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 42 of file fskmodem_int.c.
#define FLIST {1400,1800,1200,2200,1300,2100} |
Definition at line 44 of file fskmodem_int.c.
#define IGET_SAMPLE iget_sample(&buffer, len) |
Definition at line 60 of file fskmodem_int.c.
Referenced by fsk_serial(), and get_bit_raw().
#define NBW 2 |
Definition at line 41 of file fskmodem_int.c.
#define NF 6 |
Definition at line 43 of file fskmodem_int.c.
#define STATE_GET_BYTE 3 |
Definition at line 49 of file fskmodem_int.c.
#define STATE_SEARCH_STARTBIT 0 |
Definition at line 46 of file fskmodem_int.c.
#define STATE_SEARCH_STARTBIT2 1 |
Definition at line 47 of file fskmodem_int.c.
#define STATE_SEARCH_STARTBIT3 2 |
Definition at line 48 of file fskmodem_int.c.
int fsk_serial | ( | fsk_data * | fskd, | |
short * | buffer, | |||
int * | len, | |||
int * | outbyte | |||
) |
Definition at line 224 of file fskmodem_int.c.
References get_bit_raw(), idemodulator(), IGET_SAMPLE, fsk_data::instop, fsk_data::ispb, 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().
00225 { 00226 int a; 00227 int i, j, n1, r; 00228 int samples = 0; 00229 int olen; 00230 int beginlen = *len; 00231 int beginlenx; 00232 00233 switch (fskd->state) { 00234 /* Pick up where we left off */ 00235 case STATE_SEARCH_STARTBIT2: 00236 goto search_startbit2; 00237 case STATE_SEARCH_STARTBIT3: 00238 goto search_startbit3; 00239 case STATE_GET_BYTE: 00240 goto getbyte; 00241 } 00242 /* We await for start bit */ 00243 do { 00244 /* this was jesus's nice, reasonable, working (at least with RTTY) code 00245 to look for the beginning of the start bit. Unfortunately, since TTY/TDD's 00246 just start sending a start bit with nothing preceding it at the beginning 00247 of a transmission (what a LOSING design), we cant do it this elegantly */ 00248 /* NOT USED 00249 if (demodulator(zap,&x1)) 00250 return -1; 00251 for(;;) { 00252 if (demodulator(zap,&x2)) 00253 return -1; 00254 if (x1>0 && x2<0) break; 00255 x1=x2; 00256 } 00257 */ 00258 /* this is now the imprecise, losing, but functional code to detect the 00259 beginning of a start bit in the TDD sceanario. It just looks for sufficient 00260 level to maybe, perhaps, guess, maybe that its maybe the beginning of 00261 a start bit, perhaps. This whole thing stinks! */ 00262 beginlenx = beginlen; /* just to avoid unused war warnings */ 00263 if (idemodulator(fskd, &fskd->xi1, IGET_SAMPLE)) 00264 return -1; 00265 samples++; 00266 for(;;) { 00267 search_startbit2: 00268 if (*len <= 0) { 00269 fskd->state = STATE_SEARCH_STARTBIT2; 00270 return 0; 00271 } 00272 samples++; 00273 if (idemodulator(fskd, &fskd->xi2, IGET_SAMPLE)) 00274 return -1; 00275 #if 0 00276 printf("xi2 = %d ", fskd->xi2); 00277 #endif 00278 if (fskd->xi2 < 512) { 00279 break; 00280 } 00281 } 00282 search_startbit3: 00283 /* We await for 0.5 bits before using DPLL */ 00284 i = fskd->ispb / 2; 00285 if (*len < i) { 00286 fskd->state = STATE_SEARCH_STARTBIT3; 00287 return 0; 00288 } 00289 for (; i > 0; i--) { 00290 if (idemodulator(fskd, &fskd->xi1, IGET_SAMPLE)) 00291 return(-1); 00292 #if 0 00293 printf("xi1 = %d ", fskd->xi1); 00294 #endif 00295 samples++; 00296 } 00297 00298 /* x1 must be negative (start bit confirmation) */ 00299 00300 } while (fskd->xi1 > 0); 00301 fskd->state = STATE_GET_BYTE; 00302 00303 getbyte: 00304 00305 /* Need at least 80 samples (for 1200) or 00306 1320 (for 45.5) to be sure we'll have a byte */ 00307 if (fskd->nbit < 8) { 00308 if (*len < 1320) 00309 return 0; 00310 } else { 00311 if (*len < 80) 00312 return 0; 00313 } 00314 00315 /* Now we read the data bits */ 00316 j = fskd->nbit; 00317 for (a = n1 = 0; j; j--) { 00318 olen = *len; 00319 i = get_bit_raw(fskd, buffer, len); 00320 buffer += (olen - *len); 00321 if (i == -1) 00322 return -1; 00323 if (i) 00324 n1++; 00325 a >>= 1; 00326 a |= i; 00327 } 00328 j = 8 - fskd->nbit; 00329 a >>= j; 00330 00331 /* We read parity bit (if exists) and check parity */ 00332 if (fskd->parity) { 00333 olen = *len; 00334 i = get_bit_raw(fskd, buffer, len); 00335 buffer += (olen - *len); 00336 if (i == -1) 00337 return -1; 00338 if (i) 00339 n1++; 00340 if (fskd->parity == 1) { /* parity=1 (even) */ 00341 if (n1 & 1) 00342 a |= 0x100; /* error */ 00343 } else { /* parity=2 (odd) */ 00344 if (!(n1 & 1)) 00345 a |= 0x100; /* error */ 00346 } 00347 } 00348 00349 /* We read STOP bits. All of them must be 1 */ 00350 00351 for (j = fskd->instop; j; j--) { 00352 r = get_bit_raw(fskd, buffer, len); 00353 if (r == -1) 00354 return -1; 00355 if (!r) 00356 a |= 0x200; 00357 } 00358 00359 /* And finally we return 00360 * Bit 8 : Parity error 00361 * Bit 9 : Framming error 00362 */ 00363 00364 *outbyte = a; 00365 fskd->state = STATE_SEARCH_STARTBIT; 00366 return 1; 00367 }
int fskmodem_init | ( | fsk_data * | fskd | ) |
Definition at line 197 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().
00198 { 00199 int i; 00200 00201 fskd->space_filter.ip = 0; 00202 fskd->mark_filter.ip = 0; 00203 fskd->demod_filter.ip = 0; 00204 00205 for ( i = 0 ; i < 7 ; i++ ) { 00206 fskd->space_filter.icoefs[i] = 00207 coef_in[fskd->f_space_idx][fskd->bw][i] * 256; 00208 fskd->space_filter.ixv[i] = 0;; 00209 fskd->space_filter.iyv[i] = 0;; 00210 00211 fskd->mark_filter.icoefs[i] = 00212 coef_in[fskd->f_mark_idx][fskd->bw][i] * 256; 00213 fskd->mark_filter.ixv[i] = 0;; 00214 fskd->mark_filter.iyv[i] = 0;; 00215 00216 fskd->demod_filter.icoefs[i] = 00217 coef_out[fskd->bw][i] * 1024; 00218 fskd->demod_filter.ixv[i] = 0;; 00219 fskd->demod_filter.iyv[i] = 0;; 00220 } 00221 return 0; 00222 }
static int get_bit_raw | ( | fsk_data * | fskd, | |
short * | buffer, | |||
int * | len | |||
) | [static] |
Definition at line 167 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().
