System for Displaying Spectral Trends in Complex Signals

• US 20090094305A1
• Filed: 06/30/2008
• Published: 04/09/2009
• Est. Priority Date: 10/08/2003
• Status: Abandoned Application

• Current Assignee: Mark W. Johnson
• Original Assignee: Mark W. Johnson
• Inventors: Johnson, Mark W.
• Application Number:
  US12/165,115
• Publication Number:
  US 20090094305A1
• Time in Patent Office: Days
• US Class Current: 708/403
• CPC Class Codes: A61B 5/374 Detecting the frequency distribution of signals, e.g. detecting delta, theta, alpha, beta or gamma waves
• CPC Class Codes: A61B 5/7257 using Fourier transforms

Abstract

A method for displaying changes in spectral content of data signals over periods of time using a computer system. The method includes the steps of transforming time segments of digitized data signals into a frequency based spectral representation of the digitized data. The resulting spectral data are then grouped into appropriate frequency bins. Each frequency bin is normalized by the frequency range of the bin. The energy or power in each frequency bin is then multiplied by fⁿ, where f represents an estimate of the frequency of the bin, and n is an exponent which is used to normalize the frequency content of the data. A logarithmic value is then calculated for each frequency bin. The logarithmic value of each frequency bin for each time period is then mapped to a color or gray-scale value. Finally, the mapped color or gray-scale value is displayed on a computer monitor in the computer system as an image, where the signal frequency is represented along one axis, time is represented along a second axis, and the value of the energy or power at that given time and frequency is displayed as the color or gray-scale value assigned to that point.

Claims

1-4. -4. (canceled)

5. A system for displaying changes in spectral content of data signals over periods of time, comprising:

a memory for storing digitized data signals from a desired source;

a computer processing unit supporting computer software for transforming time segments of the digitized data signals into a frequency based spectral representation of the digitized data signals and grouping the resulting spectral data into appropriate frequency bins, with each frequency bin normalized by the frequency range of the bin;

wherein the computer processing unit is configured to;

multiply the energy or power in each frequency bin by fⁿ, where f represents an estimate of the frequency of the bin, and n is an exponent which is used to normalize the frequency content of the digitized data signal;

calculate a logarithmic value for each frequency bin; and

map the logarithmic value for each time period to a color or gray-scale value; and

an output device for displaying the mapped color or gray-scale value as an image, where the signal frequency is represented along one axis, time is represented along a second axis, and the value of the energy or power at that given time and frequency is displayed as the color or gray-scale assigned to that point.

6. The system of claim 5, wherein the computer processing unit is further configured to normalize the energy or power represented by each frequency bin by the total energy or power of a single wider frequency band to correct for overall fluctuations in the amplitude of the signal.

7. The system of claim 5, wherein the output device displays the frequency based spectral representation of data as a modified compressed spectral array (mCSA), with frequency along one axis and time along a second axis.

8. The system of claims 5, 6 or 7, wherein the display device is a display monitor for viewing the mapped color or gray-scale values as an image.

9. The system of claims 5, 6 or 7, wherein the display device is a printer for providing printed images of the mapped color or gray-scale values.

10. The system of claims 5 or 6, wherein the estimate of the frequency in the bin which is multiplied by the energy or power in each frequency bin is the geometric mean of the maximum and minimum frequencies of the bin.

11. The system of claims 5 or 6, wherein the estimate of the frequency in the bin which is multiplied by the energy or power in each frequency bin is the average frequency of the frequencies within the bin.

12. A system for displaying changes in spectral content of biological data signals over periods of time, comprising:

a memory for storing digitized data signals from a desired source;

a computer processing unit supporting computer software for transforming time segments of the digitized data signals into a frequency based spectral representation of the digitized data signals and grouping the resulting spectral data into appropriate frequency bins, with each frequency bin normalized by the frequency range of the bin;

wherein the computer processing unit is configured to;

multiply the energy or power in each frequency bin by f_n, where f represents an estimate of the frequency of the bin, and n is an exponent which is used to normalize the frequency content of the digitized data signal;

calculate a logarithmic value for each frequency bin; and

map the logarithmic value for each time period to a color or gray-scale value; and

an output device for displaying the mapped color or gray-scale value as an image, where the signal frequency is represented along one axis, time is represented along a second axis, and the value of the energy or power at that given time and frequency is displayed as the color or gray-scale assigned to that point.

13. The system of claim 12, wherein the biological digitized data signals stored in the memory are EEG signals, ECG signals, respiratory signals, pressure signals, temperature signals, blood gas signals, EMG signals, EOG signals and/or body motion or position signals.