| /* |
| * Copyright 2008 Free Software Foundation, Inc. |
| * |
| * This software is distributed under the terms of the GNU Affero Public License. |
| * See the COPYING file in the main directory for details. |
| * |
| * This use of this software may be subject to additional restrictions. |
| * See the LEGAL file in the main directory for details. |
| |
| This program is free software: you can redistribute it and/or modify |
| it under the terms of the GNU Affero General Public License as published by |
| the Free Software Foundation, either version 3 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU Affero General Public License for more details. |
| |
| You should have received a copy of the GNU Affero General Public License |
| along with this program. If not, see <http://www.gnu.org/licenses/>. |
| |
| */ |
| |
| |
| |
| #define NDEBUG |
| |
| #include "sigProcLib.h" |
| #include "GSMCommon.h" |
| |
| #include <Logger.h> |
| |
| #define TABLESIZE 1024 |
| |
| /** Lookup tables for trigonometric approximation */ |
| float cosTable[TABLESIZE+1]; // add 1 element for wrap around |
| float sinTable[TABLESIZE+1]; |
| |
| /** Constants */ |
| static const float M_PI_F = (float)M_PI; |
| static const float M_2PI_F = (float)(2.0*M_PI); |
| static const float M_1_2PI_F = 1/M_2PI_F; |
| |
| /** Static vectors that contain a precomputed +/- f_b/4 sinusoid */ |
| signalVector *GMSKRotation = NULL; |
| signalVector *GMSKReverseRotation = NULL; |
| |
| /** Static ideal RACH and midamble correlation waveforms */ |
| typedef struct { |
| signalVector *sequence; |
| signalVector *sequenceReversedConjugated; |
| float TOA; |
| complex gain; |
| } CorrelationSequence; |
| |
| CorrelationSequence *gMidambles[] = {NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL}; |
| CorrelationSequence *gRACHSequence = NULL; |
| |
| void sigProcLibDestroy(void) { |
| if (GMSKRotation) { |
| delete GMSKRotation; |
| GMSKRotation = NULL; |
| } |
| if (GMSKReverseRotation) { |
| delete GMSKReverseRotation; |
| GMSKReverseRotation = NULL; |
| } |
| for (int i = 0; i < 8; i++) { |
| if (gMidambles[i]!=NULL) { |
| if (gMidambles[i]->sequence) delete gMidambles[i]->sequence; |
| if (gMidambles[i]->sequenceReversedConjugated) delete gMidambles[i]->sequenceReversedConjugated; |
| delete gMidambles[i]; |
| gMidambles[i] = NULL; |
| } |
| } |
| if (gRACHSequence) { |
| if (gRACHSequence->sequence) delete gRACHSequence->sequence; |
| if (gRACHSequence->sequenceReversedConjugated) delete gRACHSequence->sequenceReversedConjugated; |
| delete gRACHSequence; |
| gRACHSequence = NULL; |
| } |
| } |
| |
| |
| |
| // dB relative to 1.0. |
| // if > 1.0, then return 0 dB |
| float dB(float x) { |
| |
| float arg = 1.0F; |
| float dB = 0.0F; |
| |
| if (x >= 1.0F) return 0.0F; |
| if (x <= 0.0F) return -200.0F; |
| |
| float prevArg = arg; |
| float prevdB = dB; |
| float stepSize = 16.0F; |
| float dBstepSize = 12.0F; |
| while (stepSize > 1.0F) { |
| do { |
| prevArg = arg; |
| prevdB = dB; |
| arg /= stepSize; |
| dB -= dBstepSize; |
| } while (arg > x); |
| arg = prevArg; |
| dB = prevdB; |
| stepSize *= 0.5F; |
| dBstepSize -= 3.0F; |
| } |
| return ((arg-x)*(dB-3.0F) + (x-arg*0.5F)*dB)/(arg - arg*0.5F); |
| |
| } |
| |
| // 10^(-dB/10), inverse of dB func. |
| float dBinv(float x) { |
| |
| float arg = 1.0F; |
| float dB = 0.0F; |
| |
| if (x >= 0.0F) return 1.0F; |
| if (x <= -200.0F) return 0.0F; |
| |
| float prevArg = arg; |
| float prevdB = dB; |
| float stepSize = 16.0F; |
| float dBstepSize = 12.0F; |
| while (stepSize > 1.0F) { |
| do { |
| prevArg = arg; |
| prevdB = dB; |
| arg /= stepSize; |
| dB -= dBstepSize; |
| } while (dB > x); |
| arg = prevArg; |
| dB = prevdB; |
| stepSize *= 0.5F; |
| dBstepSize -= 3.0F; |
| } |
| |
| return ((dB-x)*(arg*0.5F)+(x-(dB-3.0F))*(arg))/3.0F; |
| |
| } |
| |
| float vectorNorm2(const signalVector &x) |
| { |
| signalVector::const_iterator xPtr = x.begin(); |
| float Energy = 0.0; |
| for (;xPtr != x.end();xPtr++) { |
| Energy += xPtr->norm2(); |
| } |
| return Energy; |
| } |
| |
| |
| float vectorPower(const signalVector &x) |
| { |
| return vectorNorm2(x)/x.size(); |
| } |
| |
| /** compute cosine via lookup table */ |
| float cosLookup(const float x) |
| { |
| float arg = x*M_1_2PI_F; |
| while (arg > 1.0F) arg -= 1.0F; |
| while (arg < 0.0F) arg += 1.0F; |
| |
| const float argT = arg*((float)TABLESIZE); |
| const int argI = (int)argT; |
| const float delta = argT-argI; |
| const float iDelta = 1.0F-delta; |
| return iDelta*cosTable[argI] + delta*cosTable[argI+1]; |
| } |
| |
| /** compute sine via lookup table */ |
| float sinLookup(const float x) |
| { |
| float arg = x*M_1_2PI_F; |
| while (arg > 1.0F) arg -= 1.0F; |
| while (arg < 0.0F) arg += 1.0F; |
| |
| const float argT = arg*((float)TABLESIZE); |
| const int argI = (int)argT; |
| const float delta = argT-argI; |
| const float iDelta = 1.0F-delta; |
| return iDelta*sinTable[argI] + delta*sinTable[argI+1]; |
| } |
| |
