Noise spectrum equalizer

Claim 3

The method defined in claim 1 wherein said step of preconditioning each of said applied power spectrum samples comprises compressing each of said applied power spectrum samples in accordance with a log2 compression function.

Claim 4

forming a sum of adjacent N, a predetermined number, of said compressed spectrum samples at frequencies immediately below a preselected compressed spectrum sample, with said preselected sample and with adjacent N-1 of said compressed spectrum samples at frequencies immediately above said selected compressed spectrum sample;

Claim 5

forming a sum of adjacent N, a predetermined number, of said compressed spectrum samples at frequencies immediately below a preselected compressed spectrum sample, with said preselected sample and with adjacent N-1 of said compressed spectrum samples at frequencies immediately above said selected compressed spectrum sample;

Claim 6

dividing said sum by 2N;

Claim 7

dividing said sum by 2N;

Claim 10

subtracting said divided sum from said preselected compressed spectrum sample, thereby obtaining an equalized compressed spectrum sample of said preselected compressed spectrum sample;

Claim 11

subtracting said divided sum from said preselected compressed spectrum sample, thereby obtaining an equalized compressed spectrum sample of said preselected compressed spectrum sample;

Claim 14

expanding each of said compressed equalized spectrum samples in accordance with a log2 1 function, thereby obtaining equalized spectrum samples;

Claim 15

expanding each of said compressed equalized spectrum samples in accordance with a log2 1 function, thereby obtaining equalized spectrum samples;

Claim 16

The method defined in claim 4 wherein the step of detecting a set of strong periodic spectrum samples comprises the further steps of: compressing each of said applied power spectrum samples in accordance with a compression function; and detecting those of said compressed power spectrum samples that represent strong periodic signals in said functions.

Claim 17

The method defined in claim 4 wherein said step of detecting said strong periodic signals includes a plurality of detecting steps each of which comprises the substeps of: obtaining a neighborhood-mean detecting signal associated with each of said compressed spectrum samples by forming an amplitude average of only those of said compressed power spectrum samples within said preselected number of said power spectrum samples in the vicinity of each of said compressed spectrum samples, which have not been detected in a previous substep; subtracting from each of said compressed spectrum samples each of said associated neighborhood-mean detecting signals and a threshold signal of a preselected level, thereby forming a positive signed difference signal or a negative signed difference signal; and identifying all of said compressed spectrum samples forming said positive signed difference signals as belonging to said set of detected spectrum samples.

Claim 18

subtracting from said sum the compressed spectrum sample of lowest frequency included in said sum and adding to said sum the compressed spectrum sample adjacent to and higher than the highest frequency sample included in the sum;

Claim 19

subtracting from said sum the compressed spectrum sample of lowest frequency included in said sum and adding to said sum the compressed spectrum sample adjacent to and higher than the highest frequency sample included in the sum;

Claim 20

selecting a new compressed spectrum sample, adjacent to and at a higher frequency than said preselected spectrum sample, to be equalized; and

Claim 21

selecting a new compressed spectrum sample, adjacent to and at a higher frequency than said preselected spectrum sample, to be equalized; and

Claim 22

Apparatus for noise spectrum equalization of applied spectrum samples comprising: means responsive to said applied spectrum samples for compressing each of said applied spectrum samples in accordance with a predetermined compression function; means responsive to said cOmpressed spectrum samples for developing neighborhood-mean equalizing signals associated with each of said applied spectrum samples; and means responsive to said compressed spectrum samples and to said associated neighborhood-mean equalizing signals for equalizing each of said spectrum samples by arithmetically combining each of said spectrum samples with each of said associated neighborhood-mean equalizing signals.

Claim 23

Apparatus for noise spectrum equalization of applied spectrum samples comprising: means responsive to said applied spectrum samples for compressing each of said applied spectrum samples in accordance with a predetermined compression function; means responsive to said cOmpressed spectrum samples for developing neighborhood-mean equalizing signals associated with each of said applied spectrum samples; and means responsive to said compressed spectrum samples and to said associated neighborhood-mean equalizing signals for equalizing each of said spectrum samples by arithmetically combining each of said spectrum samples with each of said associated neighborhood-mean equalizing signals.

Claim 24

repeating steps (2) through (7) thereby successively equalizing higher frequency selected spectrum samples until the highest frequency spectrum sample to be equalized is processed.

Claim 25

repeating steps (2) through (7) thereby successively equalizing higher frequency selected spectrum samples until the highest frequency spectrum sample to be equalized is processed.

Claim 26

The apparatus defined in claim 7 wherein said equalizing means further comprises: means responsive to said compressed equalized spectrum samples for expanding each of said compressed equalized spectrum samples in accordance with an expansion function that is an inverse function of said compression function.

