trans

low-pass to other filter transform

Calling Sequence

hzt=trans(hz,tr_type,frq)
hzt=trans(pd,zd,gd,tr_type,frq)
[pt,zt,gt]=trans(hz,tr_type,frq)
[pt,zt,gt]=trans(pd,zd,gd,tr_type,frq)

Arguments

:hz a single input single output discrete transfer function, the low

pass filter

: :pd Vector of given filter poles : :zd Vector of given filter zeros : :gd scalar: the given filter gain : :tr_type string, the type of transformation, see description for

possible values

: :frq 2-vector of discrete cut-off frequencies (i.e., 0<frq<.5).

see description for details.

: :hzt transformed filter transfert function. : :pt vector of transformed filter zeros. : :zt vector of transformed filter poles. : :gt a scalar: transformed filter gain. :

Description

function for transforming standardized low-pass filter given its poles-zeros_gain representation into one of the following filters:

:tr_type=’lp’ low pass filter, the cutoff frequency is given by the

first entry of frq, the second one is ignored.

: :tr_type=’hp’ high pass filter, the cutoff frequency is given by the

first entry of frq, the second one is ignored.

: :tr_type=’bp’ band pass filter, the frequency range is given by

frq(1) and frq(2).

: :tr_type=’sb’ stop band filter, the frequency range is given by

frq(1) and frq(2).

:

Used functions

bilt

Examples

`clf`_()
Hlp=`iir`_(3,'lp','ellip',[0.1 0],[.08 .03]);
Hbp=trans(Hlp,'bp',[0.01 0.1]);
Hsb=trans(Hlp,'sb',[0.01 0.1])

`clf`_();`gainplot`_([Hlp;Hbp;Hsb],1d-3,0.48);
l=`legend`_(['original low pass';'band pass';'stop band']);
l.legend_location="in_lower_left";

See Also

• iir iir digital filter
• bilt bilinear or biquadratic transform SISO system given by a zero/poles representation