| |
| /** compute e^(-jx) via lookup table. */ |
| complex expjLookup(float x) |
| { |
| float arg = x*M_1_2PI_F; |
| while (arg > 1.0F) arg -= 1.0F; |
| while (arg < 0.0F) arg += 1.0F; |
| |
| const float argT = arg*((float)TABLESIZE); |
| const int argI = (int)argT; |
| const float delta = argT-argI; |
| const float iDelta = 1.0F-delta; |
| return complex(iDelta*cosTable[argI] + delta*cosTable[argI+1], |
| iDelta*sinTable[argI] + delta*sinTable[argI+1]); |
| } |
| |
| /** Library setup functions */ |
| void initTrigTables() { |
| for (int i = 0; i < TABLESIZE+1; i++) { |
| cosTable[i] = cos(2.0*M_PI*i/TABLESIZE); |
| sinTable[i] = sin(2.0*M_PI*i/TABLESIZE); |
| } |
| } |
| |
| void initGMSKRotationTables(int samplesPerSymbol) { |
| GMSKRotation = new signalVector(157*samplesPerSymbol); |
| GMSKReverseRotation = new signalVector(157*samplesPerSymbol); |
| signalVector::iterator rotPtr = GMSKRotation->begin(); |
| signalVector::iterator revPtr = GMSKReverseRotation->begin(); |
| float phase = 0.0; |
| while (rotPtr != GMSKRotation->end()) { |
| *rotPtr++ = expjLookup(phase); |
| *revPtr++ = expjLookup(-phase); |
| phase += M_PI_F/2.0F/(float) samplesPerSymbol; |
| } |
| } |
| |
| void sigProcLibSetup(int samplesPerSymbol) { |
| initTrigTables(); |
| initGMSKRotationTables(samplesPerSymbol); |
| } |
| |
| void GMSKRotate(signalVector &x) { |
| signalVector::iterator xPtr = x.begin(); |
| signalVector::iterator rotPtr = GMSKRotation->begin(); |
| if (x.isRealOnly()) { |
| while (xPtr < x.end()) { |
| *xPtr = *rotPtr++ * (xPtr->real()); |
| xPtr++; |
| } |
| } |
| else { |
| while (xPtr < x.end()) { |
| *xPtr = *rotPtr++ * (*xPtr); |
| xPtr++; |
| } |
| } |
| } |
| |
| void GMSKReverseRotate(signalVector &x) { |
| signalVector::iterator xPtr= x.begin(); |
| signalVector::iterator rotPtr = GMSKReverseRotation->begin(); |
| if (x.isRealOnly()) { |
| while (xPtr < x.end()) { |
| *xPtr = *rotPtr++ * (xPtr->real()); |
| xPtr++; |
| } |
| } |
| else { |
| while (xPtr < x.end()) { |
| *xPtr = *rotPtr++ * (*xPtr); |
| xPtr++; |
| } |
| } |
| } |
| |
| |
| signalVector* convolve(const signalVector *a, |
| const signalVector *b, |
| signalVector *c, |
| ConvType spanType, |
| unsigned startIx, |
| unsigned len) |
| { |
| if ((a==NULL) || (b==NULL)) return NULL; |
| int La = a->size(); |
| int Lb = b->size(); |
| |
| int startIndex; |
| unsigned int outSize; |
| switch (spanType) { |
| case FULL_SPAN: |
| startIndex = 0; |
| outSize = La+Lb-1; |
| break; |
| case OVERLAP_ONLY: |
| startIndex = La; |
| outSize = abs(La-Lb)+1; |
| break; |
| case START_ONLY: |
| startIndex = 0; |
| outSize = La; |
| break; |
| case WITH_TAIL: |
| startIndex = Lb; |
| outSize = La; |
| break; |
| case NO_DELAY: |
| if (Lb % 2) |
| startIndex = Lb/2; |
| else |
| startIndex = Lb/2-1; |
| outSize = La; |
| break; |
| case CUSTOM: |
| startIndex = startIx; |
| outSize = len; |
| break; |
| default: |
| return NULL; |
| } |
| |
| |
| if (c==NULL) |
| c = new signalVector(outSize); |
| else if (c->size()!=outSize) |
| return NULL; |
| |
| signalVector::const_iterator aStart = a->begin(); |
| signalVector::const_iterator bStart = b->begin(); |
| signalVector::const_iterator aEnd = a->end(); |
| signalVector::const_iterator bEnd = b->end(); |
| signalVector::iterator cPtr = c->begin(); |
| int t = startIndex; |
| int stopIndex = startIndex + outSize; |
| switch (b->getSymmetry()) { |
| case NONE: |
| { |
| while (t < stopIndex) { |
| signalVector::const_iterator aP = aStart+t; |
| signalVector::const_iterator bP = bStart; |
| if (a->isRealOnly() && b->isRealOnly()) { |
| float sum = 0.0; |
| while (bP < bEnd) { |
| if (aP < aStart) break; |
| if (aP < aEnd) sum += (aP->real())*(bP->real()); |
| aP--; |
| bP++; |
| } |
| *cPtr++ = sum; |
| } |
| else if (a->isRealOnly()) { |
| complex sum = 0.0; |
| while (bP < bEnd) { |
| if (aP < aStart) break; |
| if (aP < aEnd) sum += (*bP)*(aP->real()); |
| aP--; |
| bP++; |
| } |
| *cPtr++ = sum; |
| } |
| else if (b->isRealOnly()) { |
| complex sum = 0.0; |
| while (bP < bEnd) { |
| if (aP < aStart) break; |
| if (aP < aEnd) sum += (*aP)*(bP->real()); |
| aP--; |
| bP++; |
| } |
| *cPtr++ = sum; |
| } |
| else { |
| complex sum = 0.0; |
| while (bP < bEnd) { |
| if (aP < aStart) break; |
| if (aP < aEnd) sum += (*aP)*(*bP); |
| aP--; |
| bP++; |
| } |
| *cPtr++ = sum; |
| } |
| t++; |
| } |
| } |
| break; |
| case ABSSYM: |
| { |
| complex sum = 0.0; |
| bool isOdd = (bool) (Lb % 2); |
| if (isOdd) |
| bEnd = bStart + (Lb+1)/2; |
| else |
| bEnd = bStart + Lb/2; |
| while (t < stopIndex) { |
| signalVector::const_iterator aP = aStart+t; |
| signalVector::const_iterator aPsym = aP-Lb+1; |
| signalVector::const_iterator bP = bStart; |
| sum = 0.0; |
| if (!b->isRealOnly()) { |
| while (bP < bEnd) { |
| if (aP < aStart) break; |
| if (aP == aPsym) |
| sum+= (*aP)*(*bP); |
| else if ((aP < aEnd) && (aPsym >= aStart)) |
| sum+= ((*aP)+(*aPsym))*(*bP); |
| else if (aP < aEnd) |
| sum += (*aP)*(*bP); |
