Real-time EEG spectral analyzer
First Claim
1. A method of processing EEG signals from a plurality of channels to provide an output indicative of cerebral activity during a time period, the method comprising:
- digitizing the EEG signals from the plurality of channels during a sequence of epochs of a known time duration to provide a digital waveform for each channel during each epoch;
transforming the digitized waveforms from a time domain to a frequency domain to produce a frequency spectrum for each epoch and channel;
averaging the frequency spectra for each channel over a plurality of epochs of the time period to produce an average frequency spectrum for each channel during the time period;
deriving, for each channel, frequency band amplitude values corresponding to a plurality of frequency bands based upon the average frequency spectrum for that channel; and
providing an output indicative of cerebral activity in each of the frequency bands at each channel during the time period based upon the frequency band amplitude values.
2 Assignments
0 Petitions
Accused Products
Abstract
An electroencephelograph (EEG) signal analysis system automatically determines and displays, on a real-time basis, the frequency content of spontaneous EEG signals from the brain. The analog EEG signals from a plurality of channels are sampled and converted to digitized EEG waveforms during a continuing sequence of epochs of predetermined time duration. The digitized EEG waveform for each epoch and channel is transformed from the time domain to the frequency domain to produce a frequency spectrum representing amplitude of the EEG signal as a function of frequency. The digital data is screened both prior and subsequent to the transformation to identify those epochs which contain artifacts. During each update period, the frequency spectra for each channel from the artifact-free epochs are averaged. The amplitudes of each averaged frequency spectrum for frequencies in each of four basic frequency bands are then summed. The result is an amplitude value for each of the four frequency bands at each channel. The four amplitude values are used to update a display which contains a graphical representation of the amplitude in each of the four bands in a different color. The amplitude values are also compared with previously recorded base line values, and an audible or visual warning indication is provided when predetermined variances from the base line values occur.
142 Citations
43 Claims
-
1. A method of processing EEG signals from a plurality of channels to provide an output indicative of cerebral activity during a time period, the method comprising:
-
digitizing the EEG signals from the plurality of channels during a sequence of epochs of a known time duration to provide a digital waveform for each channel during each epoch; transforming the digitized waveforms from a time domain to a frequency domain to produce a frequency spectrum for each epoch and channel; averaging the frequency spectra for each channel over a plurality of epochs of the time period to produce an average frequency spectrum for each channel during the time period; deriving, for each channel, frequency band amplitude values corresponding to a plurality of frequency bands based upon the average frequency spectrum for that channel; and providing an output indicative of cerebral activity in each of the frequency bands at each channel during the time period based upon the frequency band amplitude values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
-
-
22. A method of processing an analog EEG signal to provide an output indicative of cerebral activity and providing an output which is periodically updated, the method comprising:
-
digitizing the analog EEG signal during a sequence of epochs of a known time duration to provide a digitized waveform for each epoch; transforming the digitized waveform for each epoch from a time domain to a frequency domain to produce a frequency spectrum for that epoch; averaging frequency spectra from a plurality of epochs corresponding to an update period to produce an average frequency spectrum; deriving a delta EEG frequency band amplitude value, a theta EEG frequency band amplitude value, an alpha EEG frequency band amplitude value, and a beta EEG frequency band amplitude value based upon the average frequency spectrum; and periodically updating a output to provide an indication of the cerebral activity in the delta, theta, alpha and beta EEG frequency bands during a completed update period based upon the frequency band amplitude values for that update period. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31)
-
-
32. A system for processing EEG signals from a plurality of channels to provide an output indicative of cerebral activity, the system comprising:
-
means for digitizing EEG signals from the plurality of channels during a sequence of epochs of a known time duration to provide a digital waveform of amplitude as a function of time for each channel during each epoch; means for transforming the digitized waveforms for each epoch and channel from a time domain to a frequency domain to produce a frequency spectrum of amplitude as a function of frequency for each epoch and channel; means for averaging the frequency spectra for each channel from a plurality of epochs of an update period to produce an average frequency spectrum for each channel during the update period; means for deriving a frequency band amplitude value for each of a plurality of frequency bands based upon the average frequency spectrum for each channel; means for displaying a visual representation of cerebral activity in each of the frequency bands at each channel as a function of display control signals; and means for periodically updating the display control signals as each update period is completed based upon the frequency band amplitude values for that update period. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43)
-
Specification