Transceiver: Add an option to send RSSI to the GSM core even if the burst is not demodulated.

The feature is enabled when the GSM core sends "SENDEMPTY 1" command.

CommonLibs/Logger.cpp

@@ -206,7 +206,7 @@ Log::~Log()
 	if (gLogToConsole||gLogToFile) {
 		int mlen = mStream.str().size();
 		int neednl = (mlen==0 || mStream.str()[mlen-1] != '\n');
-		gLogToLock.lock();
+		ScopedLock lock(gLogToLock);
 		if (gLogToConsole) {
 			// The COUT() macro prevents messages from stomping each other but adds uninteresting thread numbers,
 			// so just use std::cout.
@@ -218,7 +218,6 @@ Log::~Log()
 			if (neednl) {fputc('\n',gLogToFile);}
 			fflush(gLogToFile);
 		}
-		gLogToLock.unlock();
 	}
 }
 

README

@@ -1,168 +1,116 @@
-Welcome to the OpenBTS source code.
+This is the interface to the transcevier.
 
-
-For free support, please subscribe to openbts-discuss@lists.sourceforge.net.
-See http://sourceforge.net/mailarchive/forum.php?forum_name=openbts-discuss
-and https://lists.sourceforge.net/lists/listinfo/openbts-discuss for details.
-
-For additional information, refer to http://openbts.org.
-
-
-These are the directories:
-
-AsteriskConfig	Asterisk configuration files for use with OpenBTS.
-CommonLib	Common-use libraries, mostly C++ wrappers for basic facilities.
-Control		Control-layer functions for the protocols of GSM 04.08 and SIP.
-GSM		The GSM stack.
-SIP		Components of the SIP state machines ued by the control layer.
-SMS		The SMS stack.
-SR		The subscriber registry.
-TRXManager	The interface between the GSM stack and the radio.
-Transceiver	The software transceiver and specific installation tests.
-apps		OpenBTS application binaries.
-doc		Project documentation.
-tests		Test fixtures for subsets of OpenBTS components.
-smqueue		RFC-3428 store-and-forward server for SMS
+Each TRX Manager UDP socket interface represents a single ARFCN.
+Each of these per-ARFCN interfaces is a pair of UDP sockets, one for control and one for data.
+Give a base port B (5700), the master clock interface is at port P=B.
+The TRX-side control interface for C(N) is on  port P=B+2N+1 and the data interface is on an odd numbered port P=B+2N+2.
+The corresponding core-side interface for every socket is at P+100.
+For any given build, the number of ARFCN interfaces can be fixed.
 
 
 
-By default, OpenBTS assumes the following UDP port assignments:
+Indications on the Master Clock Interface
 
-5060 -- Asterisk SIP interface
-5061 -- local SIP softphone
-5062 -- OpenBTS SIP interface
-5063 -- smqueue SIP interface
-5064 -- subscriber registry SIP interface
-5700-range -- OpenBTS-transceiver interface
+The master clock interface is output only (from the radio).
+Messages are "indications".
 
-These can be controlled in the CONFIG table in /etc/OpenBTS.db.
+CLOCK gives the current value of the transceiver clock to be used by the core.
+This message is sent whenever a trasmission packet arrives that is too late or too early.  The clock value is NOT the current transceiver time.  It is a time setting the the core should use to give better packet arrival times.
+IND CLOCK <totalFrames>
 
-Standrd paths:
-/OpenBTS -- Binary installation.
-/etc/OpenBTS -- Configuration databases.
-/var/run/OpenBTS -- Real-time reporting databases.
 
-The script apps/setUpFiles.sh will create these directories and install the
-correct files in them.
+
+Commands on the Per-ARFCN Control Interface
+
+The per-ARFCN control interface uses a command-reponse protocol.
+Commands are NULL-terminated ASCII strings, one per UDP socket.
+Each command has a corresponding response.
+Every command is of the form:
+
+CMD <cmdtype> [params]
+
+The <cmdtype> is the actual command.
+Parameters are optional depending on the commands type.
+Every response is of the form:
+
+RSP <cmdtype> <status> [result]
+
+The <status> is 0 for success and a non-zero error code for failure.
+Successful responses may include results, depending on the command type.
+
+
+Power Control
+
+POWEROFF shuts off transmitter power and stops the demodulator.
+CMD POWEROFF
+RSP POWEROFF <status>
+
+POWERON starts the transmitter and starts the demodulator.  Initial power level is very low.
+This command fails if the transmitter and receiver are not yet tuned.
+This command fails if the transmit or receive frequency creates a conflict with another ARFCN that is already runnng.
+If the transceiver is already on, it response with success to this command.
+CMD POWERON
+RSP POWERON <status>
+
+SETPOWER sets output power in dB wrt full scale.
+This command fails if the transmitter and receiver are not running.
+CMD SETPOWER <dB>
+RSP SETPOWER <status> <dB>
+
+ADJPOWER adjusts power by the given dB step.  Response returns resulting power level wrt full scale.
+This command fails if the transmitter and receiver are not running.
+CMD ADJPOWER <dBStep>
+RSP ADJPOWER <status> <dBLevel>
+
+
+Tuning Control
+
+RXTUNE tunes the receiver to a given frequency in kHz.
+This command fails if the receiver is already running.
+(To re-tune you stop the radio, re-tune, and restart.)
+This command fails if the transmit or receive frequency creates a conflict with another ARFCN that is already runnng.
+CMD RXTUNE <kHz>
+RSP RXTUNE <status> <kHz>
+
+TXTUNE tunes the transmitter to a given frequency in kHz.
+This command fails if the transmitter is already running.
+(To re-tune you stop the radio, re-tune, and restart.)
+This command fails if the transmit or receive frequency creates a conflict with another ARFCN that is already runnng.
+CMD TXTUNE <kHz>
+RSP TXTUNE <status> <kHz>
+
+
+Timeslot Control
+
+SETSLOT sets the format of the uplink timeslots in the ARFCN.
+The <timeslot> indicates the timeslot of interest.
+The <chantype> indicates the type of channel that occupies the timeslot.
+A chantype of zero indicates the timeslot is off.
+CMD SETSLOT <timeslot> <chantype>
+RSP SETSLOT <status> <timeslot> <chantype>
+
+
+Messages on the per-ARFCN Data Interface
+
+Messages on the data interface carry one radio burst per UDP message.
+
+
+Received Data Burst
+
+1 byte timeslot index
+4 bytes GSM frame number, big endian
+1 byte RSSI in -dBm
+2 bytes correlator timing offset in 1/256 symbol steps, 2's-comp, big endian
+148 bytes soft symbol estimates, 0 -> definite "0", 255 -> definite "1"
+
+
+Transmit Data Burst
+
+1 byte timeslot index
+4 bytes GSM frame number, big endian
+1 byte transmit level wrt ARFCN max, -dB (attenuation)
+148 bytes output symbol values, 0 & 1
 