| else if (aPsym >= aStart) |
| sum += (*aPsym)*(*bP); |
| aP--; |
| aPsym++; |
| bP++; |
| } |
| } |
| else { |
| while (bP < bEnd) { |
| if (aP < aStart) break; |
| if (aP == aPsym) |
| sum+= (*aP)*(bP->real()); |
| else if ((aP < aEnd) && (aPsym >= aStart)) |
| sum+= ((*aP)+(*aPsym))*(bP->real()); |
| else if (aP < aEnd) |
| sum += (*aP)*(bP->real()); |
| else if (aPsym >= aStart) |
| sum += (*aPsym)*(bP->real()); |
| aP--; |
| aPsym++; |
| bP++; |
| } |
| } |
| *cPtr++ = sum; |
| t++; |
| } |
| } |
| break; |
| default: |
| return NULL; |
| break; |
| } |
| |
| |
| return c; |
| } |
| |
| |
| signalVector* generateGSMPulse(int symbolLength, |
| int samplesPerSymbol) |
| { |
| |
| int numSamples = samplesPerSymbol*symbolLength + 1; |
| signalVector *x = new signalVector(numSamples); |
| signalVector::iterator xP = x->begin(); |
| int centerPoint = (numSamples-1)/2; |
| for (int i = 0; i < numSamples; i++) { |
| float arg = (float) (i-centerPoint)/(float) samplesPerSymbol; |
| *xP++ = 0.96*exp(-1.1380*arg*arg-0.527*arg*arg*arg*arg); // GSM pulse approx. |
| } |
| |
| float avgAbsval = sqrtf(vectorNorm2(*x)/samplesPerSymbol); |
| xP = x->begin(); |
| for (int i = 0; i < numSamples; i++) |
| *xP++ /= avgAbsval; |
| x->isRealOnly(true); |
| x->setSymmetry(ABSSYM); |
| return x; |
| } |
| |
| signalVector* frequencyShift(signalVector *y, |
| signalVector *x, |
| float freq, |
| float startPhase, |
| float *finalPhase) |
| { |
| |
| if (!x) return NULL; |
| |
| if (y==NULL) { |
| y = new signalVector(x->size()); |
| y->isRealOnly(x->isRealOnly()); |
| if (y==NULL) return NULL; |
| } |
| |
| if (y->size() < x->size()) return NULL; |
| |
| float phase = startPhase; |
| signalVector::iterator yP = y->begin(); |
| signalVector::iterator xPEnd = x->end(); |
| signalVector::iterator xP = x->begin(); |
| |
| if (x->isRealOnly()) { |
| while (xP < xPEnd) { |
| (*yP++) = expjLookup(phase)*( (xP++)->real() ); |
| phase += freq; |
| } |
| } |
| else { |
| while (xP < xPEnd) { |
| (*yP++) = (*xP++)*expjLookup(phase); |
| phase += freq; |
| } |
| } |
| |
| |
| if (finalPhase) *finalPhase = phase; |
| |
| return y; |
| } |
| |
| signalVector* reverseConjugate(signalVector *b) |
| { |
| signalVector *tmp = new signalVector(b->size()); |
| tmp->isRealOnly(b->isRealOnly()); |
| signalVector::iterator bP = b->begin(); |
| signalVector::iterator bPEnd = b->end(); |
| signalVector::iterator tmpP = tmp->end()-1; |
| if (!b->isRealOnly()) { |
| while (bP < bPEnd) { |
| *tmpP-- = bP->conj(); |
| bP++; |
| } |
| } |
| else { |
| while (bP < bPEnd) { |
| *tmpP-- = bP->real(); |
| bP++; |
| } |
| } |
| |
| return tmp; |
| } |
| |
| signalVector* correlate(signalVector *a, |
| signalVector *b, |
| signalVector *c, |
| ConvType spanType, |
| bool bReversedConjugated, |
| unsigned startIx, |
| unsigned len) |
| { |
| signalVector *tmp = NULL; |
| |
| if (!bReversedConjugated) { |
| tmp = reverseConjugate(b); |
| } |
| else { |
| tmp = b; |
| } |
| |
| c = convolve(a,tmp,c,spanType,startIx,len); |
| |
| if (!bReversedConjugated) delete tmp; |
| |
| return c; |
| } |
| |
| |
| /* soft output slicer */ |
| bool vectorSlicer(signalVector *x) |
| { |
| |
| signalVector::iterator xP = x->begin(); |
| signalVector::iterator xPEnd = x->end(); |
| while (xP < xPEnd) { |
| *xP = (complex) (0.5*(xP->real()+1.0F)); |
| if (xP->real() > 1.0) *xP = 1.0; |
| if (xP->real() < 0.0) *xP = 0.0; |
| xP++; |
| } |
| return true; |
| } |
| |
| signalVector *modulateBurst(const BitVector &wBurst, |
| const signalVector &gsmPulse, |
| int guardPeriodLength, |
| int samplesPerSymbol) |
| { |
| |
| //static complex staticBurst[157]; |
| |
| int burstSize = samplesPerSymbol*(wBurst.size()+guardPeriodLength); |
| //signalVector modBurst((complex *) staticBurst,0,burstSize); |
| signalVector modBurst(burstSize);// = new signalVector(burstSize); |
| modBurst.isRealOnly(true); |
| //memset(staticBurst,0,sizeof(complex)*burstSize); |
| modBurst.fill(0.0); |
| signalVector::iterator modBurstItr = modBurst.begin(); |
| |
| #if 0 |
| // if wBurst is already differentially decoded |
| *modBurstItr = 2.0*(wBurst[0] & 0x01)-1.0; |
| signalVector::iterator prevVal = modBurstItr; |
| for (unsigned int i = 1; i < wBurst.size(); i++) { |
| modBurstItr += samplesPerSymbol; |
| if (wBurst[i] & 0x01) |
| *modBurstItr = *prevVal * complex(0.0,1.0); |
| else |
| *modBurstItr = *prevVal * complex(0.0,-1.0); |
| prevVal = modBurstItr; |
| } |
| #else |
| // if wBurst are the raw bits |
| for (unsigned int i = 0; i < wBurst.size(); i++) { |
| *modBurstItr = 2.0*(wBurst[i] & 0x01)-1.0; |
| modBurstItr += samplesPerSymbol; |
| } |
| |
| // shift up pi/2 |
| // ignore starting phase, since spec allows for discontinuous phase |
| GMSKRotate(modBurst); |
| #endif |
| modBurst.isRealOnly(false); |
| |
| // filter w/ pulse shape |
| signalVector *shapedBurst = convolve(&modBurst,&gsmPulse,NULL,NO_DELAY); |
| |
| //delete modBurst; |
| |
| return shapedBurst; |
| |
| } |
| |
