The Hunt for Red October (Jack Ryan, #3)

by Tom Clancy

As important as the computer was its programming software. Four years before, a Ph.D. candidate in geophysics who was working at Cal Tech’s geophysical laboratory had completed a program of six hundred thousand steps designed to predict earthquakes. The problem the program addressed was one of signal versus noise. It overcame the difficulty seismologists had discriminating between random noise that is constantly monitored on seismographs and genuinely unusual signals that foretell a seismic event. The first Defense Department use of the program was in the Air Force Technical Applications Command (AFTAC), which found it entirely satisfactory for its mission of monitoring nuclear events throughout the world in accordance with arms control treaties. The Navy Research Laboratory also redrafted it for its own purposes. Though inadequate for seismic predictions, it worked very well indeed in analyzing sonar signals. The program was known in the navy as the signal algorithmic processing system (SAPS).