FSK Modulator/Demodulator. More...
#include "asterisk.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 | IGET_SAMPLE iget_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 | |
int | fsk_serial (fsk_data *fskd, short *buffer, int *len, int *outbyte) |
int | fskmodem_init (fsk_data *fskd) |
static int | get_bit_raw (fsk_data *fskd, short *buffer, int *len) |
static int | ibpdfilter (struct filter_struct *fs, int in) |
static int | ibpfilter (struct filter_struct *fs, int in) |
static int | idemodulator (fsk_data *fskd, int *retval, int x) |
static int | iget_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_int.c.
#define BWLIST {75,800} |
Definition at line 38 of file fskmodem_int.c.
#define FLIST {1400,1800,1200,2200,1300,2100} |
Definition at line 40 of file fskmodem_int.c.
#define IGET_SAMPLE iget_sample(&buffer, len) |
Definition at line 56 of file fskmodem_int.c.
Referenced by fsk_serial(), and get_bit_raw().
#define NBW 2 |
Definition at line 37 of file fskmodem_int.c.
#define NF 6 |
Definition at line 39 of file fskmodem_int.c.
#define STATE_GET_BYTE 3 |
Definition at line 45 of file fskmodem_int.c.
Referenced by fsk_serial().
#define STATE_SEARCH_STARTBIT 0 |
Definition at line 42 of file fskmodem_int.c.
Referenced by fsk_serial().
#define STATE_SEARCH_STARTBIT2 1 |
Definition at line 43 of file fskmodem_int.c.
Referenced by fsk_serial().
#define STATE_SEARCH_STARTBIT3 2 |
Definition at line 44 of file fskmodem_int.c.
Referenced by fsk_serial().
int fsk_serial | ( | fsk_data * | fskd, |
short * | buffer, | ||
int * | len, | ||
int * | outbyte | ||
) |
Definition at line 220 of file fskmodem_int.c.
References get_bit_raw(), idemodulator(), IGET_SAMPLE, fsk_data::instop, fsk_data::ispb, len(), fsk_data::nbit, fsk_data::parity, fsk_data::state, STATE_GET_BYTE, STATE_SEARCH_STARTBIT, STATE_SEARCH_STARTBIT2, STATE_SEARCH_STARTBIT3, fsk_data::xi1, and fsk_data::xi2.
Referenced by callerid_feed(), callerid_feed_jp(), and tdd_feed().
{ 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 */ /* NOT USED 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 (idemodulator(fskd, &fskd->xi1, IGET_SAMPLE)) return -1; samples++; for(;;) { search_startbit2: if (*len <= 0) { fskd->state = STATE_SEARCH_STARTBIT2; return 0; } samples++; if (idemodulator(fskd, &fskd->xi2, IGET_SAMPLE)) return -1; #if 0 printf("xi2 = %d ", fskd->xi2); #endif if (fskd->xi2 < 512) { break; } } search_startbit3: /* We await for 0.5 bits before using DPLL */ i = fskd->ispb / 2; if (*len < i) { fskd->state = STATE_SEARCH_STARTBIT3; return 0; } for (; i > 0; i--) { if (idemodulator(fskd, &fskd->xi1, IGET_SAMPLE)) return(-1); #if 0 printf("xi1 = %d ", fskd->xi1); #endif samples++; } /* x1 must be negative (start bit confirmation) */ } while (fskd->xi1 > 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->instop; 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; }
int fskmodem_init | ( | fsk_data * | fskd | ) |
Definition at line 193 of file fskmodem_int.c.
References fsk_data::bw, fsk_data::demod_filter, fsk_data::f_mark_idx, fsk_data::f_space_idx, filter_struct::icoefs, filter_struct::ip, filter_struct::ixv, filter_struct::iyv, fsk_data::mark_filter, and fsk_data::space_filter.
Referenced by callerid_new(), and tdd_new().
{ int i; fskd->space_filter.ip = 0; fskd->mark_filter.ip = 0; fskd->demod_filter.ip = 0; for ( i = 0 ; i < 7 ; i++ ) { fskd->space_filter.icoefs[i] = coef_in[fskd->f_space_idx][fskd->bw][i] * 256; fskd->space_filter.ixv[i] = 0;; fskd->space_filter.iyv[i] = 0;; fskd->mark_filter.icoefs[i] = coef_in[fskd->f_mark_idx][fskd->bw][i] * 256; fskd->mark_filter.ixv[i] = 0;; fskd->mark_filter.iyv[i] = 0;; fskd->demod_filter.icoefs[i] = coef_out[fskd->bw][i] * 1024; fskd->demod_filter.ixv[i] = 0;; fskd->demod_filter.iyv[i] = 0;; } return 0; }
static int get_bit_raw | ( | fsk_data * | fskd, |
short * | buffer, | ||
int * | len | ||
) | [static] |
Definition at line 163 of file fskmodem_int.c.
