# US 2019/0172694 A1 · Signal processing method and system based on time-of-flight mass spectrometry and electronic apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0172694 A1 - Document ID: US20190172694A1 - Status: Published application - Kind: A1 - Application number: 16/095,747 - Filed: 2017-06-12 - Published: 2019-06-06 - Earliest claimed: 2016-06-28 - Assignees: Shimadzu Corporation - Applicants: Shimadzu Corporation - Inventors: Jiaqi SHEN; Wenjian SUN; Xiaoqiang ZHANG - Web page: https://patentgrep.com/patent/US20190172694A1 ## CPC - H01J 49/0036: {Step by step routines describing the handling of the data generated during a measurement} - H01J 49/40: Time-of-flight spectrometers (H01J49/36 takes precedence) - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract The invention provides signal processing method and system and an electronic apparatus for analysis of time-of-flight mass spectra. The method includes digitalizing an analog signal output from an ion detector to acquire complete raw time-of-flight spectra or each effective part in the raw time-of-flight spectra for a plurality of times; if the complete raw time-of-flight spectra are acquired, extracting the effective parts of each raw time-of-flight spectrum; applying a one-dimensional wavelet transform to each effective part to map to each frequency band or scale; determining positions and intensities of each spectral peak in each raw time-of-flight spectrum by detecting the maxima of an obtained wavelet coefficient distribution, and saving said peak position and intensity as characteristic data of each spectral peak; accumulating the characteristic data obtained by processing each raw time-of-flight spectrum and stacking the data to form spectral peak intensity/time-of-flight histogram. ## Claims ### Claim 1 A signal processing method for analysis of time-of-flight mass spectra, comprising: (a) digitalizing an analog signal output from an ion detector to acquire a plurality of complete raw time-of-flight spectra or acquiring all the effective parts in a plurality of raw time-of-flight spectra one by one for a plurality of times; (b) if complete raw time-of-flight spectra are acquired in said step (a), extracting all the effective parts in each of the raw time-of-flight spectra; (c) applying a one-dimensional wavelet transform to each effective part in each of the raw time-of-flight spectra to map to each frequency band or scale; (d) determining the position and the intensity of each spectral peak in each of the raw time-of-flight spectra by detecting the maxima of an obtained wavelet coefficient distribution, and saving said peak position and intensity as the characteristic data of each spectral peak; and (e) accumulating the characteristic data of said spectral peaks obtained by processing each of the raw time-of-flight spectra and stacking the data to form a spectral peak intensity/time-of-flight histogram. ### Claim 2 (depends on 1) The signal processing method for analysis of time-of-flight mass spectra according to claim 1, further comprising: performing further processing on each of the histograms so as to form a continuous spectrum for output. ### Claim 3 (depends on 1) The signal processing method for analysis of time-of-flight mass spectra according to claim 1, wherein, in said step (b), the effective spectrum parts are extracted from the raw time-of-flight spectra by taking a comparison result, which is obtained by comparing the signal amplitude of each data point in the raw time-of-flight spectra with a threshold correlated with a time-of-flight interval in which the data point is located, as a condition, the implementation mode thereof comprising any one of the following ways: 1) setting a plurality of thresholds, each of which is correlated with one time-of-flight interval defined in the raw time-of-flight spectra, and comparing the signal amplitude of each data point in each time-of-flight interval with the corresponding threshold to identify and extract a part on which the signal amplitude is higher than the threshold as the effective spectrum part; 2) setting a signal comparator, of which a first input terminal is connected to the ion detector to receive the output analog signal and of which a second input terminal inputs a signal whose amplitude is the threshold, and, when converting the analog signal into a digital signal, recording the moments when the output state of the comparator reverses, and extracting the parts of the raw time-of-flight spectrum by taking the recorded moments as starting and ending points of the effective spectrum parts. ### Claim 4 The signal processing method for analysis of time-of-flight mass spectra, comprising: filtering the detected maxima of the wavelet coefficient distribution with a preset criterion, so as to determine the position and intensity of each spectral peak therein; the criterion comprising one of the followings or a combination thereof: 1) the frequency band or scale of the maxima location is within a preset range; 2) the length of a corresponding ridge line reaches a preset threshold, the so-called ridge line is formed by the following steps: first searching the maxima on the said two-dimensional wavelet