| float sinc(float x) |
| { |
| if ((x >= 0.01F) || (x <= -0.01F)) return (sinLookup(x)/x); |
| return 1.0F; |
| } |
| |
| void delayVector(signalVector &wBurst, |
| float delay) |
| { |
| |
| int intOffset = (int) floor(delay); |
| float fracOffset = delay - intOffset; |
| |
| // do fractional shift first, only do it for reasonable offsets |
| if (fabs(fracOffset) > 1e-2) { |
| // create sinc function |
| signalVector sincVector(21); |
| sincVector.isRealOnly(true); |
| signalVector::iterator sincBurstItr = sincVector.begin(); |
| for (int i = 0; i < 21; i++) |
| *sincBurstItr++ = (complex) sinc(M_PI_F*(i-10-fracOffset)); |
| |
| signalVector shiftedBurst(wBurst.size()); |
| convolve(&wBurst,&sincVector,&shiftedBurst,NO_DELAY); |
| wBurst.clone(shiftedBurst); |
| } |
| |
| if (intOffset < 0) { |
| intOffset = -intOffset; |
| signalVector::iterator wBurstItr = wBurst.begin(); |
| signalVector::iterator shiftedItr = wBurst.begin()+intOffset; |
| while (shiftedItr < wBurst.end()) |
| *wBurstItr++ = *shiftedItr++; |
| while (wBurstItr < wBurst.end()) |
| *wBurstItr++ = 0.0; |
| } |
| else { |
| signalVector::iterator wBurstItr = wBurst.end()-1; |
| signalVector::iterator shiftedItr = wBurst.end()-1-intOffset; |
| while (shiftedItr >= wBurst.begin()) |
| *wBurstItr-- = *shiftedItr--; |
| while (wBurstItr >= wBurst.begin()) |
| *wBurstItr-- = 0.0; |
| } |
| } |
| |
| signalVector *gaussianNoise(int length, |
| float variance, |
| complex mean) |
| { |
| |
| signalVector *noise = new signalVector(length); |
| signalVector::iterator nPtr = noise->begin(); |
| float stddev = sqrtf(variance); |
| while (nPtr < noise->end()) { |
| float u1 = (float) rand()/ (float) RAND_MAX; |
| while (u1==0.0) |
| u1 = (float) rand()/ (float) RAND_MAX; |
| float u2 = (float) rand()/ (float) RAND_MAX; |
| float arg = 2.0*M_PI*u2; |
| *nPtr = mean + stddev*complex(cos(arg),sin(arg))*sqrtf(-2.0*log(u1)); |
| nPtr++; |
| } |
| |
| return noise; |
| } |
| |
| complex interpolatePoint(const signalVector &inSig, |
| float ix) |
| { |
| |
| int start = (int) (floor(ix) - 10); |
| if (start < 0) start = 0; |
| int end = (int) (floor(ix) + 11); |
| if ((unsigned) end > inSig.size()-1) end = inSig.size()-1; |
| |
| complex pVal = 0.0; |
| if (!inSig.isRealOnly()) { |
| for (int i = start; i < end; i++) |
| pVal += inSig[i] * sinc(M_PI_F*(i-ix)); |
| } |
| else { |
| for (int i = start; i < end; i++) |
| pVal += inSig[i].real() * sinc(M_PI_F*(i-ix)); |
| } |
| |
| return pVal; |
| } |
| |
| |
| |
| complex peakDetect(const signalVector &rxBurst, |
| float *peakIndex, |
| float *avgPwr) |
| { |
| |
| |
| complex maxVal = 0.0; |
| float maxIndex = -1; |
| float sumPower = 0.0; |
| |
| for (unsigned int i = 0; i < rxBurst.size(); i++) { |
| float samplePower = rxBurst[i].norm2(); |
| if (samplePower > maxVal.real()) { |
| maxVal = samplePower; |
| maxIndex = i; |
| } |
| sumPower += samplePower; |
| } |
| |
| // interpolate around the peak |
| // to save computation, we'll use early-late balancing |
| float earlyIndex = maxIndex-1; |
| float lateIndex = maxIndex+1; |
| |
| float incr = 0.5; |
| while (incr > 1.0/1024.0) { |
| complex earlyP = interpolatePoint(rxBurst,earlyIndex); |
| complex lateP = interpolatePoint(rxBurst,lateIndex); |
| if (earlyP < lateP) |
| earlyIndex += incr; |
| else if (earlyP > lateP) |
| earlyIndex -= incr; |
| else break; |
| incr /= 2.0; |
| lateIndex = earlyIndex + 2.0; |
| } |
| |
| maxIndex = earlyIndex + 1.0; |
| maxVal = interpolatePoint(rxBurst,maxIndex); |
| |
| if (peakIndex!=NULL) |
| *peakIndex = maxIndex; |
| |
| if (avgPwr!=NULL) |
| *avgPwr = (sumPower-maxVal.norm2()) / (rxBurst.size()-1); |
| |
| return maxVal; |
| |
| } |
| |
| void scaleVector(signalVector &x, |
| complex scale) |
| { |
| signalVector::iterator xP = x.begin(); |
| signalVector::iterator xPEnd = x.end(); |
| if (!x.isRealOnly()) { |
| while (xP < xPEnd) { |
| *xP = *xP * scale; |
| xP++; |
| } |
| } |
| else { |
| while (xP < xPEnd) { |
| *xP = xP->real() * scale; |
| xP++; |
| } |
| } |
| } |
| |
| /** in-place conjugation */ |
| void conjugateVector(signalVector &x) |
| { |
| if (x.isRealOnly()) return; |
| signalVector::iterator xP = x.begin(); |
| signalVector::iterator xPEnd = x.end(); |
| while (xP < xPEnd) { |
| *xP = xP->conj(); |
| xP++; |
| } |
| } |
| |
| |
| // in-place addition!! |
| bool addVector(signalVector &x, |
| signalVector &y) |
| { |
| signalVector::iterator xP = x.begin(); |
| signalVector::iterator yP = y.begin(); |
| signalVector::iterator xPEnd = x.end(); |
| signalVector::iterator yPEnd = y.end(); |
| while ((xP < xPEnd) && (yP < yPEnd)) { |
| *xP = *xP + *yP; |
| xP++; yP++; |
| } |
| return true; |
| } |
| |
| // in-place multiplication!! |
| bool multVector(signalVector &x, |
| signalVector &y) |
| { |
| signalVector::iterator xP = x.begin(); |
| signalVector::iterator yP = y.begin(); |
| signalVector::iterator xPEnd = x.end(); |
| signalVector::iterator yPEnd = y.end(); |
