dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1 | /* |
kurtis.heimerl | a198d45 | 2011-11-26 03:19:28 +0000 | [diff] [blame] | 2 | * Copyright 2008, 2011 Free Software Foundation, Inc. |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 3 | * |
| 4 | * This software is distributed under the terms of the GNU Affero Public License. |
| 5 | * See the COPYING file in the main directory for details. |
| 6 | * |
| 7 | * This use of this software may be subject to additional restrictions. |
| 8 | * See the LEGAL file in the main directory for details. |
| 9 | |
| 10 | This program is free software: you can redistribute it and/or modify |
| 11 | it under the terms of the GNU Affero General Public License as published by |
| 12 | the Free Software Foundation, either version 3 of the License, or |
| 13 | (at your option) any later version. |
| 14 | |
| 15 | This program is distributed in the hope that it will be useful, |
| 16 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 18 | GNU Affero General Public License for more details. |
| 19 | |
| 20 | You should have received a copy of the GNU Affero General Public License |
| 21 | along with this program. If not, see <http://www.gnu.org/licenses/>. |
| 22 | |
| 23 | */ |
| 24 | |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 25 | #include "sigProcLib.h" |
| 26 | #include "GSMCommon.h" |
kurtis.heimerl | a198d45 | 2011-11-26 03:19:28 +0000 | [diff] [blame] | 27 | #include "sendLPF_961.h" |
| 28 | #include "rcvLPF_651.h" |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 29 | |
Alexander Chemeris | d734e2d | 2013-06-16 14:30:58 +0400 | [diff] [blame] | 30 | using namespace GSM; |
| 31 | |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 32 | #define TABLESIZE 1024 |
| 33 | |
| 34 | /** Lookup tables for trigonometric approximation */ |
| 35 | float cosTable[TABLESIZE+1]; // add 1 element for wrap around |
| 36 | float sinTable[TABLESIZE+1]; |
| 37 | |
| 38 | /** Constants */ |
| 39 | static const float M_PI_F = (float)M_PI; |
| 40 | static const float M_2PI_F = (float)(2.0*M_PI); |
| 41 | static const float M_1_2PI_F = 1/M_2PI_F; |
| 42 | |
| 43 | /** Static vectors that contain a precomputed +/- f_b/4 sinusoid */ |
| 44 | signalVector *GMSKRotation = NULL; |
| 45 | signalVector *GMSKReverseRotation = NULL; |
| 46 | |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 47 | /* |
| 48 | * RACH and midamble correlation waveforms |
| 49 | */ |
| 50 | struct CorrelationSequence { |
| 51 | CorrelationSequence() : sequence(NULL) |
| 52 | { |
| 53 | } |
| 54 | |
| 55 | ~CorrelationSequence() |
| 56 | { |
| 57 | delete sequence; |
| 58 | } |
| 59 | |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 60 | signalVector *sequence; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 61 | float TOA; |
| 62 | complex gain; |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 63 | }; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 64 | |
Thomas Tsou | 83e0689 | 2013-08-20 16:10:01 -0400 | [diff] [blame] | 65 | /* |
| 66 | * Gaussian and empty modulation pulses |
| 67 | */ |
| 68 | struct PulseSequence { |
| 69 | PulseSequence() : gaussian(NULL), empty(NULL) |
| 70 | { |
| 71 | } |
| 72 | |
| 73 | ~PulseSequence() |
| 74 | { |
| 75 | delete gaussian; |
| 76 | delete empty; |
| 77 | } |
| 78 | |
| 79 | signalVector *gaussian; |
| 80 | signalVector *empty; |
| 81 | }; |
| 82 | |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 83 | CorrelationSequence *gMidambles[] = {NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL}; |
| 84 | CorrelationSequence *gRACHSequence = NULL; |
Thomas Tsou | 83e0689 | 2013-08-20 16:10:01 -0400 | [diff] [blame] | 85 | PulseSequence *GSMPulse = NULL; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 86 | |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 87 | void sigProcLibDestroy() |
| 88 | { |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 89 | for (int i = 0; i < 8; i++) { |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 90 | delete gMidambles[i]; |
| 91 | gMidambles[i] = NULL; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 92 | } |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 93 | |
| 94 | delete GMSKRotation; |
| 95 | delete GMSKReverseRotation; |
| 96 | delete gRACHSequence; |
| 97 | delete GSMPulse; |
| 98 | |
| 99 | GMSKRotation = NULL; |
| 100 | GMSKReverseRotation = NULL; |
| 101 | gRACHSequence = NULL; |
| 102 | GSMPulse = NULL; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 103 | } |
| 104 | |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 105 | // dB relative to 1.0. |
| 106 | // if > 1.0, then return 0 dB |
| 107 | float dB(float x) { |
| 108 | |
| 109 | float arg = 1.0F; |
| 110 | float dB = 0.0F; |
| 111 | |
| 112 | if (x >= 1.0F) return 0.0F; |
| 113 | if (x <= 0.0F) return -200.0F; |
| 114 | |
| 115 | float prevArg = arg; |
| 116 | float prevdB = dB; |
| 117 | float stepSize = 16.0F; |
| 118 | float dBstepSize = 12.0F; |
| 119 | while (stepSize > 1.0F) { |
| 120 | do { |
| 121 | prevArg = arg; |
| 122 | prevdB = dB; |
| 123 | arg /= stepSize; |
| 124 | dB -= dBstepSize; |
| 125 | } while (arg > x); |
| 126 | arg = prevArg; |
| 127 | dB = prevdB; |
| 128 | stepSize *= 0.5F; |
| 129 | dBstepSize -= 3.0F; |
| 130 | } |
| 131 | return ((arg-x)*(dB-3.0F) + (x-arg*0.5F)*dB)/(arg - arg*0.5F); |
| 132 | |
| 133 | } |
| 134 | |
| 135 | // 10^(-dB/10), inverse of dB func. |
| 136 | float dBinv(float x) { |
| 137 | |
| 138 | float arg = 1.0F; |
| 139 | float dB = 0.0F; |
| 140 | |
| 141 | if (x >= 0.0F) return 1.0F; |
| 142 | if (x <= -200.0F) return 0.0F; |
| 143 | |
| 144 | float prevArg = arg; |
| 145 | float prevdB = dB; |
| 146 | float stepSize = 16.0F; |
| 147 | float dBstepSize = 12.0F; |
| 148 | while (stepSize > 1.0F) { |
| 149 | do { |
| 150 | prevArg = arg; |
| 151 | prevdB = dB; |
| 152 | arg /= stepSize; |
| 153 | dB -= dBstepSize; |
| 154 | } while (dB > x); |
| 155 | arg = prevArg; |
| 156 | dB = prevdB; |
| 157 | stepSize *= 0.5F; |
| 158 | dBstepSize -= 3.0F; |
| 159 | } |
| 160 | |
| 161 | return ((dB-x)*(arg*0.5F)+(x-(dB-3.0F))*(arg))/3.0F; |
| 162 | |
| 163 | } |
| 164 | |
| 165 | float vectorNorm2(const signalVector &x) |
| 166 | { |
| 167 | signalVector::const_iterator xPtr = x.begin(); |
| 168 | float Energy = 0.0; |
| 169 | for (;xPtr != x.end();xPtr++) { |
| 170 | Energy += xPtr->norm2(); |
| 171 | } |
| 172 | return Energy; |
| 173 | } |
| 174 | |
| 175 | |
| 176 | float vectorPower(const signalVector &x) |
| 177 | { |
| 178 | return vectorNorm2(x)/x.size(); |
| 179 | } |
| 180 | |
| 181 | /** compute cosine via lookup table */ |
| 182 | float cosLookup(const float x) |
| 183 | { |
| 184 | float arg = x*M_1_2PI_F; |
| 185 | while (arg > 1.0F) arg -= 1.0F; |
| 186 | while (arg < 0.0F) arg += 1.0F; |
| 187 | |
| 188 | const float argT = arg*((float)TABLESIZE); |
| 189 | const int argI = (int)argT; |
| 190 | const float delta = argT-argI; |
| 191 | const float iDelta = 1.0F-delta; |
| 192 | return iDelta*cosTable[argI] + delta*cosTable[argI+1]; |
| 193 | } |
| 194 | |
| 195 | /** compute sine via lookup table */ |
| 196 | float sinLookup(const float x) |
| 197 | { |
