# US 2014/0195577 A1 · Method and Apparatus for Signal Filtering and for Improving Properties of Electronic Devices > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0195577 A1 - Document ID: US20140195577A1 - Status: Published application - Kind: A1 - Application number: 14/159,033 - Filed: 2014-01-20 - Published: 2014-07-10 - Earliest claimed: 2012-08-30 - Assignees: Avatekh, Inc. - Applicants: Avatekh, Inc. - Inventors: Alexei V. Nikitin - Web page: https://patentgrep.com/patent/US20140195577A1 ## CPC - H03H 17/0219: {Compensation of undesirable effects, e.g. quantisation noise, overflow (stability problems H03H17/0461)} - H03H 7/0153: {Electrical filters; Controlling thereof} - H03H 11/1256: {Tow-Thomas biquad} - H03H 11/1291: {Current or voltage controlled filters} - H03H 17/0201: {Wave digital filters} - H03H 21/0001: {Analogue adaptive filters} - H03H 21/0016: {Non linear filters} - H03M 1/1235: {Non-linear conversion not otherwise provided for in subgroups of H03M1/12} - H03H 11/24: Frequency-independent attenuators - H03H 2210/043: by measuring time constant - H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P) - H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C) ## Abstract The present invention relates to nonlinear signal processing, and, in particular, to adaptive nonlinear filtering of real-, complex-, and vector-valued signals utilizing analog Nonlinear Differential Limiters (NDLs), and to adaptive real-time signal conditioning, processing, analysis, quantification, comparison, and control. More generally, this invention relates to methods, processes and apparatus for real-time measuring and analysis of variables, and to generic measurement systems and processes. This invention also relates to methods and corresponding apparatus for measuring which extend to different applications and provide results other than instantaneous values of variables. The invention further relates to post-processing analysis of measured variables and to statistical analysis. The NDL-based filtering method and apparatus enable improvements in the overall properties of electronic devices including, but not limited to, improvements in performance, reduction in size, weight, cost, and power consumption, and, in particular for wireless devices, NDLs enable improvements in spectrum usage efficiency. ## Claims ### Claim 1 A method for processing a digital signal by a digital signal processing unit wherein said digital signal processing unit is configurable to perform one or more functions including a filtering function transforming an input signal into an output filtered signal, wherein said filtering function comprises a nonlinear lowpass stage characterized by a bandwidth and transforming a nonlinear lowpass stage input signal into a nonlinear lowpass stage output signal, and wherein said bandwidth depends on a magnitude of a difference between a current value of said nonlinear lowpass stage input signal and a previous value of said nonlinear lowpass stage output signal. ### Claim 2 (depends on 1) The method of claim 1 wherein said input signal comprises a signal of interest and an interfering signal affecting said signal of interest, wherein said output filtered signal is characterized by signal quality, and wherein said filtering function is configured to improve said signal quality. ### Claim 3 (depends on 2) The method of claim 2 wherein said interfering signal affecting said signal of interest is characterized by a degree of peakedness, wherein said filtering function further comprises a first filtering stage preceding said nonlinear lowpass stage, and wherein said first filtering stage is configured to increase said degree of peakedness of said interfering signal affecting said signal of interest. ### Claim 4 (depends on 1) The method of claim 1 wherein dependence of said bandwidth on said difference is further characterized by a resolution parameter, wherein said bandwidth remains essentially constant when said magnitude of said difference is smaller than said resolution parameter, and wherein said bandwidth decreases with the increase of said magnitude when said magnitude is larger than said resolution parameter. ### Claim 5 (depends on 4) The method of claim 4 wherein said input signal comprises a signal of interest and an interfering signal affecting said signal of interest, wherein said output filtered signal is characterized by signal quality, and wherein said filtering function is configured to improve said signal quality. ### Claim 6 (depends on 5) The method of claim 5 wherein said interfering signal affecting said signal of interest is characterized by a degree of peakedness, wherein said filtering function further comprises a first filtering stage preceding said nonlinear lowpass stage, and wherein said first filtering stage is configured to increase said degree of peakedness of said interfering signal affecting said signal of interest. ### Claim 7 (depends on 4) The method of claim 4 wherein said resolution parameter is indicative of a measure of central tendency of said magnitude of said difference between a current value of said nonlinear lowpass stage input signal and a previous value of said nonlinear lowpass stage output signal. ### Claim 8 (depends on 7) The method of claim 7 wherein said input signal comprises a signal of interest and an interfering