| while ((xP < xPEnd) && (yP < yPEnd)) { |
| *xP = (*xP) * (*yP); |
| xP++; yP++; |
| } |
| return true; |
| } |
| |
| |
| void offsetVector(signalVector &x, |
| complex offset) |
| { |
| signalVector::iterator xP = x.begin(); |
| signalVector::iterator xPEnd = x.end(); |
| if (!x.isRealOnly()) { |
| while (xP < xPEnd) { |
| *xP += offset; |
| xP++; |
| } |
| } |
| else { |
| while (xP < xPEnd) { |
| *xP = xP->real() + offset; |
| xP++; |
| } |
| } |
| } |
| |
| bool generateMidamble(signalVector &gsmPulse, |
| int samplesPerSymbol, |
| int TSC) |
| { |
| |
| if ((TSC < 0) || (TSC > 7)) |
| return false; |
| |
| if (gMidambles[TSC]) { |
| if (gMidambles[TSC]->sequence!=NULL) delete gMidambles[TSC]->sequence; |
| if (gMidambles[TSC]->sequenceReversedConjugated!=NULL) delete gMidambles[TSC]->sequenceReversedConjugated; |
| } |
| |
| signalVector emptyPulse(1); |
| *(emptyPulse.begin()) = 1.0; |
| |
| // only use middle 16 bits of each TSC |
| signalVector *middleMidamble = modulateBurst(gTrainingSequence[TSC].segment(5,16), |
| emptyPulse, |
| 0, |
| samplesPerSymbol); |
| signalVector *midamble = modulateBurst(gTrainingSequence[TSC], |
| gsmPulse, |
| 0, |
| samplesPerSymbol); |
| |
| if (midamble == NULL) return false; |
| if (middleMidamble == NULL) return false; |
| |
| // NOTE: Because ideal TSC 16-bit midamble is 66 symbols into burst, |
| // the ideal TSC has an + 180 degree phase shift, |
| // due to the pi/2 frequency shift, that |
| // needs to be accounted for. |
| // 26-midamble is 61 symbols into burst, has +90 degree phase shift. |
| scaleVector(*middleMidamble,complex(-1.0,0.0)); |
| scaleVector(*midamble,complex(0.0,1.0)); |
| |
| signalVector *autocorr = correlate(midamble,middleMidamble,NULL,NO_DELAY); |
| |
| if (autocorr == NULL) return false; |
| |
| gMidambles[TSC] = new CorrelationSequence; |
| gMidambles[TSC]->sequence = middleMidamble; |
| gMidambles[TSC]->sequenceReversedConjugated = reverseConjugate(middleMidamble); |
| gMidambles[TSC]->gain = peakDetect(*autocorr,&gMidambles[TSC]->TOA,NULL); |
| |
| LOG(DEBUG) << "midamble autocorr: " << *autocorr; |
| |
| LOG(DEBUG) << "TOA: " << gMidambles[TSC]->TOA; |
| |
| //gMidambles[TSC]->TOA -= 5*samplesPerSymbol; |
| |
| delete autocorr; |
| delete midamble; |
| |
| return true; |
| } |
| |
| bool generateRACHSequence(signalVector &gsmPulse, |
| int samplesPerSymbol) |
| { |
| |
| if (gRACHSequence) { |
| if (gRACHSequence->sequence!=NULL) delete gRACHSequence->sequence; |
| if (gRACHSequence->sequenceReversedConjugated!=NULL) delete gRACHSequence->sequenceReversedConjugated; |
| } |
| |
| signalVector *RACHSeq = modulateBurst(gRACHSynchSequence, |
| gsmPulse, |
| 0, |
| samplesPerSymbol); |
| |
| assert(RACHSeq); |
| |
| signalVector *autocorr = correlate(RACHSeq,RACHSeq,NULL,NO_DELAY); |
| |
| assert(autocorr); |
| |
| gRACHSequence = new CorrelationSequence; |
| gRACHSequence->sequence = RACHSeq; |
| gRACHSequence->sequenceReversedConjugated = reverseConjugate(RACHSeq); |
| gRACHSequence->gain = peakDetect(*autocorr,&gRACHSequence->TOA,NULL); |
| |
| delete autocorr; |
| |
| return true; |
| |
| } |
| |
| |
| bool detectRACHBurst(signalVector &rxBurst, |
| float detectThreshold, |
| int samplesPerSymbol, |
| complex *amplitude, |
| float* TOA) |
| { |
| |
| //static complex staticData[500]; |
| |
| //signalVector correlatedRACH(staticData,0,rxBurst.size()); |
| signalVector correlatedRACH(rxBurst.size()); |
| correlate(&rxBurst,gRACHSequence->sequenceReversedConjugated,&correlatedRACH,NO_DELAY,true); |
| |
| float meanPower; |
| complex peakAmpl = peakDetect(correlatedRACH,TOA,&meanPower); |
| |
| float valleyPower = 0.0; |
| |
| // check for bogus results |
| if ((*TOA < 0.0) || (*TOA > correlatedRACH.size())) { |
| *amplitude = 0.0; |
| return false; |
| } |
| complex *peakPtr = correlatedRACH.begin() + (int) rint(*TOA); |
| |
| LOG(DEBUG) << "RACH corr: " << correlatedRACH; |
| |
| float numSamples = 0.0; |
| for (int i = 57*samplesPerSymbol; i <= 107*samplesPerSymbol;i++) { |
| if (peakPtr+i >= correlatedRACH.end()) |
| break; |
| valleyPower += (peakPtr+i)->norm2(); |
| numSamples++; |
| } |
| |
| if (numSamples < 2) { |
| *amplitude = 0.0; |
| return false; |
| } |
| |
| float RMS = sqrtf(valleyPower/(float) numSamples)+0.00001; |
| float peakToMean = peakAmpl.abs()/RMS; |
| |
| LOG(DEBUG) << "RACH peakAmpl=" << peakAmpl << " RMS=" << RMS << " peakToMean=" << peakToMean; |
| *amplitude = peakAmpl/(gRACHSequence->gain); |
| |
| *TOA = (*TOA) - gRACHSequence->TOA - 8*samplesPerSymbol; |
| |
| LOG(DEBUG) << "RACH thresh: " << peakToMean; |
| |
| return (peakToMean > detectThreshold); |
| } |
| |
| bool energyDetect(signalVector &rxBurst, |
| unsigned windowLength, |
| float detectThreshold, |
| float *avgPwr) |
| { |
| |
| signalVector::const_iterator windowItr = rxBurst.begin(); //+rxBurst.size()/2 - 5*windowLength/2; |
| float energy = 0.0; |
| if (windowLength < 0) windowLength = 20; |
| if (windowLength > rxBurst.size()) windowLength = rxBurst.size(); |