| 198 | float arg = x*M_1_2PI_F; |
| 199 | while (arg > 1.0F) arg -= 1.0F; |
| 200 | while (arg < 0.0F) arg += 1.0F; |
| 201 | |
| 202 | const float argT = arg*((float)TABLESIZE); |
| 203 | const int argI = (int)argT; |
| 204 | const float delta = argT-argI; |
| 205 | const float iDelta = 1.0F-delta; |
| 206 | return iDelta*sinTable[argI] + delta*sinTable[argI+1]; |
| 207 | } |
| 208 | |
| 209 | |
| 210 | /** compute e^(-jx) via lookup table. */ |
| 211 | complex expjLookup(float x) |
| 212 | { |
| 213 | float arg = x*M_1_2PI_F; |
| 214 | while (arg > 1.0F) arg -= 1.0F; |
| 215 | while (arg < 0.0F) arg += 1.0F; |
| 216 | |
| 217 | const float argT = arg*((float)TABLESIZE); |
| 218 | const int argI = (int)argT; |
| 219 | const float delta = argT-argI; |
| 220 | const float iDelta = 1.0F-delta; |
| 221 | return complex(iDelta*cosTable[argI] + delta*cosTable[argI+1], |
| 222 | iDelta*sinTable[argI] + delta*sinTable[argI+1]); |
| 223 | } |
| 224 | |
| 225 | /** Library setup functions */ |
| 226 | void initTrigTables() { |
| 227 | for (int i = 0; i < TABLESIZE+1; i++) { |
| 228 | cosTable[i] = cos(2.0*M_PI*i/TABLESIZE); |
| 229 | sinTable[i] = sin(2.0*M_PI*i/TABLESIZE); |
| 230 | } |
| 231 | } |
| 232 | |
Thomas Tsou | d24cc2c | 2013-08-20 15:41:45 -0400 | [diff] [blame] | 233 | void initGMSKRotationTables(int sps) |
| 234 | { |
| 235 | GMSKRotation = new signalVector(157 * sps); |
| 236 | GMSKReverseRotation = new signalVector(157 * sps); |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 237 | signalVector::iterator rotPtr = GMSKRotation->begin(); |
| 238 | signalVector::iterator revPtr = GMSKReverseRotation->begin(); |
| 239 | float phase = 0.0; |
| 240 | while (rotPtr != GMSKRotation->end()) { |
| 241 | *rotPtr++ = expjLookup(phase); |
| 242 | *revPtr++ = expjLookup(-phase); |
Thomas Tsou | d24cc2c | 2013-08-20 15:41:45 -0400 | [diff] [blame] | 243 | phase += M_PI_F / 2.0F / (float) sps; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 244 | } |
| 245 | } |
| 246 | |
Thomas Tsou | e57004d | 2013-08-20 18:55:33 -0400 | [diff] [blame^] | 247 | bool sigProcLibSetup(int sps) |
Thomas Tsou | d24cc2c | 2013-08-20 15:41:45 -0400 | [diff] [blame] | 248 | { |
Thomas Tsou | e57004d | 2013-08-20 18:55:33 -0400 | [diff] [blame^] | 249 | if ((sps != 0) && (sps != 2) && (sps != 4)) |
| 250 | return false; |
| 251 | |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 252 | initTrigTables(); |
Thomas Tsou | d24cc2c | 2013-08-20 15:41:45 -0400 | [diff] [blame] | 253 | initGMSKRotationTables(sps); |
Thomas Tsou | 83e0689 | 2013-08-20 16:10:01 -0400 | [diff] [blame] | 254 | generateGSMPulse(sps, 2); |
Thomas Tsou | e57004d | 2013-08-20 18:55:33 -0400 | [diff] [blame^] | 255 | |
| 256 | if (!generateRACHSequence(sps)) { |
| 257 | sigProcLibDestroy(); |
| 258 | return false; |
| 259 | } |
| 260 | |
| 261 | return true; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 262 | } |
| 263 | |
| 264 | void GMSKRotate(signalVector &x) { |
| 265 | signalVector::iterator xPtr = x.begin(); |
| 266 | signalVector::iterator rotPtr = GMSKRotation->begin(); |
| 267 | if (x.isRealOnly()) { |
| 268 | while (xPtr < x.end()) { |
| 269 | *xPtr = *rotPtr++ * (xPtr->real()); |
| 270 | xPtr++; |
| 271 | } |
| 272 | } |
| 273 | else { |
| 274 | while (xPtr < x.end()) { |
| 275 | *xPtr = *rotPtr++ * (*xPtr); |
| 276 | xPtr++; |
| 277 | } |
| 278 | } |
| 279 | } |
| 280 | |
| 281 | void GMSKReverseRotate(signalVector &x) { |
| 282 | signalVector::iterator xPtr= x.begin(); |
| 283 | signalVector::iterator rotPtr = GMSKReverseRotation->begin(); |
| 284 | if (x.isRealOnly()) { |
| 285 | while (xPtr < x.end()) { |
| 286 | *xPtr = *rotPtr++ * (xPtr->real()); |
| 287 | xPtr++; |
| 288 | } |
| 289 | } |
| 290 | else { |
| 291 | while (xPtr < x.end()) { |
| 292 | *xPtr = *rotPtr++ * (*xPtr); |
| 293 | xPtr++; |
| 294 | } |
| 295 | } |
| 296 | } |
| 297 | |
| 298 | |
| 299 | signalVector* convolve(const signalVector *a, |
| 300 | const signalVector *b, |
| 301 | signalVector *c, |
| 302 | ConvType spanType, |
| 303 | unsigned startIx, |
| 304 | unsigned len) |
| 305 | { |
| 306 | if ((a==NULL) || (b==NULL)) return NULL; |
| 307 | int La = a->size(); |
| 308 | int Lb = b->size(); |
| 309 | |
| 310 | int startIndex; |
| 311 | unsigned int outSize; |
| 312 | switch (spanType) { |
| 313 | case FULL_SPAN: |
| 314 | startIndex = 0; |
| 315 | outSize = La+Lb-1; |
| 316 | break; |
| 317 | case OVERLAP_ONLY: |
| 318 | startIndex = La; |
| 319 | outSize = abs(La-Lb)+1; |
| 320 | break; |
| 321 | case START_ONLY: |
| 322 | startIndex = 0; |
| 323 | outSize = La; |
| 324 | break; |
| 325 | case WITH_TAIL: |
| 326 | startIndex = Lb; |
| 327 | outSize = La; |
| 328 | break; |
| 329 | case NO_DELAY: |
| 330 | if (Lb % 2) |
| 331 | startIndex = Lb/2; |
| 332 | else |
| 333 | startIndex = Lb/2-1; |
| 334 | outSize = La; |
| 335 | break; |
| 336 | case CUSTOM: |
| 337 | startIndex = startIx; |
| 338 | outSize = len; |
| 339 | break; |
| 340 | default: |
| 341 | return NULL; |
| 342 | } |
| 343 | |
| 344 | |
| 345 | if (c==NULL) |
| 346 | c = new signalVector(outSize); |
| 347 | else if (c->size()!=outSize) |
| 348 | return NULL; |
| 349 | |
| 350 | signalVector::const_iterator aStart = a->begin(); |
| 351 | signalVector::const_iterator bStart = b->begin(); |
| 352 | signalVector::const_iterator aEnd = a->end(); |
| 353 | signalVector::const_iterator bEnd = b->end(); |
| 354 | signalVector::iterator cPtr = c->begin(); |
| 355 | int t = startIndex; |
| 356 | int stopIndex = startIndex + outSize; |
| 357 | switch (b->getSymmetry()) { |
| 358 | case NONE: |
| 359 | { |
| 360 | while (t < stopIndex) { |
| 361 | signalVector::const_iterator aP = aStart+t; |
| 362 | signalVector::const_iterator bP = bStart; |
| 363 | if (a->isRealOnly() && b->isRealOnly()) { |
| 364 | float sum = 0.0; |
| 365 | while (bP < bEnd) { |
| 366 | if (aP < aStart) break; |
| 367 | if (aP < aEnd) sum += (aP->real())*(bP->real()); |
| 368 | aP--; |
| 369 | bP++; |
| 370 | } |
| 371 | *cPtr++ = sum; |
| 372 | } |
| 373 | else if (a->isRealOnly()) { |
| 374 | complex sum = 0.0; |
| 375 | while (bP < bEnd) { |
| 376 | if (aP < aStart) break; |
| 377 | if (aP < aEnd) sum += (*bP)*(aP->real()); |
| 378 | aP--; |
| 379 | bP++; |
| 380 | } |
| 381 | *cPtr++ = sum; |
| 382 | } |
| 383 | else if (b->isRealOnly()) { |
| 384 | complex sum = 0.0; |
| 385 | while (bP < bEnd) { |
| 386 | if (aP < aStart) break; |
| 387 | if (aP < aEnd) sum += (*aP)*(bP->real()); |
| 388 | aP--; |
| 389 | bP++; |
| 390 | } |
| 391 | *cPtr++ = sum; |
| 392 | } |
| 393 | else { |
| 394 | complex sum = 0.0; |
| 395 | while (bP < bEnd) { |
| 396 | if (aP < aStart) break; |
| 397 | if (aP < aEnd) sum += (*aP)*(*bP); |
| 398 | aP--; |
| 399 | bP++; |
| 400 | } |
| 401 | *cPtr++ = sum; |
| 402 | } |
| 403 | t++; |
| 404 | } |
| 405 | } |
| 406 | break; |
| 407 | case ABSSYM: |
| 408 | { |
| 409 | complex sum = 0.0; |
| 410 | bool isOdd = (bool) (Lb % 2); |
| 411 | if (isOdd) |
| 412 | bEnd = bStart + (Lb+1)/2; |
| 413 | else |
| 414 | bEnd = bStart + Lb/2; |
| 415 | while (t < stopIndex) { |
| 416 | signalVector::const_iterator aP = aStart+t; |