 
 
 
-Release history:
-
-Release	Name		SVN Reposiory	SVN Rev	Comments
-
-1.0	(none)		SF.net		??		completed L1, L2
-
-1.1	Arnaudville	GNU Radio	r10019 (trunk)
-
-1.2	Breaux Bridge	GNU Radio	r10088 (trunk)	GNU Build, very early assignment
-
-1.3	Carencro	KSP		r1 (trunk)	first post-injunction release
-
-1.4	Donaldsonville	KSP		r23 (trunk)	fixed Ubuntu build error
-
-1.5	Eunice		KSP		r39 (trunk)	fixed L2 bugs related to segmentation
-							removed incomplete SMS directory
-							moved "abort" calls into L3 subclasses
-
-1.6	New Iberia	KSP		r130 (trunk)	import of all 2.2 improvements to non-SMS release
-
-
-2.0	St. Francisville KSP		r54 (smswork)	SMS support
-							file-based configuration
-
-2.1	Grand Coteau	KSP		r70 (smswork)	DTMF support
-							fixed more Linux-related build errors
-								-lpthread
-								TLMessage constructor
-							expanded stack to prevent overflows in Linux
-							moved gSIPInterface to main app
-							fixed iterator bug in Pager
-
-2.2	Houma		KSP		r122 (smswork)	added LEGAL notice
-							removed Assert classes
-							stop paging on page response
-							fixed Pager-spin bug
-							fixed Transceiver spin bugs
-							fixed 2^32 microsecond rollover bug
-							reduced stack footprints in Transceiver
-							fixed SMS timestamps
-							check LAI before using TMSI in LUR
-							reduced memory requirement by 75%
-							removed PagerTest
-							fixed stale-transaction bug in paging handler
-							fixed USRP clock rollover bug
-							faster call connection
-							new USRPDevice design
-
-2.3	Jean Lafitte	KSP		r190? (trunk)	check for out-of-date RACH bursts
-							better TRX-GSM clock sync
-							formal logging system
-							command line interface
-							emergency call setup
-
-2.4	Kinder		KSP		r208? (trunk)	fixed BCCH neighbor list bug
-							support for neighbor lists
-							fixed support for non-local Asterisk servers
-							cleaner configuration management
-							more realtime control of BCCH parameters
-							proper rejection of Hold messages
-							fixed L3 hanging bug in MTDCheckBYE
-
-2.4.1	Kinder		KSP		r462		fixed lots of valgrind errors
-
-2.4.2	Kinder		KSP		r482		zero-length calling party number bug
-							g++ 4.4 #includes
-
-2.5	Lacassine	KSP		r551		imported Joshua Lackey patches
-							SIP fixes from Anne Kwong
-							SIP fixes from testing with SMS server
-							L3 TI handling fixes
-							SMS server support
-							GNU Radio 3.2 compatibility
-							configurable max range and LU-reject cause
-							"page" & "testcall" CLI features
-
-2.5.1	Lacassine	KSP		r595		fixed some build bugs for some Linux distros
-
-2.5.2	Lacassine	KSP		r630		fixed channel assignment bug for Nokia DCT4+ handsets
-
-2.5.3	Lacassine	KSP		r756		merged fix for transceiver startup crash
-								due to use of uninitialized variables (r646)
-							merged fix for fusb bug from trunk (r582)
-
-2.5.4	Lacassine	KSP		r812		merged fixes to build under latest Fedora and
-								to build with git GnuRadio (r814)
-
-2.6	Mamou		KSP		r886		fixed infamous fusb bug (r582)
-							fixed idle-filling table size bug
-							smoother uplink power control
-							load-limiting downlink power control
-							new "config" features (optional, static)
-							IMEI interrogation
-							fixed MOD "missing FIFO" bug
-							configurable short code features
-							fixed transceiver startup crash (r646)
-							readline support is back
-							fixed timing advance bug (r844)
-							added CLI "chans" command
-							track time-of-use in TMSI table (r844)
-							added CLI "noise" command (r844)
-							added CLI "rxpower" command (r844)
-							added CLI "unconfig" command
-
-2.7	Natchitoches	Range	rxxx			(never released publicly)
-							converted TMSITable to sqlite3 (r902)
-							sqlite3-based configuration (r???)
-							converted Logger to syslogd (r903)
-							added support for rest octets (r1022)
-							external database for transaction reporting (r1184)
-							external database for channel status reporting (r1203)
-							in-call delivery and submission of text messages (r1231)
-							RFC-2833 DMTF (r1249)
-
-2.8	Opelousas	Range	rxxx			move databases to /etc and /var
-							RRLP aiding support
-
-

