Added the aps calculator where blocks are neglectd below a certain threshold. Warning, this is sweep specific and is currently the method implemented in lasp_measurement. Fine for muZ, not necessarily for other stuff

cpp_src/dsp/lasp_avpowerspectra.cpp

@@ -10,7 +10,8 @@ PowerSpectra::PowerSpectra(const us nfft, const Window::WindowType w)
     : PowerSpectra(Window::create(w, nfft)) {}
 
 PowerSpectra::PowerSpectra(const vd &window)
-    : nfft(window.size()), _fft(nfft), _window(window) {
+    : nfft(window.size()), _fft(nfft), _window(window)
+{
 
   d win_pow = arma::sum(window % window) / window.size();
 
@@ -21,7 +22,8 @@ PowerSpectra::PowerSpectra(const vd &window)
   DEBUGTRACE_PRINT(win_pow);
 }
 
-ccube PowerSpectra::compute(const dmat &input) {
+ccube PowerSpectra::compute(const dmat &input)
+{
 
   /// Run very often. Silence this one.
   /* DEBUGTRACE_ENTER; */
@@ -34,11 +36,13 @@ ccube PowerSpectra::compute(const dmat &input) {
   cmat rfft = _fft.fft(input_tmp);
 
   ccube output(rfft.n_rows, input.n_cols, input.n_cols);
-  for (us i = 0; i < input.n_cols; i++) {
+  for (us i = 0; i < input.n_cols; i++)
+  {
     /// This one can be run in parallel without any problem. Note that it is
     /// the inner loop that is run in parallel.
 #pragma omp parallel for
-    for (us j = 0; j < input.n_cols; j++) {
+    for (us j = 0; j < input.n_cols; j++)
+    {
       output.slice(j).col(i) =
           _scale_fac * (rfft.col(i) % arma::conj(rfft.col(j)));
 
@@ -52,37 +56,46 @@ ccube PowerSpectra::compute(const dmat &input) {
 AvPowerSpectra::AvPowerSpectra(const us nfft, const Window::WindowType w,
                                const d overlap_percentage,
                                const d time_constant_times_fs)
-    : _ps(nfft, w) {
+    : _ps(nfft, w)
+{
 
   DEBUGTRACE_ENTER;
-  if (overlap_percentage >= 100 || overlap_percentage < 0) {
+  if (overlap_percentage >= 100 || overlap_percentage < 0)
+  {
     throw rte("Overlap percentage should be >= 0 and < 100");
   }
 
   _overlap_keep = (nfft * overlap_percentage) / 100;
   DEBUGTRACE_PRINT(_overlap_keep);
-  if (_overlap_keep >= nfft) {
+  if (_overlap_keep >= nfft)
+  {
     throw rte("Overlap is too high. Results in no jump. Please "
               "choose a smaller overlap percentage or a higher nfft");
   }
-  if (time_constant_times_fs < 0) {
+  if (time_constant_times_fs < 0)
+  {
     _mode = Mode::Averaging;
-  } else if (time_constant_times_fs == 0) {
+  }
+  else if (time_constant_times_fs == 0)
+  {
     _mode = Mode::Spectrogram;
-  } else {
+  }
+  else
+  {
     _mode = Mode::Leaking;
-    _alpha = d_exp(-static_cast<d>((nfft - _overlap_keep)/time_constant_times_fs));
+    _alpha = d_exp(-static_cast<d>((nfft - _overlap_keep) / time_constant_times_fs));
     DEBUGTRACE_PRINT(_alpha);
   }
 }
-void AvPowerSpectra::reset() {
+void AvPowerSpectra::reset()
+{
   _timeBuf.reset();
   _est.reset();
-  n_averages=0;
+  _n_averages = 0;
-
 }
 
-ccube AvPowerSpectra::compute(const dmat &timedata) {
+ccube AvPowerSpectra::compute(const dmat &timedata)
+{
 
