Transceiver52M: Add dual channel diversity receiver option

This patch add support for dual channel diversity on the receive
path. This allows two antennas two shared antennas to be used for
each ARFCN handling channel in the receiver. This configuration
may improvde performance in multi-path fading environments,
however, noise andpotential interference levels are increased due
to the higher bandwidth used.

The receive path is oversampled by a factor of four for a rate
of 1.083333 Msps. If the receive paths are tuned within a
maximum channel spacing (currently set at 600 kHz), then both
ARFCN frequencies are processed by each channel of the receiver.
Otherwise, the frequency shifted diversity path is disabled and
standard non-diversity operation takes place.

Diversity processing is handled by selecting the path with the
higheset energy level and discarding the burst on the second
path. Selection occurs on a burst-by-burst basis.

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

11 files changed, 390 insertions, 50 deletions

diff --git a/Transceiver52M/Makefile.am b/Transceiver52M/Makefile.am
index 8b37ea4..0e2276f 100644
--- a/Transceiver52M/Makefile.am
+++ b/Transceiver52M/Makefile.am
@@ -61,7 +61,8 @@ COMMON_SOURCES = \
 libtransceiver_la_SOURCES = \
 	$(COMMON_SOURCES) \
 	Resampler.cpp \
-	radioInterfaceResamp.cpp
+	radioInterfaceResamp.cpp \
+	radioInterfaceDiversity.cpp
 
 noinst_PROGRAMS = \
 	transceiver
diff --git a/Transceiver52M/Transceiver.cpp b/Transceiver52M/Transceiver.cpp
index 01fec5b..eae4e06 100644
--- a/Transceiver52M/Transceiver.cpp
+++ b/Transceiver52M/Transceiver.cpp
@@ -422,6 +422,7 @@ SoftVector *Transceiver::pullRadioVector(GSM::Time &wTime, int &RSSI,
   bool success, equalize = false;
   complex amp;
   float toa, pow, max = -1.0, avg = 0.0;
+  int max_i = -1;
   signalVector *burst;
   SoftVector *bits;
 
@@ -439,8 +440,24 @@ SoftVector *Transceiver::pullRadioVector(GSM::Time &wTime, int &RSSI,
     return NULL;
   }
 
+  /* Select the diversity channel with highest energy */
+  for (size_t i = 0; i < radio_burst->chans(); i++) {
+    energyDetect(*radio_burst->getVector(i), 20 * mSPSRx, 0.0, &pow);
+    if (pow > max) {
+      max = pow;
+      max_i = i;
+    }
+    avg += pow;
+  }
+
+  if (max_i < 0) {
+    LOG(ALERT) << "Received empty burst";
+    delete radio_burst;
+    return NULL;
+  }
+
   /* Average noise on diversity paths and update global levels */
-  burst = radio_burst->getVector();
+  burst = radio_burst->getVector(max_i);
   avg = avg / radio_burst->chans();
   mNoiseLev = mNoises.avg();
   avg = sqrt(avg);
diff --git a/Transceiver52M/UHDDevice.cpp b/Transceiver52M/UHDDevice.cpp
index 681f939..915cf32 100644
--- a/Transceiver52M/UHDDevice.cpp
+++ b/Transceiver52M/UHDDevice.cpp
@@ -78,17 +78,46 @@ static struct uhd_dev_offset uhd_offsets[NUM_USRP_TYPES * 2] = {
 	{ UMTRX, 4, 7.3846e-5, "UmTRX 4 SPS" },
 };
 
-static double get_dev_offset(enum uhd_dev_type type, int sps)
+/*
+ * Offset handling for special cases. Currently used for UmTRX dual channel
+ * diversity receiver only.
+ */
+static struct uhd_dev_offset special_offsets[] = {
+	{ UMTRX, 1, 8.0875e-5, "UmTRX diversity, 1 SPS" },
+	{ UMTRX, 4, 5.2103e-5, "UmTRX diversity, 4 SPS" },
+};
+
+static double get_dev_offset(enum uhd_dev_type type,
+			     int sps, bool diversity = false)
 {
+	/* Reject USRP1 */
 	if (type == USRP1) {
 		LOG(ERR) << "Invalid device type";
 		return 0.0;
 	}
 
