Functions  
int  dspl_ap2bpass (double *b, double *a, int n, double wp0, double wp1, double *beta, double *alpha) 
Analog lowpass prototype frequency transformation to a bandpass filter with [wp0 ... wp1] passband. More...  
int  dspl_ap2bstop (double *b, double *a, int n, double ws0, double ws1, double *beta, double *alpha) 
Analog lowpass prototype frequency transformation to a bandstop filter with [wp0 ... wp1] stopband. More...  
int  dspl_ap2high (double *b, double *a, int n, double wp, double *beta, double *alpha) 
Analog lowpass prototype frequency transformation to a highpass filter with wp cutoff. More...  
int  dspl_ap2low (double *b, double *a, int n, double wp, double *beta, double *alpha) 
Analog lowpass prototype frequency transformation to a lowpass filter with wp cutoff. More...  
int  dspl_butter_ap (double Rp, int ord, double *b, double *a) 
Analog Butterworth filter prototype. More...  
int  dspl_cheby1_ap (double Rp, int ord, double *b, double *a) 
Analog Chebyshev type 1 filter prototype. More...  
int  dspl_cheby2_ap (double Rs, int ord, double *b, double *a) 
Analog Chebyshev type 2 filter prototype. More...  
Detailed Description
Functions for digital IIR filter design.
Function Documentation
◆ dspl_ap2bpass()
int dspl_ap2bpass  (  double *  b, 
double *  a,  
int  n,  
double  wp0,  
double  wp1,  
double *  beta,  
double *  alpha  
) 
Analog lowpass prototype frequency transformation to a bandpass filter with [wp0 ... wp1]
passband.
Function transforms analog prototype filter transfer function \( H_{\text{ap}}(s) \) to a bandpass filter transfer function \( H(s) \):
\[ H(s) = H_{\text{ap}} \left(\frac{s^2 + w^2_0}{B \cdot s} \right), \]
here \(w^2_0 = \) wp0 * wp1
, \(wB = \)wp1  wp0
.
Result bandpass filter order is 2*n
.
 Parameters

[in] b Analog prototype \( H_{\text{ap}}(s) \) numerator coefficients vector pointer. Vector size is [n+1 x 1]
.[in] a Analog prototype \( H_{\text{ap}}(s) \) denominator coefficients vector pointer. Vector size is [n+1 x 1]
.[in] n Analog prototype filter order [in] wp0 Bandpass low frequency (rad/s) after transformation [in] wp1 Bandpass hight frequency (rad/s) after transformation [out] beta Analog bandpass filter \( H(s) \) numerator coefficients vector pointer after transformation. Vector size is [2n+1 x 1]
.[out] alpha Analog bandpass filter \( H(s) \) denominator coefficients vector pointer after transformation. Vector size is [2n+1 x 1]
.
 Returns
DSPL_OK
if filter has been transformed successfully or code of error otherwise.
◆ dspl_ap2bstop()
int dspl_ap2bstop  (  double *  b, 
double *  a,  
int  n,  
double  wp0,  
double  wp1,  
double *  beta,  
double *  alpha  
) 
Analog lowpass prototype frequency transformation to a bandstop filter with [wp0 ... wp1]
stopband.
Function transforms analog prototype filter transfer function \( H_{\text{ap}}(s) \) to a bandstop filter transfer function \( H(s) \):
\[ H(s) = H_{\text{ap}} \left(\frac{B \cdot s}{s^2 + w^2_0} \right), \]
here \(w^2_0 = \) wp0 * wp1
, \(wB = \)wp1  wp0
.
Result bandstop filter order is 2*n
.
 Parameters

[in] b Analog prototype \( H_{\text{ap}}(s) \) numerator coefficients vector pointer. Vector size is [n+1 x 1]
.[in] a Analog prototype \( H_{\text{ap}}(s) \) denominator coefficients vector pointer. Vector size is [n+1 x 1]
.[in] n Analog prototype filter order [in] wp0 Bandstop low frequency (rad/s) after transformation [in] wp1 Bandstop hight frequency (rad/s) after transformation [out] beta Analog bandstop filter \( H(s) \) numerator coefficients vector pointer after transformation. Vector size is [2n+1 x 1]
.[out] alpha Analog bandstop filter \( H(s) \) denominator coefficients vector pointer after transformation. Vector size is [2n+1 x 1]
.
 Returns
DSPL_OK
if filter has been transformed successfully or code of error otherwise.
◆ dspl_ap2high()
int dspl_ap2high  (  double *  b, 
double *  a,  
int  n,  
double  wp,  
double *  beta,  
double *  alpha  
) 
Analog lowpass prototype frequency transformation to a highpass filter with wp
cutoff.
Function transforms analog prototype filter transfer function \( H_{\text{ap}}(s) \) to a highpass filter transfer function \( H(s) \):
\[ H(s) = H_{\text{ap}} \left(\frac{w_p}{s} \right), \]
Result highpass filter order is n
.
 Parameters

