4/3/08
quiz review (Fig1)

digital/discrete filters
nonrecursive filter uses a nonrecursive difference equation such as:
y[n] = b3x[n] + b2x[n-1] + b1x[n-2] + b0x[n-3]
no dependence on previous outputs
single term on bottom of transfer equation such as z^3 that can be divided out easily and matches the highest power of z on the top half of the fraction
infinite impulse response (IIR) filters are recursive and can converge quickly and will have delayed terms on the bottom half of the fraction
finite impulse response (FIR) filters are not as powerful as recursive filters and must be taken to the limit to ensure that the signal is completely damped

filter design
(Fig2)
four types of filters: high pass, low pass, band pass, band stop (notch filter)
frequency domaon equivalence criterion (Fig3)
H[z] is an approx of Ha(s), but is it inferior to Ha(s)
digital filters aren't necessarily worse than analog filters, just different