kopia lustrzana https://github.com/rs1729/RS
696 wiersze
17 KiB
C
696 wiersze
17 KiB
C
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/*
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* sync header: correlation/matched filter
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* compile:
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* gcc -c demod_dft.c
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*
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* author: zilog80
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*/
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/* ------------------------------------------------------------------------------------ */
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <math.h>
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#include <complex.h>
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typedef unsigned char ui8_t;
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typedef unsigned short ui16_t;
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typedef unsigned int ui32_t;
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typedef short i16_t;
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typedef int i32_t;
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#include "demod_dft.h"
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static unsigned int sample_in, sample_out, delay;
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static int buffered = 0;
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static int L, M;
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static float *match = NULL,
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*bufs = NULL;
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static char *rawbits = NULL;
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static int Nvar = 0; // < M
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static double xsum=0, qsum=0;
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static float *xs = NULL,
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*qs = NULL;
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static float dc_ofs = 0.0;
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static float dc = 0.0;
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/* ------------------------------------------------------------------------------------ */
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static int LOG2N, N_DFT;
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static float complex *ew;
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static float complex *Fm, *X, *Z, *cx;
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static float *xn;
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static void dft_raw(float complex *Z) {
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int s, l, l2, i, j, k;
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float complex w1, w2, T;
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j = 1;
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for (i = 1; i < N_DFT; i++) {
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if (i < j) {
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T = Z[j-1];
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Z[j-1] = Z[i-1];
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Z[i-1] = T;
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}
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k = N_DFT/2;
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while (k < j) {
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j = j - k;
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k = k/2;
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}
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j = j + k;
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}
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for (s = 0; s < LOG2N; s++) {
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l2 = 1 << s;
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l = l2 << 1;
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w1 = (float complex)1.0;
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w2 = ew[s]; // cexp(-I*M_PI/(float)l2)
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for (j = 1; j <= l2; j++) {
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for (i = j; i <= N_DFT; i += l) {
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k = i + l2;
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T = Z[k-1] * w1;
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Z[k-1] = Z[i-1] - T;
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Z[i-1] = Z[i-1] + T;
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}
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w1 = w1 * w2;
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}
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}
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}
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static void dft(float *x, float complex *Z) {
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int i;
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for (i = 0; i < N_DFT; i++) Z[i] = (float complex)x[i];
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dft_raw(Z);
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}
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static void Nidft(float complex *Z, float complex *z) {
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int i;
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for (i = 0; i < N_DFT; i++) z[i] = conj(Z[i]);
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dft_raw(z);
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// idft():
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// for (i = 0; i < N_DFT; i++) z[i] = conj(z[i])/(float)N_DFT; // hier: z reell
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}
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/* ------------------------------------------------------------------------------------ */
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int getCorrDFT(int K, unsigned int pos, float *maxv, unsigned int *maxvpos) {
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int i;
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int mp = -1;
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float mx = 0.0;
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float mx2 = 0.0;
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float re_cx = 0.0;
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float xnorm = 1;
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unsigned int mpos = 0;
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dc = 0.0;
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if (K + L > N_DFT) return -1;
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if (sample_out < L) return -2;
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if (pos == 0) pos = sample_out;
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for (i = 0; i < K+L; i++) xn[i] = bufs[(pos+M -(K+L-1) + i) % M];
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while (i < N_DFT) xn[i++] = 0.0;
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dft(xn, X);
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dc = get_bufmu(pos-sample_out); //oder: dc = creal(X[0])/(K+L);
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for (i = 0; i < N_DFT; i++) Z[i] = X[i]*Fm[i];
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Nidft(Z, cx);
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// relativ Peak - Normierung erst zum Schluss;
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// dann jedoch nicht zwingend corr-Max wenn FM-Amplitude bzw. norm(x) nicht konstant
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// (z.B. rs41 Signal-Pausen). Moeglicherweise wird dann wahres corr-Max in dem
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// K-Fenster nicht erkannt, deshalb K nicht zu gross waehlen.
