diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
index 05d5617..32c61b3 100644
--- a/examples/CMakeLists.txt
+++ b/examples/CMakeLists.txt
@@ -10,8 +10,14 @@ IF(SDR_WITH_PORTAUDIO)
  add_executable(sdr_fm sdr_fm.cc)
  target_link_libraries(sdr_fm ${LIBS} libsdr)
 
-add_executable(sdr_afsk1200 sdr_afsk1200.cc)
-target_link_libraries(sdr_afsk1200 ${LIBS} libsdr)
+ add_executable(sdr_rec sdr_rec.cc)
+ target_link_libraries(sdr_rec ${LIBS} libsdr)
+
+ add_executable(sdr_wspr sdr_wspr.cc)
+ target_link_libraries(sdr_wspr ${LIBS} libsdr)
+
+ add_executable(sdr_afsk1200 sdr_afsk1200.cc)
+ target_link_libraries(sdr_afsk1200 ${LIBS} libsdr)
 ENDIF(SDR_WITH_PORTAUDIO)
 
 IF(SDR_WITH_QT5 AND SDR_WITH_FFTW AND SDR_WITH_PORTAUDIO)
@@ -22,3 +28,6 @@ ENDIF(SDR_WITH_QT5 AND SDR_WITH_FFTW AND SDR_WITH_PORTAUDIO)
 add_executable(sdr_psk31 sdr_psk31.cc)
 target_link_libraries(sdr_psk31 ${LIBS} ${QT_LIBRARIES} libsdr libsdr-gui)
 
+add_executable(sdr_rtty sdr_rtty.cc)
+target_link_libraries(sdr_rtty ${LIBS} libsdr)
+
diff --git a/examples/sdr_afsk1200.cc b/examples/sdr_afsk1200.cc
index 59caab0..95ecc31 100644
--- a/examples/sdr_afsk1200.cc
+++ b/examples/sdr_afsk1200.cc
@@ -76,11 +76,10 @@ public:
     // The input sample rate
     _sampleRate = src_cfg.sampleRate();
 
-    // Symbols per bit (limit to 32 symbols per bit)
-    _corrLen = std::min(int(_sampleRate/_baud), 31);
-
+    // Samples per bit
+    _corrLen = int(_sampleRate/_baud);
     // Compute symbol rate:
-    _symbolRate = _baud*_corrLen;
+    _symbolRate = std::min(10*_baud, _baud*_corrLen);
 
     // Samples per symbol (fractional):
     _mu = 0.0; _muIncr = _sampleRate/_symbolRate;
@@ -102,15 +101,17 @@ public:
     for (size_t i=0; i<_corrLen; i++) {
       _markLUT[i] = std::exp(std::complex<float>(0.0, phiMark));
       _spaceLUT[i] = std::exp(std::complex<float>(0.0, phiSpace));
-      phiMark  += (2.*M_PI*_Fmark)/_symbolRate;
-      phiSpace += (2.*M_PI*_Fspace)/_symbolRate;
+      phiMark  += (2.*M_PI*_Fmark)/_sampleRate;
+      phiSpace += (2.*M_PI*_Fspace)/_sampleRate;
       _markHist[i] = 0; _spaceHist[i] = 0;
     }
     _lutIdx = 0;
 
     // Get phase increment per symbol
-    //  equiv. to _phasePeriod*_baud/_symbolRate
-    _phase = 0; _phaseInc = _baud/_symbolRate;
+    _phase = 0; _omega = _baud/_symbolRate;
+    _omegaMin = _omega - 0.01*_omega;
+    _omegaMax = _omega + 0.01*_omega;
+    _gainOmega = 0.01;
 
     // Allocate output buffer:
     _buffer = Buffer<uint8_t>(src_cfg.bufferSize()/_corrLen + 1);
@@ -121,7 +122,7 @@ public:
         << " samples per symbol: " << _muIncr << std::endl
         << " symbols per bit: " << _corrLen << std::endl
         << " symbol rate: " << _symbolRate << "Hz" << std::endl
-        << " Phase incr/symbol: " << float(_phaseInc)/_phasePeriod;
+        << " Phase incr/symbol: " << float(_omega);
 
     Logger::get().log(msg);
 
@@ -134,34 +135,24 @@ public:
     while (i<buffer.size()) {
       // Update sub-sampler
       while ((_mu>1) && (i<buffer.size())) {
-        // Put sample into delay line
-        _dl[_dl_idx] = buffer[i]; _dl[_dl_idx+8] = buffer[i];
+        _markHist[_lutIdx] = float(buffer[i])*_markLUT[_lutIdx];
+        _spaceHist[_lutIdx] = float(buffer[i])*_spaceLUT[_lutIdx];
+        // Modulo LUT length
+        _lutIdx++; if (_lutIdx==_corrLen) { _lutIdx=0; }
+        float symbol = _getSymbol();
+        // Put symbol into delay line
+        _dl[_dl_idx] = symbol; _dl[_dl_idx+8] = symbol;
         _dl_idx = (_dl_idx+1)%8; _mu -= 1; i++;
       }
 
