Transceiver52M: Make GSM pulse filter internal to implementation

There is no reason expose the pulse shaping filter outside of the
signal processing calls. The main transceiver object makes no use
of the filter and there's no reason to pass it around.

Initialize the pulse shape with the signal processing library, and
maintain an internal static member like many of the other library
variables. Similarly destroy the object when the library is closed.

Signed-off-by: Thomas Tsou <tom@tsou.cc>

4 files changed, 112 insertions, 115 deletions

diff --git a/Transceiver52M/Transceiver.cpp b/Transceiver52M/Transceiver.cpp
index b60496a..a7c629e 100644
--- a/Transceiver52M/Transceiver.cpp
+++ b/Transceiver52M/Transceiver.cpp
@@ -57,15 +57,12 @@ Transceiver::Transceiver(int wBasePort,
 	 mControlSocket(wBasePort+1,TRXAddress,wBasePort+101),
 	 mClockSocket(wBasePort,TRXAddress,wBasePort+100)
 {
-  //GSM::Time startTime(0,0);
-  //GSM::Time startTime(gHyperframe/2 - 4*216*60,0);
   GSM::Time startTime(random() % gHyperframe,0);
 
   mFIFOServiceLoopThread = new Thread(32768);  ///< thread to push bursts into transmit FIFO
   mControlServiceLoopThread = new Thread(32768);       ///< thread to process control messages from GSM core
   mTransmitPriorityQueueServiceLoopThread = new Thread(32768);///< thread to process transmit bursts from GSM core
 
-
   mSPS = wSPS;
   mRadioInterface = wRadioInterface;
   mTransmitLatency = wTransmitLatency;
@@ -75,54 +72,65 @@ Transceiver::Transceiver(int wBasePort,
   mRadioInterface->getClock()->set(startTime);
   mMaxExpectedDelay = 0;
 
-  // generate pulse and setup up signal processing library
-  gsmPulse = generateGSMPulse(2, mSPS);
-  LOG(DEBUG) << "gsmPulse: " << *gsmPulse;
-  sigProcLibSetup(mSPS);
-
   txFullScale = mRadioInterface->fullScaleInputValue();
   rxFullScale = mRadioInterface->fullScaleOutputValue();
 
-  // initialize filler tables with dummy bursts, initialize other per-timeslot variables
+  mOn = false;
+  mTxFreq = 0.0;
+  mRxFreq = 0.0;
+  mPower = -10;
+  mEnergyThreshold = INIT_ENERGY_THRSHD;
+  prevFalseDetectionTime = startTime;
+
+}
+
+Transceiver::~Transceiver()
+{
+  sigProcLibDestroy();
+  mTransmitPriorityQueue.clear();
+}
+
+bool Transceiver::init()
+{
+  if (!sigProcLibSetup(mSPS)) {
+    LOG(ALERT) << "Failed to initialize signal processing library";
+    return false;
+  }
+
+  // initialize filler tables with dummy bursts
   for (int i = 0; i < 8; i++) {
-    signalVector* modBurst = modulateBurst(gDummyBurst,*gsmPulse,
+    signalVector* modBurst = modulateBurst(gDummyBurst,
 					   8 + (i % 4 == 0),
 					   mSPS);
+    if (!modBurst) {
+      sigProcLibDestroy();
+      LOG(ALERT) << "Failed to initialize filler table";
+      return false;
+    }
+
     scaleVector(*modBurst,txFullScale);
     fillerModulus[i]=26;
     for (int j = 0; j < 102; j++) {
       fillerTable[j][i] = new signalVector(*modBurst);
     }
+
     delete modBurst;
     mChanType[i] = NONE;
     channelResponse[i] = NULL;
     DFEForward[i] = NULL;
     DFEFeedback[i] = NULL;
-    channelEstimateTime[i] = startTime;
+    channelEstimateTime[i] = mTransmitDeadlineClock;
   }
 