   DEBUGTRACE_ENTER;
   DEBUGTRACE_PRINT(timedata.n_rows);
@@ -91,32 +104,42 @@ ccube AvPowerSpectra::compute(const dmat &timedata) {
   _timeBuf.push(timedata);
 
   bool run_once = false;
-  while (_timeBuf.size() >= _ps.nfft) {
+  while (_timeBuf.size() >= _ps.nfft)
+  {
 
     DEBUGTRACE_PRINT((int)_mode);
 
     dmat samples = _timeBuf.pop(_ps.nfft, _overlap_keep);
 
-    switch (_mode) {
+    switch (_mode)
+    {
     case (Mode::Spectrogram):
       DEBUGTRACE_PRINT("Spectrogram mode");
       _est = _ps.compute(samples);
+
       break;
     case (Mode::Averaging):
       DEBUGTRACE_PRINT("Averaging mode");
-      n_averages++;
+      _n_averages++;
-      if (n_averages == 1) {
+      if (_n_averages == 1)
+      {
         _est = _ps.compute(samples);
-      } else {
+
-        _est = (static_cast<d>(n_averages - 1) / n_averages) * _est +
+      }
-               _ps.compute(samples) / n_averages;
+      else
+      {
+        _est = (static_cast<d>(_n_averages - 1) / _n_averages) * _est +
+               _ps.compute(samples) / _n_averages;
       }
       break;
     case (Mode::Leaking):
       DEBUGTRACE_PRINT("Leaking mode");
-      if (arma::size(_est) == arma::size(0, 0, 0)) {
+      if (arma::size(_est) == arma::size(0, 0, 0))
+      {
         _est = _ps.compute(samples);
-      } else {
+      }
+      else
+      {
         _est = _alpha * _est + (1 - _alpha) * _ps.compute(samples);
       }
       break;
@@ -128,6 +151,135 @@ ccube AvPowerSpectra::compute(const dmat &timedata) {
   /// Othewise, we return an empty ccube.
   return run_once ? _est : ccube();
 }
-ccube AvPowerSpectra::get_est() const {
+ccube AvPowerSpectra::get_est() const
+{
+  return _est;
+}
+
+AvSweepPowerSpectra::AvSweepPowerSpectra(const us nfft, const Window::WindowType w,
+                                         const d overlap_percentage,
+                                         const d time_constant_times_fs)
+    : _nfft(nfft), _ps(nfft, w)
+{
+
+  DEBUGTRACE_ENTER;
+  if (overlap_percentage >= 100 || overlap_percentage < 0)
+  {
+    throw rte("Overlap percentage should be >= 0 and < 100");
+  }
+
+  _overlap_keep = (nfft * overlap_percentage) / 100;
+  DEBUGTRACE_PRINT(_overlap_keep);
+  if (_overlap_keep >= nfft)
+  {
+    throw rte("Overlap is too high. Results in no jump. Please "
+              "choose a smaller overlap percentage or a higher nfft");
+  }
+  if (time_constant_times_fs < 0)
+  {
+    _mode = Mode::Averaging;
+  }
+  else if (time_constant_times_fs == 0)
+  {
+    _mode = Mode::Spectrogram;
+  }
+  else
+  {
+    _mode = Mode::Leaking;
+    _alpha = d_exp(-static_cast<d>((nfft - _overlap_keep) / time_constant_times_fs));