+
       if (i<buffer.size()) {
-        // Get sample
+        // Get interpolated symbol
         float sample = interpolate(_dl.sub(_dl_idx, 8), _mu); _mu += _muIncr;
-        _markHist[_lutIdx] = sample*_markLUT[_lutIdx];
-        _spaceHist[_lutIdx] = sample*_spaceLUT[_lutIdx];
-        // Modulo LUT length
-        _lutIdx++; if (_lutIdx==_corrLen) { _lutIdx=0; }
-        float f = _getSymbol();
         // Get symbol
-        _symbols <<= 1; _symbols |= (f>0);
-
-        // If transition
-        if ((_symbols ^ (_symbols >> 1)) & 1) {
-          // Phase correction
-          if (_phase < 0.5) {
-            _phase -= _phase/10;
-          } else {
-            _phase += (1-_phase)/10;
-          }
-        }
-
+        _symbols <<= 1; _symbols |= (sample>0);
         // Advance phase
-        _phase += _phaseInc;
+        _phase += _omega;
 
         // Sample bit
         if (_phase >= 1) {
@@ -170,8 +161,21 @@ public:
           // Store bit
           _lastBits <<= 1; _lastBits |= (_symbols & 1);
           // Put decoded bit in output buffer
+          // transition -> 0; no transition -> 1
           _buffer[o++] = ((_lastBits ^ (_lastBits >> 1) ^ 1) & 1);
         }
+
+        // If transition
+        if ((_symbols ^ (_symbols >> 1)) & 1) {
+          // Phase correction
+          /*std::cerr << "Transition at phi=" << _phase << std::endl
+                    << "  update omega from " << _omega << " to "; */
+          if (_phase < 0.5) { _omega -= _gainOmega*(_phase); }
+          else { _omega += _gainOmega*(1-_phase); }
+          // Limit omega
+          _omega = std::min(_omegaMax, std::max(_omegaMin, _omega));
+          //std::cerr << _omega << std::endl;
+        }
       }
     }
     this->send(_buffer.head(o));
@@ -213,7 +217,8 @@ protected:
   uint32_t _symbols;
   uint32_t _lastBits;
   float _phase;
-  float _phaseInc;
+  float _omega, _omegaMin, _omegaMax;
+  float _gainOmega;
 