Transceiver52M/Transceiver.cpp

@@ -22,6 +22,7 @@
 */
 
 #include <stdio.h>
+#include <iomanip>      // std::setprecision
 #include "Transceiver.h"
 #include <Logger.h>
 
@@ -140,13 +141,16 @@ bool TransceiverState::init(int filler, size_t sps, float scale, size_t rtsc)
 }
 
 Transceiver::Transceiver(int wBasePort,
-			 const char *wTRXAddress,
-			 size_t wSPS, size_t wChans,
-			 GSM::Time wTransmitLatency,
-			 RadioInterface *wRadioInterface)
+                         const char *wTRXAddress,
+                         size_t wSPS, size_t wChans,
+                         GSM::Time wTransmitLatency,
+                         RadioInterface *wRadioInterface,
+                         double wRssiOffset)
   : mBasePort(wBasePort), mAddr(wTRXAddress),
     mClockSocket(wBasePort, wTRXAddress, mBasePort + 100),
+    mSendEmptyBursts(false),
     mTransmitLatency(wTransmitLatency), mRadioInterface(wRadioInterface),
+    rssiOffset(wRssiOffset),
     mSPSTx(wSPS), mSPSRx(1), mChans(wChans), mOn(false),
     mTxFreq(0.0), mRxFreq(0.0), mTSC(0), mMaxExpectedDelay(0)
 {
@@ -531,13 +535,13 @@ Transceiver::CorrType Transceiver::expectedCorrType(GSM::Time currTime,
  * Detect RACH synchronization sequence within a burst. No equalization
  * is used or available on the RACH channel.
  */
-bool Transceiver::detectRACH(TransceiverState *state,
-                             signalVector &burst,
-                             complex &amp, float &toa)
+int Transceiver::detectRACH(TransceiverState *state,
+                            signalVector &burst,
+                            complex &amp, float &toa)
 {
   float threshold = 6.0;
 
-  return detectRACHBurst(burst, threshold, mSPSRx, &amp, &toa);
+  return detectRACHBurst(burst, threshold, mSPSRx, amp, toa);
 }
 
 /*
@@ -545,12 +549,13 @@ bool Transceiver::detectRACH(TransceiverState *state,
  * state information and channel estimate if necessary. Equalization
  * is currently disabled.
  */
-bool Transceiver::detectTSC(TransceiverState *state, signalVector &burst,
-                            complex &amp, float &toa, GSM::Time &time)
+int Transceiver::detectTSC(TransceiverState *state, signalVector &burst,
+                           complex &amp, float &toa, GSM::Time &time)
 {
+  int success;
   int tn = time.TN();
   float chanOffset, threshold = 5.0;
-  bool noise, needDFE = false, estimateChan = false;
+  bool needDFE = false, estimateChan = false;
   double elapsed = time - state->chanEstimateTime[tn];
   signalVector *chanResp;
 
@@ -565,17 +570,18 @@ bool Transceiver::detectTSC(TransceiverState *state, signalVector &burst,
   }
 
   /* Detect normal burst midambles */
-  if (!analyzeTrafficBurst(burst, mTSC, threshold, mSPSRx, &amp,
-                           &toa, mMaxExpectedDelay, estimateChan,
-                           &chanResp, &chanOffset)) {
-    return false;
+  success = analyzeTrafficBurst(burst, mTSC, threshold, mSPSRx, amp,
+                                toa, mMaxExpectedDelay, estimateChan,
+                                &chanResp, &chanOffset);
+  if (success <= 0) {
+    return success;
   }
 
-  noise = state->mNoiseLev;
-  state->SNRestimate[tn] = amp.norm2() / (noise * noise + 1.0);
-
   /* Set equalizer if unabled */
   if (needDFE && estimateChan) {
+     float noise = state->mNoiseLev;
+     state->SNRestimate[tn] = amp.norm2() / (noise * noise + 1.0);
+
      state->chanResponse[tn] = chanResp;
      state->chanRespOffset[tn] = chanOffset;
      state->chanRespAmplitude[tn] = amp;
@@ -588,7 +594,7 @@ bool Transceiver::detectTSC(TransceiverState *state, signalVector &burst,
      state->chanEstimateTime[tn] = time;
   }
 
-  return true;;
+  return 1;
 }
 
 /*
@@ -615,16 +621,19 @@ SoftVector *Transceiver::demodulate(TransceiverState *state,
  * Pull bursts from the FIFO and handle according to the slot
  * and burst correlation type. Equalzation is currently disabled. 
  */
-SoftVector *Transceiver::pullRadioVector(GSM::Time &wTime, int &RSSI,
-                                         int &timingOffset, size_t chan)
+SoftVector *Transceiver::pullRadioVector(GSM::Time &wTime, double &RSSI, bool &isRssiValid,
+                                         double &timingOffset, double &noise,
+                                         size_t chan)
 {
-  bool success, equalize = false;
+  int success;
+  bool equalize = false;
   complex amp;
   float toa, pow, max = -1.0, avg = 0.0;
   int max_i = -1;
   signalVector *burst;
   SoftVector *bits = NULL;
   TransceiverState *state = &mStates[chan];
+  isRssiValid = false;
 
