decim.h

数字信号处理算法。用于多采样率系统

/****************************************************************************
*
* Name: decim.h
*
* Synopsis:
*
*   Decimates a real or complex signal.  For more information about
*   decimation, see dspGuru's Multirate FAQ at:
*
*       http://www.dspguru.com/info/faqs/mrfaq.htm
*
* Description: See function descriptons below.
*
* by Grant R. Griffin
* Provided by Iowegian's "dspGuru" service (http://www.dspguru.com).
* Copyright 2001, Iowegian International Corporation (http://www.iowegian.com)
*
*                          The Wide Open License (WOL)
*
* Permission to use, copy, modify, distribute and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice and this license appear in all source copies. 
* THIS SOFTWARE IS PROVIDED "AS IS" WITHOUT EXPRESS OR IMPLIED WARRANTY OF
* ANY KIND. See http://www.dspguru.com/wol.htm for more information.
*
*****************************************************************************/

/*****************************************************************************
Description:

    decim - "decimates" a signal by changing reducing its sampling rate by an
             integral factor via FIR filtering.

Inputs:

    factor_M:
        the decimation factor (must be >= 1)

    H_size:
        the number of taps in the filter

    p_H:
        pointer to the array of coefficients for the resampling filter.

    num_inp:
        the number of input samples

    p_inp:
        pointer to the input samples

Input/Outputs:

    p_Z:
        pointer to the delay line array (which must have  H_size elements)

Outputs:

    p_out:
        pointer to the output sample array.

    p_num_out:
        pointer to the number of output samples

*****************************************************************************/

void decim(int factor_M, int H_size, const double *const p_H,
           double *const p_Z, int num_inp, const double *p_inp,
           double *p_out, int *p_num_out);


/*****************************************************************************
Description:

    decim_complex - similar to decim except that it filters complex (real and 
                    imaginary) inputs and outputs, using a real filter.

*****************************************************************************/

void decim_complex(int factor_M, int H_size, const double *const p_H,
                   double *const p_Z_real, double *const p_Z_imag,
                   int num_inp, const double *p_inp_real,
                   const double *p_inp_imag, double *p_out_real,
                   double *p_out_imag, int * p_num_out);