| 417 | signalVector::const_iterator aPsym = aP-Lb+1; |
| 418 | signalVector::const_iterator bP = bStart; |
| 419 | sum = 0.0; |
| 420 | if (!b->isRealOnly()) { |
| 421 | while (bP < bEnd) { |
| 422 | if (aP < aStart) break; |
| 423 | if (aP == aPsym) |
| 424 | sum+= (*aP)*(*bP); |
| 425 | else if ((aP < aEnd) && (aPsym >= aStart)) |
| 426 | sum+= ((*aP)+(*aPsym))*(*bP); |
| 427 | else if (aP < aEnd) |
| 428 | sum += (*aP)*(*bP); |
| 429 | else if (aPsym >= aStart) |
| 430 | sum += (*aPsym)*(*bP); |
| 431 | aP--; |
| 432 | aPsym++; |
| 433 | bP++; |
| 434 | } |
| 435 | } |
| 436 | else { |
| 437 | while (bP < bEnd) { |
| 438 | if (aP < aStart) break; |
| 439 | if (aP == aPsym) |
| 440 | sum+= (*aP)*(bP->real()); |
| 441 | else if ((aP < aEnd) && (aPsym >= aStart)) |
| 442 | sum+= ((*aP)+(*aPsym))*(bP->real()); |
| 443 | else if (aP < aEnd) |
| 444 | sum += (*aP)*(bP->real()); |
| 445 | else if (aPsym >= aStart) |
| 446 | sum += (*aPsym)*(bP->real()); |
| 447 | aP--; |
| 448 | aPsym++; |
| 449 | bP++; |
| 450 | } |
| 451 | } |
| 452 | *cPtr++ = sum; |
| 453 | t++; |
| 454 | } |
| 455 | } |
| 456 | break; |
| 457 | default: |
| 458 | return NULL; |
| 459 | break; |
| 460 | } |
| 461 | |
| 462 | |
| 463 | return c; |
| 464 | } |
| 465 | |
| 466 | |
Thomas Tsou | 83e0689 | 2013-08-20 16:10:01 -0400 | [diff] [blame] | 467 | void generateGSMPulse(int sps, int symbolLength) |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 468 | { |
Thomas Tsou | 83e0689 | 2013-08-20 16:10:01 -0400 | [diff] [blame] | 469 | int len; |
| 470 | float arg, center; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 471 | |
Thomas Tsou | 83e0689 | 2013-08-20 16:10:01 -0400 | [diff] [blame] | 472 | delete GSMPulse; |
| 473 | |
| 474 | /* Store a single tap filter used for correlation sequence generation */ |
| 475 | GSMPulse = new PulseSequence(); |
| 476 | GSMPulse->empty = new signalVector(1); |
| 477 | GSMPulse->empty->isRealOnly(true); |
| 478 | *(GSMPulse->empty->begin()) = 1.0f; |
| 479 | |
| 480 | /* GSM pulse approximation */ |
| 481 | GSMPulse->gaussian = new signalVector(len); |
| 482 | GSMPulse->gaussian->isRealOnly(true); |
| 483 | signalVector::iterator xP = GSMPulse->gaussian->begin(); |
| 484 | |
| 485 | center = (float) (len - 1.0) / 2.0; |
| 486 | |
| 487 | for (int i = 0; i < len; i++) { |
| 488 | arg = ((float) i - center) / (float) sps; |
| 489 | *xP++ = 0.96 * exp(-1.1380 * arg * arg - |
| 490 | 0.527 * arg * arg * arg * arg); |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 491 | } |
| 492 | |
Thomas Tsou | 83e0689 | 2013-08-20 16:10:01 -0400 | [diff] [blame] | 493 | float avgAbsval = sqrtf(vectorNorm2(*GSMPulse->gaussian)/sps); |
| 494 | xP = GSMPulse->gaussian->begin(); |
| 495 | for (int i = 0; i < len; i++) |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 496 | *xP++ /= avgAbsval; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 497 | } |
| 498 | |
| 499 | signalVector* frequencyShift(signalVector *y, |
| 500 | signalVector *x, |
| 501 | float freq, |
| 502 | float startPhase, |
| 503 | float *finalPhase) |
| 504 | { |
| 505 | |
| 506 | if (!x) return NULL; |
| 507 | |
| 508 | if (y==NULL) { |
| 509 | y = new signalVector(x->size()); |
| 510 | y->isRealOnly(x->isRealOnly()); |
| 511 | if (y==NULL) return NULL; |
| 512 | } |
| 513 | |
| 514 | if (y->size() < x->size()) return NULL; |
| 515 | |
| 516 | float phase = startPhase; |
| 517 | signalVector::iterator yP = y->begin(); |
| 518 | signalVector::iterator xPEnd = x->end(); |
| 519 | signalVector::iterator xP = x->begin(); |
| 520 | |
| 521 | if (x->isRealOnly()) { |
| 522 | while (xP < xPEnd) { |
| 523 | (*yP++) = expjLookup(phase)*( (xP++)->real() ); |
| 524 | phase += freq; |
| 525 | } |
| 526 | } |
| 527 | else { |
| 528 | while (xP < xPEnd) { |
| 529 | (*yP++) = (*xP++)*expjLookup(phase); |
| 530 | phase += freq; |
| 531 | } |
| 532 | } |
| 533 | |
| 534 | |
| 535 | if (finalPhase) *finalPhase = phase; |
| 536 | |
| 537 | return y; |
| 538 | } |
| 539 | |
| 540 | signalVector* reverseConjugate(signalVector *b) |
| 541 | { |
| 542 | signalVector *tmp = new signalVector(b->size()); |
| 543 | tmp->isRealOnly(b->isRealOnly()); |
| 544 | signalVector::iterator bP = b->begin(); |
| 545 | signalVector::iterator bPEnd = b->end(); |
| 546 | signalVector::iterator tmpP = tmp->end()-1; |
| 547 | if (!b->isRealOnly()) { |
| 548 | while (bP < bPEnd) { |
| 549 | *tmpP-- = bP->conj(); |
| 550 | bP++; |
| 551 | } |
| 552 | } |
| 553 | else { |
| 554 | while (bP < bPEnd) { |
| 555 | *tmpP-- = bP->real(); |
| 556 | bP++; |
| 557 | } |
| 558 | } |
| 559 | |
| 560 | return tmp; |
| 561 | } |
| 562 | |
| 563 | signalVector* correlate(signalVector *a, |
| 564 | signalVector *b, |
| 565 | signalVector *c, |
| 566 | ConvType spanType, |
| 567 | bool bReversedConjugated, |
| 568 | unsigned startIx, |
| 569 | unsigned len) |
| 570 | { |
| 571 | signalVector *tmp = NULL; |
| 572 | |
| 573 | if (!bReversedConjugated) { |
| 574 | tmp = reverseConjugate(b); |
| 575 | } |
| 576 | else { |
| 577 | tmp = b; |
| 578 | } |
| 579 | |
| 580 | c = convolve(a,tmp,c,spanType,startIx,len); |
| 581 | |
| 582 | if (!bReversedConjugated) delete tmp; |
| 583 | |
| 584 | return c; |
| 585 | } |
| 586 | |
| 587 | |
| 588 | /* soft output slicer */ |
| 589 | bool vectorSlicer(signalVector *x) |
| 590 | { |
| 591 | |
| 592 | signalVector::iterator xP = x->begin(); |
| 593 | signalVector::iterator xPEnd = x->end(); |
| 594 | while (xP < xPEnd) { |
| 595 | *xP = (complex) (0.5*(xP->real()+1.0F)); |
| 596 | if (xP->real() > 1.0) *xP = 1.0; |
| 597 | if (xP->real() < 0.0) *xP = 0.0; |
| 598 | xP++; |
| 599 | } |
| 600 | return true; |
| 601 | } |
| 602 | |
Thomas Tsou | 83e0689 | 2013-08-20 16:10:01 -0400 | [diff] [blame] | 603 | signalVector *modulateBurst(const BitVector &wBurst, int guardPeriodLength, |
| 604 | int sps, bool emptyPulse) |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 605 | { |
Thomas Tsou | 83e0689 | 2013-08-20 16:10:01 -0400 | [diff] [blame] | 606 | int burstLen; |
| 607 | signalVector *pulse, modBurst; |
| 608 | signalVector::iterator modBurstItr; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 609 | |
Thomas Tsou | 83e0689 | 2013-08-20 16:10:01 -0400 | [diff] [blame] | 610 | if (emptyPulse) |
| 611 | pulse = GSMPulse->empty; |
| 612 | else |
| 613 | pulse = GSMPulse->gaussian; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 614 | |
Thomas Tsou | 83e0689 | 2013-08-20 16:10:01 -0400 | [diff] [blame] | 615 | burstLen = sps * (wBurst.size() + guardPeriodLength); |
| 616 | modBurst = signalVector(burstLen); |
| 617 | modBurstItr = modBurst.begin(); |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 618 | |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 619 | for (unsigned int i = 0; i < wBurst.size(); i++) { |
| 620 | *modBurstItr = 2.0*(wBurst[i] & 0x01)-1.0; |
Thomas Tsou | d24cc2c | 2013-08-20 15:41:45 -0400 | [diff] [blame] | 621 | modBurstItr += sps; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 622 | } |
| 623 | |
| 624 | // shift up pi/2 |
| 625 | // ignore starting phase, since spec allows for discontinuous phase |
| 626 | GMSKRotate(modBurst); |