| for (unsigned i = 0; i < windowLength; i++) { |
| energy += windowItr->norm2(); |
| windowItr+=4; |
| } |
| if (avgPwr) *avgPwr = energy/windowLength; |
| LOG(DEBUG) << "detected energy: " << energy/windowLength; |
| return (energy/windowLength > detectThreshold*detectThreshold); |
| } |
| |
| |
| bool analyzeTrafficBurst(signalVector &rxBurst, |
| unsigned TSC, |
| float detectThreshold, |
| int samplesPerSymbol, |
| complex *amplitude, |
| float *TOA, |
| unsigned maxTOA, |
| bool requestChannel, |
| signalVector **channelResponse, |
| float *channelResponseOffset) |
| { |
| |
| assert(TSC<8); |
| assert(amplitude); |
| assert(TOA); |
| assert(gMidambles[TSC]); |
| |
| if (maxTOA < 3*samplesPerSymbol) maxTOA = 3*samplesPerSymbol; |
| unsigned spanTOA = maxTOA; |
| if (spanTOA < 5*samplesPerSymbol) spanTOA = 5*samplesPerSymbol; |
| |
| unsigned startIx = (66-spanTOA)*samplesPerSymbol; |
| unsigned endIx = (66+16+spanTOA)*samplesPerSymbol; |
| unsigned windowLen = endIx - startIx; |
| unsigned corrLen = 2*maxTOA+1; |
| |
| unsigned expectedTOAPeak = (unsigned) round(gMidambles[TSC]->TOA + (gMidambles[TSC]->sequenceReversedConjugated->size()-1)/2); |
| |
| signalVector burstSegment(rxBurst.begin(),startIx,windowLen); |
| |
| //static complex staticData[200]; |
| //signalVector correlatedBurst(staticData,0,corrLen); |
| signalVector correlatedBurst(corrLen); |
| correlate(&burstSegment, gMidambles[TSC]->sequenceReversedConjugated, |
| &correlatedBurst, CUSTOM,true, |
| expectedTOAPeak-maxTOA,corrLen); |
| |
| float meanPower; |
| *amplitude = peakDetect(correlatedBurst,TOA,&meanPower); |
| float valleyPower = 0.0; //amplitude->norm2(); |
| complex *peakPtr = correlatedBurst.begin() + (int) rint(*TOA); |
| |
| // check for bogus results |
| if ((*TOA < 0.0) || (*TOA > correlatedBurst.size())) { |
| *amplitude = 0.0; |
| return false; |
| } |
| |
| int numRms = 0; |
| for (int i = 2*samplesPerSymbol; i <= 5*samplesPerSymbol;i++) { |
| if (peakPtr - i >= correlatedBurst.begin()) { |
| valleyPower += (peakPtr-i)->norm2(); |
| numRms++; |
| } |
| if (peakPtr + i < correlatedBurst.end()) { |
| valleyPower += (peakPtr+i)->norm2(); |
| numRms++; |
| } |
| } |
| |
| if (numRms < 2) { |
| // check for bogus results |
| *amplitude = 0.0; |
| return false; |
| } |
| |
| float RMS = sqrtf(valleyPower/(float)numRms)+0.00001; |
| float peakToMean = (amplitude->abs())/RMS; |
| |
| // NOTE: Because ideal TSC is 66 symbols into burst, |
| // the ideal TSC has an +/- 180 degree phase shift, |
| // due to the pi/4 frequency shift, that |
| // needs to be accounted for. |
| |
| *amplitude = (*amplitude)/gMidambles[TSC]->gain; |
| *TOA = (*TOA) - (maxTOA); |
| |
| LOG(DEBUG) << "TCH peakAmpl=" << amplitude->abs() << " RMS=" << RMS << " peakToMean=" << peakToMean << " TOA=" << *TOA; |
| |
| LOG(DEBUG) << "autocorr: " << correlatedBurst; |
| |
| if (requestChannel && (peakToMean > detectThreshold)) { |
| float TOAoffset = maxTOA; //gMidambles[TSC]->TOA+(66*samplesPerSymbol-startIx); |
| delayVector(correlatedBurst,-(*TOA)); |
| // midamble only allows estimation of a 6-tap channel |
| signalVector channelVector(6*samplesPerSymbol); |
| float maxEnergy = -1.0; |
| int maxI = -1; |
| for (int i = 0; i < 7; i++) { |
| if (TOAoffset+(i-5)*samplesPerSymbol + channelVector.size() > correlatedBurst.size()) continue; |
| if (TOAoffset+(i-5)*samplesPerSymbol < 0) continue; |
| correlatedBurst.segmentCopyTo(channelVector,(int) floor(TOAoffset+(i-5)*samplesPerSymbol),channelVector.size()); |
| float energy = vectorNorm2(channelVector); |
| if (energy > 0.95*maxEnergy) { |
| maxI = i; |
| maxEnergy = energy; |
| } |
| } |
| |
| *channelResponse = new signalVector(channelVector.size()); |
| correlatedBurst.segmentCopyTo(**channelResponse,(int) floor(TOAoffset+(maxI-5)*samplesPerSymbol),(*channelResponse)->size()); |
| scaleVector(**channelResponse,complex(1.0,0.0)/gMidambles[TSC]->gain); |
| LOG(DEBUG) << "channelResponse: " << **channelResponse; |
| |
| if (channelResponseOffset) |
| *channelResponseOffset = 5*samplesPerSymbol-maxI; |
| |
| } |
| |
| return (peakToMean > detectThreshold); |
| |
| } |
| |
| signalVector *decimateVector(signalVector &wVector, |
| int decimationFactor) |
| { |
| |
| if (decimationFactor <= 1) return NULL; |
| |
| signalVector *decVector = new signalVector(wVector.size()/decimationFactor); |
| decVector->isRealOnly(wVector.isRealOnly()); |
| |
| signalVector::iterator vecItr = decVector->begin(); |
| for (unsigned int i = 0; i < wVector.size();i+=decimationFactor) |
| *vecItr++ = wVector[i]; |
| |
| return decVector; |
| } |
| |
| |
| SoftVector *demodulateBurst(signalVector &rxBurst, |
| const signalVector &gsmPulse, |
| int samplesPerSymbol, |
| complex channel, |
| float TOA) |
| |
| { |
| scaleVector(rxBurst,((complex) 1.0)/channel); |
| delayVector(rxBurst,-TOA); |
| |
| signalVector *shapedBurst = &rxBurst; |
| |
| // shift up by a quarter of a frequency |