[in] b Analog prototype \( H_{\text{ap}}(s) \) numerator coefficients vector pointer. Vector size is [n+1 x 1]
.[in] a Analog prototype \( H_{\text{ap}}(s) \) denominator coefficients vector pointer. Vector size is [n+1 x 1]
.[in] n Analog prototype filter order [in] wp Highpass cutoff frequency (rad/s) after transformation [out] beta Analog highpass filter \( H(s) \) numerator coefficients vector pointer after transformation. Vector size is [n+1 x 1]
.[out] alpha Analog highpass filter \( H(s) \) denominator coefficients vector pointer after transformation. Vector size is [n+1 x 1]
.
 Returns
DSPL_OK
if filter has been transformed successfully or code of error otherwise.
◆ dspl_ap2low()
int dspl_ap2low  (  double *  b, 
double *  a,  
int  n,  
double  wp,  
double *  beta,  
double *  alpha  
) 
Analog lowpass prototype frequency transformation to a lowpass filter with wp
cutoff.
Function transforms analog prototype filter transfer function \( H_{\text{ap}}(s) \) to a lowpass filter transfer function \( H(s) \):
\[ H(s) = H_{\text{ap}} \left(\frac{s}{w_p} \right), \]
Result lowpass filter order is n
.
 Parameters

[in] b Analog prototype \( H_{\text{ap}}(s) \) numerator coefficients vector pointer. Vector size is [n+1 x 1]
.[in] a Analog prototype \( H_{\text{ap}}(s) \) denominator coefficients vector pointer. Vector size is [n+1 x 1]
.[in] n Analog prototype filter order [in] wp Lowpass cutoff frequency (rad/s) after transformation [out] beta Analog lowpass filter \( H(s) \) numerator coefficients vector pointer after transformation. Vector size is [n+1 x 1]
.[out] alpha Analog lowpass filter \( H(s) \) denominator coefficients vector pointer after transformation. Vector size is [n+1 x 1]
.
 Returns
DSPL_OK
if filter has been transformed successfully or code of error otherwise.
◆ dspl_butter_ap()
int dspl_butter_ap  (  double  Rp, 
int  ord,  
double *  b,  
double *  a  
) 
Analog Butterworth filter prototype.
Function calculates Analog Butterworth filter transfer function \(H(s)\) coefficients. Filter has order ord
cutoff frequency 1 rad/s with distortion level Rp
dB in passband (from 0 rad/s to 1 rad/s).
 Parameters

[in] Rp Filter passband distortions dB. Distortions level from 0 rad/s to 1 rad/s. Must be positive. [in] ord Filter order. Transfer function \(H(s)\) numerator and denominator coefficients number is ord+1
.[out] b Transfer function \(H(s)\) numerator coefficients vector pointer. Vector size is [ord+1 x 1]
. Memory must be allocated.[out] a Transfer function \(H(s)\) denominator coefficients vector pointer. Vector size is [ord+1 x 1]
. Memory must be allocated.
 Returns
DSPL_OK
Filter is calculated successfully .
DSPL_ERROR_FILTER_RP
ParameterRp
must be positive.
DSPL_ERROR_FILTER_ORD
Filter order must be positive.
DSPL_ERROR_PTR
Pointersb
anda
cannot be asNULL
.
◆ dspl_cheby1_ap()
int dspl_cheby1_ap  (  double  Rp, 
int  ord,  
double *  b,  
double *  a  
) 
Analog Chebyshev type 1 filter prototype.
Function calculates Analog Chebyshev type 1 filter transfer function \(H(s)\) coefficients. Filter has order ord
cutoff frequency 1 rad/s with distortion level Rp
dB in passband (from 0 rad/s to 1 rad/s). Chebyshev type 1 filter magnitude is equiripple in passband.
 Parameters

[in] Rp Filter passband distortions dB. Distortions level from 0 rad/s to 1 rad/s. Must be positive. [in] ord Filter order. Transfer function \(H(s)\) numerator and denominator coefficients number is ord+1
.[out] b Transfer function \(H(s)\) numerator coefficients vector pointer. Vector size is [ord+1 x 1]
. Memory must be allocated.[out] a Transfer function \(H(s)\) denominator coefficients vector pointer. Vector size is [ord+1 x 1]
. Memory must be allocated.
 Returns
DSPL_OK
Filter is calculated successfully .
DSPL_ERROR_FILTER_RP
ParameterRp
must be positive.
DSPL_ERROR_FILTER_ORD
Filter order must be positive.
DSPL_ERROR_PTR
Pointersb
anda
cannot be asNULL
.
◆ dspl_cheby2_ap()
int dspl_cheby2_ap  (  double  Rs, 
int  ord,  
double *  b,  
double *  a  
) 
Analog Chebyshev type 2 filter prototype.
Function calculates Analog Chebyshev type 2 filter transfer function \(H(s)\) coefficients. Filter has order ord
stopband frequency 1 rad/s with suppression level Rs
dB in stopband.
 Parameters

[in] Rs Filter stopband suppression dB. Must be positive. [in] ord Filter order. Transfer function \(H(s)\) numerator and denominator coefficients number is ord+1
.[out] b Transfer function \(H(s)\) numerator coefficients vector pointer. Vector size is [ord+1 x 1]
. Memory must be allocated.[out] a Transfer function \(H(s)\) denominator coefficients vector pointer. Vector size is [ord+1 x 1]
. Memory must be allocated.
 Returns
DSPL_OK
Filter is calculated successfully .
DSPL_ERROR_FILTER_RS
ParameterRs
must be positive.
DSPL_ERROR_FILTER_ORD
Filter order must be positive.
DSPL_ERROR_PTR
Pointersb
anda
cannot be asNULL
.
Generated on Sat Mar 11 2017 12:37:51 for DSPL  Digital signal processing library by 1.8.13
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