Abstract: A local area detection and alerting system (LDAS) for detecting potential GNSS spoofing within a protected airspace includes a ground-based control station and several RF interference (RFI) control stations spaced to define the protected airspace. Each RFI control station includes two or more reference GNSS signal receivers in communication with two or more reception (Rx) antennas, each antenna having a surveyed true location and distinct height. The reference receivers continually determine GNSS-derived absolute positions of each antenna, which are compared to their true locations to determine if GNSS spoofing is responsible for measurement anomalies. Any detection of potential spoofing is forwarded to the control station, which broadcasts regular LDAS updates indicating the presence or absence of potential spoofing to all aircraft operating within a transmission range surrounding the protected airspace.

Abstract: Systems and methods disclose a satellite communication system including a plurality of antenna elements, an interface circuit, and a transceiver circuit. Each antenna element communicates a first polarization signal and a second polarization signal. The interface circuit receives, amplifies, and splits the first polarization signals into a first polarization primary signal and a first polarization secondary signal. The interface circuit also receives, amplifies, and splits the second polarization signals into a second polarization primary signal and a second polarization secondary signal. A first summer circuit generates a first beam signal via a sum of the first and second polarization primary signals. A second summer circuit generates a second beam signal via a sum of the first and second polarization secondary signals.

Abstract: Systems and methods disclose a satellite communication system including a plurality of antenna elements, an interface circuit, and a transceiver circuit. Each antenna element communicates a first polarization signal and a second polarization signal. The interface circuit receives, amplifies, and splits the first polarization signals into a first polarization primary signal and a first polarization secondary signal. The interface circuit also receives, amplifies, and splits the second polarization signals into a second polarization primary signal and a second polarization secondary signal. A first summer circuit generates a first beam signal via a sum of the first and second polarization primary signals. A second summer circuit generates a second beam signal via a sum of the first and second polarization secondary signals.

Abstract: Disclosed is an apparatus for estimating the features of a radio frequency signal including a reference signal generator configured for generating a reference signal from a complex signal and one or more feature estimation units configured to generate one or more feature estimates from the reference signal and the complex signal. Techniques for creating reference signals from both signals spread by a scrambling code and FM signals are discussed.

Abstract: A method and a device for reconfiguring communication transmission characteristics in response to a changing communication environment is provided. An environment at a communication device is characterized to determine if a transmission parameter associated with processing of a communication signal at a physical layer or a network interface layer should change based on current conditions at the communication device. If a need is identified, a second transmission parameter is selected based on the environment monitoring. A request identifying the second transmission parameter is sent to a second communication device using an existing communication link. A response from the second communication device is received indicating acceptance or rejection of use of the second transmission parameter. If the response indicates acceptance of use of the second transmission parameter, the physical layer and/or the network interface layer are reconfigured based on the selected second transmission parameter.

Abstract: An apparatus and method for signal separation and SINR improvement is disclosed. In particular, disclosed is an iterative technique whereby a noisy signal, that may include signals from one or more distinct emitters, is first improved through an SINR improvement technique. Next, one signal from the noisy signal is identified and a reference signal substantially free of noise and interference is generated for this signal, and then this reference signal is subtracted from the noisy signal. This process is repeated until no other signals may be identified. In this way, the signal with the highest SINR may be identified first and then removed from the original signal. As such, the identified signal is no longer present as interference for the remaining signals, thus improving each of the remaining signals' respective SINRs.

Abstract: An apparatus for identifying a specific emitter in the presence of noise and/or interference is disclosed. The apparatus includes a sensor configured to sense radio frequency signal data, the signal data containing noise and signal from at least one emitter, a reference estimation unit configured to estimate a reference signal relating to the signal transmitted by one emitter, a feature estimation unit configured to generate one or more estimates of one or more feature from the reference signal and the signal transmitted by that particular emitter, and an emitter identifier configured to identify the signal transmitted by that particular emitter as belonging to a specific device using one or more feature estimates. The emitter identifier identifies the signal transmitted by that particular emitter as belonging to a specific device using Gaussian Mixture Models and the Bayesian decision engine.

