iirdecim_rrrf

Variants: iirdecim_cccf, iirdecim_crcf, iirdecim_rrrf

Infinite impulse response (IIR) decimator

Public Functions

iirdecim_rrrf iirdecim_rrrf_create(unsigned int _M, float * _b, unsigned int _nb, float * _a, unsigned int _na)
iirdecim_rrrf iirdecim_rrrf_create_default(unsigned int _M, unsigned int _order)
iirdecim_rrrf iirdecim_rrrf_create_prototype(unsigned int _M, liquid_iirdes_filtertype _ftype, liquid_iirdes_bandtype _btype, liquid_iirdes_format _format, unsigned int _order, float _fc, float _f0, float _ap, float _as)
iirdecim_rrrf iirdecim_rrrf_copy(iirdecim_rrrf _q)
int iirdecim_rrrf_destroy(iirdecim_rrrf _q)
int iirdecim_rrrf_print(iirdecim_rrrf _q)
int iirdecim_rrrf_reset(iirdecim_rrrf _q)
int iirdecim_rrrf_execute(iirdecim_rrrf _q, float * _x, float * _y)
int iirdecim_rrrf_execute_block(iirdecim_rrrf _q, float * _x, unsigned int _n, float * _y)
float iirdecim_rrrf_groupdelay(iirdecim_rrrf _q, float _fc)

Interfaces

iirdecim_rrrf iirdecim_rrrf_create(unsigned int _M, float * _b, unsigned int _nb, float * _a, unsigned int _na)∞

Create infinite impulse response decimator from external coefficients. Note that the number of feed-forward and feed-back coefficients do not need to be equal, but they do need to be non-zero. Furthermore, the first feed-back coefficient \(a_0\) cannot be equal to zero, otherwise the filter will be invalid as this value is factored out from all coefficients. For stability reasons the number of coefficients should reasonably not exceed about 8 for single-precision floating-point.

  • _M : decimation factor, 2 <= _M
  • _b : feed-forward coefficients (numerator), shape: (_nb, 1)
  • _nb : number of feed-forward coefficients, 0 < _nb
  • _a : feed-back coefficients (denominator), shape: (_na, 1)
  • _na : number of feed-back coefficients, 0 < _na

iirdecim_rrrf iirdecim_rrrf_create_default(unsigned int _M, unsigned int _order)∞

Create decimator object with default Butterworth prototype

  • _M : decimation factor, 2 <= _M
  • _order : filter order, 0 < _order

iirdecim_rrrf iirdecim_rrrf_create_prototype(unsigned int _M, liquid_iirdes_filtertype _ftype, liquid_iirdes_bandtype _btype, liquid_iirdes_format _format, unsigned int _order, float _fc, float _f0, float _ap, float _as)∞

Create IIR decimator from prototype

  • _M : decimation factor, 2 <= _M
  • _ftype : filter type (e.g. LIQUID_IIRDES_BUTTER)
  • _btype : band type (e.g. LIQUID_IIRDES_BANDPASS)
  • _format : coefficients format (e.g. LIQUID_IIRDES_SOS)
  • _order : filter order, 0 < _order
  • _fc : low-pass prototype cut-off frequency, 0 <= _fc <= 0.5
  • _f0 : center frequency (band-pass, band-stop), 0 <= _f0 <= 0.5
  • _ap : pass-band ripple in dB, 0 < _ap
  • _as : stop-band ripple in dB, 0 < _as

iirdecim_rrrf iirdecim_rrrf_copy(iirdecim_rrrf _q)∞

Copy object including all internal objects and state

int iirdecim_rrrf_destroy(iirdecim_rrrf _q)∞

Destroy decimator object and free internal memory

int iirdecim_rrrf_print(iirdecim_rrrf _q)∞

Print decimator object internals

int iirdecim_rrrf_reset(iirdecim_rrrf _q)∞

Reset decimator object

int iirdecim_rrrf_execute(iirdecim_rrrf _q, float * _x, float * _y)∞

Execute decimator on _M input samples

  • _q : decimator object
  • _x : input samples, shape: (_M, 1)
  • _y : output sample pointer

int iirdecim_rrrf_execute_block(iirdecim_rrrf _q, float * _x, unsigned int _n, float * _y)∞

Execute decimator on block of _n*_M input samples

  • _q : decimator object
  • _x : input array, shape: (_n*_M, 1)
  • _n : number of _output_ samples
  • _y : output array, [_sze: _n x 1]

float iirdecim_rrrf_groupdelay(iirdecim_rrrf _q, float _fc)∞

Compute and return group delay of object

  • _q : filter object
  • _fc : frequency to evaluate