+    DEBUGTRACE_PRINT(_alpha);
+  }
+}
+void AvSweepPowerSpectra::reset()
+{
+  _timeBuf.reset();
+  _est.reset();
+  _n_averages.reset();
+}
+
+ccube AvSweepPowerSpectra::compute(const dmat &timedata)
+{
+
+  DEBUGTRACE_ENTER;
+  DEBUGTRACE_PRINT(timedata.n_rows);
+  DEBUGTRACE_PRINT(_ps.nfft);
+
+  _timeBuf.push(timedata);
+
+  bool run_once = false;
+  while (_timeBuf.size() >= _ps.nfft)
+  {
+
+    DEBUGTRACE_PRINT((int)_mode);
+
+    dmat samples = _timeBuf.pop(_ps.nfft, _overlap_keep);
+
+    us ncols = timedata.n_cols;
+    
+    switch (_mode)
+    {
+    case (Mode::Spectrogram):
+      DEBUGTRACE_PRINT("Spectrogram mode");
+      _est = _ps.compute(samples);
+      break;
+    case (Mode::Averaging):
+    {
+      DEBUGTRACE_PRINT("Averaging mode");
+
+      ccube temp = _ps.compute(samples);
+      us nfreq = arma::size(temp)[0];
+
+      if (_est.size() == 0) {
+        // Initialize empty
+        _est = ccube(nfreq, ncols, ncols, arma::fill::zeros);
+        _n_averages = vd(nfreq, arma::fill::zeros);
+      }
+            
+      d threshold = arma::mean(arma::real(temp.slice(0).col(0)));
+      
+      for (us f=0; f < nfreq; f++)
+      {
+        if (real(temp(f, 0, 0)) > threshold)
+        {
+          _n_averages[f]++;
+          if (_n_averages[f] == 1)
+          {
+            _est.row(f) = temp.row(f);
+            // _est.subcube(f, 0, 0, f, ncols - 1, ncols - 1) = temp.subcube(f, 0, 0, f, ncols - 1, ncols - 1);
+          }
+          else
+          {
+            _est.row(f) = (static_cast<d>(_n_averages[f] - 1) / _n_averages[f]) * _est.row(f) +
+                                                             temp.row(f) / _n_averages[f];
+            // _est.subcube(f, 0, 0, f, ncols - 1, ncols - 1) = (static_cast<d>(_n_averages[f] - 1) / _n_averages[f]) * _est.subcube(f, 0, 0, f, ncols - 1, ncols - 1) +
+            //                                                  temp.subcube(f, 0, 0, f, ncols - 1, ncols - 1) / _n_averages[f];
+          }
+        }
+      }
+    }
+    break;
+
+    case (Mode::Leaking):
+      DEBUGTRACE_PRINT("Leaking mode");
+      if (arma::size(_est) == arma::size(0, 0, 0))
+      {
+        _est = _ps.compute(samples);
+      }
+      else
+      {
+        _est = _alpha * _est + (1 - _alpha) * _ps.compute(samples);
+      }
+      break;
+    } // end switch mode
+    run_once = true;
+  }
+ 
+  /// Return a copy of current estimator in case we have done one update.
+  /// Othewise, we return an empty ccube.
+  return run_once ? _est : ccube();
+}
+
+ccube AvSweepPowerSpectra::get_est() const
+{
   return _est;
 }