+	/* Special cases (e.g. diversity receiver) */
+	if (diversity) {
+		if (type != UMTRX) {
+			LOG(ALERT) << "Diversity on UmTRX only";
+			return 0.0;
+		}
+
+		switch (sps) {
+		case 1:
+			return special_offsets[0].offset;
+		case 4:
+		default:
+			return special_offsets[1].offset;
+		}
+	}
+
+	/* Normal operation */
 	switch (sps) {
 	case 1:
 		return uhd_offsets[2 * type + 0].offset;
 	case 4:
+	default:
 		return uhd_offsets[2 * type + 1].offset;
 	}
 
@@ -101,8 +130,15 @@ static double get_dev_offset(enum uhd_dev_type type, int sps)
  * The base rate is either GSM symbol rate, 270.833 kHz, or the minimum
  * usable channel spacing of 400 kHz.
  */
-static double select_rate(uhd_dev_type type, int sps)
+static double select_rate(uhd_dev_type type, int sps, bool diversity = false)
 {
+	if (diversity && (type == UMTRX)) {
+		return GSMRATE * 4;
+	} else if (diversity) {
+		LOG(ALERT) << "Diversity supported on UmTRX only";
+		return -9999.99;
+	}
+
 	if ((sps != 4) && (sps != 1))
 		return -9999.99;
 
@@ -212,7 +248,7 @@ private:
 */
 class uhd_device : public RadioDevice {
 public:
-	uhd_device(size_t sps, size_t chans);
+	uhd_device(size_t sps, size_t chans, bool diversity);
 	~uhd_device();
 
 	int open(const std::string &args, bool extref);
@@ -305,6 +341,7 @@ private:
 	std::string str_code(uhd::async_metadata_t metadata);
 
 	Thread async_event_thrd;
+	bool diversity;
 };
 
 void *async_event_loop(uhd_device *dev)
@@ -339,7 +376,7 @@ void uhd_msg_handler(uhd::msg::type_t type, const std::string &msg)
 	}
 }
 
-uhd_device::uhd_device(size_t sps, size_t chans)
+uhd_device::uhd_device(size_t sps, size_t chans, bool diversity)
 	: tx_gain_min(0.0), tx_gain_max(0.0),
 	  rx_gain_min(0.0), rx_gain_max(0.0),
 	  tx_spp(0), rx_spp(0),
@@ -348,6 +385,7 @@ uhd_device::uhd_device(size_t sps, size_t chans)
 {
 	this->sps = sps;
 	this->chans = chans;
+	this->diversity = diversity;
 }
 
 uhd_device::~uhd_device()
@@ -600,8 +638,13 @@ int uhd_device::open(const std::string &args, bool extref)
 	rx_spp = rx_stream->get_max_num_samps();
 
 	// Set rates
+	double _rx_rate;
 	double _tx_rate = select_rate(dev_type, sps);
-	double _rx_rate = _tx_rate / sps;
+	if (diversity)
+		_rx_rate = select_rate(dev_type, 1, true);
+	else
+		_rx_rate = _tx_rate / sps;
+
 	if ((_tx_rate > 0.0) && (set_rates(_tx_rate, _rx_rate) < 0))
 		return -1;
 
@@ -611,7 +654,7 @@ int uhd_device::open(const std::string &args, bool extref)
 		rx_buffers[i] = new smpl_buf(buf_len, rx_rate);
 
 	// Set receive chain sample offset 
-	double offset = get_dev_offset(dev_type, sps);
+	double offset = get_dev_offset(dev_type, sps, diversity);
 	if (offset == 0.0) {
 		LOG(ERR) << "Unsupported configuration, no correction applied";
 		ts_offset = 0;
@@ -625,11 +668,16 @@ int uhd_device::open(const std::string &args, bool extref)
 	// Print configuration
 	LOG(INFO) << "\n" << usrp_dev->get_pp_string();
 
