Abstract: Systems and methods for evaluating link performance over a multitude of frequencies for Signal-to-Noise Ratio (SNR) optimization and mitigating interference. The methods comprise: communicating, from a first communication device, a first signal over a given channel in a given frequency band; receiving, by the first communication device, spectral power measurements and a Signal-to-Total Power Ratio (STPR) estimate determined based on a second signal including the first signal combined with at least one of noise and one or more interference signals (the STPR estimate accounts for the receiver performance including chip rate processing gain and/or the performance of an interference cancellation circuit used to remove the interference signals from the second signal); and determining, by the first communication device, a predicted Signal-to-Noise Ratio (SNR) condition for a plurality of frequencies within the given frequency band using the STPR estimate and the spectral power measurements.

Abstract: Systems and methods for evaluating link performance over a multitude of frequencies for Signal-to-Noise Ratio (SNR) optimization and mitigating interference. The methods comprise: communicating, from a first communication device, a first signal over a given channel in a given frequency band; receiving, by the first communication device, spectral power measurements and a Signal-to-Total Power Ratio (STPR) estimate determined based on a second signal including the first signal combined with at least one of noise and one or more interference signals (the STPR estimate accounts for the receiver performance including chip rate processing gain and/or the performance of an interference cancellation circuit used to remove the interference signals from the second signal); and determining, by the first communication device, a predicted Signal-to-Noise Ratio (SNR) condition for a plurality of frequencies within the given frequency band using the STPR estimate and the spectral power measurements.

Abstract: Methods and systems for dynamically modifying a sampling operation of a sensor. The method includes obtaining a dynamically changing transmission characteristic based on an available channel bandwidth parameter. The dynamically changing transmission characteristic includes at least one of a sample rate, a time period, or a spectral bandwidth. The method further includes updating the sampling operation of the sensor based on the dynamically changing transmission characteristic. The method further includes measuring signal energy at a location of the sensor. The method further includes sampling the signal energy using the sampling operation to obtain sampled data. The method further includes providing the sampled data to a processing entity configured to analyze the data using a dynamically updated cross-ambiguity function.

Abstract: An angle of arrival system can be self-calibrating. The angle of arrival system can continuously estimate imperfections caused by the analog RF components and dynamically apply corrections based on these estimates. As a result, an angle of arrival system can employ inexpensive components, will not require factory calibration, but can still perform geolocation with high precision.

Abstract: Methods and systems adapted for providing a dynamically updated geolocation system. The geolocation system measures a signal, samples the signal, and applies a cross-ambiguity function to the sampled data to calculate the location of a signal source. The sampling operation and cross-ambiguity function are updated opportunistically and adaptively based on available channel resources between a plurality of sensors and a central processing location in the system. These update methods allow control of the data rate when channel resources are impacted by the physical environment where the geolocation system is operating.

Abstract: An angle of arrival system is configured to efficiently measure phase differences. The angle of arrival system includes a master receiver for demodulating the signal received at one antenna and for implementing a tracking loop to identify the timing of symbols within the signal. This timing information can be fed back as a synchronization signal to a despreader in the master receiver and to a despreader in each of a number of slave receivers to synchronize the timing at which each signal is despread. Because despreading is synchronized, the outputs of the despreaders can be used to directly calculate phase differences between each pair of signals. In this way, the slave receivers do not need to implement a demodulator or a tracking loop. When the received signal is a non-spread signal, the phase differences between each pair of signals can be calculated directly from the modulated samples of each pair of signals without despreading.

Abstract: Transmitting a signal from a transmitter. A method includes identifying a threshold spectral flux density for a given physical location. The method further includes, as a result of identifying the threshold spectral flux density, transmitting a signal at a power level causing the signal to be below the spectral flux density at the given physical location, the signal being transmitted at a data rate. The method further includes receiving feedback from a receiver indicating the signal-to-noise ratio of the signal at the receiver. The method further includes adjusting the data rate of the signal based on the feedback. The method further includes continuing transmitting the signal at the adjusted data rate and power level.

Abstract: Transmitting a signal from a transmitter. A method includes identifying a threshold spectral flux density for a given physical location. The method further includes, as a result of identifying the threshold spectral flux density, transmitting a signal at a power level causing the signal to be below the spectral flux density at the given physical location, the signal being transmitted at a data rate. The method further includes receiving feedback from a receiver indicating the signal-to-noise ratio of the signal at the receiver. The method further includes adjusting the data rate of the signal based on the feedback. The method further includes continuing transmitting the signal at the adjusted data rate and power level.

Abstract: Transmitting data in a mesh network. A method includes identifying points on a piecewise continuous surface. The piecewise continuous surface defines minimum threshold power values to maintain a predetermined signal-to-noise ratio at a predetermined bitrate for a transmitter node transmitting to one or more receiver nodes in the mesh network. Points of a constant total power surface are identified defining required ratios of transmitting power for transmitting sources of the transmitter node. One or more points on the piecewise continuous surface that intersect with the constant total power surface are identified. As a result, transmitting power levels for the transmitting sources of the transmitter node are identified. As a result, data is transmitted at or above transmitting power levels, using the transmitting sources.