   /* Blocking FIFO read */
   radioVector *radio_burst = mReceiveFIFO[chan]->read();
@@ -635,7 +644,9 @@ SoftVector *Transceiver::pullRadioVector(GSM::Time &wTime, int &RSSI,
   GSM::Time time = radio_burst->getTime();
   CorrType type = expectedCorrType(time, chan);
 
-  if ((type == OFF) || (type == IDLE)) {
+  /* No processing if the timeslot is off.
+   * Not even power level or noise calculation. */
+  if (type == OFF) {
     delete radio_burst;
     return NULL;
   }
@@ -659,7 +670,25 @@ SoftVector *Transceiver::pullRadioVector(GSM::Time &wTime, int &RSSI,
   /* Average noise on diversity paths and update global levels */
   burst = radio_burst->getVector(max_i);
   avg = sqrt(avg / radio_burst->chans());
-  state->mNoiseLev = state->mNoises.avg();
+
+  wTime = time;
+  RSSI = 20.0 * log10(rxFullScale / avg);
+
+  /* RSSI estimation are valid */
+  isRssiValid = true;
+
+  if (type == IDLE) {
+    /* Update noise levels */
+    state->mNoises.insert(avg);
+    state->mNoiseLev = state->mNoises.avg();
+    noise = 20.0 * log10(rxFullScale / state->mNoiseLev);
+
+    delete radio_burst;
+    return NULL;
+  } else {
+    /* Do not update noise levels */
+    noise = 20.0 * log10(rxFullScale / state->mNoiseLev);
+  }
 
   /* Detect normal or RACH bursts */
   if (type == TSC)
@@ -667,33 +696,27 @@ SoftVector *Transceiver::pullRadioVector(GSM::Time &wTime, int &RSSI,
   else
     success = detectRACH(state, *burst, amp, toa);
 
-  /* Update noise average if no bust detected or alert on error */
+  /* Alert an error and exit */
   if (success <= 0) {
-    if (!success) {
-      state->mNoises.insert(avg);
-    } else if (success == -SIGERR_CLIP) {
-      LOG(ALERT) << "Clipping detected on RACH input";
-    } else if (success < 0) {
-      LOG(ALERT) << "Unhandled RACH error";
+    if (success == -SIGERR_CLIP) {
+      LOG(WARNING) << "Clipping detected on received RACH or Normal Burst";
+    } else if (success != SIGERR_NONE) {
+      LOG(WARNING) << "Unhandled RACH or Normal Burst detection error";
     }
 
     delete radio_burst;
     return NULL;
   }
 
+  timingOffset = toa / mSPSRx;
+
   /* Demodulate and set output info */
   if (equalize && (type != TSC))
     equalize = false;
 
-  if (avg - state->mNoiseLev > 0.0)
-    bits = demodulate(state, *burst, amp, toa, time.TN(), equalize);
-
-  wTime = time;
-  RSSI = (int) floor(20.0 * log10(rxFullScale / avg));
-  timingOffset = (int) round(toa * 256.0 / mSPSRx);
+  bits = demodulate(state, *burst, amp, toa, time.TN(), equalize);
 
   delete radio_burst;
-
   return bits;
 }
 
@@ -836,6 +859,16 @@ void Transceiver::driveControl(size_t chan)
     sprintf(response,"RSP SETSLOT 0 %d %d",timeslot,corrCode);
 
   }
+  else if (strcmp(command,"SENDEMPTY")==0) {
+      int  sendEmptyBursts;
+      sscanf(buffer,"%3s %s %d",cmdcheck,command,&sendEmptyBursts);
+      if (sendEmptyBursts == 0 || sendEmptyBursts == 1) {
+        mSendEmptyBursts = sendEmptyBursts;
+        sprintf(response,"RSP SENDEMPTY 0 %d",sendEmptyBursts);
+      } else {
+          sprintf(response,"RSP SENDEMPTY 1 %d",sendEmptyBursts);
+      }
+  }
   else {
     LOG(WARNING) << "bogus command " << command << " on control interface.";
     sprintf(response,"RSP ERR 1");
@@ -892,36 +925,69 @@ void Transceiver::driveReceiveRadio()
 void Transceiver::driveReceiveFIFO(size_t chan)
 {
   SoftVector *rxBurst = NULL;
-  int RSSI;
-  int TOA;  // in 1/256 of a symbol
+  double RSSI;     // RSSI in dBFS
+  double RSSIdBm;  // RSSI in dBm
+  double TOA;      // in symbols
+  double noise;    // noise level in dBFS
+  double noisedBm; // noise level in dBm
   GSM::Time burstTime;
+  bool isRssiValid; // are RSSI, noise and burstTime valid
+  char burstString[gSlotLen+10];
 
-  rxBurst = pullRadioVector(burstTime, RSSI, TOA, chan);
+  rxBurst = pullRadioVector(burstTime, RSSI, isRssiValid, TOA, noise, chan);
 
-  if (rxBurst) { 
+  // If mSendEmptyBursts, then send burst data even if it is not demodulated
+  if ((rxBurst || mSendEmptyBursts) && isRssiValid) {
+    RSSIdBm = RSSI+rssiOffset;
+    noisedBm = noise+rssiOffset;
 