+	if (diversity)
+		return DIVERSITY;
+
 	switch (dev_type) {
 	case B100:
 		return RESAMP_64M;
 	case USRP2:
 		return RESAMP_100M;
+	default:
+		break;
 	}
 
 	return NORMAL;
@@ -1173,7 +1221,7 @@ std::string smpl_buf::str_code(ssize_t code)
 	}
 }
 
-RadioDevice *RadioDevice::make(size_t sps, size_t chans)
+RadioDevice *RadioDevice::make(size_t sps, size_t chans, bool diversity)
 {
-	return new uhd_device(sps, chans);
+	return new uhd_device(sps, chans, diversity);
 }
diff --git a/Transceiver52M/USRPDevice.cpp b/Transceiver52M/USRPDevice.cpp
index e330bc3..e00d54e 100644
--- a/Transceiver52M/USRPDevice.cpp
+++ b/Transceiver52M/USRPDevice.cpp
@@ -59,8 +59,7 @@ const dboardConfigType dboardConfig = TXA_RXB;
 
 const double USRPDevice::masterClockRate = 52.0e6;
 
-USRPDevice::USRPDevice(size_t sps, size_t)
-  : skipRx(skipRx)
+USRPDevice::USRPDevice(size_t sps, size_t, bool)
 {
   LOG(INFO) << "creating USRP device...";
 
@@ -601,7 +600,7 @@ bool USRPDevice::setTxFreq(double wFreq) { return true;};
 bool USRPDevice::setRxFreq(double wFreq) { return true;};
 #endif
 
-RadioDevice *RadioDevice::make(size_t sps, size_t chans)
+RadioDevice *RadioDevice::make(size_t sps, size_t chans, bool diversity)
 {
-	return new USRPDevice(sps, chans);
+	return new USRPDevice(sps, chans, diversity);
 }
diff --git a/Transceiver52M/USRPDevice.h b/Transceiver52M/USRPDevice.h
index c9f98ed..0807127 100644
--- a/Transceiver52M/USRPDevice.h
+++ b/Transceiver52M/USRPDevice.h
@@ -96,7 +96,7 @@ private:
  public:
 
   /** Object constructor */
-  USRPDevice(size_t sps, size_t chans = 1);
+  USRPDevice(size_t sps, size_t chans = 1, bool diversity = false);
 
   /** Instantiate the USRP */
   int open(const std::string &, bool);
diff --git a/Transceiver52M/radioDevice.h b/Transceiver52M/radioDevice.h
index 19b5a88..10a0b4d 100644
--- a/Transceiver52M/radioDevice.h
+++ b/Transceiver52M/radioDevice.h
@@ -35,9 +35,10 @@ class RadioDevice {
   enum TxWindowType { TX_WINDOW_USRP1, TX_WINDOW_FIXED };
 
   /* Radio interface types */
-  enum RadioInterfaceType { NORMAL, RESAMP_64M, RESAMP_100M };
+  enum RadioInterfaceType { NORMAL, RESAMP_64M, RESAMP_100M, DIVERSITY };
 
-  static RadioDevice *make(size_t sps, size_t chans = 1);
+  static RadioDevice *make(size_t sps, size_t chans = 1,
+                           bool diversity = false);
 
   /** Initialize the USRP */
   virtual int open(const std::string &args = "", bool extref = false)=0;
diff --git a/Transceiver52M/radioInterface.cpp b/Transceiver52M/radioInterface.cpp
index 43fa3a3..ff9f493 100644
--- a/Transceiver52M/radioInterface.cpp
+++ b/Transceiver52M/radioInterface.cpp
@@ -34,10 +34,9 @@ extern "C" {
 #define NUMCHUNKS	4
 
