FSK Modulator/Demodulator. More...
#include "asterisk.h"
#include <stdio.h>
#include "asterisk/fskmodem.h"
Go to the source code of this file.
Defines | |
#define | BWLIST {75,800} |
#define | FLIST {1400,1800,1200,2200,1300,2100} |
#define | GET_SAMPLE get_sample(&buffer, len) |
#define | NBW 2 |
#define | NF 6 |
#define | STATE_GET_BYTE 3 |
#define | STATE_SEARCH_STARTBIT 0 |
#define | STATE_SEARCH_STARTBIT2 1 |
#define | STATE_SEARCH_STARTBIT3 2 |
Functions | |
static int | demodulator (fsk_data *fskd, float *retval, float x) |
static float | filterL (fsk_data *fskd, float in) |
static float | filterM (fsk_data *fskd, float in) |
static float | filterS (fsk_data *fskd, float in) |
int | fsk_serial (fsk_data *fskd, short *buffer, int *len, int *outbyte) |
static int | get_bit_raw (fsk_data *fskd, short *buffer, int *len) |
static float | get_sample (short **buffer, int *len) |
Variables | |
static double | coef_in [NF][NBW][8] |
Coefficients for input filters Coefficients table, generated by program "mkfilter" mkfilter is part of the zapatatelephony.org distribution Format: coef[IDX_FREC][IDX_BW][IDX_COEF] IDX_COEF = 0 => 1/GAIN IDX_COEF = 1-6 => Coefficientes y[n]. | |
static double | coef_out [NBW][8] |
Coefficients for output filter Coefficients table, generated by program "mkfilter" Format: coef[IDX_BW][IDX_COEF] IDX_COEF = 0 => 1/GAIN IDX_COEF = 1-6 => Coefficientes y[n]. |
FSK Modulator/Demodulator.
Definition in file fskmodem_float.c.
#define BWLIST {75,800} |
Definition at line 40 of file fskmodem_float.c.
#define FLIST {1400,1800,1200,2200,1300,2100} |
Definition at line 42 of file fskmodem_float.c.
#define GET_SAMPLE get_sample(&buffer, len) |
Definition at line 58 of file fskmodem_float.c.
Referenced by fsk_serial(), and get_bit_raw().
#define NBW 2 |
Definition at line 39 of file fskmodem_float.c.
#define NF 6 |
Definition at line 41 of file fskmodem_float.c.
#define STATE_GET_BYTE 3 |
Definition at line 47 of file fskmodem_float.c.
Referenced by fsk_serial().
#define STATE_SEARCH_STARTBIT 0 |
Definition at line 44 of file fskmodem_float.c.
Referenced by fsk_serial().
#define STATE_SEARCH_STARTBIT2 1 |
Definition at line 45 of file fskmodem_float.c.
Referenced by fsk_serial().
#define STATE_SEARCH_STARTBIT3 2 |
Definition at line 46 of file fskmodem_float.c.
Referenced by fsk_serial().
static int demodulator | ( | fsk_data * | fskd, |
float * | retval, | ||
float | x | ||
) | [inline, static] |
Definition at line 167 of file fskmodem_float.c.
References fsk_data::cola_demod, fsk_data::cola_filter, fsk_data::cola_in, filterL(), filterM(), filterS(), NCOLA, and fsk_data::pcola.
Referenced by fsk_serial(), and get_bit_raw().
static float filterL | ( | fsk_data * | fskd, |
float | in | ||
) | [inline, static] |
Low-pass filter for demodulated data
Definition at line 145 of file fskmodem_float.c.
References fsk_data::bw, fsk_data::flp, fsk_data::flxv, fsk_data::flyv, and s.
Referenced by demodulator().
{ int i, j; double s; double *pc; pc = &coef_out[fskd->bw][0]; fskd->flxv[(fskd->flp + 6) & 7] = in * (*pc++); s = (fskd->flxv[fskd->flp] + fskd->flxv[(fskd->flp+6)&7]) + 6 * (fskd->flxv[(fskd->flp+1)&7] + fskd->flxv[(fskd->flp+5)&7]) + 15 * (fskd->flxv[(fskd->flp+2)&7] + fskd->flxv[(fskd->flp+4)&7]) + 20 * fskd->flxv[(fskd->flp+3)&7]; for (i = 0,j = fskd->flp;i<6;i++,j++) s += fskd->flyv[j&7]*(*pc++); fskd->flyv[j&7] = s; fskd->flp++; fskd->flp &= 7; return s; }
static float filterM | ( | fsk_data * | fskd, |
float | in | ||
) | [inline, static] |
Band-pass filter for MARK frequency
Definition at line 107 of file fskmodem_float.c.