-    LOG(DEBUG) << "burst parameters: "
-	  << " time: " << burstTime
-	  << " RSSI: " << RSSI
-	  << " TOA: "  << TOA
-	  << " bits: " << *rxBurst;
-    
-    char burstString[gSlotLen+10];
+    if (rxBurst) {
+        LOG(DEBUG) << std::fixed << std::right
+          << " time: "   << burstTime
+          << " RSSI: "   << std::setw(5) << std::setprecision(1) << RSSI << "dBFS/" << std::setw(6) << -RSSIdBm << "dBm"
+          << " noise: "  << std::setw(5) << std::setprecision(1) << noise << "dBFS/" << std::setw(6) << -noisedBm << "dBm"
+          << " TOA: "    << std::setw(5) << std::setprecision(2) << TOA
+          << " bits: "   << *rxBurst;
+    } else {
+        LOG(DEBUG) << std::fixed << std::right
+          << " time: "   << burstTime
+          << " RSSI: "   << std::setw(5) << std::setprecision(1) << RSSI << "dBFS/" << std::setw(6) << -RSSIdBm << "dBm"
+          << " noise: "  << std::setw(5) << std::setprecision(1) << noise << "dBFS/" << std::setw(6) << -noisedBm << "dBm"
+          << " no burst decoded";
+    }
+
+    // Burst time
     burstString[0] = burstTime.TN();
     for (int i = 0; i < 4; i++)
       burstString[1+i] = (burstTime.FN() >> ((3-i)*8)) & 0x0ff;
-    burstString[5] = RSSI;
-    burstString[6] = (TOA >> 8) & 0x0ff;
-    burstString[7] = TOA & 0x0ff;
-    SoftVector::iterator burstItr = rxBurst->begin();
 
-    for (unsigned int i = 0; i < gSlotLen; i++) {
-      burstString[8+i] =(char) round((*burstItr++)*255.0);
+    // Burst RSSI
+    burstString[5] = (int)RSSIdBm;
+
+    // Time Of Arrival and actual bits
+    if (rxBurst) {
+        // Convert TOA to 1/256 symbol parts, round to closest integer
+        int TOAint = (int) (TOA * 256.0 + 0.5);
+        burstString[6] = (TOAint >> 8) & 0x0ff;
+        burstString[7] = TOAint & 0x0ff;
+
+        SoftVector::iterator burstItr = rxBurst->begin();
+        for (unsigned int i = 0; i < gSlotLen; i++) {
+          burstString[8+i] =(char) round((*burstItr++)*255.0);
+        }
+        delete rxBurst;
+
+        // Unused, but we check for the packet length in osmo-bts,
+        // so leave it as is for now
+        burstString[gSlotLen+8] = 0;
+        burstString[gSlotLen+9] = 0;
+
+        mDataSockets[chan]->write(burstString,gSlotLen+10);
+    } else {
+        // Only header
+        mDataSockets[chan]->write(burstString,6);
     }
-    burstString[gSlotLen+9] = '\0';
-    delete rxBurst;
 
-    mDataSockets[chan]->write(burstString,gSlotLen+10);
   }
 }
 

Transceiver52M/Transceiver.h

@@ -97,10 +97,11 @@ public:
       @param radioInterface associated radioInterface object
   */
   Transceiver(int wBasePort,
-	      const char *TRXAddress,
-	      size_t wSPS, size_t chans,
-	      GSM::Time wTransmitLatency,
-	      RadioInterface *wRadioInterface);
+              const char *TRXAddress,
+              size_t wSPS, size_t chans,
+              GSM::Time wTransmitLatency,
+              RadioInterface *wRadioInterface,
+              double wRssiOffset);
 
   /** Destructor */
   ~Transceiver();
@@ -162,6 +163,7 @@ private:
   std::vector<UDPSocket *> mDataSockets;  ///< socket for writing to/reading from GSM core
   std::vector<UDPSocket *> mCtrlSockets;  ///< socket for writing/reading control commands from GSM core
   UDPSocket mClockSocket;                 ///< socket for writing clock updates to GSM core
+  bool mSendEmptyBursts;                  ///< send RSSI to the GSM core even if burst has not been demodulated
 
   std::vector<VectorQueue> mTxPriorityQueues;   ///< priority queue of transmit bursts received from GSM core
   std::vector<VectorFIFO *>  mReceiveFIFO;      ///< radioInterface FIFO of receive bursts
@@ -181,6 +183,8 @@ private:
   double txFullScale;                     ///< full scale input to radio
   double rxFullScale;                     ///< full scale output to radio
 
+  double rssiOffset;                      ///< RSSI to dBm conversion offset
+
   /** modulate and add a burst to the transmit queue */
   void addRadioVector(size_t chan, BitVector &bits,
                       int RSSI, GSM::Time &wTime);
@@ -192,8 +196,9 @@ private:
   void pushRadioVector(GSM::Time &nowTime);
 
   /** Pull and demodulate a burst from the receive FIFO */
-  SoftVector *pullRadioVector(GSM::Time &wTime, int &RSSI,
-                              int &timingOffset, size_t chan = 0);
+  SoftVector *pullRadioVector(GSM::Time &wTime, double &RSSI, bool &isRssiValid,
+                              double &timingOffset, double &noise,
+                              size_t chan = 0);
 
   /** Set modulus for specific timeslot */
   void setModulus(size_t timeslot, size_t chan);
@@ -205,14 +210,14 @@ private:
   void writeClockInterface(void);
 
   /** Detect RACH bursts */
-  bool detectRACH(TransceiverState *state,
-                  signalVector &burst,
-                  complex &amp, float &toa);
+  int detectRACH(TransceiverState *state,
+                 signalVector &burst,
+                 complex &amp, float &toa);
 
   /** Detect normal bursts */
-  bool detectTSC(TransceiverState *state,
-                 signalVector &burst,
-                 complex &amp, float &toa, GSM::Time &time);
+  int detectTSC(TransceiverState *state,
+                signalVector &burst,
+                complex &amp, float &toa, GSM::Time &time);
 