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//
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mx2 = 0.0; // t = L-1
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for (i = L-1; i < K+L; i++) { // i=t .. i=t+K < t+1+K
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re_cx = creal(cx[i]); // imag(cx)=0
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if (re_cx*re_cx > mx2) {
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mx = re_cx;
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mx2 = mx*mx;
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mp = i;
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}
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}
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if (mp == L-1 || mp == K+L-1) return -4; // Randwert
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// mp == t mp == K+t
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mpos = pos - (K + L-1) + mp;
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xnorm = sqrt(qs[(mpos + 2*M) % M]); // Nvar = L
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mx /= xnorm*N_DFT;
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*maxv = mx;
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*maxvpos = mpos;
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if (pos == sample_out) buffered = sample_out-mpos;
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return mp;
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}
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/* ------------------------------------------------------------------------------------ */
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static int sample_rate = 0, bits_sample = 0, channels = 0;
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static float samples_per_bit = 0;
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static int wav_ch = 0; // 0: links bzw. mono; 1: rechts
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static int findstr(char *buff, char *str, int pos) {
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int i;
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for (i = 0; i < 4; i++) {
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if (buff[(pos+i)%4] != str[i]) break;
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}
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return i;
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}
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float read_wav_header(FILE *fp, float baudrate, int wav_channel) {
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char txt[4+1] = "\0\0\0\0";
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unsigned char dat[4];
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int byte, p=0;
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if (fread(txt, 1, 4, fp) < 4) return -1;
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if (strncmp(txt, "RIFF", 4)) return -1;
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if (fread(txt, 1, 4, fp) < 4) return -1;
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// pos_WAVE = 8L
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if (fread(txt, 1, 4, fp) < 4) return -1;
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if (strncmp(txt, "WAVE", 4)) return -1;
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// pos_fmt = 12L
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for ( ; ; ) {
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if ( (byte=fgetc(fp)) == EOF ) return -1;
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txt[p % 4] = byte;
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p++; if (p==4) p=0;
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if (findstr(txt, "fmt ", p) == 4) break;
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}
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if (fread(dat, 1, 4, fp) < 4) return -1;
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if (fread(dat, 1, 2, fp) < 2) return -1;
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if (fread(dat, 1, 2, fp) < 2) return -1;
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channels = dat[0] + (dat[1] << 8);
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if (fread(dat, 1, 4, fp) < 4) return -1;
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memcpy(&sample_rate, dat, 4); //sample_rate = dat[0]|(dat[1]<<8)|(dat[2]<<16)|(dat[3]<<24);
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if (fread(dat, 1, 4, fp) < 4) return -1;
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if (fread(dat, 1, 2, fp) < 2) return -1;
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//byte = dat[0] + (dat[1] << 8);
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if (fread(dat, 1, 2, fp) < 2) return -1;
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bits_sample = dat[0] + (dat[1] << 8);
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// pos_dat = 36L + info
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for ( ; ; ) {
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if ( (byte=fgetc(fp)) == EOF ) return -1;
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txt[p % 4] = byte;
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p++; if (p==4) p=0;
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if (findstr(txt, "data", p) == 4) break;
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}
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if (fread(dat, 1, 4, fp) < 4) return -1;
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fprintf(stderr, "sample_rate: %d\n", sample_rate);
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fprintf(stderr, "bits : %d\n", bits_sample);
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fprintf(stderr, "channels : %d\n", channels);
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if (wav_channel >= 0 && wav_channel < channels) wav_ch = wav_channel;
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else wav_ch = 0;
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fprintf(stderr, "channel-In : %d\n", wav_ch+1);
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if ((bits_sample != 8) && (bits_sample != 16)) return -1;
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samples_per_bit = sample_rate/baudrate;
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fprintf(stderr, "samples/bit: %.2f\n", samples_per_bit);
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return samples_per_bit;
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}
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static int f32read_sample(FILE *fp, float *s) {
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int i;
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short b = 0;
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for (i = 0; i < channels; i++) {
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if (fread( &b, bits_sample/8, 1, fp) != 1) return EOF;
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if (i == wav_ch) { // i = 0: links bzw. mono
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//if (bits_sample == 8) sint = b-128; // 8bit: 00..FF, centerpoint 0x80=128
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//if (bits_sample == 16) sint = (short)b;
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if (bits_sample == 8) { b -= 128; }
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*s = b/128.0;
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if (bits_sample == 16) { *s /= 256.0; }
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}
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}
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return 0;
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}
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float get_bufvar(int ofs) {
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float mu = xs[(sample_out+M + ofs) % M]/Nvar;
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float var = qs[(sample_out+M + ofs) % M]/Nvar - mu*mu;
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return var;
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}