 RadioInterface::RadioInterface(RadioDevice *wRadio,
-			       int wReceiveOffset,
-			       size_t sps, size_t chans,
-			       GSM::Time wStartTime)
-  : mRadio(wRadio), mSPSTx(sps), mSPSRx(1), mChans(chans),
+                               size_t sps, size_t chans, size_t diversity,
+                               int wReceiveOffset, GSM::Time wStartTime)
+  : mRadio(wRadio), mSPSTx(sps), mSPSRx(1), mChans(chans), mMIMO(diversity),
     sendCursor(0), recvCursor(0), underrun(false), overrun(false),
     receiveOffset(wReceiveOffset), mOn(false), powerScaling(1.0),
     loadTest(false)
@@ -52,11 +51,8 @@ RadioInterface::~RadioInterface(void)
 
 bool RadioInterface::init(int type)
 {
-  if (type != RadioDevice::NORMAL)
-    return false;
-
-  if (!mChans) {
-    LOG(ALERT) << "Invalid number of channels " << mChans;
+  if ((type != RadioDevice::NORMAL) || (mMIMO > 1) || !mChans) {
+    LOG(ALERT) << "Invalid configuration";
     return false;
   }
 
@@ -251,10 +247,14 @@ bool RadioInterface::driveReceiveRadio()
    */
   while (recvSz > burstSize) {
     for (size_t i = 0; i < mChans; i++) {
-      burst = new radioVector(rcvClock, burstSize, head);
+      burst = new radioVector(rcvClock, burstSize, head, mMIMO);
+
+      for (size_t n = 0; n < mMIMO; n++) {
+        unRadioifyVector((float *)
+                         (recvBuffer[mMIMO * i + n]->begin() + readSz),
+                         *burst->getVector(n));
+      }
 
-      unRadioifyVector((float *) (recvBuffer[i]->begin() + readSz),
-                       *burst->getVector());
 
       if (mReceiveFIFO[i].size() < 32)
         mReceiveFIFO[i].write(burst);
diff --git a/Transceiver52M/radioInterface.h b/Transceiver52M/radioInterface.h
index 124cdc3..95ef2b2 100644
--- a/Transceiver52M/radioInterface.h
+++ b/Transceiver52M/radioInterface.h
@@ -20,6 +20,7 @@
 #include "radioDevice.h"
 #include "radioVector.h"
 #include "radioClock.h"
+#include "Resampler.h"
 
 static const unsigned gSlotLen = 148;      ///< number of symbols per slot, not counting guard periods
 
@@ -37,6 +38,8 @@ protected:
   size_t mSPSTx;
   size_t mSPSRx;
   size_t mChans;
+  size_t mMIMO;
+
   std::vector<signalVector *> sendBuffer;
   std::vector<signalVector *> recvBuffer;
   unsigned sendCursor;
@@ -89,9 +92,8 @@ public:
 
   /** constructor */
   RadioInterface(RadioDevice* wRadio = NULL,
-		 int receiveOffset = 3,
-		 size_t sps = 4, size_t chans = 1,
-		 GSM::Time wStartTime = GSM::Time(0));
+                 size_t sps = 4, size_t chans = 1, size_t diversity = 1,
+                 int receiveOffset = 3, GSM::Time wStartTime = GSM::Time(0));
 
   /** destructor */
   virtual ~RadioInterface();
@@ -109,7 +111,7 @@ public:
   bool tuneTx(double freq, size_t chan = 0);
 
   /** set receive frequency */
-  bool tuneRx(double freq, size_t chan = 0);
+  virtual bool tuneRx(double freq, size_t chan = 0);
 
   /** set receive gain */
   double setRxGain(double dB, size_t chan = 0);
@@ -166,13 +168,33 @@ private:
 
 public:
 
-  RadioInterfaceResamp(RadioDevice* wRadio = NULL,
-		       int receiveOffset = 3,
-		       size_t wSPS = 4, size_t chans = 1,
-		       GSM::Time wStartTime = GSM::Time(0));
+  RadioInterfaceResamp(RadioDevice* wRadio, size_t wSPS = 4, size_t chans = 1);
 