Thomas Tsou | 83e0689 | 2013-08-20 16:10:01 -0400 | [diff] [blame] | 627 | |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 628 | modBurst.isRealOnly(false); |
| 629 | |
| 630 | // filter w/ pulse shape |
Thomas Tsou | 83e0689 | 2013-08-20 16:10:01 -0400 | [diff] [blame] | 631 | signalVector *shapedBurst = convolve(&modBurst, pulse, NULL, NO_DELAY); |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 632 | |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 633 | return shapedBurst; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 634 | } |
| 635 | |
| 636 | float sinc(float x) |
| 637 | { |
| 638 | if ((x >= 0.01F) || (x <= -0.01F)) return (sinLookup(x)/x); |
| 639 | return 1.0F; |
| 640 | } |
| 641 | |
| 642 | void delayVector(signalVector &wBurst, |
| 643 | float delay) |
| 644 | { |
| 645 | |
| 646 | int intOffset = (int) floor(delay); |
| 647 | float fracOffset = delay - intOffset; |
| 648 | |
| 649 | // do fractional shift first, only do it for reasonable offsets |
| 650 | if (fabs(fracOffset) > 1e-2) { |
| 651 | // create sinc function |
| 652 | signalVector sincVector(21); |
| 653 | sincVector.isRealOnly(true); |
| 654 | signalVector::iterator sincBurstItr = sincVector.begin(); |
| 655 | for (int i = 0; i < 21; i++) |
| 656 | *sincBurstItr++ = (complex) sinc(M_PI_F*(i-10-fracOffset)); |
| 657 | |
| 658 | signalVector shiftedBurst(wBurst.size()); |
| 659 | convolve(&wBurst,&sincVector,&shiftedBurst,NO_DELAY); |
| 660 | wBurst.clone(shiftedBurst); |
| 661 | } |
| 662 | |
| 663 | if (intOffset < 0) { |
| 664 | intOffset = -intOffset; |
| 665 | signalVector::iterator wBurstItr = wBurst.begin(); |
| 666 | signalVector::iterator shiftedItr = wBurst.begin()+intOffset; |
| 667 | while (shiftedItr < wBurst.end()) |
| 668 | *wBurstItr++ = *shiftedItr++; |
| 669 | while (wBurstItr < wBurst.end()) |
| 670 | *wBurstItr++ = 0.0; |
| 671 | } |
| 672 | else { |
| 673 | signalVector::iterator wBurstItr = wBurst.end()-1; |
| 674 | signalVector::iterator shiftedItr = wBurst.end()-1-intOffset; |
| 675 | while (shiftedItr >= wBurst.begin()) |
| 676 | *wBurstItr-- = *shiftedItr--; |
| 677 | while (wBurstItr >= wBurst.begin()) |
| 678 | *wBurstItr-- = 0.0; |
| 679 | } |
| 680 | } |
| 681 | |
| 682 | signalVector *gaussianNoise(int length, |
| 683 | float variance, |
| 684 | complex mean) |
| 685 | { |
| 686 | |
| 687 | signalVector *noise = new signalVector(length); |
| 688 | signalVector::iterator nPtr = noise->begin(); |
| 689 | float stddev = sqrtf(variance); |
| 690 | while (nPtr < noise->end()) { |
| 691 | float u1 = (float) rand()/ (float) RAND_MAX; |
| 692 | while (u1==0.0) |
| 693 | u1 = (float) rand()/ (float) RAND_MAX; |
| 694 | float u2 = (float) rand()/ (float) RAND_MAX; |
| 695 | float arg = 2.0*M_PI*u2; |
| 696 | *nPtr = mean + stddev*complex(cos(arg),sin(arg))*sqrtf(-2.0*log(u1)); |
| 697 | nPtr++; |
| 698 | } |
| 699 | |
| 700 | return noise; |
| 701 | } |
| 702 | |
| 703 | complex interpolatePoint(const signalVector &inSig, |
| 704 | float ix) |
| 705 | { |
| 706 | |
| 707 | int start = (int) (floor(ix) - 10); |
| 708 | if (start < 0) start = 0; |
| 709 | int end = (int) (floor(ix) + 11); |
| 710 | if ((unsigned) end > inSig.size()-1) end = inSig.size()-1; |
| 711 | |
| 712 | complex pVal = 0.0; |
| 713 | if (!inSig.isRealOnly()) { |
| 714 | for (int i = start; i < end; i++) |
| 715 | pVal += inSig[i] * sinc(M_PI_F*(i-ix)); |
| 716 | } |
| 717 | else { |
| 718 | for (int i = start; i < end; i++) |
| 719 | pVal += inSig[i].real() * sinc(M_PI_F*(i-ix)); |
| 720 | } |
| 721 | |
| 722 | return pVal; |
| 723 | } |
| 724 | |
| 725 | |
| 726 | |
| 727 | complex peakDetect(const signalVector &rxBurst, |
| 728 | float *peakIndex, |
| 729 | float *avgPwr) |
| 730 | { |
| 731 | |
| 732 | |
| 733 | complex maxVal = 0.0; |
| 734 | float maxIndex = -1; |
| 735 | float sumPower = 0.0; |
| 736 | |
| 737 | for (unsigned int i = 0; i < rxBurst.size(); i++) { |
| 738 | float samplePower = rxBurst[i].norm2(); |
| 739 | if (samplePower > maxVal.real()) { |
| 740 | maxVal = samplePower; |
| 741 | maxIndex = i; |
| 742 | } |
| 743 | sumPower += samplePower; |
| 744 | } |
| 745 | |
| 746 | // interpolate around the peak |
| 747 | // to save computation, we'll use early-late balancing |
| 748 | float earlyIndex = maxIndex-1; |
| 749 | float lateIndex = maxIndex+1; |
| 750 | |
| 751 | float incr = 0.5; |
| 752 | while (incr > 1.0/1024.0) { |
| 753 | complex earlyP = interpolatePoint(rxBurst,earlyIndex); |
| 754 | complex lateP = interpolatePoint(rxBurst,lateIndex); |
| 755 | if (earlyP < lateP) |
| 756 | earlyIndex += incr; |
| 757 | else if (earlyP > lateP) |
| 758 | earlyIndex -= incr; |
| 759 | else break; |
| 760 | incr /= 2.0; |
| 761 | lateIndex = earlyIndex + 2.0; |
| 762 | } |
| 763 | |
| 764 | maxIndex = earlyIndex + 1.0; |
| 765 | maxVal = interpolatePoint(rxBurst,maxIndex); |
| 766 | |
| 767 | if (peakIndex!=NULL) |
| 768 | *peakIndex = maxIndex; |
| 769 | |
| 770 | if (avgPwr!=NULL) |
| 771 | *avgPwr = (sumPower-maxVal.norm2()) / (rxBurst.size()-1); |
| 772 | |
| 773 | return maxVal; |
| 774 | |
| 775 | } |
| 776 | |
| 777 | void scaleVector(signalVector &x, |
| 778 | complex scale) |
| 779 | { |
| 780 | signalVector::iterator xP = x.begin(); |
| 781 | signalVector::iterator xPEnd = x.end(); |
| 782 | if (!x.isRealOnly()) { |
| 783 | while (xP < xPEnd) { |
| 784 | *xP = *xP * scale; |
| 785 | xP++; |
| 786 | } |
| 787 | } |
| 788 | else { |
| 789 | while (xP < xPEnd) { |
| 790 | *xP = xP->real() * scale; |
| 791 | xP++; |
| 792 | } |
| 793 | } |
| 794 | } |
| 795 | |
| 796 | /** in-place conjugation */ |
| 797 | void conjugateVector(signalVector &x) |
| 798 | { |
| 799 | if (x.isRealOnly()) return; |
| 800 | signalVector::iterator xP = x.begin(); |
| 801 | signalVector::iterator xPEnd = x.end(); |
| 802 | while (xP < xPEnd) { |
| 803 | *xP = xP->conj(); |
| 804 | xP++; |
| 805 | } |
| 806 | } |
| 807 | |
| 808 | |
| 809 | // in-place addition!! |
| 810 | bool addVector(signalVector &x, |
| 811 | signalVector &y) |
| 812 | { |
| 813 | signalVector::iterator xP = x.begin(); |
| 814 | signalVector::iterator yP = y.begin(); |
| 815 | signalVector::iterator xPEnd = x.end(); |
| 816 | signalVector::iterator yPEnd = y.end(); |
| 817 | while ((xP < xPEnd) && (yP < yPEnd)) { |
| 818 | *xP = *xP + *yP; |
| 819 | xP++; yP++; |
| 820 | } |
| 821 | return true; |
| 822 | } |
| 823 | |
| 824 | // in-place multiplication!! |
| 825 | bool multVector(signalVector &x, |
| 826 | signalVector &y) |
| 827 | { |
| 828 | signalVector::iterator xP = x.begin(); |
| 829 | signalVector::iterator yP = y.begin(); |
| 830 | signalVector::iterator xPEnd = x.end(); |
| 831 | signalVector::iterator yPEnd = y.end(); |
| 832 | while ((xP < xPEnd) && (yP < yPEnd)) { |
| 833 | *xP = (*xP) * (*yP); |
| 834 | xP++; yP++; |
| 835 | } |
| 836 | return true; |
| 837 | } |
| 838 | |
| 839 | |
| 840 | void offsetVector(signalVector &x, |
| 841 | complex offset) |
| 842 | { |
| 843 | signalVector::iterator xP = x.begin(); |
| 844 | signalVector::iterator xPEnd = x.end(); |
| 845 | if (!x.isRealOnly()) { |
| 846 | while (xP < xPEnd) { |
| 847 | *xP += offset; |
| 848 | xP++; |
| 849 | } |
| 850 | } |
