kopia lustrzana https://github.com/xdsopl/qsstv
101 wiersze
2.4 KiB
C++
101 wiersze
2.4 KiB
C++
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/*
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* File psdcmean.c
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*
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* Calculates mean powerspectrum of complex input data
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* using blocklength lblock and nblocks as number
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* of blocks to be processed.
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*
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* Author M.Bos - PA0MBO
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* Date Feb 21st 2009
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*
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* resulting power spectral density of complex input
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* signal in rsbuf is stored in cpsd[]
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* length of datablock to be processed is lblock
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* nblocks is the nuber of blocks of input data
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* to be processed.
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*
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*/
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/*************************************************************************
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*
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* PA0MBO
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*
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* COPYRIGHT (C) 2009 M.Bos
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*
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* This file is part of the distribution package RXAMADRM
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*
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* This package is free software and you can redistribute is
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* and/or modify it under the terms of the GNU General Public License
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*
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* More details can be found in the accompanying file COPYING
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*************************************************************************/
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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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#include <sys/types.h>
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#include <malloc.h>
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void cfft(float *, int, int);
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void psdcmean(float *rsbuf, float *cpsd, int lblock, int nblocks)
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{
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float *pinput;
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int i, j;
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float tmpinbuf[2048];
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float result[512];
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/* check space */
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if (lblock > 1024)
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{
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printf("not enough temp space\b");
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exit(EXIT_FAILURE);
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}
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/* clear array result before accumulating new data */
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for (i = 0; i < (lblock / 2); i++)
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{
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result[i] = 0.0;
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}
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/* loop over all blocks taking care to keep track of ptr in input */
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pinput = rsbuf;
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for (j = 0; j < nblocks; j++)
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{
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/* Now fill tmpinbuf with converted data from input */
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for (i = 0; i < lblock; i++)
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{
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tmpinbuf[i * 2] = pinput[2 * i];
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tmpinbuf[i * 2 + 1] = pinput[2 * i + 1];
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}
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cfft(tmpinbuf, lblock / 2, 1);
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for (i = 1; i < lblock / 2; ++i)
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{
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result[i] +=
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sqrt(tmpinbuf[i * 2] * tmpinbuf[i * 2] +
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tmpinbuf[i * 2 + 1] * tmpinbuf[i * 2 + 1]);
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}
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pinput += 2 * lblock; /* update pointer in input data */
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}
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for (i = 0; i < lblock / 2; i++)
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{
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result[i] = (float) (10.0 * log(result[i] + 1.0e-8) / 2.305 - 14.0);
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}
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/* interchange halfs of cpsd buffer as in matlab code from
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plot_input_spectrum in diorama */
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for (i = 1; i < lblock / 4; i++)
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{
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cpsd[i] = result[lblock / 4 + i];
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cpsd[i + lblock / 4 - 1] = result[i];
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}
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}
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