Abstract: A method is described for reduced-complexity estimation of signal and data modes in high-dimensional data sets, by implementing subspace-constrained partial updates to optimize an eigenvalue-based objective function. The method selects, from a set of combiner weights, a set of update weights and a set of held weights; performs updates to the set of held weights within a reduced-dimensionality subspace and unconstrained updates to the set of update weights to produce updated combiner weights; and employs the updated combiner weights to determine at least one solution to an eigenequation or pseudo-eigenequation.

Abstract: Systems and methods are presented for communication under strong and dynamic co-channel interference, by exploiting temporal self-coherence of complex signals transmitted within a first communication band that is equal to or falls within a second communication band occupied by co-channel interference (CCI). Each complex signal comprises a first signal and at least a second signal that is a phase-shifted replica of the first signal. The communication receiver comprises a plurality of antennas receiving each complex signal substantively under the CCI, and a Dynamic Interference Cancellation and Excision processor that excises the CCI sufficiently to demodulate each complex signal.

Abstract: A method and apparatus resiliently despreads terrestrial navigation signals in which the spreading code duration is equal to an underlying baseband symbol rate, including ground beacons based on civil GNSS waveforms, and malicious spoofers. Symbol-rate synchronous channelizers exploit the baseband symbol rate, and means for blindly and resiliently detecting and determining geo-observables of those signals are described. Disclosed techniques can despread signals in arbitrary multipath, and subject to near-far interference in which the relative strength of the interferer is much higher than the despreading gain of the receiver, including near-far tonal and narrowband co-channel interference.

Abstract: An adaptive processor is configured to provide for reduced-complexity estimation of signal and data modes in high-dimensional data sets by implementing subspace-constrained partial updates to optimize an eigenvalue-based objective function. The adaptive processor selects, from a set of combiner weights, a set of update weights and a set of held weights; performs updates to the set of held weights within a reduced-dimensionality subspace and unconstrained updates to the set of update weights to produce updated combiner weights; and employs the updated combiner weights to determine at least one solution to an eigenequation or pseudo-eigenequation.

Abstract: An apparatus and digital signal processing means are disclosed for excision of co-channel interference from signals received in crowded or hostile environments using spatial/polarization diverse arrays, which reliably and rapidly identifies communication signals with transmitted features that are self-coherent over known framing intervals due to known attributes of the communication network, and exploits those features to develop diversity combining weights that substantively excise that cochannel interference from those communication signals, based on differing diversity signature, timing offset, and carrier offset between the network signals and the co-channel interferers. Co-channel interference excision may be performed in an appliqué that can be implemented without coordination with a network transceiver.

Abstract: A transmitter spreads a data signal with an inner spreading code to produce a first spread signal; modulates a link mask onto the first spread signal to produce a masked signal; spreads the masked signal with an outer spreading code to produce a second spread signal; and modulates the second spread signal onto a multitone transmission signal. The link mask can include at least one of a destination mask and a source mask. A network mask might be modulated onto the second spread signal to conceal cyclic features in a spreading format used to spread the data signal and/or the first masked signal. A receiver demodulates a received multitone transmission to produce at least one demodulated signal; demasks the at least one demodulated signal to produce at least one demasked signal; and despreads the at least one demasked signal using an adaptation algorithm to remove the outer spreading code.

Abstract: An apparatus and digital signal processing means are disclosed for excision of co-channel interference from signals received in crowded or hostile environments using spatial/polarization diverse arrays, which reliably and rapidly identifies communication signals with transmitted features that are self-coherent over known framing intervals due to known attributes of the communication network, and exploits those features to develop diversity combining weights that substantively excise that co-channel interference from those communication signals, based on differing diversity signature, timing offset, and carrier offset between the network signals and the co-channel interferers. In one embodiment, the co-channel interference excision is performed in an appliqué that can be implemented without coordination with a network transceiver.