-  mOn = false;
-  mTxFreq = 0.0;
-  mRxFreq = 0.0;
-  mPower = -10;
-  mEnergyThreshold = INIT_ENERGY_THRSHD;
-  prevFalseDetectionTime = startTime;
-}
-
-Transceiver::~Transceiver()
-{
-  delete gsmPulse;
-  sigProcLibDestroy();
-  mTransmitPriorityQueue.clear();
+  return true;
 }
-  
 
 void Transceiver::addRadioVector(BitVector &burst,
 				 int RSSI,
 				 GSM::Time &wTime)
 {
   // modulate and stick into queue 
-  signalVector* modBurst = modulateBurst(burst,*gsmPulse,
+  signalVector* modBurst = modulateBurst(burst,
 					 8 + (wTime.TN() % 4 == 0),
 					 mSPS);
   scaleVector(*modBurst,txFullScale * pow(10,-RSSI/10));
@@ -135,10 +143,7 @@ void Transceiver::addRadioVector(BitVector &burst,
 #ifdef TRANSMIT_LOGGING
 void Transceiver::unModulateVector(signalVector wVector) 
 {
-  SoftVector *burst = demodulateBurst(wVector,
-				   *gsmPulse,
-				   mSPS,
-				   1.0,0.0);
+  SoftVector *burst = demodulateBurst(wVector, mSPS, 1.0, 0.0);
   LOG(DEBUG) << "LOGGED BURST: " << *burst;
 
 /*
@@ -415,7 +420,6 @@ SoftVector *Transceiver::pullRadioVector(GSM::Time &wTime,
   if ((rxBurst) && (success)) {
     if ((corrType==RACH) || (!needDFE)) {
       burst = demodulateBurst(*vectorBurst,
-			      *gsmPulse,
 			      mSPS,
 			      amplitude,TOA);
     }
@@ -497,7 +501,7 @@ void Transceiver::driveControl()
         // Prepare for thread start
         mPower = -20;
         mRadioInterface->start();
-        generateRACHSequence(*gsmPulse, mSPS);
+        generateRACHSequence(mSPS);
 
         // Start radio interface threads.
         mFIFOServiceLoopThread->start((void * (*)(void*))FIFOServiceLoopAdapter,(void*) this);
@@ -589,8 +593,8 @@ void Transceiver::driveControl()
       sprintf(response,"RSP SETTSC 1 %d",TSC);
     else {
       mTSC = TSC;
-      generateMidamble(*gsmPulse, mSPS, TSC);
-      sprintf(response,"RSP SETTSC 0 %d",TSC);
+      generateMidamble(mSPS, TSC);
+      sprintf(response,"RSP SETTSC 0 %d", TSC);
     }
   }
   else if (strcmp(command,"SETSLOT")==0) {
diff --git a/Transceiver52M/Transceiver.h b/Transceiver52M/Transceiver.h
index 91d92b2..3175213 100644
--- a/Transceiver52M/Transceiver.h
+++ b/Transceiver52M/Transceiver.h
@@ -124,8 +124,6 @@ private:
   /** send messages over the clock socket */
   void writeClockInterface(void);
 
-  signalVector *gsmPulse;              ///< the GSM shaping pulse for modulation
-
   int mSPS;                            ///< number of samples per GSM symbol
 
   bool mOn;			       ///< flag to indicate that transceiver is powered on
@@ -168,6 +166,7 @@ public:
 
   /** start the Transceiver */
   void start();
+  bool init();
 
   /** attach the radioInterface receive FIFO */
   void receiveFIFO(VectorFIFO *wFIFO) { mReceiveFIFO = wFIFO;}
diff --git a/Transceiver52M/sigProcLib.cpp b/Transceiver52M/sigProcLib.cpp
index b7f3511..ab605cf 100644
--- a/Transceiver52M/sigProcLib.cpp
+++ b/Transceiver52M/sigProcLib.cpp
@@ -58,8 +58,27 @@ typedef struct {
   complex      gain;
 } CorrelationSequence;
 
