-900 





 10' i 



^10° 



CO 



S 10-^ 

 o 



UJ 



N 



<io--l 



10-'- 



10-4 



10- 



4 6 8 10 



DISTANCE (KILOMETERS) 



12 



CORREaED 



PREWHITENED 



10-' 10° 10' 



FREQUENCY (CYCLES/KILOMETER) 



10^ 



Figure 5-1 



Illustration of the Importance of prewhitening of amplitude 

 spectra. The raw spectrum Is the result obtained by simply 

 performing a spectral analysis on raw data. The prewhitened 

 spectrum 1s the result of. performing the same analysis on 

 data which has been convolved with a special high-pass fil- 

 ter. The corrected spectrum results from the quotient of 

 the prewhitened spectrum and the frequency spectrum of the 

 high-pass filter, and represents an estimate of the spectrum 

 of the corresponding Infinite signal from which the sample 

 data was derived. 



51 