| 851 | else { |
| 852 | while (xP < xPEnd) { |
| 853 | *xP = xP->real() + offset; |
| 854 | xP++; |
| 855 | } |
| 856 | } |
| 857 | } |
| 858 | |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 859 | bool generateMidamble(int sps, int tsc) |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 860 | { |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 861 | bool status = true; |
| 862 | complex *data = NULL; |
| 863 | signalVector *autocorr = NULL, *midamble = NULL; |
| 864 | signalVector *midMidamble = NULL; |
| 865 | |
| 866 | if ((tsc < 0) || (tsc > 7)) |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 867 | return false; |
| 868 | |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 869 | delete gMidambles[tsc]; |
| 870 | |
| 871 | /* Use middle 16 bits of each TSC. Correlation sequence is not pulse shaped */ |
| 872 | midMidamble = modulateBurst(gTrainingSequence[tsc].segment(5,16), 0, sps, true); |
| 873 | if (!midMidamble) |
| 874 | return false; |
| 875 | |
| 876 | /* Simulated receive sequence is pulse shaped */ |
| 877 | midamble = modulateBurst(gTrainingSequence[tsc], 0, sps, false); |
| 878 | if (!midamble) { |
| 879 | status = false; |
| 880 | goto release; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 881 | } |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 882 | |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 883 | // NOTE: Because ideal TSC 16-bit midamble is 66 symbols into burst, |
| 884 | // the ideal TSC has an + 180 degree phase shift, |
| 885 | // due to the pi/2 frequency shift, that |
| 886 | // needs to be accounted for. |
| 887 | // 26-midamble is 61 symbols into burst, has +90 degree phase shift. |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 888 | scaleVector(*midMidamble, complex(-1.0, 0.0)); |
| 889 | scaleVector(*midamble, complex(0.0, 1.0)); |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 890 | |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 891 | conjugateVector(*midMidamble); |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 892 | |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 893 | autocorr = correlate(midamble, midMidamble, NULL, NO_DELAY); |
| 894 | if (!autocorr) { |
| 895 | status = false; |
| 896 | goto release; |
| 897 | } |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 898 | |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 899 | gMidambles[tsc] = new CorrelationSequence; |
| 900 | gMidambles[tsc]->sequence = midMidamble; |
| 901 | gMidambles[tsc]->gain = peakDetect(*autocorr,&gMidambles[tsc]->TOA,NULL); |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 902 | |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 903 | release: |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 904 | delete autocorr; |
| 905 | delete midamble; |
| 906 | |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 907 | if (!status) { |
| 908 | delete midMidamble; |
| 909 | gMidambles[tsc] = NULL; |
| 910 | } |
| 911 | |
| 912 | return status; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 913 | } |
| 914 | |
Thomas Tsou | 83e0689 | 2013-08-20 16:10:01 -0400 | [diff] [blame] | 915 | bool generateRACHSequence(int sps) |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 916 | { |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 917 | bool status = true; |
| 918 | complex *data = NULL; |
| 919 | signalVector *autocorr = NULL; |
| 920 | signalVector *seq0 = NULL, *seq1 = NULL; |
| 921 | |
| 922 | delete gRACHSequence; |
| 923 | |
| 924 | seq0 = modulateBurst(gRACHSynchSequence, 0, sps, false); |
| 925 | if (!seq0) |
| 926 | return false; |
| 927 | |
| 928 | seq1 = modulateBurst(gRACHSynchSequence.segment(0, 40), 0, sps, true); |
| 929 | if (!seq1) { |
| 930 | status = false; |
| 931 | goto release; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 932 | } |
| 933 | |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 934 | conjugateVector(*seq1); |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 935 | |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 936 | autocorr = new signalVector(seq0->size()); |
| 937 | if (!convolve(seq0, seq1, autocorr, NO_DELAY)) { |
| 938 | status = false; |
| 939 | goto release; |
| 940 | } |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 941 | |
| 942 | gRACHSequence = new CorrelationSequence; |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 943 | gRACHSequence->sequence = seq1; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 944 | gRACHSequence->gain = peakDetect(*autocorr,&gRACHSequence->TOA,NULL); |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 945 | |
| 946 | release: |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 947 | delete autocorr; |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 948 | delete seq0; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 949 | |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 950 | if (!status) { |
| 951 | delete seq1; |
| 952 | gRACHSequence = NULL; |
| 953 | } |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 954 | |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 955 | return status; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 956 | } |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 957 | |
| 958 | bool detectRACHBurst(signalVector &rxBurst, |
| 959 | float detectThreshold, |
Thomas Tsou | d24cc2c | 2013-08-20 15:41:45 -0400 | [diff] [blame] | 960 | int sps, |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 961 | complex *amplitude, |
| 962 | float* TOA) |
| 963 | { |
| 964 | |
| 965 | //static complex staticData[500]; |
| 966 | |
| 967 | //signalVector correlatedRACH(staticData,0,rxBurst.size()); |
| 968 | signalVector correlatedRACH(rxBurst.size()); |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 969 | correlate(&rxBurst,gRACHSequence->sequence,&correlatedRACH,NO_DELAY,true); |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 970 | |
| 971 | float meanPower; |
| 972 | complex peakAmpl = peakDetect(correlatedRACH,TOA,&meanPower); |
| 973 | |
| 974 | float valleyPower = 0.0; |
| 975 | |
| 976 | // check for bogus results |
| 977 | if ((*TOA < 0.0) || (*TOA > correlatedRACH.size())) { |
| 978 | *amplitude = 0.0; |
| 979 | return false; |
| 980 | } |
| 981 | complex *peakPtr = correlatedRACH.begin() + (int) rint(*TOA); |
| 982 | |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 983 | float numSamples = 0.0; |
Thomas Tsou | d24cc2c | 2013-08-20 15:41:45 -0400 | [diff] [blame] | 984 | for (int i = 57 * sps; i <= 107 * sps; i++) { |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 985 | if (peakPtr+i >= correlatedRACH.end()) |
| 986 | break; |
| 987 | valleyPower += (peakPtr+i)->norm2(); |
| 988 | numSamples++; |
| 989 | } |
| 990 | |
| 991 | if (numSamples < 2) { |
| 992 | *amplitude = 0.0; |
| 993 | return false; |
| 994 | } |
| 995 | |
| 996 | float RMS = sqrtf(valleyPower/(float) numSamples)+0.00001; |
| 997 | float peakToMean = peakAmpl.abs()/RMS; |
| 998 | |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 999 | *amplitude = peakAmpl/(gRACHSequence->gain); |
| 1000 | |
