Motorola Corporation

General Dynamics Decision Systems, Inc.

General Dynamics C4 Systems, Inc.

Kenneth Solomon Wreschner

Eric Jay Clelland

Scott David Blanchard

Marc David Brack

Robert Lee Trapp

Keith Petticrew

Terry Winningham

Douglas Paul Dobson

Christopher Bingham Johnson

Chad Rhamy

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.

System and method for adaptive matched filter signal parameter measurement

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.

Method and apparatus for adaptive signal compression

An active signal suppression system utilizes multi-rate recombinant transmultiplexer ( ) to suppress or cancel an undesired signal ( ) from a wideband composite signal ( ) to be applied to an analog to digital converter ( ). The transmultiplexer ( ) includes a first demultiplexer ( ), multiplier ( ), switch ( ), and multiplexer ( ). The demultiplexer and multiplexer each have a poly phase filter and Fast Fourier Transform pair which permit channelization and facilitate the generation of a cancellation signal ( ) for suppression of the undesired signal. Signal cancellation circuit ( ) receives the composite signal ( ) at one input ( ) and the cancellation signal ( ) at another input ( ). A minimum mean square estimation circuit (MMSE) ( ) and a second demultiplexer ( ) are included in a feedback circuit to provide error correction. A detector and automatic gain control circuit ( ) is coupled to the first demultiplexer ( ) and the multiplier ( ) to detect the undesired signal ( ) for controlling the switch and to provide automatic gain control to a variable gain amplifier ( ) connected to the signal cancellation circuit.

Active interference suppressor utilizing recombinant transmultiplexing

A transmitter ( ) offsets the transmission time and frequency of a burst transmission such that uncertainties in reception time and reception frequency are reduced. The transmitter includes an ephemeris store ( ) that includes ephemeris data for one or more possible intended receivers ( ). Orbits of possible intended receivers are propagated, and an intended receiver is selected. Transmission time offsets are generated as a function of transmitter location and intended receiver location. Transmission frequency offsets are substantially equal to a Doppler frequency derived from the transmitter velocity and the intended receiver velocity. Guard times and guard bands are reduced in size, resulting in greater available communications bandwidth and simpler receiver designs.

Burst communications method and apparatus

The present invention describes a communications system that utilizes frequency division multiple access (FDMA), code division multiple access (CDMA), and time division multiple access (TDMA) techniques for providing efficient use of frequency spectrum while supporting a large number of transmitters/users (2-6). Many users of the communications system share a common frequency band, but each transmit their respective message bursts (50) at different and specific times via a TDMA technique. To facilitate synchronization of the TDMA technique, each transmitter of the system is synchronized to a common timing reference (1) thereby abating the need to maintain synchronization between the transmitters (2-6) and receivers (8-12) of the system. Each TDMA message is then transmitted via a spread spectrum technique by multiplying (82) the message burst to be transmitted by a pseudo-random sequence of ones and zeroes (84) and transmitting such spread spectrum message burst for reception by one or more receivers within the system.

System and method for multiple access short message communications

An asynchronous communications receiver rapidly despreads and demodulating a short, low duty cycle CDMA burst signal. The receiver includes a multichannel despreader (20) for generating a plurality of despread signals (21) corresponding to timing offsets of a spreading code. The plurality of despread signals are respectively supplied to a plurality of demodulators (22) for demodulating each despread signal and for respectively generating a plurality of soft decisions for each demodulated bit values whereby each soft decision is proportional to the quality of the received signal. The plurality of soft decisions are supplied to both a first input of a plurality of multipliers (23) and to a plurality of inputs of a selector (28). The selector processes the soft decisions from each of the demodulators and generates a message indicator (29) when a message is present. The selector also generates a plurality of weights (W1-WN) corresponding to each of the plurality of soft decisions and applies these weights to a second input of the plurality of multipliers. The multipliers multiply the soft decision by its respective weight as supplied from the selector to generate output scaled signals. Finally, a combiner (30) sums the scaled signals to provide an output bit value for applying to a message extractor (32) which generates the actual received digital message.

Apparatus for despreading and demodulating a burst CDMA signal

A receiver performs rapid adaptive interference canceling for use in despreading multiple CDMA channels sharing the same RF front end. The receiver includes a buffer (22) for providing for overlapping time samples and rate adaptation, a windowing function (24) for improving interference rejection capability and a FFT (26) for calculating the input power spectrum. The receiver further includes a circuit (28, 30) to whiten the input power spectrum. The whitened power spectrum is multiplied (32) against the frequency domain version of different spreading sequences and the inverse FFT (40) of the product is performed. The output of this inverse FFT is buffered (44) to provide multiple despread output channels, with a plurality of code phases for further processing.

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Chandler, AZ, United States of America

Kenneth Solomon Wreschner