hp2nlp.html

syntfil[HP2NLP] - frequency transformation from the highpass (HP) to the normalized lowpass (NLP) filter specification

Calling sequence:

HP2NLP(f_s, f_p, ap, as)

Parameters:

f_s - stopband frequency [Hz]

f_p - cutoff frequency [Hz]

ap - passband ripple [dB]

as - stopband attenuation [dB]

All parameters must be positive real values, where fp < fs and ap < as .

Description:

Os - stopband frequency of normalized lowpass filter [1/s]

ap - passband ripple [dB]

as - stopband attenuation [dB]

The output of function HP2NLP can be used as the input of functions ButterworthNLPOrder, ChebyshevNLPOrder, CauerNLPOrder to compute the order of approximation.

Info level:

Setting of variable infolevel[syntfil] can be used to get more detailed results.

infolevel[syntfil] =

2 - print specification of NLP (Os, ap, as)

3 - as level 2 + print specification of entered HP (f_s, f_p, ap, as) and plot HP filter specification

4 - as level 3 + plot specification of NLP

Example:

> with(syntfil):

> infolevel[syntfil]:=1;

> x:=HP2NLP(1000,2000,3,40);

> infolevel[syntfil]:=4;

> HP2NLP(1000,2000,3,40);

Filter specification:

f_s = 1000.000000 Hz

f_p = 2000.000000 Hz

ap = 3.000000 dB

as = 40.000000 dB

Specification of NLP:

Os = 2.000000 1/s

ap = 3.000000 dB

as = 40.000000 dB

See also:

LP2NLP, BP2NLP, BP22NLP, BS2NLP