+/*
+ * Gaussian and empty modulation pulses
+ */
+struct PulseSequence {
+  PulseSequence() : gaussian(NULL), empty(NULL)
+  {
+  }
+
+  ~PulseSequence()
+  {
+    delete gaussian;
+    delete empty;
+  }
+
+  signalVector *gaussian;
+  signalVector *empty;
+};
+
 CorrelationSequence *gMidambles[] = {NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL};
 CorrelationSequence *gRACHSequence = NULL;
+PulseSequence *GSMPulse = NULL;
 
 void sigProcLibDestroy(void) {
   if (GMSKRotation) {
@@ -234,6 +253,7 @@ void sigProcLibSetup(int sps)
 {
   initTrigTables();
   initGMSKRotationTables(sps);
+  generateGSMPulse(sps, 2);
 }
 
 void GMSKRotate(signalVector &x) {
@@ -439,25 +459,36 @@ signalVector* convolve(const signalVector *a,
 }
 
 
-signalVector* generateGSMPulse(int sps, int symbolLength)
+void generateGSMPulse(int sps, int symbolLength)
 {
+  int len;
+  float arg, center;
 
-  int numSamples = sps * 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) sps;
-    *xP++ = 0.96*exp(-1.1380*arg*arg-0.527*arg*arg*arg*arg); // GSM pulse approx.
+  delete GSMPulse;
+
+  /* Store a single tap filter used for correlation sequence generation */
+  GSMPulse = new PulseSequence();
+  GSMPulse->empty = new signalVector(1);
+  GSMPulse->empty->isRealOnly(true);
+  *(GSMPulse->empty->begin()) = 1.0f;
+
+  /* GSM pulse approximation */
+  GSMPulse->gaussian = new signalVector(len);
+  GSMPulse->gaussian->isRealOnly(true);
+  signalVector::iterator xP = GSMPulse->gaussian->begin();
+
+  center = (float) (len - 1.0) / 2.0;
+
+  for (int i = 0; i < len; i++) {
+    arg = ((float) i - center) / (float) sps;
+    *xP++ = 0.96 * exp(-1.1380 * arg * arg -
+                        0.527 * arg * arg * arg * arg);
   }
 
-  float avgAbsval = sqrtf(vectorNorm2(*x) / sps);
-  xP = x->begin();
-  for (int i = 0; i < numSamples; i++) 
+  float avgAbsval = sqrtf(vectorNorm2(*GSMPulse->gaussian)/sps);
+  xP = GSMPulse->gaussian->begin();
+  for (int i = 0; i < len; i++) 
     *xP++ /= avgAbsval;
-  x->isRealOnly(true);
-  x->setSymmetry(ABSSYM);
-  return x;
 }
 
 signalVector* frequencyShift(signalVector *y,
@@ -564,36 +595,22 @@ bool vectorSlicer(signalVector *x)
   return true;
 }
   
-signalVector *modulateBurst(const BitVector &wBurst,
-			    const signalVector &gsmPulse,
-			    int guardPeriodLength,
-			    int sps)
+signalVector *modulateBurst(const BitVector &wBurst, int guardPeriodLength,
+			    int sps, bool emptyPulse)
 {
+  int burstLen;
+  signalVector *pulse, modBurst;
+  signalVector::iterator modBurstItr;
+
+  if (emptyPulse)
+    pulse = GSMPulse->empty;
+  else
+    pulse = GSMPulse->gaussian;
+
+  burstLen = sps * (wBurst.size() + guardPeriodLength);
+  modBurst = signalVector(burstLen);
+  modBurstItr = modBurst.begin();
 
-  //static complex staticBurst[157];
-
-  int burstSize = sps * (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 += sps;
-    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 += sps;
@@ -602,16 +619,13 @@ signalVector *modulateBurst(const BitVector &wBurst,
   // 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);
+  signalVector *shapedBurst = convolve(&modBurst, pulse, NULL, NO_DELAY);
 
-  //delete modBurst;
-  
   return shapedBurst;
-
 }
 
 float sinc(float x) 
@@ -837,11 +851,8 @@ void offsetVector(signalVector &x,
   }
 }
 