   ~RadioInterfaceResamp();
 
   bool init(int type);
   void close();
 };
+
+class RadioInterfaceDiversity : public RadioInterface {
+public:
+  RadioInterfaceDiversity(RadioDevice* wRadio,
+                          size_t sps = 4, size_t chans = 2);
+
+  ~RadioInterfaceDiversity();
+
+  bool init(int type);
+  void close();
+  bool tuneRx(double freq, size_t chan);
+
+private:
+  std::vector<Resampler *> dnsamplers;
+  std::vector<float> phases;
+  signalVector *outerRecvBuffer;
+
+  bool mDiversity;
+  double mFreqSpacing;
+
+  bool setupDiversityChannels();
+  void pullBuffer();
+};
diff --git a/Transceiver52M/radioInterfaceDiversity.cpp b/Transceiver52M/radioInterfaceDiversity.cpp
new file mode 100644
index 0000000..8e921b1
--- /dev/null
+++ b/Transceiver52M/radioInterfaceDiversity.cpp
@@ -0,0 +1,248 @@
+/*
+ * SSE Convolution
+ * Copyright (C) 2013 Thomas Tsou <tom@tsou.cc>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <radioInterface.h>
+#include <Logger.h>
+
+#include "Resampler.h"
+
+extern "C" {
+#include "convert.h"
+}
+
+/* Resampling parameters for 64 MHz clocking */
+#define RESAMP_64M_INRATE			20
+#define RESAMP_64M_OUTRATE			80
+
+/* Downlink block size */
+#define CHUNK					625
+
+/* Universal resampling parameters */
+#define NUMCHUNKS				48
+
+/*
+ * Resampling filter bandwidth scaling factor
+ *   This narrows the filter cutoff relative to the output bandwidth
+ *   of the polyphase resampler. At 4 samples-per-symbol using the
+ *   2 pulse Laurent GMSK approximation gives us below 0.5 degrees
+ *   RMS phase error at the resampler output.
+ */
+#define RESAMP_TX4_FILTER		0.45
+
+static size_t resamp_inrate = 0;
+static size_t resamp_inchunk = 0;
+static size_t resamp_outrate = 0;
+static size_t resamp_outchunk = 0;
+
+RadioInterfaceDiversity::RadioInterfaceDiversity(RadioDevice *wRadio,
+						 size_t sps, size_t chans)
+	: RadioInterface(wRadio, sps, chans, 2), outerRecvBuffer(NULL),
+	  mDiversity(false), mFreqSpacing(0.0)
+{
+}
+
+RadioInterfaceDiversity::~RadioInterfaceDiversity()
+{
+	close();
+}
+
+void RadioInterfaceDiversity::close()
+{
+	delete outerRecvBuffer;
+
+	outerRecvBuffer = NULL;
+
+	for (size_t i = 0; i < dnsamplers.size(); i++) {
+		delete dnsamplers[i];
+		dnsamplers[i] = NULL;
+	}
+
+	if (recvBuffer.size())
+		recvBuffer[0] = NULL;
+
+	RadioInterface::close();
+}
+
+bool RadioInterfaceDiversity::setupDiversityChannels()
+{
+	size_t inner_rx_len;
+
+	/* Inner and outer rates */
+	resamp_inrate = RESAMP_64M_INRATE;
+	resamp_outrate = RESAMP_64M_OUTRATE;
+	resamp_inchunk = resamp_inrate * 4;
+	resamp_outchunk = resamp_outrate * 4;
+
+	/* Buffer lengths */
+	inner_rx_len = NUMCHUNKS * resamp_inchunk;
+
+	/* Inside buffer must hold at least 2 bursts */
+	if (inner_rx_len < 157 * mSPSRx * 2) {
+		LOG(ALERT) << "Invalid inner buffer size " << inner_rx_len;
+		return false;
+	}
+
+	/* One Receive buffer and downsampler per diversity channel */
+	for (size_t i = 0; i < mMIMO * mChans; i++) {
+		dnsamplers[i] = new Resampler(resamp_inrate, resamp_outrate);
+		if (!dnsamplers[i]->init()) {
+			LOG(ALERT) << "Rx resampler failed to initialize";
+			return false;
+		}
+
+		recvBuffer[i] = new signalVector(inner_rx_len);
+	}
+
+	return true;
+}
+
+/* Initialize I/O specific objects */
+bool RadioInterfaceDiversity::init(int type)
+{
+	int tx_len, outer_rx_len;
+
+	if ((mMIMO != 2) || (mChans != 2)) {