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float get_bufmu(int ofs) {
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float mu = xs[(sample_out+M + ofs) % M]/Nvar;
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return mu;
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}
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int f32buf_sample(FILE *fp, int inv) {
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float s = 0.0;
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float xneu, xalt;
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if (f32read_sample(fp, &s) == EOF) return EOF;
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if (inv) s = -s;
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bufs[sample_in % M] = s - dc_ofs;
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xneu = bufs[(sample_in ) % M];
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xalt = bufs[(sample_in+M - Nvar) % M];
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xsum += xneu - xalt; // + xneu - xalt
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qsum += (xneu - xalt)*(xneu + xalt); // + xneu*xneu - xalt*xalt
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xs[sample_in % M] = xsum;
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qs[sample_in % M] = qsum;
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sample_out = sample_in - delay;
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sample_in += 1;
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return 0;
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}
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static int read_bufbit(int symlen, char *bits, unsigned int mvp, int reset) {
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// symlen==2: manchester2 0->10,1->01->1: 2.bit
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static unsigned int rcount;
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static float rbitgrenze;
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double sum = 0.0;
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if (reset) {
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rcount = 0;
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rbitgrenze = 0;
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}
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rbitgrenze += samples_per_bit;
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do {
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sum += bufs[(rcount + mvp + M) % M];
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rcount++;
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} while (rcount < rbitgrenze); // n < samples_per_bit
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if (symlen == 2) {
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rbitgrenze += samples_per_bit;
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do {
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sum -= bufs[(rcount + mvp + M) % M];
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rcount++;
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} while (rcount < rbitgrenze); // n < samples_per_bit
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}
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if (symlen != 2) {
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if (sum >= 0) *bits = '1';
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else *bits = '0';
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}
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else {
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if (sum >= 0) strncpy(bits, "10", 2);
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else strncpy(bits, "01", 2);
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}
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return 0;
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}
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int headcmp(int symlen, char *hdr, int len, unsigned int mvp, int inv, int option_dc) {
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int errs = 0;
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int pos;
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int step = 1;
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char sign = 0;
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if (symlen != 1) step = 2;
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if (inv) sign=1;
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for (pos = 0; pos < len; pos += step) {
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read_bufbit(symlen, rawbits+pos, mvp+1-(int)(len*samples_per_bit), pos==0);
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}
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rawbits[pos] = '\0';
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while (len > 0) {
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if ((rawbits[len-1]^sign) != hdr[len-1]) errs += 1;
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len--;
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}
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if (option_dc && errs < 3) {
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dc_ofs += dc;
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}
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return errs;
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}
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/* -------------------------------------------------------------------------- */
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int read_sbit(FILE *fp, int symlen, int *bit, int inv, int ofs, int reset) {
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// symlen==2: manchester2 10->0,01->1: 2.bit
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static double bitgrenze;
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static unsigned long scount;
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float sample;
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double sum = 0.0;
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if (reset) {
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scount = 0;
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bitgrenze = 0;
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}
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if (symlen == 2) {
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bitgrenze += samples_per_bit;
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do {
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if (buffered > 0) buffered -= 1;
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else if (f32buf_sample(fp, inv) == EOF) return EOF;
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sample = bufs[(sample_out-buffered + ofs + M) % M];
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sum -= sample;
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scount++;
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} while (scount < bitgrenze); // n < samples_per_bit
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}
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bitgrenze += samples_per_bit;
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do {
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if (buffered > 0) buffered -= 1;
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else if (f32buf_sample(fp, inv) == EOF) return EOF;
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sample = bufs[(sample_out-buffered + ofs + M) % M];
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sum += sample;
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scount++;
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} while (scount < bitgrenze); // n < samples_per_bit
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if (sum >= 0) *bit = 1;
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else *bit = 0;
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return 0;
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}
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int read_spkbit(FILE *fp, int symlen, int *bit, int inv, int ofs, int reset, int spike) {
