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: 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: 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: 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: The present invention is generally directed to using code division multiplexing (CDM) on the beacon and traffic channels while lowering the power of the beacon channel so that it rides under the traffic channel and becomes very difficult to detect. In this way, the beacon channel can contain sensitive information for decoding the traffic channel while remaining hidden from unintended recipients. By hiding the beacon channel, the CDM technique can be particularly beneficial in adaptive waveform systems where sensitive traffic channel acquisition information is regularly transmitted to the receiver.

Abstract: A digital electronic message comprising datawords to be transmitted in a communications system can be encoded prior to transmission using an asymmetric error detection coding scheme. The coding scheme is asymmetric because the coding scheme includes multiple codeword groups each with a different minimum coding distance. The codewords in a group having a greater minimum coding distance can correspond to datawords that have a relatively high susceptibility to transmission errors. The codewords in a group having a lesser minimum coding distance can correspond to datawords that have a relatively low susceptibility to transmission errors.