L-3 Communications Corporation

Micron Communications, Inc.

Micron Technology Incorporated

Lockheed Martin Corporation

Unisys Corporation

Dan M Griffin

Thomas R Giallorenzi

Johnny M Harris

Richard B Ertel

Eric K Hall

Lee A Butterfield

George Edward Pax

Samuel Charles Kingston

James E O'Toole

Randal R Sylvester

Philip L Stephenson

David W Thorson

Teren G Jameson

Sam Kingston

Michael J Hurst

David J Moore

David G Landon

Zachary C Bagley

L Andrew Gibson

Jeffrey B Bench

DeLon K Jones

Lyman D Horne

Anthony D Smith

Steven B Perkins

Tom R Giallorenzi

David William Matolak

Kenneth C Bark

Scott C Smedley

Kyle L Henderson

Stephen A Laraway

R William Steagall

Leroy Andrew Gibson, Jr

Rolf K Thompson

A data alignment method is provided by iteratively increasing the delay of each data input line of a system component until a test signal transmitted on each data input line is received at the system component at substantially a predetermined time.

System and method for data input alignment

A digital communications receiver can comprise a digital filter that can be configured and later reconfigured multiple times as, for example, a matched filter, an equalizer, a matched filter and equalizer, or the like. For example, the digital filter can be initially configured as a matched filter for use with a correlation module to detect pilot symbols. Detected pilot symbols can be utilized to estimate characteristics of a channel from the distant transmitter to the receiver, and the estimated channel characteristics can be used to determine coefficients for an equalizer for reducing channel distortion in future transmissions received over the channel. The digital filter can then be configured as an equalizer or a matched filter and equalizer. If the later, the digital filter can both equalize incoming transmissions from the distant transmitter and, with a correlation module, identify any pilot symbols in the transmissions. Any detected pilot symbols can be utilized to determine again equalizer coefficients for equalizing transmissions received over the channel, and the digital filter can be updated accordingly.

Decoupled equalizer in a communications receiver

A digital signal processing (DSP) apparatus is used for processing a plurality of different signals. The DSP apparatus includes a DSP module configured to perform a DSP algorithm on samples of the signals. The DSP apparatus also has a parameter memory that includes a plurality of memory cells. The parameter memory has a signal number input and a parameter output. The parameter output is connected to the DSP module. The parameter memory is configured to output to the parameter output a parameter corresponding to a signal identifier at the signal number input.

Digital signal processing apparatus having parameter memory device and process of using such

A digital signal processing (DSP) apparatus can be used to process a serial stream of digital signal samples of a plurality of 'n' number of different signals. The DSP apparatus can include a DSP module configured to perform a DSP algorithm on digital signal samples of the signals. The DSP apparatus can have a delay memory with an 'n' number of memory cells that each corresponding to one of the signals. The delay memory can also have a digital signal sample input connected to said initial input of said DSP module, a signal-number-in input, a signal-number-out input, and a digital signal sample output connected to said delay input of said DSP module. The delay memory can be configured to store a digital signal sample at the digital signal sample input in a memory cells identified by a signal identifier at said signal-number-in input. The delay memory can also be configured to output at the digital signal sample output a digital signal sample stored in a memory cells identified by a signal identifier at the signal-number-out input.

Digital signal processing apparatus with a delay memory having a plurality of memory cells and process for using same

An apparatus and method for correlating a signal over a correlation interval while accommodating spreading code frequency offset is described. In one embodiment, the apparatus includes a plurality of correlators, where each correlator forms a correlation result corresponding to a unique code frequency offset hypothesis. Each correlator selects samples from a tapped delay line at a tap position moved along the delay line at a rate corresponding to the correlator unique code frequency offset hypothesis.

Correlation apparatus and method for accommodating spreading code frequency offset

A first node seeking entry into a secure spread spectrum communications network sends a discovery burst at a low rate, and sends traffic bursts at a higher rate to exchange data rate for range. A receiving node receives discovery bursts via an omni-directional link and transmits and receives traffic bursts via directional links. As a node within the network detects a fading signal, it transmits a discovery burst at low rate on both its uplink and downlink channels. Other nodes may reply via the original uplink channel, and the fading node updates a list of candidate nodes through which it can relay through the network to its intended recipient by reversing the link direction of its original uplink and original downlink channels.

