The Aerospace Corporation

Samuel Joseph Curry

Robert Bernhard Dybdal

Flavio Lorenzelli

David M Schwartz

Christopher Joseph Clark

Don J Hinshilwood

Lan Xu

Masahiro Sayano

John F Collins

Kristine Y Tsai

Keith M SooHoo

Under one aspect of the present invention, a system for processing a group of signals and interference includes (a) an analog-to-digital (A/D) converter for digitizing the group of signals and the interference; (b) a Fourier transform circuit for obtaining a Fourier transform of the digitized group of signals and the interference and to provide as output spectral bins, at least one of which contains the interference; (c) a power analysis circuit for comparing the collective power level of the spectral bins to a predetermined threshold, and if the collective power level exceeds the predetermined threshold, and for excising at least one bin that contains the interference; and (d) an inverse Fourier transform circuit for obtaining an inverse Fourier transform of the remaining spectral bins and outputting a digitized group of signals less the interference in any excised spectral bin.

Systems and methods for reducing narrow bandwidth interference contained in broad bandwidth signals

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

Embodiments of the invention provide systems and methods for systems and methods for adaptively canceling interfering signals generated by a transmission antenna. Under one aspect, a system includes: an auxiliary antenna co-located with the main antenna, the auxiliary antenna configured to transmit an auxiliary signal to the victim antenna; a sensing antenna located on a line-of-sight path between the transmission antenna and the victim antenna, the sensing antenna configured to receive a composite of the interference and the auxiliary signal, and to output a first signal based on the received composite; a controller comprising an input coupled to the sensing antenna and configured to receive the first signal, the controller being configured to adjust at least one of an amplitude, a phase, a polarization, and a frequency characteristic of the auxiliary signal based on the first signal so as to reduce the composite of the interference and the auxiliary signal received by the sensing antenna.

Systems and methods for protecting a receiving antenna from interference by a transmitting antenna

Systems and methods for increasing communications bandwidth using non-orthogonal polarizations are provided herein. Under one aspect, a method of transmitting M independent signals, where M is at least 3, includes receiving the M signals from respective sources; at a transmitter polarization module, obtaining first and second linear combinations of the M signals; providing the first and second linear combinations to first and second input ports of a transmitter antenna; and transmitting with the transmitter antenna the first linear combination at a first polarization and the second linear combination at a second polarization orthogonal to the first polarization. The method may further include receiving at a receiver antenna the first linear combination at the first polarization, and the second linear combination at the second polarization; obtaining at receiver circuitry the M signals based on the received first and second linear combinations; and outputting the M signals on respective output ports.

Systems and methods for increasing communications bandwidth using non-orthogonal polarizations

Systems and methods for increasing communication throughput by superimposing multiple signal components in the same bandwidth are disclosed. Cochannel interference is reduced by using signal separation algorithms. The signal separation algorithms may use both a priori information about the superimposed signals and measured channel parameters. In addition, error correction encoding and interleaving may be used to reduce signal power and obviate the need for ideal signal separation.

Methods and systems for increased communication throughput

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

An apparatus includes antenna elements configured to receive a signal including pseudo-random code, and electronics configured to use the pseudo-random code to determine time delays of signals incident upon the antenna elements and to compensate the signals to coherently combine the antenna elements.

Coherently combining antennas

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.

Convolutional despreading method for rapid code phase determination of chipping codes of spread spectrum systems

An adaptive transmitting antenna includes an array of antenna elements having respective weighing coefficients to respectively transmit components of a transmit signal which reduces locally reflective multipath signals received by the transmitting antenna to sample respective reflective components which are summed and cross correlated to a time delayed transmit signal to produce a correlated output indicative of the reflective signal strength. The correlated output is minimized by adjusting the weighing coefficients so that the transmit signal has reduced multipath distortions. The adaptive technique is well suited for mobile telephone transmitters moving about objects tending to reflect and distort transmitted signals.

Adaptive transmitting antenna

An adaptive receiving antenna reduces interference arriving in the main beam of the antenna by redirecting the antenna beam away from the interference source. The receiving antenna projects the main beam to receive desired source signals from a source direction and may receive interfering signals from the interfering source. The antenna system measures the strength of the source signal and interference signal for controlling the direction of the main beam to marginally decrease the received desired source signal while substantially decreasing the received interfering signal to increase the desired source signal to interfering signal ratio so that the desired source signal can be received in the presence of interference.

Growing community of inventors

Redondo Beach, CA, United States of America

Samuel Joseph Curry