Abstract: An adaptive processor implements partial updates when it adjusts weights to optimize adaptation criteria in signal estimation, parameter estimation, or data dimensionality reduction algorithms. The adaptive processor designates some of the weights to be update weights and the other weights to be held weights. Unconstrained updates are performed on the update weights, whereas updates to the set of held weights are performed within a reduced-dimensionality subspace. Updates to the held weights and the update weights employ adapt-path operations for tuning the adaptive processor to process signal data during or after tuning.

Abstract: A method and apparatus detects and estimates geo-observables of navigation signals employing civil formats with repeating baseband signal components, i.e., “pilot signals,” including true GNSS signals generated by satellite vehicles (SV’s) or ground beacons (pseudolites), and malicious GNSS signals, e.g., spoofers and repeaters. Multi-subband symbol-rate synchronous channelization can exploit the full substantive bandwidth of the GNSS signals with managed complexity in each subband. Spatial/polarization receivers can be provided to remove interference and geolocate non-GNSS jamming sources, as well as targeted GNSS spoofers that emulate GNSS signals.

Abstract: An adaptive processor implements partial updates when it adjusts weights to optimize adaptation criteria in signal estimation, parameter estimation, or data dimensionality reduction algorithms. The adaptive processor designates some of the weights to be update weights and the other weights to be held weights. Unconstrained updates are performed on the update weights, whereas updates to the set of held weights are performed within a reduced-dimensionality subspace. Updates to the held weights and the update weights employ adapt-path operations for tuning the adaptive processor to process signal data during or after tuning.

Abstract: A method and apparatus detects and estimates geo-observables of navigation signals employing civil formats with repeating baseband signal components, i.e., “pilot signals,” including true GNSS signals generated by satellite vehicles (SV's) or ground beacons (pseudolites), and malicious GNSS signals, e.g., spoofers and repeaters. Multi-subband symbol-rate synchronous channelization can exploit the full substantive bandwidth of the GNSS signals with managed complexity in each subband. Spatial/polarization receivers can be provided to remove interference and geolocate non-GNSS jamming sources, as well as targeted GNSS spoofers that emulate GNSS signals. This can provide time-to-first-fix (TTFF) over much smaller time intervals than existing GNSS methods; can operate in the presence of signals with much wider disparity in received power than existing techniques; and can operate in the presence of arbitrary multipath.

Abstract: An apparatus and digital signal processing means are disclosed for excision of co-channel interference from signals received in crowded or hostile environments using spatial/polarization diverse arrays, which reliably and rapidly identifies communication signals with transmitted features that are self-coherent over known framing intervals due to known attributes of the communication network, and exploits those features to develop diversity combining weights that substantively excise that co-channel interference from those communication signals, based on differing diversity signature, timing offset, and carrier offset between the network signals and the co-channel interferers. In one embodiment, the co-channel interference excision is performed in an appliqué that can be implemented without coordination with a network transceiver.

Abstract: Co-channel beacon transmissions are provided with at least one of spectral redundancy and temporal redundancy. A receiver produces a snapshot of a superposition of received co-channel beacon transmissions. Subcarrier demodulation, code nulling, or a Class-C linear minimum-mean-square error (MMSE) operation separates multiples ones of the co-channel beacon transmissions or eliminates inter-symbol interference and inter-subcarrier interference in the snapshot. Receiver operations can be performed at a network user, a network node, or a network operations center.

Abstract: An apparatus and digital signal processing means are disclosed to reliably and rapidly receive and detect navigation signals, e.g., Global Navigation Satellite System (GNSS) signals, such as Global Position System (GPS) L1 legacy, L1C, and L5 signals, using combinations of spatially diverse antenna arrays, polarization-diverse antenna arrays, frequency-channelized analysis filters, and perfect-reconstruction synthesis filters, by exploiting features of those signals that are self-coherent over known framing intervals. Among other advantages, the means can reliably and rapidly identify navigation signals based on those features, improve their quality ahead of, or during, signal despreading operations, and detect and excise inadvertent or targeted electronic attack (EA) measures, e.g., navigation signal spoofers, and narrowband or wideband jamming and co-channel interference.