Abstract: The present disclosure is directed to a system and method for providing directional spectral awareness via an antenna system which includes a single parasitic antenna and a processor, the processor being communicatively coupled with the parasitic antenna. The antenna system allows for quick scanning of all sectors included in a plurality of sectors of an RF environment being monitored by the antenna system. The antenna system also allows for monitoring sectors of interest. The directionality of the parasitic antenna of the antenna system may reduce interference and multipath along with providing improved SNR due to antenna gain, thereby allowing for collection of signals of interest in a more favorable environment, thereby enabling analysis such as frequency and spatial use, signal detection, signal identification, and source geolocation to succeed when it may have failed if an omni-directional antenna were used.

Abstract: An apparatus for sensing and classifying radio communications is provided. The apparatus includes one or more sensor units configured to detect radio frequency signals, a signal classifier configured to classify the detected radio frequency signals into a classification, the classification including at least one known signal type and an unknown signal type, a clustering learning algorithm capable of finding clusters of common signals among the previously seen unknown signals. The system is then further configured to use these clusters to retrain the signal classifier to recognize these signals as a new signal type.

Abstract: An apparatus for identifying a specific emitter in the presence of noise and/or interference is disclosed. The apparatus includes a sensor configured to sense radio frequency signal data, the signal data containing noise and signal from at least one emitter, a reference estimation unit configured to estimate a reference signal relating to the signal transmitted by one emitter, a feature estimation unit configured to generate one or more estimates of one or more feature from the reference signal and the signal transmitted by that particular emitter, and an emitter identifier configured to identify the signal transmitted by that particular emitter as belonging to a specific device using one or more feature estimates. The emitter identifier identifies the signal transmitted by that particular emitter as belonging to a specific device using Gaussian Mixture Models and the Bayesian decision engine.

Abstract: The present invention is a geolocation system for providing coordinated sensing and precision geolocation of a target emitter. The system may include a Quint Networking Technology (QNT) subsystem which may be configured receiving, detecting and identifying a target emitter signal. The QNT subsystem may be further configured for extracting a carrier phase of the signal. The system may further include a Real Time Kinematic Global Positioning System (RTK GPS) subsystem for determining a position of the geolocation system relative to a position of a second geolocation system. Further, the system may be configured for communicating with the second geolocation system via a QNT communication data link for: determining a QNT time difference via signal carrier phase differencing for calculating a time difference between the geolocation systems and geolocating the target emitter based on both the relative position information of the geolocation systems and the calculated time difference between the geolocation systems.

Abstract: A method is provided to control scheduling of transmission and reception by a TDMA radio. This method allows individual transmissions and receptions to be independently configured for different frequencies, coding rates, modulation schemes, in fact anything which the radio modem allows to be configured. In addition, this scheduling and configuration may be configured and reconfigured in real time without disrupting radio operations.

Abstract: Spectral environment estimation systems and methods are provided for use with frequency hopped communications systems. A spectral sensor is configured to receive input signals from a signal aperture and to perform spectral estimations on the input signals to generate a frequency domain spectral estimate. Ordinary spectral characterization circuitry is configured to receive the frequency domain spectral estimate as an input and to produce an ordinary frequency domain spectral environment estimate based on the spectral estimate. Frequency hopping translation circuitry is configured to receive the frequency domain spectral estimate from the spectral sensor as an input and to produce a de-hopped channel domain spectral estimate based on the frequency domain spectral estimate.

Abstract: The present invention is directed to accurate GPS (global positioning system)-free relative navigation between an unmanned aerial vehicle (UAV) and a tanker aircraft. The UAV transmits a signal which is received by an antenna array at the tanker aircraft. Horizontal relative position of the UAV is determined by calculating range and bearing based on time and phase differences in the received signal. Vertical relative position of the UAV is determined by comparing the altitude of the UAV with the altitude of the tanker aircraft. The tanker aircraft then transmits a navigation solution based on the relative position of the UAV which is received by the UAV. The UAV may utilize the navigation solution transmitted by the tanker aircraft as a backup to a GPS determined navigation solution, in a GPS denied scenario, or in combination with an INS (inertial navigation system) determined navigation solution.