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// symlen==2: manchester2 10->0,01->1: 2.bit
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static double bitgrenze;
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static unsigned long scount;
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float sample;
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float avg;
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float ths = 0.5, scale = 0.27;
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double sum = 0.0;
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if (reset) {
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scount = 0;
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bitgrenze = 0;
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}
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if (symlen == 2) {
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bitgrenze += samples_per_bit;
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do {
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if (buffered > 0) buffered -= 1;
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else if (f32buf_sample(fp, inv) == EOF) return EOF;
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sample = bufs[(sample_out-buffered + ofs + M) % M];
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avg = 0.5*(bufs[(sample_out-buffered-1 + ofs + M) % M]
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+bufs[(sample_out-buffered+1 + ofs + M) % M]);
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if (spike && fabs(sample - avg) > ths) sample = avg + scale*(sample - avg); // spikes
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sum -= sample;
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scount++;
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} while (scount < bitgrenze); // n < samples_per_bit
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}
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bitgrenze += samples_per_bit;
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do {
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if (buffered > 0) buffered -= 1;
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else if (f32buf_sample(fp, inv) == EOF) return EOF;
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sample = bufs[(sample_out-buffered + ofs + M) % M];
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avg = 0.5*(bufs[(sample_out-buffered-1 + ofs + M) % M]
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+bufs[(sample_out-buffered+1 + ofs + M) % M]);
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if (spike && fabs(sample - avg) > ths) sample = avg + scale*(sample - avg); // spikes
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sum += sample;
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scount++;
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} while (scount < bitgrenze); // n < samples_per_bit
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if (sum >= 0) *bit = 1;
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else *bit = 0;
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return 0;
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}
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/* -------------------------------------------------------------------------- */
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int read_softbit(FILE *fp, int symlen, int *bit, float *sb, float level, int inv, int ofs, int reset) {
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// symlen==2: manchester2 10->0,01->1: 2.bit
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static double bitgrenze;
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static unsigned long scount;
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float sample;
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double sum = 0.0;
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int n = 0;
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if (reset) {
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scount = 0;
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bitgrenze = 0;
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}
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if (symlen == 2) {
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bitgrenze += samples_per_bit;
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do {
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if (buffered > 0) buffered -= 1;
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else if (f32buf_sample(fp, inv) == EOF) return EOF;
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sample = bufs[(sample_out-buffered + ofs + M) % M];
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if (scount > bitgrenze-samples_per_bit && scount < bitgrenze-2)
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{
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sum -= sample;
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n++;
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}
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scount++;
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} while (scount < bitgrenze); // n < samples_per_bit
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}
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bitgrenze += samples_per_bit;
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do {
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if (buffered > 0) buffered -= 1;
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else if (f32buf_sample(fp, inv) == EOF) return EOF;
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sample = bufs[(sample_out-buffered + ofs + M) % M];
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if (scount > bitgrenze-samples_per_bit && scount < bitgrenze-2)
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{
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sum += sample;
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n++;
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}
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scount++;
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} while (scount < bitgrenze); // n < samples_per_bit
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if (sum >= 0) *bit = 1;
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else *bit = 0;
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*sb = sum / n;
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if (*sb > +2.5*level) *sb = +0.8*level;
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if (*sb > +level) *sb = +level;
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if (*sb < -2.5*level) *sb = -0.8*level;
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if (*sb < -level) *sb = -level;
|
|
|
|
*sb /= level;
|
|
|
|
return 0;
|
|
}
|
|
|
|
float header_level(char hdr[], int hLen, unsigned int pos, int inv) {
|
|
int n, bitn;
|
|
int sgn = 0;
|
|
double s = 0.0;
|
|
double sum = 0.0;
|
|
|
|
n = 0;
|
|
bitn = 0;
|
|
while ( bitn < hLen && (n < L) ) {
|
|
sgn = (hdr[bitn]&1)*2-1; // {'0','1'} -> {-1,1}
|
|
s = bufs[(pos-L + n + M) % M];
|
|
if (inv) s = -s;
|
|
sum += s * sgn;
|
|
n++;
|
|
bitn = n / samples_per_bit;
|
|
}
|
|
sum /= n;
|
|
|
|
return sum;
|
|
}
|
|
|
|
/* -------------------------------------------------------------------------- */
|
|
|
|
|
|
static double norm2_match() {
|
|
int i;
|
|
double x, y = 0.0;
|
|
for (i = 0; i < L; i++) {
|
|
x = match[i];
|
|
y += x*x;
|
|
}
|
|
return y;
|
|
}
|
|
|
|
int init_buffers(char hdr[], int hLen, int shape) {
|
|
//hLen = strlen(header) = HEADLEN;
|
|
|
|
int i, pos;
|
|
float b, x;
|
|
float normMatch;
|
|
|
|
float alpha, sqalp, a = 1.0;
|
|
|
|
int p2 = 1;
|
|
int K;
|
|
int n, k;
|
|
float *m = NULL;
|
|
|
|
|
|
L = hLen * samples_per_bit + 0.5;
|
|
M = 3*L;
|
|
// if (samples_per_bit < 6) M = 6*L;
|
|
|
|
sample_in = 0;
|
|
|
|
p2 = 1;
|
|
while (p2 < M) p2 <<= 1;
|
|
while (p2 < 0x2000) p2 <<= 1; // or 0x4000, if sample not too short
|
|
M = p2;
|
|
N_DFT = p2;
|
|
LOG2N = log(N_DFT)/log(2)+0.1; // 32bit cpu ... intermediate floating-point precision
|
|
//while ((1 << LOG2N) < N_DFT) LOG2N++; // better N_DFT = (1 << LOG2N) ...