+		LOG(ALERT) << "Unsupported channel configuration " << mChans;
+		return false;
+	}
+
+	/* Resize for channel combination */
+	sendBuffer.resize(mChans);
+	recvBuffer.resize(mChans * mMIMO);
+	convertSendBuffer.resize(mChans);
+	convertRecvBuffer.resize(mChans);
+	mReceiveFIFO.resize(mChans);
+	dnsamplers.resize(mChans * mMIMO);
+	phases.resize(mChans);
+
+	if (!setupDiversityChannels())
+		return false;
+
+	tx_len = CHUNK * mSPSTx;
+	outer_rx_len = resamp_outchunk;
+
+	for (size_t i = 0; i < mChans; i++) {
+		/* Full rate float and integer outer receive buffers */
+		convertRecvBuffer[i] = new short[outer_rx_len * 2];
+
+		/* Send buffers (not-resampled) */
+		sendBuffer[i] = new signalVector(tx_len);
+		convertSendBuffer[i] = new short[tx_len * 2];
+	}
+
+	outerRecvBuffer = new signalVector(outer_rx_len, dnsamplers[0]->len());
+
+	return true;
+}
+
+bool RadioInterfaceDiversity::tuneRx(double freq, size_t chan)
+{
+	double f0, f1;
+
+	if (chan > 1)
+		return false;
+
+	if (!mRadio->setRxFreq(freq, chan))
+		return false;
+
+	f0 = mRadio->getRxFreq(0);
+	f1 = mRadio->getRxFreq(1);
+
+	mFreqSpacing = f1 - f0;
+
+	if (abs(mFreqSpacing) <= 600e3)
+		mDiversity = true;
+	else
+		mDiversity = false;
+
+	return true;
+}
+
+/* Receive a timestamped chunk from the device */
+void RadioInterfaceDiversity::pullBuffer()
+{
+	bool local_underrun;
+	int rc, num, path0, path1;
+	signalVector *shift, *base;
+	float *in, *out, rate = -mFreqSpacing * 2.0 * M_PI / 1.08333333e6;
+
+	if (recvCursor > recvBuffer[0]->size() - resamp_inchunk)
+		return;
+
+	/* Outer buffer access size is fixed */
+	num = mRadio->readSamples(convertRecvBuffer,
+				  resamp_outchunk,
+				  &overrun,
+				  readTimestamp,
+				  &local_underrun);
+	if ((size_t) num != resamp_outchunk) {
+		LOG(ALERT) << "Receive error " << num;
+		return;
+	}
+
+	for (size_t i = 0; i < mChans; i++) {
+		convert_short_float((float *) outerRecvBuffer->begin(),
+			    convertRecvBuffer[i], 2 * resamp_outchunk);
+
+		if (!i) {
+			path0 = 0;
+			path1 = 2;
+		} else {
+			path0 = 3;
+			path1 = 1;
+		}
+
+		/* Diversity path 1 */
+		base = outerRecvBuffer;
+		in = (float *) base->begin();
+		out = (float *) (recvBuffer[path0]->begin() + recvCursor);
+
+		rc = dnsamplers[2 * i + 0]->rotate(in, resamp_outchunk,
+						   out, resamp_inchunk);
+		if (rc < 0) {
+			LOG(ALERT) << "Sample rate downsampling error";
+		}
+
+		/* Enable path 2 if Nyquist bandwidth is sufficient */
+		if (!mDiversity)
+			continue;
+
+		/* Diversity path 2 */
+		shift = new signalVector(base->size(), base->getStart());
+		in = (float *) shift->begin();
+		out = (float *) (recvBuffer[path1]->begin() + recvCursor);
+
+		rate = i ? -rate : rate;
+		if (!frequencyShift(shift, base, rate, phases[i], &phases[i])) {
+			LOG(ALERT) << "Frequency shift failed";
+		}
+
+		rc = dnsamplers[2 * i + 1]->rotate(in, resamp_outchunk,
+						   out, resamp_inchunk);
+		if (rc < 0) {
+			LOG(ALERT) << "Sample rate downsampling error";
+		}
+
+		delete shift;
+	}
+
+	underrun |= local_underrun;
+	readTimestamp += (TIMESTAMP) resamp_outchunk;
+	recvCursor += resamp_inchunk;
+}
diff --git a/Transceiver52M/radioInterfaceResamp.cpp b/Transceiver52M/radioInterfaceResamp.cpp
index 95ed16d..6f14a42 100644
--- a/Transceiver52M/radioInterfaceResamp.cpp
+++ b/Transceiver52M/radioInterfaceResamp.cpp
@@ -50,16 +50,14 @@ extern "C" {
 