Abstract: A method and apparatus for reception of signals with unpredictable transmission properties enabling physically secure, unscheduled and interference-resistant communication over machine-to-machine (M2M) networks is claimed. A physical structure employs combinations of unpredictable physical dwells, spreading vectors, and selection of intended receivers. Reception methods employ blind detection and signal separation techniques, which can detect and extract transmissions intended for a receiver, and excise transmissions not intended for that receiver, as part of the despreading procedure, even if received at much higher power levels than the intended transmissions.

Abstract: A method and apparatus detects and estimates geo-observables of navigation signals employing civil formats with repeating baseband signal components, i.e., “pilot signals,” including true GNSS signals generated by satellite vehicles (SV's) or ground beacons (pseudolites), and malicious GNSS signals, e.g., spoofers and repeaters. Multi-subband symbol-rate synchronous channelization can exploit the full substantive bandwidth of the GNSS signals with managed complexity in each subband. Spatial/polarization receivers can be provided to remove interference and geolocate non-GNSS jamming sources, as well as targeted GNSS spoofers that emulate GNSS signals. This can provide time-to-first-fix (TTFF) over much smaller time intervals than existing GNSS methods; can operate in the presence of signals with much wider disparity in received power than existing techniques; and can operate in the presence of arbitrary multipath.

Abstract: A method and apparatus is claimed here for reduced-complexity detection and estimation of geo-observables of global navigation satellite systems (GNSS) signals employing civil formats with repeating ranging codes, including true GNSS signals generated by satellite vehicles (SV's) or ground beacons (pseudo-lites), and malicious GNSS signals, e.g., spoofers and repeaters, using multi-subband symbol-rate synchronous channelization architectures that can exploit the full substantive bandwidth of the GNSS signals with managed complexity in each subband. Aspects employing spatial/polarization receivers are also claimed that can remove and geolocate non-GNSS jammers received by the system, as well as targeted GNSS spoofers that can otherwise emulate GNSS signals received at victim receivers.

Abstract: An apparatus and digital signal processing means are disclosed to reliably and rapidly receive and detect navigation signals, e.g., Global Navigation Satellite System (GNSS) signals, such as Global Position System (GPS) L1 legacy, L1C, and L5 signals, using combinations of spatially diverse antenna arrays, polarization-diverse antenna arrays, frequency-channelized analysis filters, and perfect-reconstruction synthesis filters, by exploiting features of those signals that are self-coherent over known framing intervals. Among other advantages, the means can reliably and rapidly identify navigation signals based on those features, improve their quality ahead of, or during, signal despreading operations, and detect and excise inadvertent or targeted electronic attack (EA) measures, e.g., navigation signal spoofers, and narrowband or wideband jamming and co-channel interference.

Abstract: A method and apparatus for reception of signals with unpredictable transmission properties enabling physically secure, unscheduled and interference-resistant communication over machine-to-machine (M2M) networks is claimed. A physical structure comprising combinations of unpredictable physical dwells, spreading vectors, and selection of intended receivers is described. Reception methods employing blind detection and signal separation techniques are then described, which can detect and extract transmissions intended for a receiver, and excise transmissions not intended for that receiver, as part of the despreading procedure, even if received at much higher power levels than the intended transmissions.

Abstract: An adaptive processor implements partial updates when it adjusts weights to optimize adaptation criteria in signal estimation, parameter estimation, or data dimensionality reduction algorithms. The adaptive processor designates some of the weights to be update weights and the other weights to be held weights. Unconstrained updates are performed on the update weights, whereas updates to the set of held weights are performed within a reduced-dimensionality subspace. Updates to the held weights and the update weights employ adapt-path operations for tuning the adaptive processor to process signal data during or after tuning.