|
|
|
|
delay = L/16;
|
|
K = M-L - delay; // L+K < M
|
|
|
|
Nvar = L; //L/2; // = L/k
|
|
|
|
|
|
bufs = (float *)calloc( M+1, sizeof(float)); if (bufs == NULL) return -100;
|
|
match = (float *)calloc( L+1, sizeof(float)); if (match == NULL) return -100;
|
|
|
|
xs = (float *)calloc( M+1, sizeof(float)); if (xs == NULL) return -100;
|
|
qs = (float *)calloc( M+1, sizeof(float)); if (qs == NULL) return -100;
|
|
|
|
|
|
rawbits = (char *)calloc( 2*hLen+1, sizeof(char)); if (rawbits == NULL) return -100;
|
|
|
|
for (i = 0; i < M; i++) bufs[i] = 0.0;
|
|
|
|
alpha = exp(0.8);
|
|
sqalp = sqrt(alpha/M_PI);
|
|
//a = sqalp;
|
|
|
|
for (i = 0; i < L; i++) {
|
|
pos = i/samples_per_bit;
|
|
x = (i - pos*samples_per_bit)*2.0/samples_per_bit - 1;
|
|
a = sqalp;
|
|
|
|
if ( ( pos < hLen-1 && hdr[pos]!=hdr[pos+1] && x > 0.0 )
|
|
|| ( pos > 0 && hdr[pos-1]!=hdr[pos] && x < 0.0 ) ) // x=0: a=sqalp
|
|
{
|
|
switch (shape) {
|
|
case 1: if ( fabs(x) > 0.6 ) a *= (1 - fabs(x))/0.6;
|
|
break;
|
|
case 2: a = sqalp * exp(-alpha*x*x);
|
|
break;
|
|
case 3: a = 1 - fabs( x );
|
|
break;
|
|
default: a = sqalp;
|
|
if (i-pos*samples_per_bit < 2 ||
|
|
i-pos*samples_per_bit > samples_per_bit-2) a = 0.8*sqalp;
|
|
}
|
|
}
|
|
|
|
b = ((hdr[pos] & 0x1) - 0.5)*2.0; // {-1,+1}
|
|
b *= a;
|
|
|
|
match[i] = b;
|
|
}
|
|
|
|
normMatch = sqrt(norm2_match());
|
|
for (i = 0; i < L; i++) {
|
|
match[i] /= normMatch;
|
|
}
|
|
|
|
|
|
xn = calloc(N_DFT+1, sizeof(float)); if (xn == NULL) return -1;
|
|
|
|
ew = calloc(LOG2N+1, sizeof(complex float)); if (ew == NULL) return -1;
|
|
Fm = calloc(N_DFT+1, sizeof(complex float)); if (Fm == NULL) return -1;
|
|
X = calloc(N_DFT+1, sizeof(complex float)); if (X == NULL) return -1;
|
|
Z = calloc(N_DFT+1, sizeof(complex float)); if (Z == NULL) return -1;
|
|
cx = calloc(N_DFT+1, sizeof(complex float)); if (cx == NULL) return -1;
|
|
|
|
for (n = 0; n < LOG2N; n++) {
|
|
k = 1 << n;
|
|
ew[n] = cexp(-I*M_PI/(float)k);
|
|
}
|
|
|
|
m = calloc(N_DFT+1, sizeof(float)); if (m == NULL) return -1;
|
|
for (i = 0; i < L; i++) m[L-1 - i] = match[i]; // t = L-1
|
|
while (i < N_DFT) m[i++] = 0.0;
|
|
dft(m, Fm);
|
|
|
|
free(m); m = NULL;
|
|
|
|
return K;
|
|
}
|
|
|
|
int free_buffers() {
|
|
|
|
if (match) { free(match); match = NULL; }
|
|
if (bufs) { free(bufs); bufs = NULL; }
|
|
if (xs) { free(xs); xs = NULL; }
|
|
if (qs) { free(qs); qs = NULL; }
|
|
if (rawbits) { free(rawbits); rawbits = NULL; }
|
|
|
|
if (xn) { free(xn); xn = NULL; }
|
|
if (ew) { free(ew); ew = NULL; }
|
|
if (Fm) { free(Fm); Fm = NULL; }
|
|
if (X) { free(X); X = NULL; }
|
|
if (Z) { free(Z); Z = NULL; }
|
|
if (cx) { free(cx); cx = NULL; }
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* ------------------------------------------------------------------------------------ */
|
|
|
|
unsigned int get_sample() {
|
|
return sample_out;
|
|
}
|
|
|