Abstract: The present invention is directed to a small size and light weight small form factor user system suitable for having TTNT connectivity which consumes minimum power to operate. The small form factor user system having TTNT connectivity may be capable of interacting in a low latency real time manner with airborne networks. The small form factor user system having TTNT connectivity may have significantly reduced radio power consumption and form factor size through maintaining core capabilities of the full size TTNT terminal while relaxing other capabilities. An encapsulated message structure may be utilized to simplify communication between the TTNT small form factor user system and the full size TTNT nodes.

Abstract: A spread spectrum communication system includes a transceiver configured to transmit a spread spectrum waveform. The spread spectrum waveform comprises transmitted signals at varying frequencies within a radio frequency spectrum of operation. The frequency variation is controlled according to a hopping sequence. A spectral sensor of the communication system is configured to dynamically scan the radio frequency spectrum of operation and to generate channel occupancy data based upon the scans. A real time hopping sequence generator is configured to dynamically generate the hopping sequence in real time as a function of the channel occupancy data.

Abstract: The present invention provides a method for using an Organization and Control Proxy (OCP) to configure a network communications infrastructure. OCP functionality is distributed across nodes possessing OCP elements. Intercommunication between the OCP elements is implemented via a unifying mesh waveform for network discovery, propagation of network and radio-frequency (RF) socket usage information, and management and control of instances of dynamic socket waveforms. An extensible language for specification of waveform properties is used by the OCP elements to negotiate spectral use information and to negotiate configurations between two or more endpoints of a dynamic socket waveform connection. A network stack is configured by the OCP to provide requested service to an end user.

Abstract: A system capable of operation with dynamic sockets includes a plurality of communications devices. Each of the plurality of communications devices includes high band channel radio resources capable of communications at 900-2800 MHz and socket radio resources capable of communications at 30-1000 MHz. The high band channel radio resources and the socket radio resources are significantly separated in frequency so that the high band channel radio resources and the socket radio resources are suitable for concurrent operation with no interference and minimal isolation, co-site problems to solve in each of the plurality of communications devices. The plurality of communications devices are connected to a unifying mesh network by the high band channel radio resources. The unifying mesh network is suitable for allowing the plurality of communications devices to communicate with one another.

Abstract: A receiver for carrier frequency estimation via symbol rate estimation in the presence of carrier frequency error for use in signal acquisition and signal demodulation of spread-spectrum chips affected by Doppler shift in an advanced tactical data link. Received LPD signals with a very low signal-to-noise ratio are input to a receiver designed to tolerate carrier frequency error caused by Doppler shift. Extremely low signal-to-noise ratio and short dwell times due to spread spectrum modulation and frequency-hopping make direct estimation of carrier frequency impractical. A method and apparatus is disclosed to use the error is symbol rate, the nominal carrier frequency, and the nominal transmitted symbol rate to estimate carrier frequency error. This enables longer coherent integration times and improves LPD receiver performance.

Abstract: A receiver for computationally efficient signal acquisition of spread-spectrum chips affected by Doppler shift in an advanced tactical data link. Received signals with a very low signal-to-noise ratio are parsed in a multi-stage signal acquisition circuit architecture, and compared to a known sequence to determine correlation over a subset of the known sequence. Chip-rate-coherent correlation is performed over an interval of time for which the effect of Doppler shift on the chip rate are negligible. A non-coherent block then integrates intermediate metrics to obtain final metrics for the entire known sequence. The parsing of the correlation into subsets and stages allows for a more computationally efficient solution to the Doppler shift chip rate error problem by reducing the number of intermediate metrics that must be computed at high speed.