LIST OF FIGURES 



Page 



Figure 1 - Block Diagram of the SEADAC 33 



Figure 2 - Page of a "Book" Showing Record of Seakeeping 



Events Recorded on Magnetic Tape 34 



Figure 3 - The Integrated Spectrum of a Pitch Record Super- 

 posed on the Energy Spectrum of the Same Record 35 



Figure 4 - SEADAC Analysis of a Pitch Record Using 2- , 5- , and 



10-CPS Filters 36 



Figure 5 - Spectral Density Functions Computed from the Same 



Seakeeping Record for Slow Scan ^nd Fast Scan 37 



Figure 6 - Energy Spectra of Several Seakeeping Events 



Analyzed by the SEADAC with the Numerically Com- 

 puted Energy Spectra Superposed 38-40 



Figure 7 - Calibration Curves for 2-, 5-, 10-, and 20-CPS 



Filters 41 



Figure 8 - Analog Spectral Density of a Seakeeping Event 



with Appropriate Calibration Curve 42 



Figure 9 - Analog Spectral Density of a Seakeeping Event with 



Cumulative Energy Distribution Function Superimposed 42 



Figure 10 - Reliability of Spectral Density Estimates 43 



Figure 11 - 90-Percent Confidence Bands (Dashed Lines) Applied to 



a Spectrum with 31.64 Degrees of Freedom 44 



Figure 12 - Block Diagram of Proposed Extensions to the SEADAC. . 45 



Figure 13 - Computation of Spectral Density and Total Energy by: 

 1) Successive Steps in one Analyzer, and 2) Simul- 

 taneous Calculation in the Same Analyzer with the 

 Addition of Another Power Integrator and X - Y 

 Recorder 46 



Figure 14 - An Example of a Modulated Carrier Wave 47 



Figure 15 - The Spectrum of the Relative Amplitudes of the 

 Components of a Modulated Wave as a Function of 

 the Frequency of Those Component s 47 



