USA As Represented by Secretary of the Navy

Thomas W Schlosser

James W Bond

Carey E Priebe

William Y Velez

David J Marchette

George A Evanoff, Jr

Karl J Cain

A masked signal transceiver of the present invention comprises a transmitter for transmitting a combined signal of a primary communications signal and an attenuated secondary communications signal occupying substantially the same frequency band concurrently. A receiver receives the combined signal and demodulates the primary communications signal to extract the primary communications signal information. An adaptive locally optimum processor separates the secondary communications signal from the combined signal. The secondary communications signal is then demodulated to extract the secondary communications signal information.

Masked signal transceiver

A signal quality measurement device of the present invention comprises a deviation function for determining a measured deviation value from envelope amplitude samples of a communications signal and a table function of deviation values versus signal-to-noise ratios computed from a statistical model of atmospheric noise for finding a signal-to-noise ratio that corresponds to the measured deviation value.

Signal quality measurement device

Processors which process baseband received signal sample amplitudes and ones which process baseband received sample phases are combined in a single general processor which cancels a greater variety of interference than any of the individual processors incorporated into it. This processor combines a wide-range of processors, for example, processors which filter baseband in-phase/quadrature sample amplitudes and phases. This general processor performs against any interferer as well as, or better than, the best of the processors it includes. The general processor assesses individual processor outputs and weights these so that those processors with the best interference suppressed outputs are utilized to form an interference suppressed output.

Adaptive processor integrator for interference suppression

A system for encoding and decoding a binary encoded text message using coxt-based error detection and correction implements the stops of: a) defining a dictionary of m dictionary words, W.sub.i, where each dictionary word is assigned a unique binary code word, represented by a series of bits, and an identifier, IDFR.sub.i such that for any two words W.sub.p and W.sub.q from the dictionary, if IDFR.sub.p =IDFR.sub.q, then the binary code word for the word W.sub.p differs from the binary code word for the word W.sub.q by more than one bit, and where i, p, and q are each an index from 1 to (m-1), and m is a positive integer; b) receiving a message comprised of words selected from the dictionary; c) encoding the message to form an encoded message comprised of selected ones of the dictionary words; d) transmitting the encoded message; receiving the encoded message; e) decoding the encoded message to form a decoded message comprised of decoded message words; f) displaying the decoded message words; and g) displaying candidate words from the dictionary having code words one bit different from the code words associated with suspected erroneous words selected from the decoded message words if the decoded message includes any suspected erroneous words.

Context based error detection and correction for binary encoded text

Signals are processed along two paths, one determining the optimum freque band from which atmospheric noise will be analyzed and the other which performs statistical analysis of the frequency band found to be optimum. The band-setting path may include broadband filtering to limit a search to a desired band. A fast Fourier transform (FFT) sorts the analog-to-digitally converted signals into consecutive frequency bands identified herein as frequency bins. The magnitude of the signals falling within each frequency bin is determined and the average frequency bin magnitude is ascertained. Broadband peaks are searched by noting which frequency bin magnitudes are a predetermined amount over the average frequency bin magnitude. These frequency bins are 'marked' and the bins are then searched to determine the longest series of frequency bins between marks, thereby determining the widest frequency band bounded by broadband signals. In the statistical path, band path filtering is used to eliminate the broadband signals by setting the lower and upper cut-off frequencies according to the optimum frequency band found. The analog to digitally converted signals are fast Fourier transformed and the magnitude of the frequency bins are determined. Harmonics are excised through calculating the average magnitude of the frequency bins and normalizing any frequency bin with a magnitude greater than a predetermined amount over the average frequency bin magnitude.

Self-adjusting statistical noise analyzer with interference suppression

An interference suppression system utilizes an adaptive locally optimum detection algorithm derived from kernel estimation. By utilizing this algorithm in the processor of the invention, fewer receive samples are required to obtain useful estimates of required probability density functions. The new adaptive locally optimum detection algorithm is useable in applications involving very high sampling rates and is thus suitable for rapidly and radically changing interference environments encompassing a wide range of frequencies.

Kernel adaptive interference suppression system

A two-dimensional interference suppression system utilizes adaptive locally optimum detection algorithms derived from kernel estimation. By using these algorithms in the process of the invention, fewer receive samples are required to obtain useful estimates of probability density functions. The new adaptive locally optimum detection algorithms lend themselves to use with simple processors permitting applications involving very high sampling rates.

Two-dimensional kernel adaptive interference suppression system

A method and apparatus are provided for suppressing interference from a sence of bandspread communication signals received by a radio receiver. Each sample is defined as a vector having signal and interference vector components. The interference vector component is such that: 1) the interference dominates the signal vector component, and 2) the phase of the interference vector components in the sequence changes slowly with time. Interference is suppressed while a portion of the signal vector component that is normal to the interference vector component is estimated as an indication of the bandspread communication signal. To do this, a phase angle is determined for each sample based upon each sample's defined vector. The phase angle for each sample is transformed into a corresponding phase vector based on a symmetric sampling of phase angles from previous and subsequent received signal samples. All terms of each corresponding phase vector are summed and averaged to generate a corresponding average phase gain for each sample. Each corresponding average phase gain is multiplied by a vector normal to the corresponding sample's defined vector to estimate the signal vector that is normal to the interference vector for each sample. The method and apparatus are effective whenever the phase of the interference vector components is characterized as having a frequency of change that is less than 1/2T, where T is the time required to receive the symmetric sampling.

Method and apparatus for suppressing interference from bandspread

A multisignal combiner is provided for weighting the best performing signal of an amplitude transform signal and a phase difference transform signal produced by a processor which receives a two dimensional signal and has intermediate signals which are a variance of the amplitude and a variance of the phase difference of the received signal. A device is provided for receiving the variance of the amplitude and the variance of the phase difference for producing a pair of weighting factors, each of which is inversely proportional to the size of the variances of the respective values, and a third weighting factor which is 1 minus the weighting factor of the signal which has the smallest variance. The transformed signals are weighted by the weighting factors and the received signal is weighted by the third weighting factor. The weighted signals are then summed to provide a final output signal which has it's best performing signal component enhanced relative to the other signal components.

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San Diego, CA, United States of America

Thomas W Schlosser