Portability | requires multi-parameter type classes |
---|---|
Stability | provisional |
Maintainer | synthesizer@henning-thielemann.de |
State variable filter. One filter that generates lowpass, bandpass, highpass, bandlimit at once.
- data Parameter a = Parameter {}
- storeParameter :: Storable a => Dictionary (Parameter a)
- data Result a = Result {}
- storeResult :: Storable a => Dictionary (Result a)
- parameter :: C a => Pole a -> Parameter a
- type State v = (v, v)
- step :: (C a, C a v) => Parameter a -> v -> State (State v) (Result v)
- modifierInit :: (C a, C a v) => Initialized (State v) (v, v) (Parameter a) v (Result v)
- modifier :: (C a, C a v) => Simple (State v) (Parameter a) v (Result v)
- causal :: (C a, C a v) => T (Parameter a, v) (Result v)
- runInit :: (C a, C a v) => (v, v) -> T (Parameter a) -> T v -> T (Result v)
- run :: (C a, C a v) => T (Parameter a) -> T v -> T (Result v)
Documentation
storeParameter :: Storable a => Dictionary (Parameter a)Source
storeResult :: Storable a => Dictionary (Result a)Source
parameter :: C a => Pole a -> Parameter aSource
The computation of the internal parameters is a bit complicated, but it fulfills the following properties:
- At the resonance frequency the band pass has 180 degree phase shift. This is also approximately the frequency where the filter has maximum output. Even more important, this is the frequency where the band limit filter works.
- At the resonance frequency highpass, lowpass, and bandpass
amplify by the factor
resonance
. - The lowpass amplifies the frequency zero by factor 1.
- The highpass amplifies the highest representable (Nyquist) frequency by the factor 1.
- The bandlimit amplifies both frequency zero and Nyquist frequency by factor one and cancels the resonance frequency.
step :: (C a, C a v) => Parameter a -> v -> State (State v) (Result v)Source
Universal filter: Computes high pass, band pass, low pass in one go
modifierInit :: (C a, C a v) => Initialized (State v) (v, v) (Parameter a) v (Result v)Source