### Block: BandstopBiQ

Inports
In | Input In(k)

Outports
Out | Output Out(k)

Mask Parameters
Name | ID | Description
characteristic | 1 | The filter characteristic is one of Butterworth (=Bessel) or Chebyshev
fc1 | 2 | Lower cut-off frequency in Hz
fc2 | 3 | Upper cut-off frequency in Hz
rc | 4 | Attenuation at cut-off frequencies
ts_fact | 5 | Multiplication factor of base sampling time (in integer format)

##### Description:

Calculates the filter coefficients for a second order bandstop and performs filtering on input signal.

Second order transfer function used:

H(z) = (b0.z2 + b1.z + b2) / (z2 + a1.z + a2)

Butterworth

- center frequency fc

  - center frequency fc is given by fc2 = f c 12 * f c 22

  - phase discontinuity @center frequency fc

- @lower cut-off frequency fc 1

  - -3dB attenuation

  - -45 degree phaseshift

- @upper cut-off frequency fc 2

  - -3dB attenuation

  - 45 degree phaseshift

- passband

  - roll-off dynamics are constant and not adjustable

E.g.:
The cut-off frequencies are fc 1 = 100Hz and fc 2 = 300Hz.
The bodeplot is shown in the figure 1 below.

Figure 1: Bodeplot Butterworth bandstop.

Chebyshev
Note: A second order Chebyshev I bandstop has the same bodeplot as a second order Chebyshev II bandstop. Hence, only the ’Chebyshev’ option is given.

- center frequency fc

  - center frequency fc is given by fc2 = f c 12 * f c 22

  - phase discontinuity @center frequency fc

- @lower cut-off frequency fc 1

  - -rcdB attenuation

  - -phaseshift proportional to rc

- @upper cut-off frequency fc 2

  - -rcdB attenuation

  - phaseshift proportional to rc

- passband

  - roll-off dynamics are adjustable using parameter rc

E.g.:
The cut-off frequencies are fc 1 = 100Hz and fc 2 = 300Hz.
The parameter rc is set to 10dB.
The bodeplot is shown in the figure 2 below.

Figure 2: Bodeplot Chebyshev bandstop. rc = 10dB

Bessel
Note: A second order Bessel bandstop behaves exactly like a second order Butterworth bandstop. Hence, no ’Bessel’ option is given.

##### Implementations:

FiP16 | 16 Bit Fixed Point Implementation
FiP32 | 32 Bit Fixed Point Implementation
Float32 | 32 Bit Floating Point Implementation
Float64 | 64 Bit Floating Point Implementation

#### Implementation: FiP16

16 Bit Fixed Point Implementation

Inports Data Type
In | int16

Outports Data Type
Out | int16

#### Implementation: FiP32

32 Bit Fixed Point Implementation

Inports Data Type
In | int32

Outports Data Type
Out | int32

#### Implementation: Float32

32 Bit Floating Point Implementation

Inports Data Type
In | float32

Outports Data Type
Out | float32

#### Implementation: Float64

64 Bit Floating Point Implementation

Inports Data Type
In | float64

Outports Data Type
Out | float64