point of intersection in the pw stop plane then determines the 
value of 7 which is equal to .81 radians per second. Next lo- 
cate the line t., - 15 hrs = 25 hrs, and the line labeled 
1050 km(= 848 + 200). The intersection of these two lines in 
the M yt Q4 plane then determines the value of / 7 which equals 
e402 radians per second. The value, .402, corresponds to a per- 
iod of 15.63 sec, and .81 corresponds to a period of 9675 seconds. 
All spectral periods greater than 15.63 seconds or leS$ than 7.75 
seconds will not be present at the point and time of *bservation. 
The filter for the given set of parameters thenmequals one 
inside of an area element in the p» ,© plane bounded by oF = 49.4 
degrees, ©, = 39.8 degrees, # , = .81, (a segment of a circle), 
and p, = 402. Inside this area the forecasted power spectrum 
equals the power spectrum at the source, and outside of this area, 
it is equal to zero. The wave system at the point and time of ob- 
servation is then the Lebesgue Power Integral over this forecasted 
power spectrum. 
Some examples 
The filter given by equation (9.62) can best be evaluated by 
brute force. The filter given by equation (9.63) is simply a special 
case of the filter given by equation (9.68) when F equals zero. 
Figure 26 shows the cutoff boundaries of the three filters described 
above for various values of the parameters. The values appropriate 
to equation (9.62) are shown by the dotted lines when needed. The 
values appropriate to equation (9.63) are shown by dashed lines 
when needed and the values appropriate to equation (9.68) are given 
by the solid lines. The © band width is the same for all three 
= 244) = 
