Abstract: An RF receiver (12) includes a channel estimator (52). The channel estimator (52) includes a channel estimation filter (82), error signal generator (84), and normalized Least-Mean-Square (NLMS) filter-definition generator 36. The filter (82), error generator (84) and NLMS filter-definition generator (86) function together as an adaptive estimator. An error signal (90) is formed with a received signal (48). The filter (82) filters an estimated transmit signal (74) constructed from lower confidence decision data (66) and higher confidence known preamble data (30?). .An adaptive filter definition (94) is formed in a feedback, loop which minimizes correlation between the estimated transmit signal (74) and the error signal (90). A convergence signal (122) is modulated in synchronism with the changes between lower and higher confidence data in the estimated transmit signal (74).

Abstract: A symbol synchronizer (100) is provided for a software-defined communications system (10). The symbol synchronizer (100), when integrated into either a pre- or post-detection diversity signal combiner (108, 208), enables highly accurate signal synchronization with minimal added system complexity. The symbol synchronizer (100) includes a single complex sliding window-matched filter (102) for filtering an input digital signal with a match filtering function based on predetermined signal transfer function characteristics to average out receiver noise from the signal. A signal delay bank (84) includes a plurality of delay blocks each for delaying the digital signal filtered by the single matched filter for a predetermined number of samples. A complex correlator (88) correlates the digital signal filtered by the single complex sliding window matched filter (102) and delayed by the complex correlator (88) with a correlator reference signal, and selects an index of a path having a peak correlator value.

Abstract: A communication network (22) includes a central node (30) loaded with a trusted key (26) and key material (56) corresponding to an asymmetric key agreement protocol (48). The network (22) further includes vulnerable nodes (32) loaded with key material (69) corresponding to the protocol (48). Successive secure connections (68, 70) are established between the central node (30) and the vulnerable nodes (32) using the key material (56, 69) to generate a distinct session key (52) for each of the secure connections (68, 70). The trusted key (26) and one of the session keys (52) are utilized to produce a mission key (39). The mission key (39) is transferred from the central node (30) to each of the vulnerable nodes (32) via each of the secure connections (68, 70) using the corresponding current session key (52). The mission key (39) functions for secure communication within the communication network (22).

Abstract: An embodiment of a method for parameterizing an input signal includes non-linearly transforming the input signal, removing higher order terms by passing the input signal through a low pass filter to produce a linear combination of data symbols and DC components, solving for the DC components, separating a plurality of mixed baseband signals from the input signal, and coordinate transforming each of the separated signals from polar coordinates to Cartesian coordinates. An embodiment of a receiver includes a non-linear transform operator receiving a digitized input signal and adapted to produce a linear combination of data symbols, DC components, and carrier effects; a low-pass filter for removing higher order terms; a separator unit for separating the plurality of mixed baseband signals; and a coordinate transform for converting the separated signals from polar coordinates to Cartesian coordinates.

Abstract: A programmable electronic device (10) stores a number of cipher-text software modules (14) to which access is granted after evaluating a user's token (55, 80, 82), a software-restriction class (58) for a requested software module (14), and/or a currently active access-control model (60). Access-control models (60) span a range from uncontrolled to highly restrictive. Models (60) become automatically activated and deactivated as users are added to and deleted from the device (10). A virtual internal user proxy that does not require users to provide tokens (80, 82) is used to enable access to modules (16) classified in a global software-restriction class (62) or when an uncontrolled-access-control model (68) is active. Both licensed modules (76) and unlicensed modules (18,78) may be loaded in the device (10). However, no keys are provided to enable decryption of unlicensed modules (18,78).

Abstract: A feed assembly (26) for an antenna system (38) includes a first feed element (30) that propagates a first beam (32) and a second feed element (34) that propagates a second beam (36). The second feed element (34) is collocated with, but displaced vertically from, the first feed element (30) to achieve angular diversity in elevation. Each of the feed elements (30, 34) has an elongated conical shape and is formed from a dielectric material. The feed assembly (26) operates within the Ku-band frequency range to yield high gain, collimated, independent first and second beams (32, 34). The feed assembly (26) can be implemented in a tropospheric scatter communication system (38) in conjunction with a reflector (22) to provide concurrent transmit and receive capability via the two independent, angularly separated first and second beams (32, 36).