References fsk_data::bw, fsk_data::f_mark_idx, fsk_data::fmp, fsk_data::fmxv, fsk_data::fmyv, and s.
Referenced by demodulator().
{ int i, j; double s; double *pc; pc = &coef_in[fskd->f_mark_idx][fskd->bw][0]; fskd->fmxv[(fskd->fmp+6)&7] = in*(*pc++); s = (fskd->fmxv[(fskd->fmp + 6) & 7] - fskd->fmxv[fskd->fmp]) + 3 * (fskd->fmxv[(fskd->fmp + 2) & 7] - fskd->fmxv[(fskd->fmp + 4) & 7]); for (i = 0, j = fskd->fmp; i < 6; i++, j++) s += fskd->fmyv[j&7]*(*pc++); fskd->fmyv[j&7] = s; fskd->fmp++; fskd->fmp &= 7; return s; }
static float filterS | ( | fsk_data * | fskd, |
float | in | ||
) | [inline, static] |
Band-pass filter for SPACE frequency
Definition at line 126 of file fskmodem_float.c.
References fsk_data::bw, fsk_data::f_space_idx, fsk_data::fsp, fsk_data::fsxv, fsk_data::fsyv, and s.
Referenced by demodulator().
{ int i, j; double s; double *pc; pc = &coef_in[fskd->f_space_idx][fskd->bw][0]; fskd->fsxv[(fskd->fsp+6)&7] = in*(*pc++); s = (fskd->fsxv[(fskd->fsp + 6) & 7] - fskd->fsxv[fskd->fsp]) + 3 * (fskd->fsxv[(fskd->fsp + 2) & 7] - fskd->fsxv[(fskd->fsp + 4) & 7]); for (i = 0, j = fskd->fsp; i < 6; i++, j++) s += fskd->fsyv[j&7]*(*pc++); fskd->fsyv[j&7] = s; fskd->fsp++; fskd->fsp &= 7; return s; }
int fsk_serial | ( | fsk_data * | fskd, |
short * | buffer, | ||
int * | len, | ||
int * | outbyte | ||
) |
Definition at line 222 of file fskmodem_float.c.
References demodulator(), get_bit_raw(), GET_SAMPLE, len(), fsk_data::nbit, fsk_data::nstop, fsk_data::parity, ast_frame::samples, fsk_data::spb, fsk_data::state, STATE_GET_BYTE, STATE_SEARCH_STARTBIT, STATE_SEARCH_STARTBIT2, STATE_SEARCH_STARTBIT3, fsk_data::x1, and fsk_data::x2.
{ int a; int i,j,n1,r; int samples = 0; int olen; int beginlen=*len; int beginlenx; switch (fskd->state) { /* Pick up where we left off */ case STATE_SEARCH_STARTBIT2: goto search_startbit2; case STATE_SEARCH_STARTBIT3: goto search_startbit3; case STATE_GET_BYTE: goto getbyte; } /* We await for start bit */ do { /* this was jesus's nice, reasonable, working (at least with RTTY) code to look for the beginning of the start bit. Unfortunately, since TTY/TDD's just start sending a start bit with nothing preceding it at the beginning of a transmission (what a LOSING design), we cant do it this elegantly */ /* if (demodulator(zap,&x1)) return(-1); for (;;) { if (demodulator(zap,&x2)) return(-1); if (x1>0 && x2<0) break; x1 = x2; } */ /* this is now the imprecise, losing, but functional code to detect the beginning of a start bit in the TDD sceanario. It just looks for sufficient level to maybe, perhaps, guess, maybe that its maybe the beginning of a start bit, perhaps. This whole thing stinks! */ beginlenx=beginlen; /* just to avoid unused war warnings */ if (demodulator(fskd, &fskd->x1, GET_SAMPLE)) return -1; samples++; for (;;) { search_startbit2: if (*len <= 0) { fskd->state = STATE_SEARCH_STARTBIT2; return 0; } samples++; if (demodulator(fskd, &fskd->x2, GET_SAMPLE)) return(-1); #if 0 printf("x2 = %5.5f ", fskd->x2); #endif if (fskd->x2 < -0.5) break; } search_startbit3: /* We await for 0.5 bits before using DPLL */ i = fskd->spb/2; if (*len < i) { fskd->state = STATE_SEARCH_STARTBIT3; return 