ii-9 



and for the cross-correlation of slope: 



S (0) = S* (a) r e'K^''2-^l^^V^2-^l^^ dG (,.31) 



where the starred spectra are those measured by the instrument. 



The transfer function alters only the phase, not the 

 amplitude, and is a function of wave frequency, direction, and gage 

 length of the instrument arms. The corrections require one to know 

 the wave direction of each frequency component a p riori . These can 

 be calculated (if two transducers along an axis are functioning 

 properly) using the simultaneous solution of a set of equations such 



S (o) = S* (a) 

 nn nn^ 



X X 



■^^^t^^^r^o^^^^yr^o^^ de 



,2^ (^-32) 



S (a) =S* (a) e^t'^x^^S-^O^^^^^B-V^ de 



S (a) = S* (a) r e^f'^x(^2-^o)^\^^2-V^ dS ■ 



S (a) = S* (a) r e^t^x(^4-V-^^(^4-V^ de ^''^'^ 



