon acquisition of a suitable number of records, an over-determined system may be established that is used in iterative processing to solve for location and/or bias values associated with the respective common-mode bias for each group of records. As such, improved receiver performance may be realized.

Abstract: Techniques for allowing a remote or fielded receiver to derive a precise time reference (such as Coordinated Universal Time (UTC)) when the fielded receiver is not able to derive time directly from received GPS signals. One or more fixed DME reference stations are located within range of DME beacon signals from an existing DME beacon station, the DME reference stations also having the capability to receive GPS signals and derive UTC therefrom. Based on the known distance between the DME reference station and the DME beacon station, the DME reference station can determine the time of transmission from the DME beacon station of each DME beacon signal. This time tag information is then provided to the fielded receiver, which is also within range of DME beacon signals from the DME beacon station. With this time tag information, the fielded receiver can correlate that with the received DME beacon signals and derive UTC to within an acceptably small margin.

Abstract: A method and system for precise position determination of general Internet Protocol (IP) network-connected devices. A method enables use of remote intelligence located at strategic network points to distribute relevant assistance data to IP devices with embedded receivers. Assistance is tailored to provide physical timing, frequency and real time signal status data using general broadband communication protocols. Relevant assistance data enables several complementary forms of signal processing gain critical to acquire and measure weakened or distorted in-building Global Navigation Satellite Services (GNSS) signals and to ultimately extract corresponding pseudo-range time components. A method to assemble sets of GNSS measurements that are observed over long periods of time while using standard satellite navigation methods, and once compiled, convert using standard methods each pseudo-range into usable path distances used to calculate a precise geographic position to a known degree of accuracy.

Abstract: Synchronization of a time base at a local clock to a reference time. Initially, correction data (e.g., synchronization data) may be derived from packet data received over an asynchronous packet-switched network (e.g., the internet). Correction data derived from the packet data may be used to correct at least a portion of the time base (e.g., a frequency component). In turn, once the time base is corrected (e.g., to better than a predetermined quality threshold), the source of synchronization data may change to an alternate (e.g., more accurate source) such as positioning signals from a positioning system. In this regard, the corrected time base may be used to assist in acquiring such positioning signals to allow for higher accuracy correction. Furthermore, use of the positioning system may allow for correction of a phase of the time base (e.g., to align the phase to the positioning system. In turn, an accurate time base may be utilized (e.g.

Abstract: Approaches to signal processing using tapered coherent integration time period durations. In this regard, signal processing of received signals (e.g., received satellite navigation signals) may be received at a receiver. The received signals may be processed in a coherent integration process whereby the duration of subsequent coherent integration time periods are reduced in response to errors resulting from frequency instability that grows in time. As such, relatively long durations for coherent integration times may result in improved signal to noise ratios (SNRs) for integrated signals in initial coherent integration time periods. However, as errors that are introduced into the signal processing due grow over time, the durations of subsequent coherent integration time periods may be reduced, thus reducing the effect of the error in a SNR of resulting integrated signals. In turn, receiver sensitivity may be improved.

Abstract: Location of one or more devices in a monitored environment based at least in part on data communications between a device and a communication array disposed relative to the monitored environment. The communication array may include a plurality of nodes, at least two of which may be in operative communication with a mobile device. The plurality of nodes may be synchronized to a common time base with communications over a packet-switched communication network (e.g., employing IP communications or the like). In turn, communications between nodes of known location and a device may be used to determine ranging values at least in part based on characteristics (e.g., time of flight) of the communication. As such, a location may be determined by, for example, multilateration of a plurality of ranging values.

Abstract: A method and system for precise position determination of general Internet Protocol (IP) network-connected devices. A method enables use of remote intelligence located at strategic network points to distribute relevant assistance data to IP devices with embedded receivers. Assistance is tailored to provide physical timing, frequency and real time signal status data using general broadband communication protocols. Relevant assistance data enables several complementary forms of signal processing gain critical to acquire and measure weakened or distorted in-building Global Navigation Satellite Services (GNSS) signals and to ultimately extract corresponding pseudo-range time components. A method to assemble sets of GNSS measurements that are observed over long periods of time while using standard satellite navigation methods, and once compiled, convert using standard methods each pseudo-range into usable path distances used to calculate a precise geographic position to a known degree of accuracy.

Abstract: Approaches to signal processing using tapered coherent integration time period durations. In this regard, signal processing of received signals (e.g., received satellite navigation signals) may be received at a receiver. The received signals may be processed in a coherent integration process whereby the duration of subsequent coherent integration time periods are reduced in response to errors resulting from frequency instability that grows in time. As such, relatively long durations for coherent integration times may result in improved signal to noise ratios (SNRs) for integrated signals in initial coherent integration time periods. However, as errors that are introduced into the signal processing due grow over time, the durations of subsequent coherent integration time periods may be reduced, thus reducing the effect of the error in a SNR of resulting integrated signals. In turn, receiver sensitivity may be improved.

Abstract: Location of one or more devices in a monitored environment based at least in part on data communications between a device and a communication array disposed relative to the monitored environment. The communication array may include a plurality of nodes, at least two of which may be in operative communication with a mobile device. The plurality of nodes may be synchronized to a common time base with communications over a packet-switched communication network (e.g., employing IP communications or the like). In turn, communications between nodes of known location and a device may be used to determine ranging values at least in part based on characteristics (e.g., time of flight) of the communication. As such, a location may be determined by, for example, multilateration of a plurality of ranging values.