Block: HighpassBiQ



PIC




Inports


In

Input In(k)






Outports


Out

Output Out(k)







Mask Parameters



Name

ID

Description




characteristic

1

The filter characteristic is one of Butterworth, Chebyshev I, Chebyshev II (also known as inverse Chebyshev) or Bessel




fc

2

Cut-off frequency in Hz




rp

3

The passband ripple is only used and verified with ’Chebyshev I’ filters.

Must be a positive number




rs

4

The stopband ripple is only used and verified with ’Chebyshev II’ filters.

Must be a positive number




ts_fact

5

Multiplication factor of base sampling time (in integer format)





Description:

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

Second order transfer function used:

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

Butterworth

E.g.: Cut-off frequency is 10Hz. The bodeplot is shown in the figure 1 below.


PIC

Figure 1: Bodeplot Butterworth highpass.


Chebyshev I

E.g.:
Cut-off frequency is 10Hz.
The maximal ripple in the passband rp must be given in [dB].
To show the mentioned trade-off, two bodelplots are shown. One with a small and one with a bigger rp. The bodeplot is shown in the figures 2 and 3 below.


PIC

Figure 2: Bodeplot Chebyshev I highpass. rp = 5dB



PIC

Figure 3: Bodeplot Chebyshev I highpass. rp = 20dB


Chebyshev II
Also known as inverse Chebyshev filter.

E.g.:
Cut-off frequency is 10Hz.
The maximal ripple in the stopband rs must be given in [dB].
To show the mentioned trade-off, two bodelplots are shown. One with a small and one with a bigger rs. The bodeplot is shown in the figures 4 and 5 below.


PIC

Figure 4: Bodeplot Chebyshev II highpass. rs = 5dB



PIC

Figure 5: Bodeplot Chebyshev II highpass. rs = 20dB


Bessel

E.g.:
Cut-off frequency is 10Hz.
The bodeplot is shown in the figure 6 below.


PIC

Figure 6: Bodeplot Bessel highpass.


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