■^t-'V\J-'-^■\fV\r\J\J\/^\^^-^^^^ 



FIG. 1. Plots of measured inten- 

 sity /, phase 41, and high-passed 

 phase, and of the components A' 

 and Y (in arbitrary pressure units) 

 of acoustic pressure at Bermuda, 

 22 Sept. -17 Oct. 1973. 



Time (days) 



refers to the uncensored record). A typical signal-to- 

 noise ratio is 27 dB [Ted Birdsall (personal communi- 

 cation)], and a removal of deeper fades (say F=30 dB) 

 would be associated with noise statistics rather than 



multipath statistics. 



The crucial importance of sampling needs to be 

 stressed. From a numerical experiment (Sec. VII) we 



140r 



130- 



db 



120 



110 



6 7 



Time (hrs) 

 FIG. 2. A 14-h sample of intensity / and phase * drawn on an enlarged scale. 



236 



