mirror of
https://gitea.osmocom.org/cellular-infrastructure/osmo-trx.git
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b3a0ca42db
git-svn-id: http://wush.net/svn/range/software/public/openbts/trunk@2307 19bc5d8c-e614-43d4-8b26-e1612bc8e597
1487 lines
38 KiB
C++
1487 lines
38 KiB
C++
/*
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* Copyright 2008 Free Software Foundation, Inc.
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*
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* This software is distributed under the terms of the GNU Affero Public License.
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* See the COPYING file in the main directory for details.
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*
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* This use of this software may be subject to additional restrictions.
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* See the LEGAL file in the main directory for details.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU Affero General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Affero General Public License for more details.
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You should have received a copy of the GNU Affero General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#define NDEBUG
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#include "sigProcLib.h"
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#include "GSMCommon.h"
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#include <Logger.h>
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#define TABLESIZE 1024
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/** Lookup tables for trigonometric approximation */
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float cosTable[TABLESIZE+1]; // add 1 element for wrap around
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float sinTable[TABLESIZE+1];
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/** Constants */
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static const float M_PI_F = (float)M_PI;
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static const float M_2PI_F = (float)(2.0*M_PI);
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static const float M_1_2PI_F = 1/M_2PI_F;
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/** Static vectors that contain a precomputed +/- f_b/4 sinusoid */
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signalVector *GMSKRotation = NULL;
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signalVector *GMSKReverseRotation = NULL;
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/** Static ideal RACH and midamble correlation waveforms */
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typedef struct {
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signalVector *sequence;
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signalVector *sequenceReversedConjugated;
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float TOA;
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complex gain;
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} CorrelationSequence;
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CorrelationSequence *gMidambles[] = {NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL};
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CorrelationSequence *gRACHSequence = NULL;
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void sigProcLibDestroy(void) {
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if (GMSKRotation) {
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delete GMSKRotation;
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GMSKRotation = NULL;
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}
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if (GMSKReverseRotation) {
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delete GMSKReverseRotation;
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GMSKReverseRotation = NULL;
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}
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for (int i = 0; i < 8; i++) {
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if (gMidambles[i]!=NULL) {
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if (gMidambles[i]->sequence) delete gMidambles[i]->sequence;
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if (gMidambles[i]->sequenceReversedConjugated) delete gMidambles[i]->sequenceReversedConjugated;
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delete gMidambles[i];
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gMidambles[i] = NULL;
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}
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}
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if (gRACHSequence) {
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if (gRACHSequence->sequence) delete gRACHSequence->sequence;
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if (gRACHSequence->sequenceReversedConjugated) delete gRACHSequence->sequenceReversedConjugated;
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delete gRACHSequence;
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gRACHSequence = NULL;
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}
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}
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// dB relative to 1.0.
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// if > 1.0, then return 0 dB
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float dB(float x) {
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float arg = 1.0F;
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float dB = 0.0F;
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if (x >= 1.0F) return 0.0F;
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if (x <= 0.0F) return -200.0F;
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float prevArg = arg;
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float prevdB = dB;
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float stepSize = 16.0F;
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float dBstepSize = 12.0F;
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while (stepSize > 1.0F) {
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do {
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prevArg = arg;
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prevdB = dB;
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arg /= stepSize;
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dB -= dBstepSize;
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} while (arg > x);
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arg = prevArg;
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dB = prevdB;
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stepSize *= 0.5F;
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dBstepSize -= 3.0F;
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}
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return ((arg-x)*(dB-3.0F) + (x-arg*0.5F)*dB)/(arg - arg*0.5F);
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}
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// 10^(-dB/10), inverse of dB func.