   static const uint32_t _phasePeriod = 0x10000u;
   static const uint32_t _phaseMask   = 0x0ffffu;
diff --git a/examples/sdr_rec.cc b/examples/sdr_rec.cc
new file mode 100644
index 0000000..bd8e6c0
--- /dev/null
+++ b/examples/sdr_rec.cc
@@ -0,0 +1,130 @@
+#include "demod.hh"
+#include "rtlsource.hh"
+#include "baseband.hh"
+#include "autocast.hh"
+#include "portaudio.hh"
+#include "wavfile.hh"
+
+#include <iostream>
+#include <csignal>
+
+using namespace sdr;
+
+static void __sigint_handler(int signo) {
+  std::cerr << "Stop Queue..." << std::endl;
+  // On SIGINT -> stop queue properly
+  Queue::get().stop();
+  Queue::get().wait();
+}
+
+
+int main(int argc, char *argv[]) {
+  if (3 > argc) {
+    std::cout << "USAGE: sdr_rec FREQUENCY MODE [OUTPUT.wav]" << std::endl; return -1;
+  }
+
+  // get frequency
+  double freq = atof(argv[1]);
+  std::string mode = argv[2];
+  // Get output file (if given)
+  std::string outFile;
+  if (4 <= argc) { outFile = argv[3]; }
+
+  sdr::Logger::get().addHandler(
+        new sdr::StreamLogHandler(std::cerr, sdr::LOG_DEBUG));
+
+  // Register handler:
+  signal(SIGINT, __sigint_handler);
+
+  PortAudio::init();
+
+  // obtain base-band config
+  double f_center = 0, f_filter = 0, flt_width = 0;
+  int sub_sample = 1; double out_f_sample = 12e3;
+  if (mode == "WFM") {
+    f_center = 0; f_filter = 0; flt_width = 50e3;
+    out_f_sample = 48e3;
+  } else if (mode == "NFM") {
+    f_center = 0; f_filter = 0; flt_width = 12.5e3;
+    out_f_sample = 12e3;
+  } else if (mode == "AM") {
+    f_center = 0; f_filter = 0; flt_width = 15e3;
+    out_f_sample = 12e3;
+  } else if (mode == "USB") {
+    f_center = 0; f_filter = 1500; flt_width = 3e3;
+    out_f_sample = 12e3;
+  } else if (mode == "LSB") {
+    f_center = 0; f_filter = -1500; flt_width = 3e3;
+    out_f_sample = 12e3;
+  } else {
+    std::cerr << "Unknown mode '" << mode
+              << "': Possible values are WFM, NFM, AM, USB, LSB." << std::endl;
+    return -1;
+  }
+
+  // Create nodes
+  RTLSource src(freq, 1e6);
+  AutoCast< std::complex<int16_t> > cast;
+  IQBaseBand<int16_t> baseband(f_center, f_filter, flt_width, 16, sub_sample, out_f_sample);
+  FMDemod<int16_t>    *fm_demod = 0;
+  FMDeemph<int16_t>   *fm_deemph = 0;
+  AMDemod<int16_t>    *am_demod = 0;
+  USBDemod<int16_t>   *usb_demod = 0;
+  PortSink            audio;
+  WavSink<int16_t>    *wav_sink = 0;
+
+  if (outFile.size()) {
+    wav_sink = new WavSink<int16_t>(outFile);
+  }
+
+  // Assemble processing chain:
+  src.connect(&cast, true);
+  cast.connect(&baseband);
+
+  if (mode == "WFM") {
+    fm_demod = new FMDemod<int16_t>();
+    fm_deemph= new FMDeemph<int16_t>();
+    baseband.connect(fm_demod, true);
+    fm_demod->connect(fm_deemph, true);
+    fm_deemph->connect(&audio);
+    if (wav_sink) { fm_deemph->connect(wav_sink); }
+  } else if (mode == "NFM") {
+    fm_demod = new FMDemod<int16_t>();
+    fm_deemph= new FMDeemph<int16_t>();
+    fm_demod->connect(fm_deemph, true);
+    baseband.connect(fm_demod, true);
+    fm_demod->connect(fm_deemph, true);
+    fm_deemph->connect(&audio);
+    if (wav_sink) { fm_deemph->connect(wav_sink); }
+  } else if (mode == "AM") {
+    am_demod = new AMDemod<int16_t>();
+    baseband.connect(am_demod);
+    am_demod->connect(&audio);
+    if (wav_sink) { am_demod->connect(wav_sink); }
+  } else if ((mode == "USB") || (mode == "LSB")){
+    usb_demod = new USBDemod<int16_t>();
+    baseband.connect(usb_demod);
+    usb_demod->connect(&audio);
+    if (wav_sink) { usb_demod->connect(wav_sink); }
+  }
+
+  Queue::get().addStart(&src, &RTLSource::start);
+  Queue::get().addStop(&src, &RTLSource::stop);
+
+  std::cerr << "Start recording at " << src.frequency()
+            << "Hz in mode " << mode << ". Press CTRL-C to stop recoding." << std::endl;
+
+  Queue::get().start();
+  Queue::get().wait();
+
+  if (fm_demod) { delete fm_demod; }
+  if (fm_deemph) { delete fm_deemph; }
+  if (usb_demod) { delete usb_demod; }
+  if (wav_sink) { delete wav_sink; }
+
+  PortAudio::terminate();
+
+  std::cerr << "Recording stopped." << std::endl;
+
+  return 0;
+}
diff --git a/examples/sdr_rtty.cc b/examples/sdr_rtty.cc
new file mode 100644
index 0000000..301d870
--- /dev/null
+++ b/examples/sdr_rtty.cc
@@ -0,0 +1,48 @@
+#include "baseband.hh"
+#include "autocast.hh"