coefficient distribution and set as the starting point; connecting each said starting point to the neighboring maxima on the one-dimensional wavelet coefficient distribution with respect to time on the next scale/frequency band; extending each line to the neighboring maxima on the one-dimensional wavelet coefficient distribution with respect to time on the next scale/frequency band; and so forth until the upper/lower limit of the range of the scale/frequency band is reached; 3) the corresponding signal-to-noise ratio reaches a preset threshold. ### Claim 5 (depends on 3) The signal processing method for analysis of time-of-flight mass spectra according to claim 3, further comprising: stacking the accumulated characteristic data of spectral peaks and merging at least two adjacent time-of-flight intervals to form the spectral peak intensity/time-of-flight histogram. ### Claim 6 (depends on 1) The signal processing method for analysis of time-of-flight mass spectra according to claim 1, wherein the signal processing method for analysis of time-of-flight mass spectra is implemented on a plurality of or multiple groups of arithmetical units; the arithmetical units comprise one of the followings: (1) field-programmable gate arrays; (2) digital signal processors; (3) graphics processing units; or a combination thereof. ### Claim 7 (depends on 6) The signal processing method for analysis of time-of-flight mass spectra according to claim 6, wherein the mode of implementing on multiple groups of arithmetical units comprises: each group of the arithmetical unit groups processing the raw time-of-flight mass spectra assigned thereto respectively; or in the group of arithmetical units processing one raw time-of-flight mass spectrum, each arithmetical unit is assigned one effective spectrum part extracted from said raw time-of-flight mass spectrum for further processing. ### Claim 8 (depends on 1) The signal processing method for analysis of time-of-flight mass spectra according to claim 1, wherein, after said step (b), the method further comprises: accumulating the extracted effective parts of a plurality of continuously acquired raw time-of-flight mass spectra, the number of the plurality of raw time-of-flight mass spectra being 1/N of the number of the raw time-of-flight mass spectra required to be processed to form one spectral peak intensity/time-of-flight histogram, N being an integer not less than 20, and then executing step (c) and the following steps on the accumulated result spectra. ### Claim 9 (depends on 1) The signal processing method for analysis of time-of-flight mass spectra according to claim 1, wherein, after step (a), the method further comprises: accumulating the acquired plurality of continuously collected raw time-of-flight mass spectra, the number of the plurality of raw time-of-flight mass spectra being 1/N of the number of the raw time-of-flight mass spectra required to be processed to form one spectral peak intensity/time-of-flight histogram, N being an integer not less than 20, and then executing step (b) and the following steps on the accumulated result spectra. ### Claim 10 A signal processing system for analysis of time-of-flight mass spectra, comprising: an raw spectrum acquisition module, which is configured to digitalize an analog signal output from an ion detector to acquire a plurality of complete raw time-of-flight spectra or acquire each effective part in a plurality of raw time-of-flight spectra one by one for a plurality of times; an optional extraction module, which is configured to extract the effective parts from each complete raw time-of-flight spectrum; a wavelet transform module, which is configured to apply a one-dimensional wavelet transform to each effective spectrum part in each of the raw time-of-flight spectra to map to each frequency band or scale; a peak detection module, which is configured to determine the position and intensity of each spectral peak in each raw time-of-flight mass spectrum by detecting maxima on the obtained wavelet coefficient distribution, and save said peak position and intensity as characteristic data of each spectral peak; and an analysis module, which is configured to accumulate the characteristic data of spectral peaks obtained by processing each of the raw time-of-flight mass spectra and stack the data to form a spectral peak intensity/time-of-flight histogram. ### Claim 11 (depends on 10) The signal processing system for analysis of time-of-flight mass spectra according to claim 10, further comprising: a continuous spectrum processing module, which is configured to perform further processing on each of the histograms so as to form a continuous spectrum for output. ### Claim 12 (depends on 10) The signal processing system for analysis of time-of-flight mass spectra according to claim 10, wherein, in the optional extraction module, the effective spectrum part is extracted from the raw time-of-flight mass spectrum by taking a comparison result, which is obtained by comparing the signal amplitude of each data point in the raw time-of-flight spectra with a threshold corresponding to the time-of-flight interval in which the data point is located, as a condition, the implementation