 static Resampler *upsampler = NULL;
 static Resampler *dnsampler = NULL;
-static int resamp_inrate = 0;
-static int resamp_inchunk = 0;
-static int resamp_outrate = 0;
-static int resamp_outchunk = 0;
+static size_t resamp_inrate = 0;
+static size_t resamp_inchunk = 0;
+static size_t resamp_outrate = 0;
+static size_t resamp_outchunk = 0;
 
 RadioInterfaceResamp::RadioInterfaceResamp(RadioDevice *wRadio,
-					   int wReceiveOffset,
-					   size_t sps, size_t chan,
-					   GSM::Time wStartTime)
-	: RadioInterface(wRadio, wReceiveOffset, sps, chan, wStartTime),
+					   size_t sps, size_t chans)
+	: RadioInterface(wRadio, sps, chans),
 	  innerSendBuffer(NULL), outerSendBuffer(NULL),
 	  innerRecvBuffer(NULL), outerRecvBuffer(NULL)
 {
@@ -191,7 +189,7 @@ void RadioInterfaceResamp::pullBuffer()
 				       &overrun,
 				       readTimestamp,
 				       &local_underrun);
-	if (num_recv != resamp_outchunk) {
+	if (num_recv != (int) resamp_outchunk) {
 		LOG(ALERT) << "Receive error " << num_recv;
 		return;
 	}
diff --git a/Transceiver52M/runTransceiver.cpp b/Transceiver52M/runTransceiver.cpp
index e85ce56..a2267e2 100644
--- a/Transceiver52M/runTransceiver.cpp
+++ b/Transceiver52M/runTransceiver.cpp
@@ -114,7 +114,7 @@ int testConfig(const char *filename)
 
 int main(int argc, char *argv[])
 {
-  int trxPort, radioType, chans = 1, extref = 0, fail = 0;
+  int trxPort, radioType, chans = 1, extref = 0, fail = 0, diversity = 0;
   std::string logLevel, trxAddr, deviceArgs = "";
   RadioDevice *usrp = NULL;
   RadioInterface *radio = NULL;
@@ -162,7 +162,10 @@ int main(int argc, char *argv[])
 
   srandom(time(NULL));
 
-  usrp = RadioDevice::make(SPS, chans);
+  if (diversity)
+    chans = 2;
+
+  usrp = RadioDevice::make(SPS, chans, diversity);
   radioType = usrp->open(deviceArgs, extref);
   if (radioType < 0) {
     LOG(ALERT) << "Transceiver exiting..." << std::endl;
@@ -171,11 +174,14 @@ int main(int argc, char *argv[])
 
   switch (radioType) {
   case RadioDevice::NORMAL:
-    radio = new RadioInterface(usrp, 3, SPS, chans);
+    radio = new RadioInterface(usrp, SPS, chans);
     break;
   case RadioDevice::RESAMP_64M:
   case RadioDevice::RESAMP_100M:
-    radio = new RadioInterfaceResamp(usrp, 3, SPS, chans);
+    radio = new RadioInterfaceResamp(usrp, SPS, chans);
+    break;
+  case RadioDevice::DIVERSITY:
+    radio = new RadioInterfaceDiversity(usrp, SPS, chans);
     break;
   default:
     LOG(ALERT) << "Unsupported configuration";