Claim 27

Apparatus for spectrum equalization of applied power spectrum samples representative of functions containing periodic signals embedded in noise comprising: means responsive to said applied power spectrum samples for detecting spectrum samples which are representative of strong periodic signals in said functions; means, responsive to said applied power spectrum samples and to said means for detecting strong periodic signals, for developing a neighborhood-mean equalizing signal associated with each of said power spectrum samples by forming an amplitude average of only those of said power spectrum samples, within a preselected number of said power spectrum samples in the vicinity of each of said power spectrum samples, which have not been detected in said means for detecting strong periodic signals; and means responsive to said power spectrum samples and to said associated neighborhood-mean equalizing signals for equalizing each of said power spectrum samples by arithmetically combining each of said power spectrum samples with each of said associated neighborhood-mean equalizing signals.

Claim 28

Apparatus for spectrum equalization of applied power spectrum samples representative of functions containing periodic signals embedded in noise comprising: means responsive to said applied power spectrum samples for detecting spectrum samples which are representative of strong periodic signals in said functions; means, responsive to said applied power spectrum samples and to said means for detecting strong periodic signals, for developing a neighborhood-mean equalizing signal associated with each of said power spectrum samples by forming an amplitude average of only those of said power spectrum samples, within a preselected number of said power spectrum samples in the vicinity of each of said power spectrum samples, which have not been detected in said means for detecting strong periodic signals; and means responsive to said power spectrum samples and to said associated neighborhood-mean equalizing signals for equalizing each of said power spectrum samples by arithmetically combining each of said power spectrum samples with each of said associated neighborhood-mean equalizing signals.

Claim 29

The apparatus defined in claim 9 wherein said means for developing a neighborhood-mean equalizing signal comprises: a first transmission gate responsive to said applied power spectrum samples and to said means for detecting strong periodic signals for gating said applied power spectrum samples; a first sum accumulator responsive to said first transmission gate output signals for developing an accumulated sum of the 2N most recently applied of said power spectrum samples; a pulse generator responsive to said applied power spectrum samples for generating a pulse at each appearance of said applied power spectrum samples; a second transmission gate responsive to said pulse generator and to said means for forming said set of detected spectrum samples output signal for gating said pulse generator pulses; a second sum accumulator responsive to said second transmission gate for developing an accumulated sum of said gated pulses corresponding to the appearance of the most recent 2N of said pulses applied to said second transmission gate; and means for dividing said first accumulator output signal by said second accumulator output signal, thereby forming the desired neighborhood-mean equalizing signal.

Claim 30

The apparatus defined in claim 9 wherein said means for detecting strong periodic signals comprises: means for compressing each of said applied spectrum samples in accordance with a compression function; and means for detecting those of said compressed spectrum samples that represent strong periodic signals.

Claim 31

The apparatus defined in claim 11, wherein said means for equalizing comprises: means for subtracting from each of said compressed power spectrum samples each of said associated neighborhood-mean equalizing signals; and means responsive to said subtracting means output signal for expanding said signal in accordance with an expansion function that is an inverse function of said compression function.

Claim 32

The apparatus defined in claim 12, wherein said compression function and expansion function are a log2 function and a log2 1 function, respectivelY.

Claim 33

The apparatus defined in claim 9, wherein said means for detecting strong periodic signals further comprises: means for compressing each of said applied spectrum samples by a compression function; and means, responsive to the output signal of said means for compressing, for successively detecting those of said compressed power spectrum samples that represent strong periodic signals.

Claim 34

The apparatus defined in claim 14, wherein said means for successively detecting spectrum samples which represent strong periodic signals comprises a cascade interconnection of a plurality of detection stages, each stage responsive to said compressed spectrum samples and to said detected spectrum samples from the immediately preceding detection stage.

Claim 35

The apparatus defined in claim 15 wherein at least one of said detection stages comprises: switched averager means, responsive to said compressed spectrum samples and to said detected spectrum samples from said immediately preceding detection stage, for developing neighborhood-mean detecting signals associated with each compressed spectrum sample, by forming an amplitude average of only those of said compressed spectrum samples in the neighborhood of said associated spectrum sample which are not included in the set of detected spectrum samples from said previous detection stage; first subtraction means responsive to said compressed spectrum samples and to said switched averager means output signal for subtracting each of said associated neighborhood-mean detecting signals from each of its said associated compressed spectrum samples; and second subtraction means, responsive to said first subtraction means output signals, for subtracting from said first subtraction means output signal a threshold signal of a preselected level, thereby developing a second subtraction means output signal which indicates, by its sign, the existence of compressed spectrum samples indicative of strong periodic signals in said function.