n<-200;set.seed(164664)
r1<-0.6;r2<-0.99
y1<-arima.sim(n,model=list(ar=c(r1+r2,-r1*r2),order=c(2,0,0)))
y2<-arima.sim(n,model=list(ar=c(r1),order=c(1,1,0)))
plot(y1,xlab=expression(t),type="n",ylim=range(c(y1,y2)))
lines(y1);lines(y2,col="red")

par(mfrow=c(2,2))
acf(y1,main="ACF",lag.max=50)
pacf(y1,main="PACF",lag.max=50)
acf(y2,main="ACF",lag.max=50)
pacf(y2,main="PACF",lag.max=50)
par(mfrow=c(1,1))