Cfft - Continuous Fast Fourier Transform

This document provides a technical write-up for a Continuous Fast Fourier Transform (CFFT) program designed for the PDP-12 computer. Developed by J. R. Mason at the UCLA Brain Research Institute, the program is a modification of a previous Cooley-Tukey algorithm (DECUS L-25) to allow for continuous sampling and spectral analysis of EEG data.

Key features and details include:

• Functionality: The package samples data from an analog channel, calculates the spectra for fixed 1792-sample (17.5 second) epochs, and writes the results to LINCtape.
• Components: The program is divided into four main parts: CFFS (sampling and interrupts), CFFTW (spectrum computation), CDIS (display), and SINTB (sine table).
• Operation: Users can control the display via the teletype (scaling data up or down) and switch between a point-based display and a bar-chart using sense switches.
• Technical Requirements: It requires a PDP-12 with 8K memory, a KW12 clock, and TU55 LINCtape drives.
• Context: The document also includes supplementary information regarding the foundational FFOURIER and FFSAMPLE programs from which this version was derived.