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float dBinv(float x) {
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float arg = 1.0F;
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float dB = 0.0F;
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if (x >= 0.0F) return 1.0F;
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if (x <= -200.0F) return 0.0F;
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float prevArg = arg;
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float prevdB = dB;
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float stepSize = 16.0F;
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float dBstepSize = 12.0F;
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while (stepSize > 1.0F) {
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do {
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prevArg = arg;
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prevdB = dB;
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arg /= stepSize;
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dB -= dBstepSize;
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} while (dB > x);
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arg = prevArg;
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dB = prevdB;
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stepSize *= 0.5F;
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dBstepSize -= 3.0F;
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}
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return ((dB-x)*(arg*0.5F)+(x-(dB-3.0F))*(arg))/3.0F;
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}
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float vectorNorm2(const signalVector &x)
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{
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signalVector::const_iterator xPtr = x.begin();
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float Energy = 0.0;
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for (;xPtr != x.end();xPtr++) {
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Energy += xPtr->norm2();
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}
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return Energy;
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}
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float vectorPower(const signalVector &x)
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{
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return vectorNorm2(x)/x.size();
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}
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/** compute cosine via lookup table */
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float cosLookup(const float x)
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{
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float arg = x*M_1_2PI_F;
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while (arg > 1.0F) arg -= 1.0F;
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while (arg < 0.0F) arg += 1.0F;
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const float argT = arg*((float)TABLESIZE);
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const int argI = (int)argT;
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const float delta = argT-argI;
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const float iDelta = 1.0F-delta;
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return iDelta*cosTable[argI] + delta*cosTable[argI+1];
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}
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/** compute sine via lookup table */
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float sinLookup(const float x)
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{
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float arg = x*M_1_2PI_F;
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while (arg > 1.0F) arg -= 1.0F;
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while (arg < 0.0F) arg += 1.0F;
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const float argT = arg*((float)TABLESIZE);
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const int argI = (int)argT;
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const float delta = argT-argI;
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const float iDelta = 1.0F-delta;
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return iDelta*sinTable[argI] + delta*sinTable[argI+1];
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}
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/** compute e^(-jx) via lookup table. */
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complex expjLookup(float x)
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{
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float arg = x*M_1_2PI_F;
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while (arg > 1.0F) arg -= 1.0F;
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while (arg < 0.0F) arg += 1.0F;
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const float argT = arg*((float)TABLESIZE);
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const int argI = (int)argT;
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const float delta = argT-argI;
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const float iDelta = 1.0F-delta;
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return complex(iDelta*cosTable[argI] + delta*cosTable[argI+1],
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iDelta*sinTable[argI] + delta*sinTable[argI+1]);
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}
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/** Library setup functions */
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void initTrigTables() {
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for (int i = 0; i < TABLESIZE+1; i++) {
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cosTable[i] = cos(2.0*M_PI*i/TABLESIZE);
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sinTable[i] = sin(2.0*M_PI*i/TABLESIZE);
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}
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}
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void initGMSKRotationTables(int samplesPerSymbol) {
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GMSKRotation = new signalVector(157*samplesPerSymbol);
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GMSKReverseRotation = new signalVector(157*samplesPerSymbol);
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signalVector::iterator rotPtr = GMSKRotation->begin();
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signalVector::iterator revPtr = GMSKReverseRotation->begin();
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float phase = 0.0;
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while (rotPtr != GMSKRotation->end()) {
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*rotPtr++ = expjLookup(phase);
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*revPtr++ = expjLookup(-phase);
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phase += M_PI_F/2.0F/(float) samplesPerSymbol;
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}
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}
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void sigProcLibSetup(int samplesPerSymbol) {
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initTrigTables();
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initGMSKRotationTables(samplesPerSymbol);
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}
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void GMSKRotate(signalVector &x) {
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signalVector::iterator xPtr = x.begin();
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signalVector::iterator rotPtr = GMSKRotation->begin();
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if (x.isRealOnly()) {
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while (xPtr < x.end()) {
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*xPtr = *rotPtr++ * (xPtr->real());
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xPtr++;
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}
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}
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else {
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while (xPtr < x.end()) {
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*xPtr = *rotPtr++ * (*xPtr);
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xPtr++;
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}
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}
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}
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void GMSKReverseRotate(signalVector &x) {
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signalVector::iterator xPtr= x.begin();
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signalVector::iterator rotPtr = GMSKReverseRotation->begin();
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if (x.isRealOnly()) {
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while (xPtr < x.end()) {
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*xPtr = *rotPtr++ * (xPtr->real());
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xPtr++;