mode thereof comprising any one of the following ways: 1) setting a plurality of thresholds, each of which is correlated with one time-of-flight interval defined in the raw time-of-flight spectra, and comparing the signal amplitude of each data point in each time-of-flight interval with the corresponding threshold to identify and extract the part on which the signal amplitude is higher than the threshold as the effective spectrum part; 2) setting a signal comparator, of which a first input terminal is connected to the ion detector to receive the output analog signal and of which a second input terminal inputs a signal whose amplitude is the threshold, and, when converting the analog signal into a digital signal, recording the moments when the output state of the comparator reverses, and extracting the parts of the raw time-of-flight spectrum by taking the moments as starting and ending points of the effective spectrum parts. ### Claim 13 (depends on 10) The signal processing system for analysis of time-of-flight mass spectra according to claim 10, comprising: filtering the detected maxima of the wavelet coefficient distribution with a preset criterion, so as to determine the position and intensity of each spectral peak therein; the criterion comprising one of the followings or a combination thereof: 1) the frequency band or scale of the maxima location is within a preset range; 2) the length of a corresponding ridge line reaches a preset threshold, the so-called ridge line is formed by the following steps: searching the maxima on the said two-dimensional wavelet coefficient distribution and set as the starting point; connecting each said starting point to the neighboring maxima on the one-dimensional wavelet coefficient distribution with respect to time on the next scale/frequency band; extending each line to the neighboring maxima on the one-dimensional wavelet coefficient distribution with respect to time on the next scale/frequency band; and so forth until the upper/lower limit of the range of the scale/frequency band is reached; 3) the corresponding signal-to-noise ratio reaches a preset threshold. ### Claim 14 (depends on 13) The signal processing system for analysis of time-of-flight mass spectra according to claim 13, wherein the continuous spectrum processing module is further configured to stack the accumulated characteristic data of the spectral peaks and merge at least two adjacent time-of-flight intervals to form the spectral peak intensity/time-of-flight histogram. ### Claim 15 (depends on 10) The signal processing system for analysis of time-of-flight mass spectra according to claim 10, wherein the signal processing system for analysis of time-of-flight mass spectra comprises a plurality of or multiple groups of arithmetical units to realize functions; the arithmetical units comprise one of the followings: (1) field-programmable gate arrays; (2) digital signal processors; (3) graphics processing units; or a combination thereof. ### Claim 16 (depends on 15) The signal processing system for analysis of time-of-flight mass spectra according to claim 15, wherein the mode of implementing on multiple groups of arithmetical units comprises: each group of the arithmetical units processing the raw time-of-flight mass spectra assigned thereto respectively; or in the group of arithmetical units processing one raw time-of-flight mass spectrum, each arithmetical unit is assigned one effective spectrum part extracted from said raw time-of-flight mass spectrum for further processing. ### Claim 17 (depends on 10) The signal processing system for analysis of time-of-flight mass spectra according to claim 10, further comprising: a module for accumulation of the effective spectrum parts, which is configured to accumulate the effective parts of a plurality of raw time-of-flight spectra continuously acquired by the extraction module, the number of the plurality of raw time-of-flight mass spectra being 1/N of the number of the raw time-of-flight mass spectra required to be processed to form one spectral peak intensity/time-of-flight histogram, N being an integer not less than 20; said module for accumulation of the effective spectrum parts outputting the accumulation result of the effective parts of a plurality of said raw spectra to the wavelet transform module for subsequent processing. ### Claim 18 (depends on 10) The signal processing system for analysis of time-of-flight mass spectra according to claim 10, further comprising: a spectrum accumulation module, which is configured to accumulate a plurality of raw time-of-flight spectra continuously acquired by the raw spectrum acquisition module, the number of the plurality of raw time-of-flight spectra being 1/N of the number of the raw time-of-flight spectra required to be processed to form one spectral peak intensity/time-of-flight histogram, N being an integer not less than 20; said spectrum accumulation module outputting the accumulation result of the plurality of raw time-of-flight spectra to the extraction module for subsequent processing. ### Claim 19 (depends on 10) An electronic apparatus, comprising the signal processing system for analysis of time-of-flight mass spectra according to claim 10.