signal affecting said signal of interest, wherein said output filtered signal is characterized by signal quality, and wherein said filtering function is configured to improve said signal quality. ### Claim 9 (depends on 8) The method of claim 8 wherein said interfering signal affecting said signal of interest is characterized by a degree of peakedness, wherein said filtering function further comprises a first filtering stage preceding said nonlinear lowpass stage, and wherein said first filtering stage is configured to increase said degree of peakedness of said interfering signal affecting said signal of interest. ### Claim 10 (depends on 4) The method of claim 4 further comprising an additional lowpass stage transforming an additional lowpass stage input into an additional lowpass stage output, wherein said additional lowpass stage input is indicative of said nonlinear lowpass stage input signal, and wherein said resolution parameter is indicative of a measure of tendency of a magnitude of differences between values of said additional lowpass stage input and values of said additional lowpass stage output. ### Claim 11 (depends on 10) The method of claim 10 wherein said input signal comprises a signal of interest and an interfering signal affecting said signal of interest, wherein said output filtered signal is characterized by signal quality, and wherein said filtering function is configured to improve said signal quality. ### Claim 12 (depends on 11) The method of claim 11 wherein said interfering signal affecting said signal of interest is characterized by a degree of peakedness, wherein said filtering function further comprises a first filtering stage preceding said nonlinear lowpass stage, and wherein said first filtering stage is configured to increase said degree of peakedness of said interfering signal affecting said signal of interest. ### Claim 13 (depends on 1) The method of claim 1 wherein said bandwidth depends on nonlinear lowpass stage filter parameters, and wherein at least one of said nonlinear lowpass stage filter parameters is a controlled parameter dynamically controlled by said difference between a current value of said nonlinear lowpass stage input signal and a previous value of said nonlinear lowpass stage output signal. ### Claim 14 (depends on 13) The method of claim 13 wherein said input signal comprises a signal of interest and an interfering signal affecting said signal of interest, wherein said output filtered signal is characterized by signal quality, and wherein said filtering function is configured to improve said signal quality. ### Claim 15 (depends on 14) The method of claim 14 wherein said interfering signal affecting said signal of interest is characterized by a degree of peakedness, wherein said filtering function further comprises a first filtering stage preceding said nonlinear lowpass stage, and wherein said first filtering stage is configured to increase said degree of peakedness of said interfering signal affecting said signal of interest. ### Claim 16 (depends on 13) The method of claim 13 wherein said dependence of said controlled parameter on said difference is further characterized by a resolution parameter, wherein said bandwidth remains essentially constant when said magnitude is smaller than said resolution parameter, and wherein said bandwidth decreases with the increase of said magnitude when said magnitude is larger than said resolution parameter. ### Claim 17 (depends on 16) The method of claim 16 wherein said input signal comprises a signal of interest and an interfering signal affecting said signal of interest, wherein said output filtered signal is characterized by signal quality, and wherein said filtering function is configured to improve said signal quality. ### Claim 18 (depends on 17) The method of claim 17 wherein said interfering signal affecting said signal of interest is characterized by a degree of peakedness, wherein said filtering function further comprises a first filtering stage preceding said nonlinear lowpass stage, and wherein said first filtering stage is configured to increase said degree of peakedness of said interfering signal affecting said signal of interest. ### Claim 19 (depends on 16) The method of claim 16 wherein said resolution parameter is indicative of a measure of tendency of said magnitude of said difference between a current value of said nonlinear lowpass stage input signal and a previous value of said nonlinear lowpass stage output signal. ### Claim 20 (depends on 19) The method of claim 19 wherein said input signal comprises a signal of interest and an interfering signal affecting said signal of interest, wherein said output filtered signal is characterized by signal quality, and wherein said filtering function is configured to improve said signal quality. ### Claim 21 (depends on 20) The method of claim 20 wherein said interfering signal affecting said signal of interest is characterized by a degree of peakedness, wherein said filtering function further comprises a first filtering stage preceding said nonlinear lowpass stage, and wherein said first filtering stage is configured to increase said degree of peakedness of said interfering signal affecting said signal of interest. ### Claim 22 (depends on 16) The method of claim 16 further comprising an additional lowpass stage