hpf.h File Reference

High Pass Filter. More...

#include "math.h"

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Data Structures
struct	a_hpf
	instance structure for High Pass Filter More...

Macros
#define	A_HPF_INIT(alpha)
#define	A_HPF_INIT2(fc, ts)
#define	A_HPF_GEN(fc, ts)

Typedefs
typedef struct a_hpf	a_hpf
	instance structure for High Pass Filter
typedef struct a_hpf	a::hpf

Functions
double	a_hpf_gen (double fc, double ts)
	generate for High Pass Filter
void	a_hpf_init (a_hpf *ctx, double alpha)
	initialize for High Pass Filter
double	a_hpf_iter (a_hpf *ctx, double x)
	calculate for High Pass Filter
void	a_hpf_zero (a_hpf *ctx)
	zeroing for High Pass Filter

Detailed Description

High Pass Filter.

high frequencies are passed, low frequencies are attenuated.

\[ RC\frac{\text{d}(V_{\mathrm i}-V_{\mathrm o})}{\text{dt}}=V_{\mathrm o} \]

\[ RC\frac{[V_{\mathrm i}(n)-V_{\mathrm i}(n-1)]-[V_{\mathrm o}(n)-V_{\mathrm o}(n-1)]}{T_s}=V_{\mathrm o}(n) \]

\[ V_{\mathrm o}(n)=\frac{RC}{RC+T_s}[V_{\mathrm o}(n-1)+V_{\mathrm i}(n)-V_{\mathrm i}(n-1)] \]

\[ \alpha=\frac{RC}{RC+T_s}=\frac{1}{2\pi f_c T_s + 1} \]

\[ V_{\mathrm o}(n)=\alpha[V_{\mathrm o}(n-1)+V_{\mathrm i}(n)-V_{\mathrm i}(n-1)] \]

https://en.wikipedia.org/wiki/High-pass_filter