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Thesis - Leigh Moody.pdf - Bad Request - Cranfield University

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Appendix I / Utilities / Digital Filters<br />

_ _<br />

For the 3 rd order Butterworth filter,<br />

⎧ ⎡ −1<br />

⎪ ⎢<br />

⎪<br />

⎢<br />

⎨ ⎢ 1<br />

⎪ ⎢<br />

⎪ ⎢<br />

⎪ ⎢<br />

⎩ ⎣ 0<br />

k<br />

,<br />

,<br />

,<br />

=<br />

3<br />

0<br />

−1<br />

1<br />

⇒<br />

For the 4 th order Butterworth filter,<br />

⎧ ⎡ −1.<br />

847759065<br />

⎪ ⎢<br />

⎪ ⎢<br />

⎪ ⎢ 1<br />

⎪ ⎢<br />

⎨ ⎢<br />

⎪ ⎢ 0<br />

⎪ ⎢<br />

⎪ ⎢<br />

⎪ ⎢<br />

⎪⎩<br />

⎣ 0<br />

,<br />

,<br />

,<br />

,<br />

Z<br />

k<br />

=<br />

−1<br />

k<br />

0<br />

1<br />

0<br />

4<br />

,<br />

,<br />

,<br />

,<br />

: =<br />

,<br />

,<br />

,<br />

⇒<br />

22.8-16<br />

{ A , B , C }<br />

0 ⎤<br />

⎥<br />

⎥<br />

−1<br />

⎥<br />

⎥<br />

⎥<br />

0 ⎥<br />

⎦<br />

,<br />

⎛<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎝<br />

1<br />

0<br />

0<br />

⎞<br />

⎟<br />

⎟<br />

⎟<br />

⎟<br />

⎟<br />

⎟<br />

⎠<br />

{ A , B , C }<br />

0<br />

0<br />

− 0.<br />

765366865<br />

1<br />

,<br />

,<br />

,<br />

,<br />

,<br />

0 ⎤<br />

⎥<br />

⎥<br />

0 ⎥<br />

⎥<br />

⎥<br />

−1<br />

⎥<br />

⎥<br />

⎥<br />

0 ⎥<br />

⎦<br />

: =<br />

⎛<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎝<br />

: =<br />

( ) 1<br />

−1<br />

−<br />

I − 2 ⋅ ω ⋅ ∆t<br />

⋅ A<br />

M<br />

B<br />

k<br />

,<br />

0<br />

0<br />

1<br />

⎞<br />

⎟<br />

⎟<br />

⎟<br />

⎟<br />

⎟<br />

⎟<br />

⎠<br />

T<br />

⎫<br />

⎪<br />

⎪<br />

⎬<br />

⎪<br />

⎪<br />

⎪<br />

⎭<br />

Equation 22.8-113<br />

⎛<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎝<br />

1<br />

0<br />

0<br />

0<br />

⎞<br />

⎟<br />

⎟<br />

⎟<br />

⎟<br />

⎟<br />

⎟<br />

⎟<br />

⎟<br />

⎟<br />

⎠<br />

,<br />

⎛<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎜<br />

⎝<br />

0<br />

0<br />

0<br />

1<br />

⎞<br />

⎟<br />

⎟<br />

⎟<br />

⎟<br />

⎟<br />

⎟<br />

⎟<br />

⎟<br />

⎟<br />

⎠<br />

Equation 22.8-114<br />

Equation 22.8-115<br />

The argument (I) is to be used for filter re-initialisation. This has not been<br />

implemented in the current utility function and the input should always be<br />

set to zero. Each filter is identified by a unique number (N).<br />

T<br />

⎫<br />

⎪<br />

⎪<br />

⎪<br />

⎪<br />

⎬<br />

⎪<br />

⎪<br />

⎪<br />

⎪<br />

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