| // ignore starting phase, since spec allows for discontinuous phase |
| GMSKReverseRotate(*shapedBurst); |
| |
| // run through slicer |
| if (samplesPerSymbol > 1) { |
| signalVector *decShapedBurst = decimateVector(*shapedBurst,samplesPerSymbol); |
| shapedBurst = decShapedBurst; |
| } |
| |
| LOG(DEBUG) << "shapedBurst: " << *shapedBurst; |
| |
| vectorSlicer(shapedBurst); |
| |
| SoftVector *burstBits = new SoftVector(shapedBurst->size()); |
| |
| SoftVector::iterator burstItr = burstBits->begin(); |
| signalVector::iterator shapedItr = shapedBurst->begin(); |
| for (; shapedItr < shapedBurst->end(); shapedItr++) |
| *burstItr++ = shapedItr->real(); |
| |
| if (samplesPerSymbol > 1) delete shapedBurst; |
| |
| return burstBits; |
| |
| } |
| |
| |
| // 1.0 is sampling frequency |
| // must satisfy cutoffFreq > 1/filterLen |
| signalVector *createLPF(float cutoffFreq, |
| int filterLen, |
| float gainDC) |
| { |
| |
| signalVector *LPF = new signalVector(filterLen-1); |
| LPF->isRealOnly(true); |
| LPF->setSymmetry(ABSSYM); |
| signalVector::iterator itr = LPF->begin(); |
| double sum = 0.0; |
| for (int i = 1; i < filterLen; i++) { |
| float ys = sinc(M_2PI_F*cutoffFreq*((float)i-(float)(filterLen)/2.0F)); |
| float yg = 4.0F * cutoffFreq; |
| // Blackman -- less brickwall (sloping transition) but larger stopband attenuation |
| 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)); |
| // Hamming -- more brickwall with smaller stopband attenuation |
| //float yw = 0.53836F - 0.46164F * cos(((float)i)*M_2PI_F/(float)(filterLen+1)); |
| *itr++ = (complex) ys*yg*yw; |
| sum += ys*yg*yw; |
| } |
| |
| float normFactor = gainDC/sum; //sqrtf(gainDC/vectorNorm2(*LPF)); |
| // normalize power |
| itr = LPF->begin(); |
| for (int i = 1; i < filterLen; i++) { |
| *itr = *itr*normFactor; |
| itr++; |
| } |
| return LPF; |
| |
| } |
| |
| |
| |
| #define POLYPHASESPAN 10 |
| |
| // assumes filter group delay is 0.5*(length of filter) |
| signalVector *polyphaseResampleVector(signalVector &wVector, |
| int P, int Q, |
| signalVector *LPF) |
| |
| { |
| |
| bool deleteLPF = false; |
| |
| if (LPF==NULL) { |
| float cutoffFreq = (P < Q) ? (1.0/(float) Q) : (1.0/(float) P); |
| LPF = createLPF(cutoffFreq/3.0,100*POLYPHASESPAN+1,Q); |
| deleteLPF = true; |
| } |
| |
| signalVector *resampledVector = new signalVector((int) ceil(wVector.size()*(float) P / (float) Q)); |
| resampledVector->fill(0); |
| resampledVector->isRealOnly(wVector.isRealOnly()); |
| signalVector::iterator newItr = resampledVector->begin(); |
| |
| //FIXME: need to update for real-only vectors |
| int outputIx = (LPF->size()+1)/2/Q; //((P > Q) ? P : Q); |
| while (newItr < resampledVector->end()) { |
| int outputBranch = (outputIx*Q) % P; |
| int inputOffset = (outputIx*Q - outputBranch)/P; |
| signalVector::const_iterator inputItr = wVector.begin() + inputOffset; |
| signalVector::const_iterator filtItr = LPF->begin() + outputBranch; |
| while (inputItr >= wVector.end()) { |
| inputItr--; |
| filtItr+=P; |
| } |
| complex sum = 0.0; |
| if ((LPF->getSymmetry()!=ABSSYM) || (P>1)) { |
| if (!LPF->isRealOnly()) { |
| while ( (inputItr >= wVector.begin()) && (filtItr < LPF->end()) ) { |
| sum += (*inputItr)*(*filtItr); |
| inputItr--; |
| filtItr += P; |
| } |
| } |
| else { |
| while ( (inputItr >= wVector.begin()) && (filtItr < LPF->end()) ) { |
| sum += (*inputItr)*(filtItr->real()); |
| inputItr--; |
| filtItr += P; |
| } |
| } |
| } |
| else { |
| signalVector::const_iterator revInputItr = inputItr- LPF->size() + 1; |
| signalVector::const_iterator filtMidpoint = LPF->begin()+(LPF->size()-1)/2; |
| if (!LPF->isRealOnly()) { |
| while (filtItr <= filtMidpoint) { |
| if (inputItr < revInputItr) break; |
| if (inputItr == revInputItr) |
| sum += (*inputItr)*(*filtItr); |
| else if ( (inputItr < wVector.end()) && (revInputItr >= wVector.begin()) ) |
| sum += (*inputItr + *revInputItr)*(*filtItr); |
| else if ( inputItr < wVector.end() ) |
| sum += (*inputItr)*(*filtItr); |
| else if ( revInputItr >= wVector.begin() ) |
| sum += (*revInputItr)*(*filtItr); |
| inputItr--; |
| revInputItr++; |
| filtItr++; |
| } |
| } |
| else { |
| while (filtItr <= filtMidpoint) { |
| if (inputItr < revInputItr) break; |
| if (inputItr == revInputItr) |
| sum += (*inputItr)*(filtItr->real()); |
| else if ( (inputItr < wVector.end()) && (revInputItr >= wVector.begin()) ) |
| sum += (*inputItr + *revInputItr)*(filtItr->real()); |
| else if ( inputItr < wVector.end() ) |
| sum += (*inputItr)*(filtItr->real()); |
| else if ( revInputItr >= wVector.begin() ) |
| sum += (*revInputItr)*(filtItr->real()); |
| inputItr--; |
| revInputItr++; |
| filtItr++; |
| } |
| } |
| } |
| *newItr = sum; |
| newItr++; |
| outputIx++; |
| } |
| |
| if (deleteLPF) delete LPF; |
| |
| return resampledVector; |
| } |
| |
| |
| signalVector *resampleVector(signalVector &wVector, |
| float expFactor, |
| complex endPoint) |
| |
| { |
| |
| if (expFactor < 1.0) return NULL; |
| |
