Author: Frieda Rods and Noel Flemming

Submitted by: T. Joe Willey, Ph.D., Loma Linda University, Loma Linda, California

The Spectral Analysis System is a series of programs developed for processing EEG data. To facilitate transitions from one to another, the programs have been placed in an executive. The system is designed to handle one channel at a time to allow for more flexibility. However, data from several channels can be digitized simultaneously and then separated into single channels for the analysis. This set of programs was developed for a particular environment, but could be applicable to a wide variety of settings. The system consists of the following programs:

DIGITIZE: Converts up to 16 channels of analog input signal to digital data stored in LINCtape with no gaps in real time.

DATA UNSCRAMBLER: Unscrambles interleaved data from up to four channels stored by DIGITIZE.

WILD POINT EDITOR: Checks digital data for possible artifacts by finding points of large amplitude. The editor has several editing options.

FFT POWER SPECTRA: Computes power spectra by the sum of the squares of FFT coefficients and stores 64 components per spectrum on LINCtape. Also the program creates a format block. It uses DECUS 8-143 as the computing kernel.

FORMATTER: Accepts alphanumeric identification of data and control parameters to be used by AUTOMATIC PLOTTER.

AUTOMATIC PLOTTER: Plots serial FFT spectra using hidden line suppression methods from data stored on LINCtape ac¬ cording to format control parameters. Alphanumeric identification is plotted with the group. This program can bootstrap from one format block to the next for continuing operations.

FREQUENCY BAND PLOT: Computes and plots averages and standard deviations for a specified frequency band from spectra stored on LINCtape and displays them sequentially. The band plot can be plotted or typed out; alphanumeric identification is included with the output.

SPY: Moving window display of data on tape (modified from DECUS No. 12-57).

Minimum Hardware: PDP-12 with 8K core, VR12 display and 2 LINC transports; KE12 extended arithmetic element; AD 12 A/D converters, 8 channels; ASR33 teletype or equivalent; CALCOMP plotter or equivalent

Source Language: LAP6-DIAL-M3

Catalog: December 1974