USA As Represented by Secretary of the Navy

James R Zeidler

Bernard Widrow

John M McCool

James W Bond

David W Stein

Stefen Hui

Robert H Hearn

Douglas M Chabries

Richard Nguyen

Charles A Hewett

Carl R Zeisse

John T Rickard

Robert R Kolesar

A A Louis Beex

Randall H Moore

Khosrow L Moazed

A signal processing method comprises: a) detecting sample auxiliary signals from an auxiliary signal and sample reference signals from a reference signal at different times; b) applying an auxiliary weight from a set of auxiliary weights to a corresponding sample auxiliary signal to create weighted sample auxiliary signals; c) applying a reference weight from a set of reference weights to a corresponding sample reference signal to create weighted sample reference signals; d) creating a summation value that represents the sum of the weighted sample auxiliary signals and the weighted sample reference signals; e) creating an error signal that represents the difference between the desired signal and the summation value; f) scaling the error signal to generate an update function; g) detecting the error signal; h) applying the update function to each of the auxiliary weights and reference weights; and i) returning to step (a).

Multichannel adaptive filter for noise and/or interference cancellation

The frequency domain kernel processor of the present invention comprises a cheduler for selecting samples from blocks of Fourier transform coefficients in a predetermined sequence and for outputting the selected samples as serial terms s and as parallel terms u. A transform processor is coupled to the scheduler to receive the terms s and u. The transform processor comprises transform calculators for calculating output values p and f as functions of terms s and u to model the interference and to reveal the desired signal, a first sum calculator for calculating a sum of p values, a second summing calculator for calculating a sum of f values, and a divider for calculating, the quotient of the sum of p values divided by the sum of f values. An output buffer stores the outputs of the divider for formatting as a spectral display.

Frequency domain kernel processor

A frequency domain kernel phase processor comprises an input buffer to st Fourier coefficients input from a Fourier transform of a communications signal. A communications signal suitable for processing by the present invention typically comprises a desired signal masked by a stronger interference signal having varying power that spans a range of frequency bins encompassing the desired signal. A scheduler inputs Fourier transform coefficients from the input buffer and generates a series of magnitude squares and symmetric phase differences for each frequency bin. The magnitude squares and the symmetric phase differences are output to phase transform processors which transform the symmetric phase differences to reveal the desired signal. The transformed outputs from the phase transform processors are output to an output buffer to be formatted and displayed.

Frequency domain kernel phase processor

A field effect transistor comprises a diamond substrate which has a p-type ion implanted region coterminous with a surface of the diamond substrate, wherein the ion implanted region has a hole concentration in the range of 1.times.10.sup.15 to 1.times.10.sup.17 holes/cm.sup.2, and a hole mobility equal to or greater than 1 cm.sup.2 /V-sec; spaced apart source and drain electrodes formed over the p-type ion implanted region on the surface of the diamond substrate; an electrically insulating material formed over the p-type ion implanted region on the surface of the diamond substrate between the source and drain electrodes; and a gate electrode formed on the surface of the insulating material.

Ion implanted diamond metal-insulator-semiconductor field effect

A method is disclosed for fabricating ohmic contacts on semiconducting diamond. A carbide forming metal is deposited over a surface of the semiconducting diamond. In some applications, one or more layers of an intermediate metal are deposited over the carbide forming metal. A corrosion resistant metal is then deposited over the intermediate metal, if present, or the carbide forming metal. The semiconducting diamond and metals are heated in an inert environment at a temperature anywhere from 350 to 1200 degrees Celsius.

Method for fabricating ohmic contacts on semiconducting diamond

An apparatus and technique reduces the data transmission rate required to ansmit acoustic signals from undersea sensors to remote monitoring locations without degrading the surveillance information content of the signals. The signals are digitized and fed to an adaptive line enhancer (Wiener filter) which processes them so that a fast Fourier transform (Karhunen-Loeve approximation) coefficient generator can feed representative signals to a programmable quantizer and a signal averager. When significant shifts are detected in the fast Fourier transform coefficient variances, responsive signals are generated by the programmable quantizer for adaptive bit allocation. An interconnected multiplexer transmits multiplexed signals to the remote monitoring station where the inverse of the foregoing allows an analysis of the acoustic signals being monitored.

Adaptive quantizer for acoustic binary information transmission

A correlator which is capable of correlating two or more signals of unknown frequency and bandwidth receives inputs on each of two or more channels. For the case of a two-channel, or pairwise, correlator the two channels are designated a first channel and a second channel. For the pairwise correlator, a first adaptive linear predictive (ALP) filter filters the input signal from the first channel and a second ALP filter filters the input signal from the second channel, the two output signals of the filters being x(k) and y(k). The adaptive linear predictive filter is an adaptive time-domain digital filter which adapts its impulse response according to a certain algorithm. The filter output represents an adaptive linear predictive estimate of the current input value, based on many past inputs. The input signals to the two channels of the pairwise correlator may correspond to sensor outputs from two or more widely separated sensors. The two output signals x(k) and y(k), are correlated in a pairwise correlator to result in a signal which corresponds to an estimate of the magnitude-squared coherence between the signal x(k) and a time-delayed, frequency-shifted, version of the signal y(k).

Adaptive correlator

An adaptive detector comprises an adaptive linear prediction filter (ALPF) nd a detection processor. The adaptive filter comprises an input filter, adapted to receive an input signal x(k) and delay it by a time .DELTA.. An L-point, or L-tap, adaptive filter has an input connected to the output of the input filter, a signal r(k) appearing at the output of the filter. A means for summing has two inputs, one for receiving the signal x(k) and the other for receiving an inverted signal from the adaptive filter, the output of the summer being an error signal .epsilon.(k). A feedback amplifier, whose input is connected to the output of the summer, takes a portion 2.mu., of the output signal .epsilon.(k) and feeds it back to the adaptive filter, thereby modifying the tap weights of the adaptive filter. The detection processor comprises a circuit, whose input is connected to the output of the adaptive filter, to receive the signal r(k), for performing a K-point discrete Fourier transform (DFT) on the signal r(k). A spectral analyzer, whose input is connected to the output of the DFT circuit, performs a spectral analysis on the output signal.

Adaptive detector

An input signal X(j) is fed directly to the positive port of a summing function and is simultaneously fed through a parallel channel in which it is delayed, and passed through an adaptive linear transversal filter, the output being then subtracted from the instantaneous input signal X(j). The difference, X(j)-Y(j), between these two signals is the error signal .epsilon.(j). .epsilon.(j) is multiplied by a gain .mu. and fed back to the adaptive filter to readjust the weights of the filter. The weights of the filter are readjusted until .epsilon.(j) is minimized according to the recursive algorithm: ##EQU1## where the arrow above a term indicates that the term is a signal vector. Thus, when the means square error is minimized, W.sub.(j+1) =W.sub.(j), and the filter is stabilized.

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San Diego, CA, United States of America

James R Zeidler