k 
Y,= ») Boi (2.127) 
tT=0 
syy(@) = |G@)P’sxx(w) (2.128) 
k . 
G(@) = Ss &r ene, (2.129) 
tT=0 
4. Low-pass digital filter (Fig. 2.25) 
{ G (w) 
1.0 
71 — @ 1 
Fig. 2.25. Low-—pass filter. 
For example, the simplest equation for this type will be 
1 
Y; = race + X;). (2.130) 
Then 
syy(w) = IG(w)?sxx(w) 
1 2 
= a +e! | syx(w) 
=5(1 + cos w}syx(w). (2.131) 
5. High-pass digital filter (Fig. 2.26) 
51 