Thomas Tsou | d24cc2c | 2013-08-20 15:41:45 -0400 | [diff] [blame] | 1001 | *TOA = (*TOA) - gRACHSequence->TOA - 8 * sps; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1002 | |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1003 | return (peakToMean > detectThreshold); |
| 1004 | } |
| 1005 | |
| 1006 | bool energyDetect(signalVector &rxBurst, |
| 1007 | unsigned windowLength, |
| 1008 | float detectThreshold, |
| 1009 | float *avgPwr) |
| 1010 | { |
| 1011 | |
| 1012 | signalVector::const_iterator windowItr = rxBurst.begin(); //+rxBurst.size()/2 - 5*windowLength/2; |
| 1013 | float energy = 0.0; |
| 1014 | if (windowLength < 0) windowLength = 20; |
| 1015 | if (windowLength > rxBurst.size()) windowLength = rxBurst.size(); |
| 1016 | for (unsigned i = 0; i < windowLength; i++) { |
| 1017 | energy += windowItr->norm2(); |
| 1018 | windowItr+=4; |
| 1019 | } |
| 1020 | if (avgPwr) *avgPwr = energy/windowLength; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1021 | return (energy/windowLength > detectThreshold*detectThreshold); |
| 1022 | } |
| 1023 | |
| 1024 | |
| 1025 | bool analyzeTrafficBurst(signalVector &rxBurst, |
| 1026 | unsigned TSC, |
| 1027 | float detectThreshold, |
Thomas Tsou | d24cc2c | 2013-08-20 15:41:45 -0400 | [diff] [blame] | 1028 | int sps, |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1029 | complex *amplitude, |
| 1030 | float *TOA, |
| 1031 | unsigned maxTOA, |
| 1032 | bool requestChannel, |
| 1033 | signalVector **channelResponse, |
| 1034 | float *channelResponseOffset) |
| 1035 | { |
| 1036 | |
| 1037 | assert(TSC<8); |
| 1038 | assert(amplitude); |
| 1039 | assert(TOA); |
| 1040 | assert(gMidambles[TSC]); |
| 1041 | |
Thomas Tsou | d24cc2c | 2013-08-20 15:41:45 -0400 | [diff] [blame] | 1042 | if (maxTOA < 3*sps) maxTOA = 3*sps; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1043 | unsigned spanTOA = maxTOA; |
Thomas Tsou | d24cc2c | 2013-08-20 15:41:45 -0400 | [diff] [blame] | 1044 | if (spanTOA < 5*sps) spanTOA = 5*sps; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1045 | |
Thomas Tsou | d24cc2c | 2013-08-20 15:41:45 -0400 | [diff] [blame] | 1046 | unsigned startIx = 66*sps-spanTOA; |
| 1047 | unsigned endIx = (66+16)*sps+spanTOA; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1048 | unsigned windowLen = endIx - startIx; |
| 1049 | unsigned corrLen = 2*maxTOA+1; |
| 1050 | |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 1051 | unsigned expectedTOAPeak = (unsigned) round(gMidambles[TSC]->TOA + (gMidambles[TSC]->sequence->size()-1)/2); |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1052 | |
| 1053 | signalVector burstSegment(rxBurst.begin(),startIx,windowLen); |
| 1054 | |
| 1055 | //static complex staticData[200]; |
| 1056 | //signalVector correlatedBurst(staticData,0,corrLen); |
| 1057 | signalVector correlatedBurst(corrLen); |
Thomas Tsou | e5dcfc4 | 2013-08-20 16:27:12 -0400 | [diff] [blame] | 1058 | correlate(&burstSegment, gMidambles[TSC]->sequence, |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1059 | &correlatedBurst, CUSTOM,true, |
| 1060 | expectedTOAPeak-maxTOA,corrLen); |
| 1061 | |
| 1062 | float meanPower; |
| 1063 | *amplitude = peakDetect(correlatedBurst,TOA,&meanPower); |
| 1064 | float valleyPower = 0.0; //amplitude->norm2(); |
| 1065 | complex *peakPtr = correlatedBurst.begin() + (int) rint(*TOA); |
| 1066 | |
| 1067 | // check for bogus results |
| 1068 | if ((*TOA < 0.0) || (*TOA > correlatedBurst.size())) { |
| 1069 | *amplitude = 0.0; |
| 1070 | return false; |
| 1071 | } |
| 1072 | |
| 1073 | int numRms = 0; |
Thomas Tsou | d24cc2c | 2013-08-20 15:41:45 -0400 | [diff] [blame] | 1074 | for (int i = 2*sps; i <= 5*sps;i++) { |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1075 | if (peakPtr - i >= correlatedBurst.begin()) { |
| 1076 | valleyPower += (peakPtr-i)->norm2(); |
| 1077 | numRms++; |
| 1078 | } |
| 1079 | if (peakPtr + i < correlatedBurst.end()) { |
| 1080 | valleyPower += (peakPtr+i)->norm2(); |
| 1081 | numRms++; |
| 1082 | } |
| 1083 | } |
| 1084 | |
| 1085 | if (numRms < 2) { |
| 1086 | // check for bogus results |
| 1087 | *amplitude = 0.0; |
| 1088 | return false; |
| 1089 | } |
| 1090 | |
| 1091 | float RMS = sqrtf(valleyPower/(float)numRms)+0.00001; |
| 1092 | float peakToMean = (amplitude->abs())/RMS; |
| 1093 | |
| 1094 | // NOTE: Because ideal TSC is 66 symbols into burst, |
| 1095 | // the ideal TSC has an +/- 180 degree phase shift, |
| 1096 | // due to the pi/4 frequency shift, that |
| 1097 | // needs to be accounted for. |
| 1098 | |
| 1099 | *amplitude = (*amplitude)/gMidambles[TSC]->gain; |
| 1100 | *TOA = (*TOA) - (maxTOA); |
| 1101 | |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1102 | if (requestChannel && (peakToMean > detectThreshold)) { |
Thomas Tsou | d24cc2c | 2013-08-20 15:41:45 -0400 | [diff] [blame] | 1103 | float TOAoffset = maxTOA; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1104 | delayVector(correlatedBurst,-(*TOA)); |
| 1105 | // midamble only allows estimation of a 6-tap channel |
Thomas Tsou | d24cc2c | 2013-08-20 15:41:45 -0400 | [diff] [blame] | 1106 | signalVector chanVector(6 * sps); |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1107 | float maxEnergy = -1.0; |
| 1108 | int maxI = -1; |
| 1109 | for (int i = 0; i < 7; i++) { |
Thomas Tsou | d24cc2c | 2013-08-20 15:41:45 -0400 | [diff] [blame] | 1110 | if (TOAoffset + (i-5) * sps + chanVector.size() > correlatedBurst.size()) |
| 1111 | continue; |
| 1112 | if (TOAoffset + (i-5) * sps < 0) |
| 1113 | continue; |
| 1114 | correlatedBurst.segmentCopyTo(chanVector, |
| 1115 | (int) floor(TOAoffset + (i - 5) * sps), |
| 1116 | chanVector.size()); |
| 1117 | float energy = vectorNorm2(chanVector); |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1118 | if (energy > 0.95*maxEnergy) { |
| 1119 | maxI = i; |
| 1120 | maxEnergy = energy; |
| 1121 | } |
| 1122 | } |
| 1123 | |
Thomas Tsou | d24cc2c | 2013-08-20 15:41:45 -0400 | [diff] [blame] | 1124 | *channelResponse = new signalVector(chanVector.size()); |
| 1125 | correlatedBurst.segmentCopyTo(**channelResponse, |
| 1126 | (int) floor(TOAoffset + (maxI - 5) * sps), |
| 1127 | (*channelResponse)->size()); |
| 1128 | scaleVector(**channelResponse, complex(1.0, 0.0) / gMidambles[TSC]->gain); |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1129 | |
| 1130 | if (channelResponseOffset) |
Thomas Tsou | d24cc2c | 2013-08-20 15:41:45 -0400 | [diff] [blame] | 1131 | *channelResponseOffset = 5 * sps - maxI; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1132 | |
| 1133 | } |
| 1134 | |
| 1135 | return (peakToMean > detectThreshold); |
| 1136 | |
| 1137 | } |
| 1138 | |
| 1139 | signalVector *decimateVector(signalVector &wVector, |
| 1140 | int decimationFactor) |
| 1141 | { |
| 1142 | |
| 1143 | if (decimationFactor <= 1) return NULL; |
| 1144 | |
| 1145 | signalVector *decVector = new signalVector(wVector.size()/decimationFactor); |
| 1146 | decVector->isRealOnly(wVector.isRealOnly()); |
| 1147 | |
| 1148 | signalVector::iterator vecItr = decVector->begin(); |
| 1149 | for (unsigned int i = 0; i < wVector.size();i+=decimationFactor) |
| 1150 | *vecItr++ = wVector[i]; |
| 1151 | |
| 1152 | return decVector; |
| 1153 | } |