References f, fsk_data::icont, idemodulator(), IGET_SAMPLE, fsk_data::pllids, fsk_data::pllispb, fsk_data::pllispb2, and fsk_data::xi0.
Referenced by fsk_serial().
{ /* This function implements a DPLL to synchronize with the bits */ int f; int ix; /* PLL coeffs are set up in callerid_new */ for (f = 0;;) { if (idemodulator(fskd, &ix, IGET_SAMPLE)) return(-1); if ((ix * fskd->xi0) < 0) { /* Transicion */ if (!f) { if (fskd->icont < (fskd->pllispb2)) { fskd->icont += fskd->pllids; } else { fskd->icont -= fskd->pllids; } f = 1; } } fskd->xi0 = ix; fskd->icont += 32; if (fskd->icont > fskd->pllispb) { fskd->icont -= fskd->pllispb; break; } } f = (ix > 0) ? 0x80 : 0; return f; }
static int ibpdfilter | ( | struct filter_struct * | fs, |
int | in | ||
) | [inline, static] |
Integer Pass Band demodulator filter
Definition at line 93 of file fskmodem_int.c.
References filter_struct::icoefs, filter_struct::ip, filter_struct::ixv, filter_struct::iyv, and s.
Referenced by idemodulator().
{ int i,j; int s; int64_t s_interim; /* integer filter */ s = in * fs->icoefs[0]; fs->ixv[(fs->ip + 6) & 7] = s; s = (fs->ixv[fs->ip] + fs->ixv[(fs->ip + 6) & 7]) + 6 * (fs->ixv[(fs->ip + 1) & 7] + fs->ixv[(fs->ip + 5) & 7]) + 15 * (fs->ixv[(fs->ip + 2) & 7] + fs->ixv[(fs->ip + 4) & 7]) + 20 * fs->ixv[(fs->ip + 3) & 7]; for (i = 1, j = fs->ip; i < 7; i++, j++) { /* Promote operation to 64 bit to prevent overflow that occurred in 32 bit) */ s_interim = (int64_t)(fs->iyv[j & 7]) * (int64_t)(fs->icoefs[i]) / (int64_t)(1024); s += (int) s_interim; } fs->iyv[j & 7] = s; fs->ip++; fs->ip &= 7; return s; }
static int ibpfilter | ( | struct filter_struct * | fs, |
int | in | ||
) | [inline, static] |
Integer Band Pass filter
Definition at line 122 of file fskmodem_int.c.
References filter_struct::icoefs, filter_struct::ip, filter_struct::ixv, filter_struct::iyv, and s.
Referenced by idemodulator().
{ int i, j; int s; int64_t s_interim; /* integer filter */ s = in * fs->icoefs[0] / 256; fs->ixv[(fs->ip + 6) & 7] = s; s = (fs->ixv[(fs->ip + 6) & 7] - fs->ixv[fs->ip]) + 3 * (fs->ixv[(fs->ip + 2) & 7] - fs->ixv[(fs->ip + 4) & 7]); for (i = 1, j = fs->ip; i < 7; i++, j++) { s_interim = (int64_t)(fs->iyv[j & 7]) * (int64_t)(fs->icoefs[i]) / (int64_t)(256); s += (int) s_interim; } fs->iyv[j & 7] = s; fs->ip++; fs->ip &= 7; return s; }
static int idemodulator | ( | fsk_data * | fskd, |
int * | retval, | ||
int | x | ||
) | [inline, static] |
Definition at line 147 of file fskmodem_int.c.
References fsk_data::demod_filter, ibpdfilter(), ibpfilter(), id, fsk_data::mark_filter, and fsk_data::space_filter.
Referenced by fsk_serial(), and get_bit_raw().
{ int is, im, id; int ilin2; is = ibpfilter(&fskd->space_filter, x); im = ibpfilter(&fskd->mark_filter, x); ilin2 = ((im * im) - (is * is)) / (256 * 256); id = ibpdfilter(&fskd->demod_filter, ilin2); *retval = id; return 0; }
static int iget_sample | ( | short ** | buffer, |
int * | len | ||
) | [inline, static] |
Definition at line 47 of file fskmodem_int.c.
{ int retval; retval = (int) **buffer; (*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 64 of file fskmodem_int.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 86 of file fskmodem_int.c.