Abstract: Optimizations are provided for controlling an amount of radiated power (i.e. spectral flux density) that is being transmitted to a particular location. To that end, one or more antennas are used to transmit a power signal. Then, position information for each of those antennas is determined. Additionally, environmental information for the environment in which the antennas are operating is also determined. Also, an antenna radiation pattern for each of those antennas is also determined. Thereafter, how much power is radiated to a particular location is controlled so that the power never exceeds a certain threshold value. This control is achieved by dynamically adjusting the transmit power of the antennas based on the information obtained from the position information, the environmental information, and the antenna radiation pattern information.

Abstract: An angle of arrival system can be self-calibrating. The angle of arrival system can continuously estimate imperfections caused by the analog RF components and dynamically apply corrections based on these estimates. As a result, an angle of arrival system can employ inexpensive components, will not require factory calibration, but can still perform geolocation with high precision.

Abstract: Geolocating an emitter of a low probability of detection (LPD) signal being transmitted from the emitter in an environment with a noise floor, where the LPD signal is below the noise floor. At a sensor node, a version of the LPD signal is received from the emitter. For the version of the LPD signal, cyclostationary feature detection or energy detection of the version of the LPD signal is performed. A low probability of detection descriptor word, including at least one of a frequency feature of the version of the LPD signal or an energy feature of the version of the LPD signal is created. The low probability of detection descriptor word is provided to a data processor, where the data processor is configured to use a plurality of low probability of detection descriptor words from different sensor nodes for different versions of the LPD signal to geolocate the emitter.

Abstract: The application is generally directed to transmitting and receiving signals in a fashion that can mask the presence of the signals by including timing information in the signals using artifacts in a carrier signal. For example, one embodiment includes a method of transmitting a signal in a way to mask the presence of the signal or to reduce the ability of external entities to extract data from the signal. The method includes accessing a data signal. A phase of the data signal is correlated to a phase of a substantially continuous carrier signal carrying the data signal. The substantially continuous carrier signal carrying the data signal with the phase of the data signal correlated to the phase of the substantially continuous carrier signal is transmitted to a receiver, such that the data signal can be extracted by using phase correlation between the data signal and the substantially continuous carrier signal.

Abstract: An angle of arrival system can be self-calibrating. The angle of arrival system can continuously estimate imperfections caused by the analog RF components and dynamically apply corrections based on these estimates. As a result, an angle of arrival system can employ inexpensive components, will not require factory calibration, but can still perform geolocation with high precision.

Abstract: An angle of arrival system is configured to efficiently measure phase differences. The angle of arrival system includes a master receiver for demodulating the signal received at one antenna and for implementing a tracking loop to identify the timing of symbols within the signal. This timing information can be fed back as a synchronization signal to a despreader in the master receiver and to a despreader in each of a number of slave receivers to synchronize the timing at which each signal is despread. Because despreading is synchronized, the outputs of the despreaders can be used to directly calculate phase differences between each pair of signals. In this way, the slave receivers do not need to implement a demodulator or a tracking loop. When the received signal is a non-spread signal, the phase differences between each pair of signals can be calculated directly from the modulated samples of each pair of signals without despreading.

Abstract: Embodiments are directed to systems and methods for selecting appropriate transmission configurations in a mobile ad hoc frequency division duplexing mesh network. In one scenario, a node receives transmission parameters from a neighboring node, where the transmission parameters include an indication of the node's current transmission configuration. The node receives network parameters from neighboring nodes, where the network parameters include connection information describing the node's current network connection to the neighboring nodes. Then, based on the received transmission parameters and the received network parameters, the node calculates a change factor which indicates the desirability of changing transmission configuration.

Abstract: A virtual boresight vector for an antenna array can be calculated. The virtual boresight vector defines the direction an antenna array is pointing and can be used to ensure that angle of arrival measurements are performed with high accuracy. The virtual boresighting process can include positioning a calibration node at two different locations in order to obtain different covariance matrices. With the covariance matrices and based on knowing the angle between the two locations, an angle of arrival node can perform a process to calculate a precise angle between the antenna array and the second location.

Abstract: An antenna array can be quickly and efficiently designed to meet specified performance criteria. A system can be configured to receive various performance criteria as inputs, and from these inputs, identify how elements of an antenna array should be arranged so that the antenna array will meet the performance criteria. An iterative process can be performed to identify at least one arrangement of elements that will best meet the performance criteria while also complying with specified structural constraints.

Abstract: Embodiments are directed to systems and methods for communicating between nodes in a mobile ad hoc network. In one scenario, a node in a mobile ad hoc network communicates with another node in the network using both code division multiple access (CDMA) and frequency division duplexing. The communication is coded prior to transmission to the other node, and includes applying direct sequence spread spectrum (DSSS) modulation to a transmission signal at a specified bit rate over a specified spectrum. The DSSS coding is applied in accordance with a processing gain which spreads the spectrum relative to the bit rate of the transmission. The coded communication is then transmitted over a specified frequency band allocated to the node over which the node transmits data and over which the other node receives the data.

Abstract: Embodiments are directed to synchronizing time among nodes in a network. In one scenario, a first node receives a timing message which provides an indication of the current time as measured by a second node at transmission of the timing message. The first node determines the timing message propagation time between the first and second nodes using a determined transmission frequency of the timing messages, an internal clock reading of a clock that indicates the current time in the first node, and timing and frequency measurements obtained at the first and second nodes. The first node also applies a weighting factor to the current time of the first node to adjust the current time forward or backward, and combines the determined propagation time with the adjusted clock time of the first node to generate a new, synchronized time and transmission frequency, which is broadcasted to other nodes in the network.