+#include "demod.hh"
+#include "wavfile.hh"
+#include "portaudio.hh"
+
+using namespace sdr;
+
+static void __sigint_handler(int signo) {
+  // On SIGINT -> stop queue properly
+  Queue::get().stop();
+}
+
+
+int main(int argc, char *argv[]) {
+  if (2 != argc) {
+    std::cerr << "Usage: sdr_rtty FILENAME" << std::endl;
+    return -1;
+  }
+
+  sdr::Logger::get().addHandler(
+        new sdr::StreamLogHandler(std::cerr, sdr::LOG_DEBUG));
+
+  // Register handler:
+  signal(SIGINT, __sigint_handler);
+
+  PortAudio::init();
+  Queue &queue = Queue::get();
+
+  WavSource src(argv[1]);
+  AutoCast< std::complex<int16_t> > cast;
+  IQBaseBand<int16_t> baseband(0, 2144., 200.0, 63, 1);
+  baseband.setCenterFrequency(2144.0);
+
+  PortSink sink;
+  src.connect(&cast, true);
+  cast.connect(&baseband, true);
+  baseband.connect(&sink);
+
+  queue.addIdle(&src, &WavSource::next);
+
+  queue.start();
+  queue.wait();
+
+  PortAudio::terminate();
+
+  return 0;
+}
diff --git a/examples/sdr_wspr.cc b/examples/sdr_wspr.cc
new file mode 100644
index 0000000..aa834f3
--- /dev/null
+++ b/examples/sdr_wspr.cc
@@ -0,0 +1,72 @@
+#include "demod.hh"
+#include "rtlsource.hh"
+#include "baseband.hh"
+#include "autocast.hh"
+#include "portaudio.hh"
+#include "wavfile.hh"
+
+#include <iostream>
+#include <csignal>
+
+using namespace sdr;
+
+static void __sigint_handler(int signo) {
+  std::cerr << "Stop Queue..." << std::endl;
+  // On SIGINT -> stop queue properly
+  Queue::get().stop();
+  Queue::get().wait();
+}
+
+
+int main(int argc, char *argv[]) {
+  if (2 > argc) {
+    std::cout << "USAGE: sdr_wspr FREQUENCY [OUTPUT.wav]" << std::endl; return -1;
+  }
+
+  // get frequency
+  double freq = atof(argv[1]);
+  // Get output file (if given)
+  std::string outFile;
+  if (4 <= argc) { outFile = argv[3]; }
+
+
+  sdr::Logger::get().addHandler(
+        new sdr::StreamLogHandler(std::cerr, sdr::LOG_DEBUG));
+
+  // Register handler:
+  signal(SIGINT, __sigint_handler);
+
+  PortAudio::init();
+
+
+  // Create nodes
+  RTLSource src(freq, 240e3);   // <- set sample rate to 240kHz -> 20*12kHz
+  AutoCast< std::complex<int16_t> > cast;
+  IQBaseBand<int16_t> baseband(0, 1500, 3000, 16, 1, 12000);
+  USBDemod<int16_t>   usb_demod;
+  PortSink            audio;
+  WavSink<int16_t>    *wav_sink = outFile.size() ? new WavSink<int16_t>(outFile) : 0;
+
+  src.connect(&cast, true);
+  cast.connect(&baseband, true);
+  baseband.connect(&usb_demod, true);
+  usb_demod.connect(&audio, false);
+  if (wav_sink) { usb_demod.connect(wav_sink); }
+
+  Queue::get().addStart(&src, &RTLSource::start);
+  Queue::get().addStop(&src, &RTLSource::stop);
+
+  std::cerr << "Start recording at " << src.frequency()
+            << "Hz. Press CTRL-C to stop recoding." << std::endl;
+
+  Queue::get().start();
+  Queue::get().wait();
+
+  if (wav_sink) { delete wav_sink; }
+
+  PortAudio::terminate();
+
+  std::cerr << "Recording stopped." << std::endl;
+
+  return 0;
+}
diff --git a/src/baseband.hh b/src/baseband.hh
index a079575..4304fe4 100644
--- a/src/baseband.hh
+++ b/src/baseband.hh
@@ -32,7 +32,7 @@ public:
 public:
   /** Constructor, the filter center frequency @c Ff equals the given center frequency @c Fc. */
   IQBaseBand(double Fc, double width, size_t order, size_t sub_sample, double oFs=0.0)
-    : Sink<CScalar>(), Source(), FreqShiftBase<Scalar>(_Fc, 0),
+    : Sink<CScalar>(), Source(), FreqShiftBase<Scalar>(Fc, 0),
       _Fc(Fc), _Ff(Fc), _Fs(0), _width(width), _order(std::max(size_t(1), order)),
       _sub_sample(sub_sample), _oFs(oFs), _ring_offset(0), _sample_count(0),
       _last(0), _kernel(_order)
@@ -44,7 +44,7 @@ public:
 
   /** Constructor. */
   IQBaseBand(double Fc, double Ff, double width, size_t order, size_t sub_sample, double oFs=0.0)
-    : Sink<CScalar>(), Source(), FreqShiftBase<Scalar>(_Fc, 0),
+    : Sink<CScalar>(), Source(), FreqShiftBase<Scalar>(Fc, 0),
       _Fc(Fc), _Ff(Ff), _Fs(0), _width(width), _order(std::max(size_t(1), order)),
       _sub_sample(sub_sample), _oFs(oFs), _ring_offset(0), _sample_count(0),
       _last(0), _kernel(_order)
diff --git a/src/demod.hh b/src/demod.hh
index 7c7ea87..729fa43 100644
--- a/src/demod.hh
+++ b/src/demod.hh
@@ -108,6 +108,7 @@ public:
   {
     // pass...
   }
+
   /** Destructor. */
   virtual ~USBDemod() {
     // pass...