| signalVector *retVec = new signalVector((int) ceil(wVector.size()*expFactor)); |
| |
| float t = 0.0; |
| |
| signalVector::iterator retItr = retVec->begin(); |
| while (retItr < retVec->end()) { |
| unsigned tLow = (unsigned int) floor(t); |
| unsigned tHigh = tLow + 1; |
| if (tLow > wVector.size()-1) break; |
| if (tHigh > wVector.size()) break; |
| complex lowPoint = wVector[tLow]; |
| complex highPoint = (tHigh == wVector.size()) ? endPoint : wVector[tHigh]; |
| complex a = (tHigh-t); |
| complex b = (t-tLow); |
| *retItr = (a*lowPoint + b*highPoint); |
| t += 1.0/expFactor; |
| } |
| |
| return retVec; |
| |
| } |
| |
| |
| // Assumes symbol-spaced sampling!!! |
| // Based upon paper by Al-Dhahir and Cioffi |
| bool designDFE(signalVector &channelResponse, |
| float SNRestimate, |
| int Nf, |
| signalVector **feedForwardFilter, |
| signalVector **feedbackFilter) |
| { |
| |
| signalVector G0(Nf); |
| signalVector G1(Nf); |
| signalVector::iterator G0ptr = G0.begin(); |
| signalVector::iterator G1ptr = G1.begin(); |
| signalVector::iterator chanPtr = channelResponse.begin(); |
| |
| int nu = channelResponse.size()-1; |
| |
| *G0ptr = 1.0/sqrtf(SNRestimate); |
| for(int j = 0; j <= nu; j++) { |
| *G1ptr = chanPtr->conj(); |
| G1ptr++; chanPtr++; |
| } |
| |
| signalVector *L[Nf]; |
| signalVector::iterator Lptr; |
| float d; |
| for(int i = 0; i < Nf; i++) { |
| d = G0.begin()->norm2() + G1.begin()->norm2(); |
| L[i] = new signalVector(Nf+nu); |
| Lptr = L[i]->begin()+i; |
| G0ptr = G0.begin(); G1ptr = G1.begin(); |
| while ((G0ptr < G0.end()) && (Lptr < L[i]->end())) { |
| *Lptr = (*G0ptr*(G0.begin()->conj()) + *G1ptr*(G1.begin()->conj()) )/d; |
| Lptr++; |
| G0ptr++; |
| G1ptr++; |
| } |
| complex k = (*G1.begin())/(*G0.begin()); |
| |
| if (i != Nf-1) { |
| signalVector G0new = G1; |
| scaleVector(G0new,k.conj()); |
| addVector(G0new,G0); |
| |
| signalVector G1new = G0; |
| scaleVector(G1new,k*(-1.0)); |
| addVector(G1new,G1); |
| delayVector(G1new,-1.0); |
| |
| scaleVector(G0new,1.0/sqrtf(1.0+k.norm2())); |
| scaleVector(G1new,1.0/sqrtf(1.0+k.norm2())); |
| G0 = G0new; |
| G1 = G1new; |
| } |
| } |
| |
| *feedbackFilter = new signalVector(nu); |
| L[Nf-1]->segmentCopyTo(**feedbackFilter,Nf,nu); |
| scaleVector(**feedbackFilter,(complex) -1.0); |
| conjugateVector(**feedbackFilter); |
| |
| signalVector v(Nf); |
| signalVector::iterator vStart = v.begin(); |
| signalVector::iterator vPtr; |
| *(vStart+Nf-1) = (complex) 1.0; |
| for(int k = Nf-2; k >= 0; k--) { |
| Lptr = L[k]->begin()+k+1; |
| vPtr = vStart + k+1; |
| complex v_k = 0.0; |
| for (int j = k+1; j < Nf; j++) { |
| v_k -= (*vPtr)*(*Lptr); |
| vPtr++; Lptr++; |
| } |
| *(vStart + k) = v_k; |
| } |
| |
| *feedForwardFilter = new signalVector(Nf); |
| signalVector::iterator w = (*feedForwardFilter)->begin(); |
| for (int i = 0; i < Nf; i++) { |
| delete L[i]; |
| complex w_i = 0.0; |
| int endPt = ( nu < (Nf-1-i) ) ? nu : (Nf-1-i); |
| vPtr = vStart+i; |
| chanPtr = channelResponse.begin(); |
| for (int k = 0; k < endPt+1; k++) { |
| w_i += (*vPtr)*(chanPtr->conj()); |
| vPtr++; chanPtr++; |
| } |
| *w = w_i/d; |
| w++; |
| } |
| |
| |
| return true; |
| |
| } |
| |
| // Assumes symbol-rate sampling!!!! |
| SoftVector *equalizeBurst(signalVector &rxBurst, |
| float TOA, |
| int samplesPerSymbol, |
| signalVector &w, // feedforward filter |
| signalVector &b) // feedback filter |
| { |
| |
| delayVector(rxBurst,-TOA); |
| |
| signalVector* postForwardFull = convolve(&rxBurst,&w,NULL,FULL_SPAN); |
| |
| signalVector* postForward = new signalVector(rxBurst.size()); |
| postForwardFull->segmentCopyTo(*postForward,w.size()-1,rxBurst.size()); |
| delete postForwardFull; |
| |
| signalVector::iterator dPtr = postForward->begin(); |
| signalVector::iterator dBackPtr; |
| signalVector::iterator rotPtr = GMSKRotation->begin(); |
| signalVector::iterator revRotPtr = GMSKReverseRotation->begin(); |
| |
| signalVector *DFEoutput = new signalVector(postForward->size()); |
| signalVector::iterator DFEItr = DFEoutput->begin(); |
| |
| // NOTE: can insert the midamble and/or use midamble to estimate BER |
| for (; dPtr < postForward->end(); dPtr++) { |
| dBackPtr = dPtr-1; |
| signalVector::iterator bPtr = b.begin(); |
| while ( (bPtr < b.end()) && (dBackPtr >= postForward->begin()) ) { |
| *dPtr = *dPtr + (*bPtr)*(*dBackPtr); |
| bPtr++; |
| dBackPtr--; |
| } |
| *dPtr = *dPtr * (*revRotPtr); |
| *DFEItr = *dPtr; |
| // make decision on symbol |
| *dPtr = (dPtr->real() > 0.0) ? 1.0 : -1.0; |
| //*DFEItr = *dPtr; |
| *dPtr = *dPtr * (*rotPtr); |
| DFEItr++; |
| rotPtr++; |
| revRotPtr++; |
| } |
| |
| vectorSlicer(DFEoutput); |
| |
| SoftVector *burstBits = new SoftVector(postForward->size()); |
| SoftVector::iterator burstItr = burstBits->begin(); |
| DFEItr = DFEoutput->begin(); |
| for (; DFEItr < DFEoutput->end(); DFEItr++) |
| *burstItr++ = DFEItr->real(); |
| |
| delete postForward; |
| |
| delete DFEoutput; |
| |
| return burstBits; |
| } |