00168 { 00169 /* This function implements a DPLL to synchronize with the bits */ 00170 int f; 00171 00172 int ix; 00173 /* PLL coeffs are set up in callerid_new */ 00174 for (f = 0;;) { 00175 if (idemodulator(fskd, &ix, IGET_SAMPLE)) return(-1); 00176 if ((ix * fskd->xi0) < 0) { /* Transicion */ 00177 if (!f) { 00178 if (fskd->icont < (fskd->pllispb2)) { 00179 fskd->icont += fskd->pllids; 00180 } else { 00181 fskd->icont -= fskd->pllids; 00182 } 00183 f = 1; 00184 } 00185 } 00186 fskd->xi0 = ix; 00187 fskd->icont += 32; 00188 if (fskd->icont > fskd->pllispb) { 00189 fskd->icont -= fskd->pllispb; 00190 break; 00191 } 00192 } 00193 f = (ix > 0) ? 0x80 : 0; 00194 return f; 00195 }
static int ibpdfilter | ( | struct filter_struct * | fs, | |
int | in | |||
) | [inline, static] |
Integer Pass Band demodulator filter
Definition at line 97 of file fskmodem_int.c.
References filter_struct::icoefs, filter_struct::ip, filter_struct::ixv, and filter_struct::iyv.
Referenced by idemodulator().
00098 { 00099 int i,j; 00100 int s; 00101 int64_t s_interim; 00102 00103 /* integer filter */ 00104 s = in * fs->icoefs[0]; 00105 fs->ixv[(fs->ip + 6) & 7] = s; 00106 00107 s = (fs->ixv[fs->ip] + fs->ixv[(fs->ip + 6) & 7]) + 00108 6 * (fs->ixv[(fs->ip + 1) & 7] + fs->ixv[(fs->ip + 5) & 7]) + 00109 15 * (fs->ixv[(fs->ip + 2) & 7] + fs->ixv[(fs->ip + 4) & 7]) + 00110 20 * fs->ixv[(fs->ip + 3) & 7]; 00111 00112 for (i = 1, j = fs->ip; i < 7; i++, j++) { 00113 /* Promote operation to 64 bit to prevent overflow that occurred in 32 bit) */ 00114 s_interim = (int64_t)(fs->iyv[j & 7]) * 00115 (int64_t)(fs->icoefs[i]) / 00116 (int64_t)(1024); 00117 s += (int) s_interim; 00118 } 00119 fs->iyv[j & 7] = s; 00120 fs->ip++; 00121 fs->ip &= 7; 00122 return s; 00123 }
static int ibpfilter | ( | struct filter_struct * | fs, | |
int | in | |||
) | [inline, static] |
Integer Band Pass filter
Definition at line 126 of file fskmodem_int.c.
References filter_struct::icoefs, filter_struct::ip, filter_struct::ixv, and filter_struct::iyv.
Referenced by idemodulator().
00127 { 00128 int i, j; 00129 int s; 00130 int64_t s_interim; 00131 00132 /* integer filter */ 00133 s = in * fs->icoefs[0] / 256; 00134 fs->ixv[(fs->ip + 6) & 7] = s; 00135 00136 s = (fs->ixv[(fs->ip + 6) & 7] - fs->ixv[fs->ip]) 00137 + 3 * (fs->ixv[(fs->ip + 2) & 7] - fs->ixv[(fs->ip + 4) & 7]); 00138 00139 for (i = 1, j = fs->ip; i < 7; i++, j++) { 00140 s_interim = (int64_t)(fs->iyv[j & 7]) * 00141 (int64_t)(fs->icoefs[i]) / 00142 (int64_t)(256); 00143 s += (int) s_interim; 00144 } 00145 fs->iyv[j & 7] = s; 00146 fs->ip++; 00147 fs->ip &= 7; 00148 return s; 00149 }
static int idemodulator | ( | fsk_data * | fskd, | |
int * | retval, | |||
int | x | |||
) | [inline, static] |
Definition at line 151 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().
00152 { 00153 int is, im, id; 00154 int ilin2; 00155 00156 is = ibpfilter(&fskd->space_filter, x); 00157 im = ibpfilter(&fskd->mark_filter, x); 00158 00159 ilin2 = ((im * im) - (is * is)) / (256 * 256); 00160 00161 id = ibpdfilter(&fskd->demod_filter, ilin2); 00162 00163 *retval = id; 00164 return 0; 00165 }
static int iget_sample | ( | short ** | buffer, | |
int * | len | |||
) | [inline, static] |
Definition at line 51 of file fskmodem_int.c.
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 68 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 90 of file fskmodem_int.c.