The Aerospace Corporation

David M Schwartz

Samuel Joseph Curry

Masahiro Sayano

Michael S Cheung

Kristine Y Tsai

Oliver D Ambrosia

John F Collins

A system comprises a transmitter configured to receive at least one message that corresponds to at least one set of data received from at least one user. The transmitter includes a modulating device that is configured to generate at least one signal that corresponds to the received message, wherein the signal includes at least one sequence of a plurality of hopping patterns. A receiver is coupled to the transmitter, wherein the receiver is configured to receive the signal. The receiver includes a demodulating device that is configured to identify the sequence of the hopping patterns and to determine at least one variable that corresponds to the sequence of the hopping patterns. The demodulating device is further configured to generate at least one output that is based on the determined variable, wherein the output is displayed such that at least one other user is enabled to view the output.

Systems and methods for use in communicating data

A detection system includes a receiver configured to generate a receiver signal representative of detected electromagnetic energy, and an analog-to-digital converter (ADC) configured to generate a plurality of signal samples based on the receiver signal. The detection system also includes a detection module configured to identify a plurality of sample offsets for the signal samples, and execute a plurality of autocorrelation functions on the signal samples to provide an output of each of the autocorrelation functions, wherein each autocorrelation function is executed on at least a portion of the signal samples identified by a sample offset of the plurality of sample offsets. The detection module is also configured to compute a sum of the autocorrelation function outputs, normalize the sum of the autocorrelation function outputs, and determine whether a signal of interest is present within the electromagnetic energy based on the normalized sum.

Detection system, controller, and method of detecting a signal of interest

A method for acquiring Global Positioning System (GPS) code includes describing GPS code as a Low Density Parity Check (LDPC) code, and decoding the LDPC code to achieve acquisition by directly solving for the correct code phase.

Acquisition and encoding of GPS codes

A convolutional despreading method takes advantage of the algebraic structure of the spreading code and applies convolutional type decoding to received signal chip symbols to rapidly estimate code phase, preferably used for rapid acquisition of direct sequence spread spectrum signals. Modeled reduced-state structures having branchword transitions are used to reduce metric computations. The reduced state structures and algebraic structures provide additive constraints for modifying convolutional sequential metric searching for improved speed of code phase determination. The convolution despreading method preferably uses a modified convolutional sequential search algorithm, such as, a modified Fano Tree convolutional sequential search, or, a modified Viterbi trellis convolutional sequential search. The method can also directly determine a modulated data stream, when present, to provide demodulated data without necessarily performing conventional cross correlation despreading. A metric state processors then functions as an ad hoc despreader. The convolutional despreading method is particularly useful in direct sequence spread spectrum systems where the use of chip spreading codes requires code phase determination for rapid acquisition of direct sequence spread spectrum signals.

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Northridge, CA, United States of America

David M Schwartz