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/*
* File psdmean.c
*
* Calculates mean powerspectrum of input data
* using blocklength lblock and nblocks as number
* of blocks to be processed.
*
* Author M.Bos - PA0MBO
* Date Feb 21st 2009
*
* resulting power spectral density of real input data
* vector input[] is stored in psd[]
* lblock is the length of the block of data to be
* processed and nblock is the number of data blocks
* to be processed
*
*/
/*************************************************************************
*
* PA0MBO
*
* COPYRIGHT (C) 2009 M.Bos
*
* This file is part of the distribution package RXAMADRM
*
* This package is free software and you can redistribute is
* and/or modify it under the terms of the GNU General Public License
*
* More details can be found in the accompanying file COPYING
*************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <sys/types.h>
#include <malloc.h>
void rfft(float *, int, int);
void psdmean(float *input, float *psd, int lblock, int nblocks)
{
float *pinput;
int i, j;
float tmpinbuf[1024];
/* check for space allocated */
if (lblock > 1024)
{
printf("lblokc param too large in call psdmean\n");
exit(EXIT_FAILURE);
}
/* clear array psd before accumulating new data */
for (i = 0; i < lblock / 2; i++)
{
psd[i] = 0.0;
}
/* loop over all blocks taking care to keep track of ptr in input */
pinput = input;
for (j = 0; j < nblocks; j++)
{
/* Now fill tmpinbuf with converted data from input */
for (i = 0; i < lblock; i++)
{
tmpinbuf[i] = pinput[i];
}
rfft(tmpinbuf, lblock / 2, 1);
for (i = 1; i < lblock / 2; ++i)
{
psd[i] += sqrt(tmpinbuf[i * 2] * tmpinbuf[i * 2] + tmpinbuf[2 * i + 1] * tmpinbuf[2 * i + 1]);
}
pinput += lblock; /* update pointer in input data */
}
for (i = 1; i < lblock / 2; ++i)
psd[i] = (float) (10.0 * log(psd[i] + 1.0e-8) / 2.3025 - 14.0);
}
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