iirinterp_rrrf

Infinite impulse response (IIR) interpolator

Variants: iirinterp_cccf, iirinterp_crcf, iirinterp_rrrf

Public Functions

iirinterp_rrrf iirinterp_rrrf_create(unsigned int _M, float * _b, unsigned int _nb, float * _a, unsigned int _na)
iirinterp_rrrf iirinterp_rrrf_create_default(unsigned int _M, unsigned int _order)
iirinterp_rrrf iirinterp_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)
iirinterp_rrrf iirinterp_rrrf_copy(iirinterp_rrrf _q)
void iirinterp_rrrf_destroy(iirinterp_rrrf _q)
void iirinterp_rrrf_print(iirinterp_rrrf _q)
void iirinterp_rrrf_reset(iirinterp_rrrf _q)
void iirinterp_rrrf_execute(iirinterp_rrrf _q, float _x, float * _y)
void iirinterp_rrrf_execute_block(iirinterp_rrrf _q, float * _x, unsigned int _n, float * _y)
float iirinterp_rrrf_groupdelay(iirinterp_rrrf _q, float _fc)

Interfaces

iirinterp_rrrf iirinterp_rrrf_create(unsigned int _M, float * _b, unsigned int _nb, float * _a, unsigned int _na)

Create infinite impulse response interpolator 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 : interpolation 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

iirinterp_rrrf iirinterp_rrrf_create_default(unsigned int _M, unsigned int _order)

Create interpolator object with default Butterworth prototype

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

iirinterp_rrrf iirinterp_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 interpolator from prototype

  • _M : interpolation 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

iirinterp_rrrf iirinterp_rrrf_copy(iirinterp_rrrf _q)

Copy object including all internal objects and state

void iirinterp_rrrf_destroy(iirinterp_rrrf _q)

Destroy interpolator object and free internal memory

void iirinterp_rrrf_print(iirinterp_rrrf _q)

Print interpolator object internals to stdout

void iirinterp_rrrf_reset(iirinterp_rrrf _q)

Reset interpolator object

void iirinterp_rrrf_execute(iirinterp_rrrf _q, float _x, float * _y)

Execute interpolation on single input sample and write \(M\) output samples (\(M\) is the interpolation factor)

  • _q : iirinterp object
  • _x : input sample
  • _y : output sample array, shape: (_M, 1)

void iirinterp_rrrf_execute_block(iirinterp_rrrf _q, float * _x, unsigned int _n, float * _y)

Execute interpolation on block of input samples

  • _q : iirinterp object
  • _x : input array, shape: (_n, 1)
  • _n : size of input array
  • _y : output sample array, shape: (_M*_n, 1)

float iirinterp_rrrf_groupdelay(iirinterp_rrrf _q, float _fc)

Compute and return group delay of object

  • _q : filter object
  • _fc : frequency to evaluate