transforming an additional lowpass stage input into an additional lowpass stage output, wherein said additional lowpass stage input is indicative of said nonlinear lowpass stage input signal, and wherein said resolution parameter is indicative of a measure of tendency of a magnitude of differences between values of said additional lowpass stage input and values of said additional lowpass stage output. ### Claim 23 (depends on 22) The method of claim 22 wherein said input signal comprises a signal of interest and an interfering signal affecting said signal of interest, wherein said output filtered signal is characterized by signal quality, and wherein said filtering function is configured to improve said signal quality. ### Claim 24 (depends on 23) The method of claim 23 wherein said interfering signal affecting said signal of interest is characterized by a degree of peakedness, wherein said filtering function further comprises a first filtering stage preceding said nonlinear lowpass stage, and wherein said first filtering stage is configured to increase said degree of peakedness of said interfering signal affecting said signal of interest. ### Claim 25 A digital signal processing apparatus comprising a digital signal processing unit configurable to perform one or more functions including a filtering function transforming an input signal into an output filtered signal, wherein said filtering function comprises a nonlinear lowpass stage characterized by a bandwidth and transforming a nonlinear lowpass stage input signal into a nonlinear lowpass stage output signal, and wherein said bandwidth depends on a magnitude of a difference between a current value of said nonlinear lowpass stage input signal and a previous value of said nonlinear lowpass stage output signal. ### Claim 26 (depends on 25) The apparatus of claim 25 wherein said input signal comprises a signal of interest and an interfering signal affecting said signal of interest, wherein said output filtered signal is characterized by signal quality, and wherein said filtering function is configured to improve said signal quality. ### Claim 27 (depends on 26) The apparatus of claim 26 wherein said interfering signal affecting said signal of interest is characterized by a degree of peakedness, wherein said filtering function further comprises a first filtering stage preceding said nonlinear lowpass stage, and wherein said first filtering stage is configured to increase said degree of peakedness of said interfering signal affecting said signal of interest. ### Claim 28 (depends on 25) The apparatus of claim 25 wherein dependence of said bandwidth on said difference is further characterized by a resolution parameter, wherein said bandwidth remains essentially constant when said magnitude of said difference is smaller than said resolution parameter, and wherein said bandwidth decreases with the increase of said magnitude when said magnitude is larger than said resolution parameter. ### Claim 29 (depends on 28) The apparatus of claim 28 wherein said input signal comprises a signal of interest and an interfering signal affecting said signal of interest, wherein said output filtered signal is characterized by signal quality, and wherein said filtering function is configured to improve said signal quality. ### Claim 30 (depends on 29) The apparatus of claim 29 wherein said interfering signal affecting said signal of interest is characterized by a degree of peakedness, wherein said filtering function further comprises a first filtering stage preceding said nonlinear lowpass stage, and wherein said first filtering stage is configured to increase said degree of peakedness of said interfering signal affecting said signal of interest. ### Claim 31 (depends on 28) The apparatus of claim 28 further comprising means for obtaining a measure of tendency of said magnitude of said difference between a current value of said nonlinear lowpass stage input signal and a previous value of said nonlinear lowpass stage output signal, and wherein said resolution parameter is indicative of said measure of tendency. ### Claim 32 (depends on 31) The apparatus of claim 31 wherein said input signal comprises a signal of interest and an interfering signal affecting said signal of interest, wherein said output filtered signal is characterized by signal quality, and wherein said filtering function is configured to improve said signal quality. ### Claim 33 (depends on 32) The apparatus of claim 32 wherein said interfering signal affecting said signal of interest is characterized by a degree of peakedness, wherein said filtering function further comprises a first filtering stage preceding said nonlinear lowpass stage, and wherein said first filtering stage is configured to increase said degree of peakedness of said interfering signal affecting said signal of interest. ### Claim 34 (depends on 28) The apparatus of claim 28 further comprising an additional lowpass stage trans-forming an additional lowpass stage input into an additional lowpass stage output, wherein said additional lowpass stage input is indicative of said nonlinear lowpass stage input signal, further comprising means for obtaining a measure of tendency of a magnitude of differences between values of said additional lowpass stage input and values of said additional lowpass stage output, and wherein