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}
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}
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else {
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while (xPtr < x.end()) {
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*xPtr = *rotPtr++ * (*xPtr);
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xPtr++;
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}
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}
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}
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signalVector* convolve(const signalVector *a,
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const signalVector *b,
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signalVector *c,
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ConvType spanType,
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unsigned startIx,
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unsigned len)
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{
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if ((a==NULL) || (b==NULL)) return NULL;
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int La = a->size();
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int Lb = b->size();
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int startIndex;
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unsigned int outSize;
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switch (spanType) {
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case FULL_SPAN:
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startIndex = 0;
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outSize = La+Lb-1;
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break;
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case OVERLAP_ONLY:
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startIndex = La;
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outSize = abs(La-Lb)+1;
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break;
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case START_ONLY:
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startIndex = 0;
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outSize = La;
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break;
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case WITH_TAIL:
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startIndex = Lb;
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outSize = La;
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break;
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case NO_DELAY:
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if (Lb % 2)
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startIndex = Lb/2;
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else
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startIndex = Lb/2-1;
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outSize = La;
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break;
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case CUSTOM:
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startIndex = startIx;
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outSize = len;
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break;
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default:
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return NULL;
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}
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if (c==NULL)
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c = new signalVector(outSize);
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else if (c->size()!=outSize)
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return NULL;
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signalVector::const_iterator aStart = a->begin();
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signalVector::const_iterator bStart = b->begin();
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signalVector::const_iterator aEnd = a->end();
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signalVector::const_iterator bEnd = b->end();
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signalVector::iterator cPtr = c->begin();
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int t = startIndex;
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int stopIndex = startIndex + outSize;
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switch (b->getSymmetry()) {
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case NONE:
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{
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while (t < stopIndex) {
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signalVector::const_iterator aP = aStart+t;
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signalVector::const_iterator bP = bStart;
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if (a->isRealOnly() && b->isRealOnly()) {
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float sum = 0.0;
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while (bP < bEnd) {
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if (aP < aStart) break;
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if (aP < aEnd) sum += (aP->real())*(bP->real());
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aP--;
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bP++;
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}
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*cPtr++ = sum;
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}
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else if (a->isRealOnly()) {
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complex sum = 0.0;
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while (bP < bEnd) {
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if (aP < aStart) break;
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if (aP < aEnd) sum += (*bP)*(aP->real());
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aP--;
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bP++;
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}
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*cPtr++ = sum;
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}
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else if (b->isRealOnly()) {
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complex sum = 0.0;
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while (bP < bEnd) {
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if (aP < aStart) break;
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if (aP < aEnd) sum += (*aP)*(bP->real());
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aP--;
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bP++;
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}
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*cPtr++ = sum;
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}
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else {
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complex sum = 0.0;
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while (bP < bEnd) {
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if (aP < aStart) break;
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if (aP < aEnd) sum += (*aP)*(*bP);
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aP--;
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bP++;
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}
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*cPtr++ = sum;
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}
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t++;
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}
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}
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break;
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case ABSSYM:
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{
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complex sum = 0.0;
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bool isOdd = (bool) (Lb % 2);
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if (isOdd)
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bEnd = bStart + (Lb+1)/2;
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else
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bEnd = bStart + Lb/2;
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while (t < stopIndex) {
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signalVector::const_iterator aP = aStart+t;
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signalVector::const_iterator aPsym = aP-Lb+1;
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signalVector::const_iterator bP = bStart;
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sum = 0.0;
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if (!b->isRealOnly()) {
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while (bP < bEnd) {
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if (aP < aStart) break;
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if (aP == aPsym)
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sum+= (*aP)*(*bP);
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else if ((aP < aEnd) && (aPsym >= aStart))