Fast and long range node discovery in spread spectrum networks

A system and method for detecting a presence and frequency offset of a spread spectrum radio frequency signal is disclosed. The method comprises receiving the spread spectrum radio signal. The signal can be sampled to form a plurality of signal samples. Each signal sample can be multiplied by a complex conjugate of a proximate signal sample to form a plurality of signal sample pairs. The signal sample pairs can be summed over a predetermined dwell time period to form a data vector having a magnitude and angle offset to enable detection of the signal and to enable a frequency offset between the spread spectrum radio frequency signal and a receiver frequency reference to be determined.

System and method for detecting a presence and frequency offset of a spread spectrum radio frequency signal

Correlation apparatus and method for accomodating spreading code frequency offset

A system and method for detecting a spread spectrum encoded message within a received signal is described. The spread spectrum encoded message has an unknown code phase, unknown code frequency offset, and unknown carrier frequency offset. A plurality of code phase hypotheses, code frequency offset hypotheses, and carrier frequency offset hypotheses are searched in parallel. The unknown code phase, unknown code frequency offset, and unknown carrier frequency offset may also be estimated.

Spread spectrum detection system and method

A technique for receiving multiple spread spectrum bursts is disclosed. Each spread spectrum burst is encoded with a common spreading code and may include an individual message and unique signal parameters. The technique includes the detection of the spread spectrum encoded bursts and estimation of the reception signal parameters. A single one of a plurality of burst receivers is assigned to each detected burst to extract the individual message of the detected burst.

System and method for receiving spread spectrum encoded bursts using a common spreading code

A first node initiating communications with a second node already in a secure network sends a discovery burst having a preamble portion and a payload portion. The preamble portion is sent at a varying frequency between high and low thresholds that are reflective of Doppler uncertainty between the nodes. The second node continuously listens at a frequency, termed an acquisition frequency. A data sequence in the preamble portion, known to the second node, is received and used to determine the receive instant in the preamble portion, and thereby compare against the known frequency ramp to determine the frequency at which the payload portion will be received. Preferably, the first node varies the preamble portion between thresholds more than once within the time span of a single preamble portion, and the preamble and payload portions are spread with different spreading codes. The preamble portion may also be disguised with noise generated by the first node.

Method and apparatus to initiate communications between an unknown node and an existing secure network

A parallel correlator and method includes temporarily storing in a series of P sequence registers, each of length R, serial bit-sequences of a code of length N=P*R. In a first-level of processing, certain unique bit sequences are inverted to reduce the number of unique bit sequences by half. Identical bit-sequences are then combined and temporarily stored in a first-level sub-accumulation register. Alternatively, bit sequences differing by only one bit may be combined in a common first-level sub-accumulation register. Further levels of similar processing may be imposed, where each subsequent level taps and inverts only a portion of the bits in the above level of processing, thereby reducing the number of unique bit sequences. Finally, all negative energy is combined in one register position, inverted, and added to all positive energy in the other register positions. When the spreading code was aligned among the series of sequence registers, the energy is added coherently and an energy peak is output, indicating alignment of the spreading code in the sequence registers.

Sub-sequence accumulation filter and method

A correlator despreads a P/N long code constructed from two or more constituent codes A, B, C having N, M and L elements respectively. In a third stage, L filter taps decorrelate elements of the third constituent code from the input received signal, leaving elements of code AB. The outputs of the third stage delay line are summed and input into a second stage delay line having M filter taps to decorrelate the elements of the second constituent code from the input to the second stage, leaving elements of code A. The outputs of the second stage delay line are summed and input to a first stage delay line having N filter taps. The output of the first stage delay line is summed and input into a shift register. An energy peak in the shift register indicates the phase of the P/N elements in the register is proper.

Multi-rate spread spectrum composite code

A system and method for determining a fine frequency offset of a composite code spread spectrum signal is disclosed. The method includes despreading at least one component of the composite spread spectrum signal to form a partially despread composite spread spectrum signal. A set of on-time samples are selected from the signal. The set of on-time samples are rotated by a predetermined frequency amount. The set of rotated samples are placed into a plurality of frequency bins, with each frequency bin representative of a different frequency estimate. An energy for the signal in each frequency bin is determined to find the bin having the greatest energy.

System and method for determining a fine frequency offset of a received signal

A system for the efficient use of CORDIC rotators is provided. The system includes at least one first rotator operating in vector mode and includes a sign storage buffer. The system also includes at least one bit inverter coupled between the first rotator and a second rotator, the second rotator operating in rotation mode.

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Bountiful, UT, United States of America

Dan M Griffin