said resolution parameter is indicative of said measure of tendency. ### Claim 35 (depends on 34) The apparatus of claim 34 wherein said input signal comprises a signal of interest and an interfering signal affecting said signal of interest, wherein said output filtered signal is characterized by signal quality, and wherein said filtering function is configured to improve said signal quality. ### Claim 36 (depends on 35) The apparatus of claim 35 wherein said interfering signal affecting said signal of interest is characterized by a degree of peakedness, wherein said filtering function further comprises a first filtering stage preceding said nonlinear lowpass stage, and wherein said first filtering stage is configured to increase said degree of peakedness of said interfering signal affecting said signal of interest. ### Claim 37 (depends on 25) The apparatus of claim 25 wherein said bandwidth depends on nonlinear lowpass stage filter parameters, and wherein at least one of said nonlinear lowpass stage filter parameters is a controlled parameter dynamically controlled by said difference between a current value of said nonlinear lowpass stage input signal and a previous value of said nonlinear lowpass stage output signal. ### Claim 38 (depends on 37) The apparatus of claim 37 wherein said input signal comprises a signal of interest and an interfering signal affecting said signal of interest, wherein said output filtered signal is characterized by signal quality, and wherein said filtering function is configured to improve said signal quality. ### Claim 39 (depends on 38) The apparatus of claim 38 wherein said interfering signal affecting said signal of interest is characterized by a degree of peakedness, wherein said filtering function further comprises a first filtering stage preceding said nonlinear lowpass stage, and wherein said first filtering stage is configured to increase said degree of peakedness of said interfering signal affecting said signal of interest. ### Claim 40 (depends on 37) The apparatus of claim 37 wherein said dependence of said controlled parameter on said difference is further characterized by a resolution parameter, wherein said bandwidth remains essentially constant when said magnitude is smaller than said resolution parameter, and wherein said bandwidth decreases with the increase of said magnitude when said magnitude is larger than said resolution parameter. ### Claim 41 (depends on 40) The apparatus of claim 40 wherein said input signal comprises a signal of interest and an interfering signal affecting said signal of interest, wherein said output filtered signal is characterized by signal quality, and wherein said filtering function is configured to improve said signal quality. ### Claim 42 (depends on 41) The apparatus of claim 41 wherein said interfering signal affecting said signal of interest is characterized by a degree of peakedness, wherein said filtering function further comprises a first filtering stage preceding said nonlinear lowpass stage, and wherein said first filtering stage is configured to increase said degree of peakedness of said interfering signal affecting said signal of interest. ### Claim 43 (depends on 40) The apparatus of claim 40 further comprising means for obtaining a measure of tendency of said magnitude of said difference between a current value of said nonlinear lowpass stage input signal and a previous value of said nonlinear lowpass stage output signal, and wherein said resolution parameter is indicative of said measure of tendency. ### Claim 44 (depends on 43) The apparatus of claim 43 wherein said input signal comprises a signal of interest and an interfering signal affecting said signal of interest, wherein said output filtered signal is characterized by signal quality, and wherein said filtering function is configured to improve said signal quality. ### Claim 45 (depends on 44) The apparatus of claim 44 wherein said interfering signal affecting said signal of interest is characterized by a degree of peakedness, wherein said filtering function further comprises a first filtering stage preceding said nonlinear lowpass stage, and wherein said first filtering stage is configured to increase said degree of peakedness of said interfering signal affecting said signal of interest. ### Claim 46 (depends on 40) The apparatus of claim 40 further comprising an additional lowpass stage trans-forming an additional lowpass stage input into an additional lowpass stage output, wherein said additional lowpass stage input is indicative of said nonlinear lowpass stage input signal, further comprising means for obtaining a measure of tendency of a magnitude of differences between values of said additional lowpass stage input and values of said additional lowpass stage output, and wherein said resolution parameter is indicative of said measure of tendency. ### Claim 47 (depends on 46) The apparatus of claim 46 wherein said input signal comprises a signal of interest and an interfering signal affecting said signal of interest, wherein said output filtered signal is characterized by signal quality, and wherein said filtering function is configured to improve said signal quality. ### Claim 48 (depends on 47) The apparatus of claim 47 wherein said interfering signal affecting said signal of interest is characterized by a degree of