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sum+= ((*aP)+(*aPsym))*(*bP);
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else if (aP < aEnd)
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sum += (*aP)*(*bP);
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else if (aPsym >= aStart)
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sum += (*aPsym)*(*bP);
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aP--;
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aPsym++;
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bP++;
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}
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}
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else {
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while (bP < bEnd) {
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if (aP < aStart) break;
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if (aP == aPsym)
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sum+= (*aP)*(bP->real());
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else if ((aP < aEnd) && (aPsym >= aStart))
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sum+= ((*aP)+(*aPsym))*(bP->real());
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else if (aP < aEnd)
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sum += (*aP)*(bP->real());
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else if (aPsym >= aStart)
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sum += (*aPsym)*(bP->real());
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aP--;
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aPsym++;
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bP++;
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}
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}
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*cPtr++ = sum;
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t++;
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}
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}
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break;
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default:
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return NULL;
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break;
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}
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return c;
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}
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signalVector* generateGSMPulse(int symbolLength,
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int samplesPerSymbol)
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{
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int numSamples = samplesPerSymbol*symbolLength + 1;
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signalVector *x = new signalVector(numSamples);
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signalVector::iterator xP = x->begin();
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int centerPoint = (numSamples-1)/2;
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for (int i = 0; i < numSamples; i++) {
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float arg = (float) (i-centerPoint)/(float) samplesPerSymbol;
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*xP++ = 0.96*exp(-1.1380*arg*arg-0.527*arg*arg*arg*arg); // GSM pulse approx.
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}
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float avgAbsval = sqrtf(vectorNorm2(*x)/samplesPerSymbol);
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xP = x->begin();
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for (int i = 0; i < numSamples; i++)
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*xP++ /= avgAbsval;
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x->isRealOnly(true);
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x->setSymmetry(ABSSYM);
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return x;
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}
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signalVector* frequencyShift(signalVector *y,
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signalVector *x,
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float freq,
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float startPhase,
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float *finalPhase)
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{
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if (!x) return NULL;
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if (y==NULL) {
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y = new signalVector(x->size());
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y->isRealOnly(x->isRealOnly());
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if (y==NULL) return NULL;
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}
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if (y->size() < x->size()) return NULL;
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float phase = startPhase;
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signalVector::iterator yP = y->begin();
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signalVector::iterator xPEnd = x->end();
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signalVector::iterator xP = x->begin();
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if (x->isRealOnly()) {
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while (xP < xPEnd) {
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(*yP++) = expjLookup(phase)*( (xP++)->real() );
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phase += freq;
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}
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}
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else {
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while (xP < xPEnd) {
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(*yP++) = (*xP++)*expjLookup(phase);
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phase += freq;
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}
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}
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if (finalPhase) *finalPhase = phase;
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return y;
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}
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signalVector* reverseConjugate(signalVector *b)
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{
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signalVector *tmp = new signalVector(b->size());
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tmp->isRealOnly(b->isRealOnly());
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signalVector::iterator bP = b->begin();
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signalVector::iterator bPEnd = b->end();
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signalVector::iterator tmpP = tmp->end()-1;
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if (!b->isRealOnly()) {
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while (bP < bPEnd) {
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*tmpP-- = bP->conj();
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bP++;
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}
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}
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else {
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while (bP < bPEnd) {
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*tmpP-- = bP->real();
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bP++;
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}
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}
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return tmp;
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}
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signalVector* correlate(signalVector *a,
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signalVector *b,
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signalVector *c,
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ConvType spanType,
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bool bReversedConjugated,
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unsigned startIx,
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unsigned len)
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{
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signalVector *tmp = NULL;
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if (!bReversedConjugated) {
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tmp = reverseConjugate(b);
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}
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else {
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tmp = b;
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}
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c = convolve(a,tmp,c,spanType,startIx,len);
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if (!bReversedConjugated) delete tmp;
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return c;
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|
}
|
|
|
|
|
|
/* 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;
|
|
}
|