Abstract: A multi-carrier communication system (400) groups subchannels (802) into different quality-of-signal (QoS) regions (804). An unconstrained optimization process (1200) is performed independently for the subchannels (802) of the different QoS regions (804) to allocate bit rates and power to the individual subchannels (802) so that the indicated QoS will result. Coders (504, 508, 512, 516, 1700) partition and error-correction encode source information using encoding schemes matched to the different QoS regions (804). A set (1100) of only a few directed QoS partition vectors (1102) direct the unconstrained optimization process (1200) to attempt bit-rate and power allocations on only a few promising groupings of subchannels (802) and QoS regions (804). An iterative process may take place between bit-rate and power allocation on one side and source information coding on the other for different directed QoS partition vectors (1102) to identify the best solution.

Abstract: A separation management system (32) for governing interaction between code within a code base (50) operable on a computer (30) determines a region in a memory (44) of the computer (30) in which the code base (50) resides and defines container boundaries (118, 124, 130, 135) in the region for a plurality of containers (95). Each of the containers (95) contains subsets of the code (120, 126, 132, 137) that cannot be trusted. A policy (94) is created that governs interaction between the subsets of the code in the containers (95). The code base (50) is executed in the computer (30) in accordance with the policy (94) such that the subsets of code within the containers (95) are prevented from accessing code outside of their respective containers (95) when access is disallowable as indicated by the policy (94).

Abstract: A system (100) and method for the reception and despreading of a code-division multiple access (CDMA) global positioning system (GPS) signal (200), or other direct-sequence spread-spectrum (DSSS) signals, is provided. An antenna array (102) receives the DSSS signal (200) over a plurality of elements (116). A preprocessor (104) down converts and digitizes the DSSS signal (200) to produce a signal stream (202) in the time domain. An FFT (106) transforms the signal stream (202) to the frequency domain. A beam former (108) generates a reception beam (201) for the DSSS signal (200) in the frequency domain, and also implements a narrowband frequency notch, if desired. A despreader (110) despreads the transformed signal stream (204) in the frequency domain. An IFFT (112) transforms the despread signal stream (208) back to the time domain. And a postprocessor (114) converts the transformed despread signal stream (210) into a desired received signal stream (212) in the time domain.

Abstract: A multi-carrier communication system (400) groups subchannels (802) into different quality-of-signal (QoS) regions (804). An unconstrained optimization process (1200) is performed independently for the subchannels (802) of the different QoS regions (804) to allocate bit rates and power to the individual subchannels (802) so that the indicated QoS will result. Coders (504, 508, 512, 516) partition and error-correction encode source information using encoding schemes matched to the different QoS regions (804). A set (1100) of only a few directed QoS partition vectors (1102) direct the unconstrained optimization process (1200) to attempt bit-rate and power allocations on only a few promising groupings of subchannels (802) and QoS regions (804). An iterative process may take place between bit-rate and power allocation on one side and source information coding on the other for different directed QoS partition vectors (1102) to identify the best solution.

Abstract: A robust and flexible system for signal parameter measurements in the field of signal processing dynamically uses signal parameters from previous signal detections and parametric priorities to adaptively control and process the signal in an efficient and reliable manner. The system provides for improved fine grain signal parameter measurements through the use of adaptive arbitration to control signal processing. The system improves measurement accuracy for various signal characteristics including pulse width, amplitude, frequency and timing information. The system also provides signal parameter measurements while requiring less power, size, and weight than conventional systems.

Abstract: A method and system is disclosed for cross-correlating information between the domains of network management and network security. The present invention discloses a model representing the security domain that can be used to define relationship between devices and events in the security domain in the context of a managed network. With this model, a security topology of the network security domain can be created based on the current implementation of the network. This model and topology allows the present invention to correlate relevant network security information to diagnose problems as they occur by using events detected within the network. Using the disclosed method and system for correlating information in the network security, the present invention provides further enhancements over conventional methods by cross-correlating information between the network security and network management domains to aid in their detection and analysis of problems.

