T-61.140, 21.6.2004

1a) LTI, linear and time-invariant, ...
1b) x(t) = x(t+T) ...

2a) y1[n] = h1[n] * x[n] = {_1_, 1, -2}
2b) h[0] = h[1] = 0
2c) h2[n] = {_-1_, 1, 2, -1, 2}

3a) y[n] = 0.8 x[n] - 0.7 y[n-1]
3b) IIR, 1
3c) H(e^jw) = 0.8/(1 + 0.7 e^-jw)
3d) HP, {0, pi/2, pi} -> ~{0.5,  0.66,  2.66}

4) 14 kHz ^ 
          |\___
          |
          ------>
          0   pi

5A) H(e^jw) = (1 + 1.902 e^-jw + e^-j2w)/(1 - 0.95 e^-jw)
    h[100] = 0.0243
5B) LTI-BP