   /** Demodulat burst and output soft bits */
   SoftVector *demodulate(TransceiverState *state,

Transceiver52M/UHDDevice.cpp

@@ -210,8 +210,7 @@ uhd::time_spec_t convert_time(TIMESTAMP ticks, double rate)
 
 TIMESTAMP convert_time(uhd::time_spec_t ts, double rate)
 {
-	TIMESTAMP ticks = ts.get_full_secs() * rate;
-	return ts.get_tick_count(rate) + ticks;
+	return (TIMESTAMP)(ts.get_real_secs() * rate + 0.5);
 }
 
 /*
@@ -290,7 +289,7 @@ public:
 	uhd_device(size_t sps, size_t chans, bool diversity, double offset);
 	~uhd_device();
 
-	int open(const std::string &args, bool extref);
+	int open(const std::string &args, bool extref, bool swap_channels);
 	bool start();
 	bool stop();
 	bool restart();
@@ -694,7 +693,7 @@ bool uhd_device::parse_dev_type()
 	return true;
 }
 
-int uhd_device::open(const std::string &args, bool extref)
+int uhd_device::open(const std::string &args, bool extref, bool swap_channels)
 {
 	// Find UHD devices
 	uhd::device_addr_t addr(args);
@@ -720,7 +719,7 @@ int uhd_device::open(const std::string &args, bool extref)
 	// Verify and set channels
 	if ((dev_type == B210) && (chans == 2)) {
 	} else if ((dev_type == UMTRX) && (chans == 2)) {
-		uhd::usrp::subdev_spec_t subdev_spec("A:0 B:0");
+		uhd::usrp::subdev_spec_t subdev_spec(swap_channels?"B:0 A:0":"A:0 B:0");
 		usrp_dev->set_tx_subdev_spec(subdev_spec);
 		usrp_dev->set_rx_subdev_spec(subdev_spec);
 	} else if (chans != 1) {
@@ -1430,6 +1429,19 @@ ssize_t smpl_buf::write(void *buf, size_t len, TIMESTAMP timestamp)
 	if ((timestamp + len) <= time_end)
 		return ERROR_TIMESTAMP;
 
+	if (timestamp < time_end) {
+		LOG(ERR) << "Overwriting old buffer data: timestamp="<<timestamp<<" time_end="<<time_end;
+		uhd::time_spec_t ts = convert_time(timestamp, clk_rt);
+		LOG(DEBUG) << "Requested timestamp = " << timestamp << " (real_sec=" << std::fixed << ts.get_real_secs() << " = " << convert_time(ts, clk_rt) << ") rate=" << clk_rt;
+		// Do not return error here, because it's a rounding error and is not fatal
+	}
+	if (timestamp > time_end && time_end != 0) {
+		LOG(ERR) << "Skipping buffer data: timestamp="<<timestamp<<" time_end="<<time_end;
+		uhd::time_spec_t ts = convert_time(timestamp, clk_rt);
+		LOG(DEBUG) << "Requested timestamp = " << timestamp << " (real_sec=" << std::fixed << ts.get_real_secs() << " = " << convert_time(ts, clk_rt) << ") rate=" << clk_rt;
+		// Do not return error here, because it's a rounding error and is not fatal
+	}
+
 	// Starting index
 	size_t write_start = (data_start + (timestamp - time_start)) % buf_len;
 

Transceiver52M/USRPDevice.cpp

@@ -89,7 +89,7 @@ USRPDevice::USRPDevice(size_t sps, size_t, bool)
 #endif
 }
 
-int USRPDevice::open(const std::string &, bool)
+int USRPDevice::open(const std::string &, bool, bool)
 {
   writeLock.unlock();
 

Transceiver52M/USRPDevice.h

@@ -99,7 +99,7 @@ private:
   USRPDevice(size_t sps, size_t chans = 1, bool diversity = false);
 
   /** Instantiate the USRP */
-  int open(const std::string &, bool);
+  int open(const std::string &, bool, bool);
 
   /** Start the USRP */
   bool start();

Transceiver52M/osmo-trx.cpp

@@ -70,6 +70,8 @@ struct trx_config {
 	Transceiver::FillerType filler;
 	bool diversity;
 	double offset;
+	double rssi_offset;
+	bool swap_channels;
 };
 
 ConfigurationTable gConfig;
@@ -185,6 +187,8 @@ bool trx_setup_config(struct trx_config *config)
 	ost << "   C0 Filler Table......... " << fillstr << std::endl;
 	ost << "   Diversity............... " << divstr << std::endl;
 	ost << "   Tuning offset........... " << config->offset << std::endl;
+	ost << "   RSSI to dBm offset...... " << config->rssi_offset << std::endl;
+	ost << "   Swap channels........... " << config->swap_channels << std::endl;
 	std::cout << ost << std::endl;
 
 	return true;
@@ -240,7 +244,7 @@ Transceiver *makeTransceiver(struct trx_config *config, RadioInterface *radio)
 	VectorFIFO *fifo;
 
 	trx = new Transceiver(config->port, config->addr.c_str(), config->sps,
-			      config->chans, GSM::Time(3,0), radio);
+		config->chans, GSM::Time(3,0), radio, config->rssi_offset);
 	if (!trx->init(config->filler, config->rtsc)) {
 		LOG(ALERT) << "Failed to initialize transceiver";
 		delete trx;
@@ -292,7 +296,9 @@ static void print_help()
 		"  -c    Number of ARFCN channels (default=1)\n"
 		"  -f    Enable C0 filler table\n"
 		"  -o    Set baseband frequency offset (default=auto)\n"
-		"  -r    Random burst test mode with TSC\n",
+		"  -r    Random burst test mode with TSC\n"
+		"  -R    RSSI to dBm offset in dB (default=0)\n"
+		"  -S    Swap channels (UmTRX only)\n",
 		"EMERG, ALERT, CRT, ERR, WARNING, NOTICE, INFO, DEBUG");
 }
 