| 1154 | |
| 1155 | |
Thomas Tsou | 83e0689 | 2013-08-20 16:10:01 -0400 | [diff] [blame] | 1156 | SoftVector *demodulateBurst(signalVector &rxBurst, int sps, |
| 1157 | complex channel, float TOA) |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1158 | { |
| 1159 | scaleVector(rxBurst,((complex) 1.0)/channel); |
| 1160 | delayVector(rxBurst,-TOA); |
| 1161 | |
| 1162 | signalVector *shapedBurst = &rxBurst; |
| 1163 | |
| 1164 | // shift up by a quarter of a frequency |
| 1165 | // ignore starting phase, since spec allows for discontinuous phase |
| 1166 | GMSKReverseRotate(*shapedBurst); |
| 1167 | |
| 1168 | // run through slicer |
Thomas Tsou | d24cc2c | 2013-08-20 15:41:45 -0400 | [diff] [blame] | 1169 | if (sps > 1) { |
| 1170 | signalVector *decShapedBurst = decimateVector(*shapedBurst, sps); |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1171 | shapedBurst = decShapedBurst; |
| 1172 | } |
| 1173 | |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1174 | vectorSlicer(shapedBurst); |
| 1175 | |
| 1176 | SoftVector *burstBits = new SoftVector(shapedBurst->size()); |
| 1177 | |
| 1178 | SoftVector::iterator burstItr = burstBits->begin(); |
| 1179 | signalVector::iterator shapedItr = shapedBurst->begin(); |
| 1180 | for (; shapedItr < shapedBurst->end(); shapedItr++) |
| 1181 | *burstItr++ = shapedItr->real(); |
| 1182 | |
Thomas Tsou | d24cc2c | 2013-08-20 15:41:45 -0400 | [diff] [blame] | 1183 | if (sps > 1) |
| 1184 | delete shapedBurst; |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1185 | |
| 1186 | return burstBits; |
| 1187 | |
| 1188 | } |
| 1189 | |
| 1190 | |
| 1191 | // 1.0 is sampling frequency |
| 1192 | // must satisfy cutoffFreq > 1/filterLen |
| 1193 | signalVector *createLPF(float cutoffFreq, |
| 1194 | int filterLen, |
| 1195 | float gainDC) |
| 1196 | { |
kurtis.heimerl | a198d45 | 2011-11-26 03:19:28 +0000 | [diff] [blame] | 1197 | #if 0 |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1198 | signalVector *LPF = new signalVector(filterLen-1); |
| 1199 | LPF->isRealOnly(true); |
| 1200 | LPF->setSymmetry(ABSSYM); |
| 1201 | signalVector::iterator itr = LPF->begin(); |
| 1202 | double sum = 0.0; |
| 1203 | for (int i = 1; i < filterLen; i++) { |
| 1204 | float ys = sinc(M_2PI_F*cutoffFreq*((float)i-(float)(filterLen)/2.0F)); |
| 1205 | float yg = 4.0F * cutoffFreq; |
| 1206 | // Blackman -- less brickwall (sloping transition) but larger stopband attenuation |
| 1207 | float yw = 0.42 - 0.5*cos(((float)i)*M_2PI_F/(float)(filterLen)) + 0.08*cos(((float)i)*2*M_2PI_F/(float)(filterLen)); |
| 1208 | // Hamming -- more brickwall with smaller stopband attenuation |
| 1209 | //float yw = 0.53836F - 0.46164F * cos(((float)i)*M_2PI_F/(float)(filterLen+1)); |
| 1210 | *itr++ = (complex) ys*yg*yw; |
| 1211 | sum += ys*yg*yw; |
| 1212 | } |
kurtis.heimerl | a198d45 | 2011-11-26 03:19:28 +0000 | [diff] [blame] | 1213 | #else |
| 1214 | double sum = 0.0; |
| 1215 | signalVector *LPF; |
| 1216 | signalVector::iterator itr; |
| 1217 | if (filterLen == 651) { // receive LPF |
| 1218 | LPF = new signalVector(651); |
| 1219 | LPF->isRealOnly(true); |
| 1220 | itr = LPF->begin(); |
| 1221 | for (int i = 0; i < filterLen; i++) { |
| 1222 | *itr++ = complex(rcvLPF_651[i],0.0); |
| 1223 | sum += rcvLPF_651[i]; |
| 1224 | } |
| 1225 | } |
| 1226 | else { |
| 1227 | LPF = new signalVector(961); |
| 1228 | LPF->isRealOnly(true); |
| 1229 | itr = LPF->begin(); |
| 1230 | for (int i = 0; i < filterLen; i++) { |
| 1231 | *itr++ = complex(sendLPF_961[i],0.0); |
| 1232 | sum += sendLPF_961[i]; |
| 1233 | } |
| 1234 | } |
| 1235 | #endif |
| 1236 | |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1237 | float normFactor = gainDC/sum; //sqrtf(gainDC/vectorNorm2(*LPF)); |
| 1238 | // normalize power |
| 1239 | itr = LPF->begin(); |
kurtis.heimerl | a198d45 | 2011-11-26 03:19:28 +0000 | [diff] [blame] | 1240 | for (int i = 0; i < filterLen; i++) { |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1241 | *itr = *itr*normFactor; |
| 1242 | itr++; |
| 1243 | } |
| 1244 | return LPF; |
| 1245 | |
| 1246 | } |
| 1247 | |
| 1248 | |
| 1249 | |
| 1250 | #define POLYPHASESPAN 10 |
| 1251 | |
| 1252 | // assumes filter group delay is 0.5*(length of filter) |
| 1253 | signalVector *polyphaseResampleVector(signalVector &wVector, |
| 1254 | int P, int Q, |
| 1255 | signalVector *LPF) |
| 1256 | |
| 1257 | { |
| 1258 | |
| 1259 | bool deleteLPF = false; |
| 1260 | |
| 1261 | if (LPF==NULL) { |
| 1262 | float cutoffFreq = (P < Q) ? (1.0/(float) Q) : (1.0/(float) P); |
| 1263 | LPF = createLPF(cutoffFreq/3.0,100*POLYPHASESPAN+1,Q); |
| 1264 | deleteLPF = true; |
| 1265 | } |
| 1266 | |
| 1267 | signalVector *resampledVector = new signalVector((int) ceil(wVector.size()*(float) P / (float) Q)); |
| 1268 | resampledVector->fill(0); |
| 1269 | resampledVector->isRealOnly(wVector.isRealOnly()); |
| 1270 | signalVector::iterator newItr = resampledVector->begin(); |
| 1271 | |
| 1272 | //FIXME: need to update for real-only vectors |
| 1273 | int outputIx = (LPF->size()+1)/2/Q; //((P > Q) ? P : Q); |
| 1274 | while (newItr < resampledVector->end()) { |
| 1275 | int outputBranch = (outputIx*Q) % P; |
| 1276 | int inputOffset = (outputIx*Q - outputBranch)/P; |
| 1277 | signalVector::const_iterator inputItr = wVector.begin() + inputOffset; |
| 1278 | signalVector::const_iterator filtItr = LPF->begin() + outputBranch; |
| 1279 | while (inputItr >= wVector.end()) { |
| 1280 | inputItr--; |
| 1281 | filtItr+=P; |
| 1282 | } |
| 1283 | complex sum = 0.0; |
| 1284 | if ((LPF->getSymmetry()!=ABSSYM) || (P>1)) { |
| 1285 | if (!LPF->isRealOnly()) { |
| 1286 | while ( (inputItr >= wVector.begin()) && (filtItr < LPF->end()) ) { |
| 1287 | sum += (*inputItr)*(*filtItr); |
| 1288 | inputItr--; |
| 1289 | filtItr += P; |
| 1290 | } |
| 1291 | } |
| 1292 | else { |
| 1293 | while ( (inputItr >= wVector.begin()) && (filtItr < LPF->end()) ) { |
| 1294 | sum += (*inputItr)*(filtItr->real()); |
| 1295 | inputItr--; |
| 1296 | filtItr += P; |
| 1297 | } |
| 1298 | } |
| 1299 | } |
| 1300 | else { |
| 1301 | signalVector::const_iterator revInputItr = inputItr- LPF->size() + 1; |
| 1302 | signalVector::const_iterator filtMidpoint = LPF->begin()+(LPF->size()-1)/2; |
| 1303 | if (!LPF->isRealOnly()) { |
| 1304 | while (filtItr <= filtMidpoint) { |
| 1305 | if (inputItr < revInputItr) break; |
| 1306 | if (inputItr == revInputItr) |
| 1307 | sum += (*inputItr)*(*filtItr); |
| 1308 | else if ( (inputItr < wVector.end()) && (revInputItr >= wVector.begin()) ) |
| 1309 | sum += (*inputItr + *revInputItr)*(*filtItr); |
| 1310 | else if ( inputItr < wVector.end() ) |
| 1311 | sum += (*inputItr)*(*filtItr); |
| 1312 | else if ( revInputItr >= wVector.begin() ) |
| 1313 | sum += (*revInputItr)*(*filtItr); |
| 1314 | inputItr--; |
| 1315 | revInputItr++; |
| 1316 | filtItr++; |
| 1317 | } |
| 1318 | } |
| 1319 | else { |
| 1320 | while (filtItr <= filtMidpoint) { |
| 1321 | if (inputItr < revInputItr) break; |
| 1322 | if (inputItr == revInputItr) |
| 1323 | sum += (*inputItr)*(filtItr->real()); |
| 1324 | else if ( (inputItr < wVector.end()) && (revInputItr >= wVector.begin()) ) |