peakedness, wherein said filtering function further comprises a first filtering stage preceding said nonlinear lowpass stage, and wherein said first filtering stage is configured to increase said degree of peakedness of said interfering signal affecting said signal of interest. ### Claim 49 A digital signal processing apparatus comprising a digital signal processing unit configurable to perform one or more functions including a filtering function transforming an input signal into an output filtered signal, wherein said filtering function comprises a nonlinear lowpass stage characterized by a bandwidth and transforming a nonlinear lowpass stage input signal into a nonlinear lowpass stage output signal, wherein said bandwidth is operable to depend on a control signal, further comprising a control signal block operable to output said control signal, wherein said control signal is a function of a plurality of input signals of said control signal block, and wherein said plurality of input signals of said control signal block comprises said nonlinear lowpass stage input signal and a feedback of said nonlinear lowpass stage output signal. ### Claim 50 (depends on 49) The apparatus of claim 49 wherein said input signal comprises a signal of interest and an interfering signal affecting said signal of interest, wherein said output filtered signal is characterized by signal quality, and wherein said filtering function is configured to improve said signal quality. ### Claim 51 (depends on 50) The apparatus of claim 50 wherein said interfering signal affecting said signal of interest is characterized by a degree of peakedness, wherein said filtering function further comprises a first filtering stage preceding said nonlinear lowpass stage, and wherein said first filtering stage is configured to increase said degree of peakedness of said interfering signal affecting said signal of interest. ### Claim 52 (depends on 49) The apparatus of claim 49 wherein said plurality of input signals of said control signal block further comprises one or more input signals selected from the group comprising a signal indicative of said nonlinear lowpass stage input signal, a signal indicative of said nonlinear lowpass stage input signal filtered with a linear filter, a gain control signal, a resolution parameter control signal, and any combinations thereof. ### Claim 53 (depends on 52) The apparatus of claim 52 wherein said input signal comprises a signal of interest and an interfering signal affecting said signal of interest, wherein said output filtered signal is characterized by signal quality, and wherein said filtering function is configured to improve said signal quality. ### Claim 54 (depends on 53) The apparatus of claim 53 wherein said interfering signal affecting said signal of interest is characterized by a degree of peakedness, wherein said filtering function further comprises a first filtering stage preceding said nonlinear lowpass stage, and wherein said first filtering stage is configured to increase said degree of peakedness of said interfering signal affecting said signal of interest. ### Claim 55 (depends on 49) The apparatus of claim 49 wherein said bandwidth depends on nonlinear lowpass stage filter parameters, and wherein at least one of said nonlinear lowpass stage filter parameters is a controlled parameter dynamically controlled by said control signal. ### Claim 56 (depends on 55) The apparatus of claim 55 wherein said input signal comprises a signal of interest and an interfering signal affecting said signal of interest, wherein said output filtered signal is characterized by signal quality, and wherein said filtering function is configured to improve said signal quality. ### Claim 57 (depends on 56) The apparatus of claim 56 wherein said interfering signal affecting said signal of interest is characterized by a degree of peakedness, wherein said filtering function further comprises a first filtering stage preceding said nonlinear lowpass stage, and wherein said first filtering stage is configured to increase said degree of peakedness of said interfering signal affecting said signal of interest. ### Claim 58 (depends on 55) The apparatus of claim 55 wherein said plurality of input signals of said control signal block further comprises one or more input signals selected from the group comprising a signal indicative of said nonlinear lowpass stage input signal, a signal indicative of said nonlinear lowpass stage input signal filtered with a linear filter, a gain control signal, a resolution parameter control signal, and any combinations thereof. ### Claim 59 (depends on 58) The apparatus of claim 58 wherein said input signal comprises a signal of interest and an interfering signal affecting said signal of interest, wherein said output filtered signal is characterized by signal quality, and wherein said filtering function is configured to improve said signal quality. ### Claim 60 (depends on 59) The apparatus of claim 59 wherein said interfering signal affecting said signal of interest is characterized by a degree of peakedness, wherein said filtering function further comprises a first filtering stage preceding said nonlinear lowpass stage, and wherein said first filtering stage is configured to increase said degree of peakedness of said interfering signal affecting said signal of interest.