@@ -308,8 +314,10 @@ static void handle_options(int argc, char **argv, struct trx_config *config)
 	config->filler = Transceiver::FILLER_ZERO;
 	config->diversity = false;
 	config->offset = 0.0;
+	config->rssi_offset = 0.0;
+	config->swap_channels = false;
 
-	while ((option = getopt(argc, argv, "ha:l:i:p:c:dxfo:s:r:")) != -1) {
+	while ((option = getopt(argc, argv, "ha:l:i:p:c:dxfo:s:r:R:S")) != -1) {
 		switch (option) {
 		case 'h':
 			print_help();
@@ -349,6 +357,12 @@ static void handle_options(int argc, char **argv, struct trx_config *config)
 			config->rtsc = atoi(optarg);
 			config->filler = Transceiver::FILLER_RAND;
 			break;
+		case 'R':
+			config->rssi_offset = atof(optarg);
+			break;
+		case 'S':
+			config->swap_channels = true;
+			break;
 		default:
 			print_help();
 			exit(0);
@@ -393,7 +407,7 @@ int main(int argc, char *argv[])
 	/* Create the low level device object */
 	usrp = RadioDevice::make(config.sps, config.chans,
 				 config.diversity, config.offset);
-	type = usrp->open(config.dev_args, config.extref);
+	type = usrp->open(config.dev_args, config.extref, config.swap_channels);
 	if (type < 0) {
 		LOG(ALERT) << "Failed to create radio device" << std::endl;
 		goto shutdown;

Transceiver52M/radioDevice.h

@@ -41,7 +41,7 @@ class RadioDevice {
                            bool diversity = false, double offset = 0.0);
 
   /** Initialize the USRP */
-  virtual int open(const std::string &args = "", bool extref = false)=0;
+  virtual int open(const std::string &args = "", bool extref = false, bool swap_channels = false)=0;
 
   virtual ~RadioDevice() { }
 

Transceiver52M/sigProcLib.cpp

@@ -28,6 +28,7 @@
 
 #include "sigProcLib.h"
 #include "GSMCommon.h"
+#include "Logger.h"
 
 extern "C" {
 #include "convolve.h"
@@ -1284,12 +1285,12 @@ static float computePeakRatio(signalVector *corr,
   complex *peak;
   float rms, avg = 0.0;
 
-  peak = corr->begin() + (int) rint(toa);
-
   /* Check for bogus results */
   if ((toa < 0.0) || (toa > corr->size()))
     return 0.0;
 
+  peak = corr->begin() + (int) rint(toa);
+
   for (int i = 2 * sps; i <= 5 * sps; i++) {
     if (peak - i >= corr->begin()) {
       avg += (peak - i)->norm2();
@@ -1372,18 +1373,74 @@ static int detectBurst(signalVector &burst,
   return 1;
 }
 
-static int detectClipping(signalVector &burst, float thresh)
+static float maxAmplitude(signalVector &burst)
 {
-	for (size_t i = 0; i < burst.size(); i++) {
-		if (fabs(burst[i].real()) > thresh)
-			return 1;
-		if (fabs(burst[i].imag()) > thresh)
-			return 1;
-	}
+    float max = 0.0;
+    for (size_t i = 0; i < burst.size(); i++) {
+        if (fabs(burst[i].real()) > max)
+            max = fabs(burst[i].real());
+        if (fabs(burst[i].imag()) > max)
+            max = fabs(burst[i].imag());
+    }
 
-	return 0;
+    return max;
 }
 
+/*
+ * RACH/Normal burst detection with clipping detection
+ *
+ * Correlation window parameters:
+ *   target: Tail bits + burst length
+ *   head: Search symbols before target
+ *   tail: Search symbols after target
+ */
+int detectGeneralBurst(signalVector &rxBurst,
+                       float thresh,
+                       int sps,
+                       complex &amp,
+                       float &toa,
+                       int target, int head, int tail,
+                       CorrelationSequence *sync)
+{
+  int rc, start, len;
+  bool clipping = false;
+  signalVector *corr;
+
+  if ((sps != 1) && (sps != 4))
+    return -SIGERR_UNSUPPORTED;
+
+  // Detect potential clipping
+  // We still may be able to demod the burst, so we'll give it a try
+  // and only report clipping if we can't demod.
+  float maxAmpl = maxAmplitude(rxBurst);
+  if (maxAmpl > CLIP_THRESH) {
+    LOG(DEBUG) << "max burst amplitude: " << maxAmpl << " is above the clipping threshold: " << CLIP_THRESH << std::endl;
+    clipping = true;
+  }
+
+  start = (target - head) * sps - 1;
+  len = (head + tail) * sps;
+  corr = new signalVector(len);
+
+  rc = detectBurst(rxBurst, *corr, sync,
+                   thresh, sps, &amp, &toa, start, len);
+  delete corr;
+
+  if (rc < 0) {
+    return -SIGERR_INTERNAL;
+  } else if (!rc) {
+    amp = 0.0f;
+    toa = 0.0f;
+    return clipping?-SIGERR_CLIP:SIGERR_NONE;
+  }
+
+  /* Subtract forward search bits from delay */
+  toa -= head * sps;
+
+  return 1;
+}
+
+
 /* 
  * RACH burst detection
  *
@@ -1393,53 +1450,23 @@ static int detectClipping(signalVector &burst, float thresh)
  *   tail: Search 10 symbols after target
  */
 int detectRACHBurst(signalVector &rxBurst,
-		    float thresh,
-		    int sps,
-		    complex *amp,
-		    float *toa)
+            float thresh,
+            int sps,
+            complex &amp,
+            float &toa)
 {
-  int rc, start, target, head, tail, len;
-  float _toa;
-  complex _amp;
-  signalVector *corr;
+  int rc, target, head, tail;
   CorrelationSequence *sync;
 