-bool generateMidamble(signalVector &gsmPulse,
-		      int sps,
-		      int TSC)
+bool generateMidamble(int sps, int TSC)
 {
-
   if ((TSC < 0) || (TSC > 7)) 
     return false;
 
@@ -850,18 +861,13 @@ bool generateMidamble(signalVector &gsmPulse,
     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,
-					 sps);
+					 sps, true);
   signalVector *midamble = modulateBurst(gTrainingSequence[TSC],
-                                         gsmPulse,
                                          0,
-                                         sps);
+                                         sps, false);
   
   if (midamble == NULL) return false;
   if (middleMidamble == NULL) return false;
@@ -895,17 +901,14 @@ bool generateMidamble(signalVector &gsmPulse,
   return true;
 }
 
-bool generateRACHSequence(signalVector &gsmPulse,
-			  int sps)
+bool generateRACHSequence(int sps)
 {
-  
   if (gRACHSequence) {
     if (gRACHSequence->sequence!=NULL) delete gRACHSequence->sequence;
     if (gRACHSequence->sequenceReversedConjugated!=NULL) delete gRACHSequence->sequenceReversedConjugated;
   }
 
   signalVector *RACHSeq = modulateBurst(gRACHSynchSequence,
-					gsmPulse,
 					0,
 					sps);
 
@@ -1136,12 +1139,8 @@ signalVector *decimateVector(signalVector &wVector,
 }
 
 
-SoftVector *demodulateBurst(signalVector &rxBurst,
-			 const signalVector &gsmPulse,
-			 int sps,
-			 complex channel,
-			 float TOA) 
-
+SoftVector *demodulateBurst(signalVector &rxBurst, int sps,
+                            complex channel, float TOA) 
 {
   scaleVector(rxBurst,((complex) 1.0)/channel);
   delayVector(rxBurst,-TOA);
diff --git a/Transceiver52M/sigProcLib.h b/Transceiver52M/sigProcLib.h
index e91644c..a9fabb0 100644
--- a/Transceiver52M/sigProcLib.h
+++ b/Transceiver52M/sigProcLib.h
@@ -125,7 +125,7 @@ signalVector* convolve(const signalVector *a,
 	@param symbolLength The size of the pulse.
 	@return The GSM pulse.
 */
-signalVector* generateGSMPulse(int sps, int symbolLength);
+void generateGSMPulse(int sps, int symbolLength);
 
 /** 
         Frequency shift a vector.
@@ -162,9 +162,8 @@ bool vectorSlicer(signalVector *x);
 
 /** GMSK modulate a GSM burst of bits */
 signalVector *modulateBurst(const BitVector &wBurst,
-			    const signalVector &gsmPulse,
 			    int guardPeriodLength,
-			    int sps);
+			    int sps, bool emptyPulse = false);
 
 /** Sinc function */
 float sinc(float x);
@@ -229,15 +228,14 @@ void offsetVector(signalVector &x,
         @param TSC The training sequence [0..7]
         @return Success.
 */
-bool generateMidamble(signalVector &gsmPulse, int sps, int tsc);
+bool generateMidamble(int sps, int tsc);
 /**
         Generate a modulated RACH sequence, stored within the library.
         @param gsmPulse The GSM pulse used for modulation.
         @param sps The number of samples per GSM symbol.
         @return Success.
 */
-bool generateRACHSequence(signalVector &gsmPulse,
-			  int sps);
+bool generateRACHSequence(int sps);
 
 /**
         Energy detector, checks to see if received burst energy is above a threshold.
@@ -310,11 +308,8 @@ signalVector *decimateVector(signalVector &wVector,
         @param TOA The time-of-arrival of the received burst.
         @return The demodulated bit sequence.
 */
-SoftVector *demodulateBurst(signalVector &rxBurst,
-			 const signalVector &gsmPulse,
-			 int sps,
-			 complex channel,
-			 float TOA);
+SoftVector *demodulateBurst(signalVector &rxBurst, int sps,
+                            complex channel, float TOA);
 
 /**
         Creates a simple Kaiser-windowed low-pass FIR filter.