| 1325 | sum += (*inputItr + *revInputItr)*(filtItr->real()); |
| 1326 | else if ( inputItr < wVector.end() ) |
| 1327 | sum += (*inputItr)*(filtItr->real()); |
| 1328 | else if ( revInputItr >= wVector.begin() ) |
| 1329 | sum += (*revInputItr)*(filtItr->real()); |
| 1330 | inputItr--; |
| 1331 | revInputItr++; |
| 1332 | filtItr++; |
| 1333 | } |
| 1334 | } |
| 1335 | } |
| 1336 | *newItr = sum; |
| 1337 | newItr++; |
| 1338 | outputIx++; |
| 1339 | } |
| 1340 | |
| 1341 | if (deleteLPF) delete LPF; |
| 1342 | |
| 1343 | return resampledVector; |
| 1344 | } |
| 1345 | |
| 1346 | |
| 1347 | signalVector *resampleVector(signalVector &wVector, |
| 1348 | float expFactor, |
| 1349 | complex endPoint) |
| 1350 | |
| 1351 | { |
| 1352 | |
| 1353 | if (expFactor < 1.0) return NULL; |
| 1354 | |
| 1355 | signalVector *retVec = new signalVector((int) ceil(wVector.size()*expFactor)); |
| 1356 | |
| 1357 | float t = 0.0; |
| 1358 | |
| 1359 | signalVector::iterator retItr = retVec->begin(); |
| 1360 | while (retItr < retVec->end()) { |
| 1361 | unsigned tLow = (unsigned int) floor(t); |
| 1362 | unsigned tHigh = tLow + 1; |
| 1363 | if (tLow > wVector.size()-1) break; |
| 1364 | if (tHigh > wVector.size()) break; |
| 1365 | complex lowPoint = wVector[tLow]; |
| 1366 | complex highPoint = (tHigh == wVector.size()) ? endPoint : wVector[tHigh]; |
| 1367 | complex a = (tHigh-t); |
| 1368 | complex b = (t-tLow); |
| 1369 | *retItr = (a*lowPoint + b*highPoint); |
| 1370 | t += 1.0/expFactor; |
| 1371 | } |
| 1372 | |
| 1373 | return retVec; |
| 1374 | |
| 1375 | } |
| 1376 | |
| 1377 | |
| 1378 | // Assumes symbol-spaced sampling!!! |
| 1379 | // Based upon paper by Al-Dhahir and Cioffi |
| 1380 | bool designDFE(signalVector &channelResponse, |
| 1381 | float SNRestimate, |
| 1382 | int Nf, |
| 1383 | signalVector **feedForwardFilter, |
| 1384 | signalVector **feedbackFilter) |
| 1385 | { |
| 1386 | |
| 1387 | signalVector G0(Nf); |
| 1388 | signalVector G1(Nf); |
| 1389 | signalVector::iterator G0ptr = G0.begin(); |
| 1390 | signalVector::iterator G1ptr = G1.begin(); |
| 1391 | signalVector::iterator chanPtr = channelResponse.begin(); |
| 1392 | |
| 1393 | int nu = channelResponse.size()-1; |
| 1394 | |
| 1395 | *G0ptr = 1.0/sqrtf(SNRestimate); |
| 1396 | for(int j = 0; j <= nu; j++) { |
| 1397 | *G1ptr = chanPtr->conj(); |
| 1398 | G1ptr++; chanPtr++; |
| 1399 | } |
| 1400 | |
| 1401 | signalVector *L[Nf]; |
| 1402 | signalVector::iterator Lptr; |
| 1403 | float d; |
| 1404 | for(int i = 0; i < Nf; i++) { |
| 1405 | d = G0.begin()->norm2() + G1.begin()->norm2(); |
| 1406 | L[i] = new signalVector(Nf+nu); |
| 1407 | Lptr = L[i]->begin()+i; |
| 1408 | G0ptr = G0.begin(); G1ptr = G1.begin(); |
| 1409 | while ((G0ptr < G0.end()) && (Lptr < L[i]->end())) { |
| 1410 | *Lptr = (*G0ptr*(G0.begin()->conj()) + *G1ptr*(G1.begin()->conj()) )/d; |
| 1411 | Lptr++; |
| 1412 | G0ptr++; |
| 1413 | G1ptr++; |
| 1414 | } |
| 1415 | complex k = (*G1.begin())/(*G0.begin()); |
| 1416 | |
| 1417 | if (i != Nf-1) { |
| 1418 | signalVector G0new = G1; |
| 1419 | scaleVector(G0new,k.conj()); |
| 1420 | addVector(G0new,G0); |
| 1421 | |
| 1422 | signalVector G1new = G0; |
| 1423 | scaleVector(G1new,k*(-1.0)); |
| 1424 | addVector(G1new,G1); |
| 1425 | delayVector(G1new,-1.0); |
| 1426 | |
| 1427 | scaleVector(G0new,1.0/sqrtf(1.0+k.norm2())); |
| 1428 | scaleVector(G1new,1.0/sqrtf(1.0+k.norm2())); |
| 1429 | G0 = G0new; |
| 1430 | G1 = G1new; |
| 1431 | } |
| 1432 | } |
| 1433 | |
| 1434 | *feedbackFilter = new signalVector(nu); |
| 1435 | L[Nf-1]->segmentCopyTo(**feedbackFilter,Nf,nu); |
| 1436 | scaleVector(**feedbackFilter,(complex) -1.0); |
| 1437 | conjugateVector(**feedbackFilter); |
| 1438 | |
| 1439 | signalVector v(Nf); |
| 1440 | signalVector::iterator vStart = v.begin(); |
| 1441 | signalVector::iterator vPtr; |
| 1442 | *(vStart+Nf-1) = (complex) 1.0; |
| 1443 | for(int k = Nf-2; k >= 0; k--) { |
| 1444 | Lptr = L[k]->begin()+k+1; |
| 1445 | vPtr = vStart + k+1; |
| 1446 | complex v_k = 0.0; |
| 1447 | for (int j = k+1; j < Nf; j++) { |
| 1448 | v_k -= (*vPtr)*(*Lptr); |
| 1449 | vPtr++; Lptr++; |
| 1450 | } |
| 1451 | *(vStart + k) = v_k; |
| 1452 | } |
| 1453 | |
| 1454 | *feedForwardFilter = new signalVector(Nf); |
| 1455 | signalVector::iterator w = (*feedForwardFilter)->begin(); |
| 1456 | for (int i = 0; i < Nf; i++) { |
| 1457 | delete L[i]; |
| 1458 | complex w_i = 0.0; |
| 1459 | int endPt = ( nu < (Nf-1-i) ) ? nu : (Nf-1-i); |
| 1460 | vPtr = vStart+i; |
| 1461 | chanPtr = channelResponse.begin(); |
| 1462 | for (int k = 0; k < endPt+1; k++) { |
| 1463 | w_i += (*vPtr)*(chanPtr->conj()); |
| 1464 | vPtr++; chanPtr++; |
| 1465 | } |
| 1466 | *w = w_i/d; |
| 1467 | w++; |
| 1468 | } |
| 1469 | |
| 1470 | |
| 1471 | return true; |
| 1472 | |
| 1473 | } |
| 1474 | |
| 1475 | // Assumes symbol-rate sampling!!!! |
| 1476 | SoftVector *equalizeBurst(signalVector &rxBurst, |
| 1477 | float TOA, |
Thomas Tsou | d24cc2c | 2013-08-20 15:41:45 -0400 | [diff] [blame] | 1478 | int sps, |
dburgess | b3a0ca4 | 2011-10-12 07:44:40 +0000 | [diff] [blame] | 1479 | signalVector &w, // feedforward filter |
| 1480 | signalVector &b) // feedback filter |
| 1481 | { |
| 1482 | |
| 1483 | delayVector(rxBurst,-TOA); |
| 1484 | |
| 1485 | signalVector* postForwardFull = convolve(&rxBurst,&w,NULL,FULL_SPAN); |
| 1486 | |
| 1487 | signalVector* postForward = new signalVector(rxBurst.size()); |
| 1488 | postForwardFull->segmentCopyTo(*postForward,w.size()-1,rxBurst.size()); |
| 1489 | delete postForwardFull; |
| 1490 | |
| 1491 | signalVector::iterator dPtr = postForward->begin(); |
| 1492 | signalVector::iterator dBackPtr; |
| 1493 | signalVector::iterator rotPtr = GMSKRotation->begin(); |
| 1494 | signalVector::iterator revRotPtr = GMSKReverseRotation->begin(); |
| 1495 | |
| 1496 | signalVector *DFEoutput = new signalVector(postForward->size()); |
| 1497 | signalVector::iterator DFEItr = DFEoutput->begin(); |
| 1498 | |
| 1499 | // NOTE: can insert the midamble and/or use midamble to estimate BER |
| 1500 | for (; dPtr < postForward->end(); dPtr++) { |
| 1501 | dBackPtr = dPtr-1; |
| 1502 | signalVector::iterator bPtr = b.begin(); |
| 1503 | while ( (bPtr < b.end()) && (dBackPtr >= postForward->begin()) ) { |
| 1504 | *dPtr = *dPtr + (*bPtr)*(*dBackPtr); |
| 1505 | bPtr++; |
| 1506 | dBackPtr--; |
| 1507 | } |
| 1508 | *dPtr = *dPtr * (*revRotPtr); |
| 1509 | *DFEItr = *dPtr; |
| 1510 | // make decision on symbol |
| 1511 | *dPtr = (dPtr->real() > 0.0) ? 1.0 : -1.0; |
| 1512 | //*DFEItr = *dPtr; |
| 1513 | *dPtr = *dPtr * (*rotPtr); |
| 1514 | DFEItr++; |
| 1515 | rotPtr++; |
| 1516 | revRotPtr++; |
| 1517 | } |
| 1518 | |
| 1519 | vectorSlicer(DFEoutput); |
| 1520 | |
| 1521 | SoftVector *burstBits = new SoftVector(postForward->size()); |
| 1522 | SoftVector::iterator burstItr = burstBits->begin(); |
| 1523 | DFEItr = DFEoutput->begin(); |
| 1524 | for (; DFEItr < DFEoutput->end(); DFEItr++) |
| 1525 | *burstItr++ = DFEItr->real(); |
| 1526 | |
| 1527 | delete postForward; |
| 1528 | |
| 1529 | delete DFEoutput; |
| 1530 | |
| 1531 | return burstBits; |
| 1532 | } |