Adding in the missing Transceiver52M directory
git-svn-id: http://wush.net/svn/range/software/public/openbts/trunk@2307 19bc5d8c-e614-43d4-8b26-e1612bc8e597
diff --git a/Transceiver52M/sigProcLib.cpp b/Transceiver52M/sigProcLib.cpp
new file mode 100644
index 0000000..fe09c16
--- /dev/null
+++ b/Transceiver52M/sigProcLib.cpp
@@ -0,0 +1,1486 @@
+/*
+* 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;
+}