Abstract: A method and apparatus for adaptive signal compression of unknown signals uses minimal power and bandwidth to transmit data. The method provides adaptive signal compression with minimal loss and distortion by extracting only information of interest and recreating the full signal. The method uses a single resolution filter bank for channelizing a data stream for transmission. The method removes unwanted or unneeded information before transmitting the data by using fidelity and user controls and detection capabilities. The method provides significant signal compression where signals are sparse in frequency, time, or both and does not rely on a priori knowledge of the signal. After transmission, the system generates a signal using the data received as well as filling in the non-transmitted portions of the signal by manipulating the transmitted data. The system then formats the signal into the original data stream using a reconstruction filter bank.

Abstract: An analog-to-digital converter (“ADC”) architecture as described herein utilizes a digital signal processor having suitably configured waveform prediction logic that can predict expected types of input signals. The ADC architecture subtracts the predictable signal components from the analog input signal prior to the analog-to-digital conversion, which extends the dynamic range of the ADC employed by the ADC architecture. In practice, the ADC architecture can subtract predictable strong signal components from an analog input signal such that the ADC can apply its available dynamic range to the remaining weak signal components.

Abstract: A knowledge-based hierarchical method for detecting regions of interests (ROIs) uses prior knowledge of the targets and the image resolution in detecting ROIs. The result produces ROIs that contain only one target that is completely enclosed within the ROI. The detected ROI can conform to the shape of the target even if the target is of irregular shape. Furthermore, the method works well with images that contain connected targets or targets broken into pieces. The method is not sensitive to contrast levels and is robust to noise. Thus, this method effectively detects ROIs in common real world imagery that has a low resolution without costly processing while providing fast and robust results.

Abstract: A method and system for detecting GPS interference is disclosed. In one exemplary embodiment, a method for detecting interference in a Global Positioning System comprises the steps of receiving at least one satellite signal from one or more satellites in a Global Positioning System; identifying a noise floor value from the at least one satellite signal; identifying an interference signal based on the noise floor value; determining an interference value for the interference signal from the noise floor value wherein a level of the noise floor value corresponds to a level of interference; and providing the interference value to at least one user for informing the user of the interference signal.

Abstract: The present invention pertains to a battery adapter that may include a battery housing. The housing may be made essentially of a substantially rigid material. This housing may be configured to hold one or more batteries. A bottom portion may be provided and may be configured to be disposed at a first end of the housing. The bottom portion may include a venting portion configured to permit the flow of gasses from within the housing to the exterior of the housing. Alternatively, the venting portion may be located anywhere on the housing. A membrane may be disposed over the venting portion. This membrane may be configured to rupture when a high pressure builds up within the housing.

Abstract: The present invention relates to an agent for distributed networking and a processor-readable software code. The agent may include, for example, a cosite analyzer, an EMI sniffer, an asset controller module, an asset discovery module, and a link negotiator. The agent may be configured to initiate and optimize network configurations for radio communications systems based on parameters. The software code may receive data associated with a network plan, may determine if any planned links are included in the network plan and may establish connectivity of a confirmed link between at least two nodes in the network. Additionally, the software code may determine if a non-planned link should be added to the network and may establish connectivity for the non-planned link based on a priority associated with the non-planned link.

Abstract: A method and apparatus for storing and updating information in a multicast system is represented by a tree data structure. The method and apparatus defines and populates a set of keys for each node in the tree. The number and content of the set of keys may vary depending on whether a node is an internal node or a leaf node. The method and apparatus can use these keys to update information in some leaves while excluding the information from other leaves. The method and apparatus can analyze the system to determine a minimum number of messages that need to be sent in order to update the information stored in leaves. The method and apparatus then sends the minimum number of messages throughout the system where each message can only be read by a particular subset set of the leaves that have the correct key to read that particular message.

Abstract: A satellite positioning system and method of maintaining the positioning and clock data of a satellite using as few as one or two monitoring stations is disclosed. Each satellite of the positioning system determines its own positioning and clock data relative to other satellites in a constellation. One or more satellite signal monitoring stations receive relative clock and positioning data from a plurality of satellites in the constellation. A constellation solution which is applicable to all of the satellites in the constellation is calculated by treating the constellation as a rigid body at a fixed point in time. The constellation solution is transmitted to a satellite of the constellation which disseminates the solution through a crosslink network within the constellation for use by each satellite to update its individual positioning and clock data as needed.