a,(1 + a2) 
when a2 >0 and re ety < 1, the spectrum has a peak at 
a2 
-1 a,(1 +a,) 
Oo= SG el Seen ZANE 5.116 
poor aa] sn 
a\(1 + a2) 
When a2 < 0 and reac ee < 1, the spectrum has a trough at the same wo as shown in 
2 
Fig. 5.19. 
a, <0 
USCA eo en(tiesca 
4a, 4a, 
Fig. 5.19. s(w) of AR(2). 
5.23.7 Example of AR(2). In Fig. 5.20, an example of the AR(2) process for a; = 
-0.5, a2= 0.8,02 = 1.0, expressed as X,—0.5 X,_; + 0.8 X;2=€,, was generated over t= 1 
to 600, using the same pure random process €, as was generated in Fig. 5.4. A part of this 
process (t = 100 to 250) is also shown with the time axis extended. Its readings are listed 
in Appendix Al as Table A1.3; pp. 251, 254, and 255. 
129 