0; } for (; i>0; i--) { if (demodulator(fskd, &fskd->x1, GET_SAMPLE)) return(-1); #if 0 printf("x1 = %5.5f ", fskd->x1); #endif samples++; } /* x1 must be negative (start bit confirmation) */ } while (fskd->x1 > 0); fskd->state = STATE_GET_BYTE; getbyte: /* Need at least 80 samples (for 1200) or 1320 (for 45.5) to be sure we'll have a byte */ if (fskd->nbit < 8) { if (*len < 1320) return 0; } else { if (*len < 80) return 0; } /* Now we read the data bits */ j = fskd->nbit; for (a = n1 = 0; j; j--) { olen = *len; i = get_bit_raw(fskd, buffer, len); buffer += (olen - *len); if (i == -1) return(-1); if (i) n1++; a >>= 1; a |= i; } j = 8-fskd->nbit; a >>= j; /* We read parity bit (if exists) and check parity */ if (fskd->parity) { olen = *len; i = get_bit_raw(fskd, buffer, len); buffer += (olen - *len); if (i == -1) return(-1); if (i) n1++; if (fskd->parity == 1) { /* parity=1 (even) */ if (n1&1) a |= 0x100; /* error */ } else { /* parity=2 (odd) */ if (!(n1&1)) a |= 0x100; /* error */ } } /* We read STOP bits. All of them must be 1 */ for (j = fskd->nstop;j;j--) { r = get_bit_raw(fskd, buffer, len); if (r == -1) return(-1); if (!r) a |= 0x200; } /* And finally we return */ /* Bit 8 : Parity error */ /* Bit 9 : Framming error*/ *outbyte = a; fskd->state = STATE_SEARCH_STARTBIT; return 1; }
static int get_bit_raw | ( | fsk_data * | fskd, |
short * | buffer, | ||
int * | len | ||
) | [static] |
Definition at line 187 of file fskmodem_float.c.
References fsk_data::cont, demodulator(), f, GET_SAMPLE, fsk_data::spb, and fsk_data::x0.
Referenced by fsk_serial().
{ /* This function implements a DPLL to synchronize with the bits */ float x,spb,spb2,ds; int f; spb = fskd->spb; if (fskd->spb == 7) spb = 8000.0 / 1200.0; ds = spb/32.; spb2 = spb/2.; for (f = 0;;) { if (demodulator(fskd, &x, GET_SAMPLE)) return -1; if ((x * fskd->x0) < 0) { /* Transition */ if (!f) { if (fskd->cont<(spb2)) fskd->cont += ds; else fskd->cont -= ds; f = 1; } } fskd->x0 = x; fskd->cont += 1.; if (fskd->cont > spb) { fskd->cont -= spb; break; } } f = (x > 0) ? 0x80 : 0; return f; }
static float get_sample | ( | short ** | buffer, |
int * | len | ||
) | [inline, static] |
Definition at line 49 of file fskmodem_float.c.
{ float retval; retval = (float) **buffer / 256; (*buffer)++; (*len)--; return retval; };
double coef_in[NF][NBW][8] [static] |
Coefficients for input filters Coefficients table, generated by program "mkfilter" mkfilter is part of the zapatatelephony.org distribution Format: coef[IDX_FREC][IDX_BW][IDX_COEF] IDX_COEF = 0 => 1/GAIN IDX_COEF = 1-6 => Coefficientes y[n].
Definition at line 67 of file fskmodem_float.c.
double coef_out[NBW][8] [static] |
{ { 1.3868644653e-08,-6.3283665042e-01,4.0895057217e+00,-1.1020074592e+01,1.5850766191e+01,-1.2835109292e+01,5.5477477340e+00,0.0000000000e+00, }, { 3.1262119724e-03,-7.8390522307e-03,8.5209627801e-02,-4.0804129163e-01,1.1157139955e+00,-1.8767603680e+00,1.8916395224e+00,0.0000000000e+00, }, }
Coefficients for output filter Coefficients table, generated by program "mkfilter" Format: coef[IDX_BW][IDX_COEF] IDX_COEF = 0 => 1/GAIN IDX_COEF = 1-6 => Coefficientes y[n].
Definition at line 100 of file fskmodem_float.c.