-  if ((sps != 1) && (sps != 4))
-    return -SIGERR_UNSUPPORTED;
-
-  if (detectClipping(rxBurst, CLIP_THRESH))
-    return -SIGERR_CLIP;
-
   target = 8 + 40;
   head = 4;
   tail = 10;
-
-  start = (target - head) * sps - 1;
-  len = (head + tail) * sps;
   sync = gRACHSequence;
-  corr = new signalVector(len);
 
-  rc = detectBurst(rxBurst, *corr, sync,
-                   thresh, sps, &_amp, &_toa, start, len);
-  delete corr;
+  rc = detectGeneralBurst(rxBurst, thresh, sps, amp, toa,
+                          target, head, tail, sync);
 
-  if (rc < 0) {
-    return -SIGERR_INTERNAL;
-  } else if (!rc) {
-    if (amp)
-      *amp = 0.0f;
-    if (toa)
-      *toa = 0.0f;
-    return 0;
-  }
-
-  /* Subtract forward search bits from delay */
-  if (toa)
-    *toa = _toa - head * sps;
-  if (amp)
-    *amp = _amp;
-
-  return 1;
+  return rc;
 }
 
 /* 
@@ -1451,60 +1478,32 @@ int detectRACHBurst(signalVector &rxBurst,
  *   tail: Search 4 symbols + maximum expected delay
  */
 int analyzeTrafficBurst(signalVector &rxBurst, unsigned tsc, float thresh,
-                        int sps, complex *amp, float *toa, unsigned max_toa,
+                        int sps, complex &amp, float &toa, unsigned max_toa,
                         bool chan_req, signalVector **chan, float *chan_offset)
 {
-  int rc, start, target, head, tail, len;
-  complex _amp;
-  float _toa;
-  signalVector *corr;
+  int rc, target, head, tail;
   CorrelationSequence *sync;
 
-  if ((tsc < 0) || (tsc > 7) || ((sps != 1) && (sps != 4)))
+  if ((tsc < 0) || (tsc > 7))
     return -SIGERR_UNSUPPORTED;
 
-  if (detectClipping(rxBurst, CLIP_THRESH))
-    return -SIGERR_CLIP;
-
   target = 3 + 58 + 16 + 5;
   head = 4;
   tail = 4 + max_toa;
-
-  start = (target - head) * sps - 1;
-  len = (head + tail) * sps;
   sync = gMidambles[tsc];
-  corr = new signalVector(len);
 
-  rc = detectBurst(rxBurst, *corr, sync,
-                   thresh, sps, &_amp, &_toa, start, len);
-  delete corr;
-
-  if (rc < 0) {
-    return -SIGERR_INTERNAL;
-  } else if (!rc) {
-    if (amp)
-      *amp = 0.0f;
-    if (toa)
-      *toa = 0.0f;
-    return 0;
-  }
-
-  /* Subtract forward search bits from delay */
-  _toa -= head * sps;
-  if (toa)
-    *toa = _toa;
-  if (amp)
-    *amp = _amp;
+  rc = detectGeneralBurst(rxBurst, thresh, sps, amp, toa,
+                          target, head, tail, sync);
 
   /* Equalization not currently supported */
-  if (chan_req) {
+  if (rc > 0 && chan_req) {
     *chan = new signalVector(6 * sps);
 
     if (chan_offset)
       *chan_offset = 0.0;
   }
 
-  return 1;
+  return rc;
 }
 
 signalVector *decimateVector(signalVector &wVector, size_t factor)

Transceiver52M/sigProcLib.h

@@ -192,8 +192,8 @@ bool energyDetect(signalVector &rxBurst,
 int detectRACHBurst(signalVector &rxBurst,
                     float detectThreshold,
                     int sps,
-                    complex *amplitude,
-                    float* TOA);
+                    complex &amplitude,
+                    float &TOA);
 
 /**
         Normal burst correlator, detector, channel estimator.
@@ -210,15 +210,15 @@ int detectRACHBurst(signalVector &rxBurst,
         @return positive if threshold value is reached, negative on error, zero otherwise
 */
 int analyzeTrafficBurst(signalVector &rxBurst,
-			unsigned TSC,
-			float detectThreshold,
-			int sps,
-			complex *amplitude,
-			float *TOA,
+                        unsigned TSC,
+                        float detectThreshold,
+                        int sps,
+                        complex &amplitude,
+                        float &TOA,
                         unsigned maxTOA,
                         bool requestChannel = false,
-			signalVector** channelResponse = NULL,
-			float *channelResponseOffset = NULL);
+                        signalVector** channelResponse = NULL,
+                        float *channelResponseOffset = NULL);
 
 /**
 	Decimate a vector.

utils/clockdump.sh

@@ -0,0 +1,3 @@
+#!/bin/sh
+sudo tcpdump -i lo0 -A udp port 5700
+