cpp_src/dsp/lasp_avpowerspectra.h

@@ -81,7 +81,7 @@ class AvPowerSpectra {
 
   Mode _mode;
   d _alpha;          // Only valid in case of 'Leaking'
-  us n_averages = 0; // Only valid in case of 'Averaging'
+  us _n_averages = 0; // Only valid in case of 'Averaging'
 
   PowerSpectra _ps;
   /**
@@ -165,3 +165,107 @@ public:
   us exactOverlapSamples() const { return _ps.nfft - _overlap_keep; }
 };
 /** @} */
+
+
+/**
+ * @brief Estimate cross-power spectra using Welch' method of spectral
+ * estimation. The exact amount of overlap in Welch' method is rounded up to a
+ * certain amount of samples. This class is specifically for sweeps and will ignore
+ * fft blocks where the auto-power of the "reference" signal is below the average 
+ * when in averaging mode.
+ */
+class AvSweepPowerSpectra {
+
+  enum class Mode {
+    Averaging = 0,  // Averaging all time date
+    Leaking = 1,    // Exponential weighting of an "instantaneous cps"
+    Spectrogram = 2 // Instantenous spectrum, no averaging
+  };
+
+  Mode _mode;
+  d _alpha;          // Only valid in case of 'Leaking'
+  us _nfft;
+  vd _n_averages { 1, arma::fill::zeros}; // Only valid in case of 'Averaging'
+
+  PowerSpectra _ps;
+  /**
+   * @brief Current estimate of cross-spectral density
+   */
+  ccube _est;
+
+  /**
+   * @brief Buffer of storage of time data.
+   */
+  TimeBuffer _timeBuf;
+  /**
+   * @brief The amount of samples to keep in the overlap
+   */
+  us _overlap_keep;
+
+public:
+  /**
+   * @brief Initalize averaged power spectra computer. If a time constant is
+   * given > 0, it is used in a kind of exponential weighting.
+   *
+   * @param nfft The fft length
+   * @param w The window type.
+   * @param overlap_percentage A number 0 < overlap_percentage <= 100. It
+   * determines the amount of overlap used in Welch' method. A typical value is
+   * 50 %, i.e. 50.
+   * @param fs_tau Value should either be < 0, indicating that the
+   * estimate is averages over all time data.
+   * For a value = 0 the instantaneous power spectrum is returned, which can be
+   * interpreted as the spectrogram. For a value > 0 a exponential forgetting is
+   * used, where the value is used as the time constant such that the decay
+   * follows approximately the trend exp(-n/fs_tau), where n is the
+   * sample number in the power spectra. To choose 'fast' time weighting, set
+   * time_constant to the value of fs*0.125, where fs denotes the sampling
+   * frequency.
+   **/
+  AvSweepPowerSpectra(const us nfft = 2048,
+                 const Window::WindowType w = Window::WindowType::Hann,
+                 const d overlap_percentage = 50.,
+                 const d fs_tau = -1);
+                 
+  AvSweepPowerSpectra(const AvSweepPowerSpectra &) = delete;
+  AvSweepPowerSpectra &operator=(const AvSweepPowerSpectra &) = delete;
+
+  /**
+   * @brief Reset to empty state. Clears the time buffer and sets estimator to
+   * empty.
+   */
+  void reset();
+
+  /**
+   * @brief Compute an update of the power spectra based on given time data.
+   * Note that the number of channels is determined from the first time this
+   * function is called. If a later call has an incompatible number of
+   * channels, a runtime error is thrown.
+   *
+   * @param timedata
+   *
+   * @return a copy of the latest estimate of the power spectra. an
+   * update is only given if the amount of new time data is enough to compute a
+   * new estimate. if no new estimate is available, it returns an empty ccube.
+   * Note that the latest available estimate can be obtained using get_est().
+   * */
+  ccube compute(const dmat &timedata);
+
+  /**
+   * @brief Returns the latest estimate of cps (cross-power spectra.
+   *
+   * @return a copy of the latest estimate of the power spectra. an
+   * update is only given if the amount of new time data is enough to compute a
+   * new estimate. If no estimate is available, it returns an empty ccube.
+   * */
+  ccube get_est() const;
+
+  /**
+   * @brief The overlap is rounded to a certain amount of time samples. This
+   * function returns that value.
+   *
+   * @return The amount of samples in overlapping.
+   */
+  us exactOverlapSamples() const { return _ps.nfft - _overlap_keep; }
+};
+/** @} */

cpp_src/pybind11/lasp_dsp_pybind.cpp

@@ -129,6 +129,29 @@ void init_dsp(py::module &m) {
     return CubeToNpy<c>(est);
   });
 
+  /// AvSweepPowerSpectra
+  py::class_<AvSweepPowerSpectra> asps(m, "AvSweepPowerSpectra");
+  asps.def(py::init<const us, const Window::WindowType, const d, const d>(),
+          py::arg("nfft") = 2048,
+          py::arg("windowType") = Window::WindowType::Hann,
+          py::arg("overlap_percentage") = 50.0,
+          py::arg("time_constant") = -1);
+
+  asps.def("compute", [](AvSweepPowerSpectra &asps, dpyarray timedata) {
+    std::optional<ccube> res;
+    dmat timedata_mat = NpyToMat<d, false>(timedata);
+    {
+      py::gil_scoped_release release;
+      res = asps.compute(timedata_mat);
+    }
+
+    return CubeToNpy<c>(res.value_or(ccube(0, 0, 0)));
+  });
+  asps.def("get_est", [](const AvSweepPowerSpectra &sps) {
+    ccube est = sps.get_est();
+    return CubeToNpy<c>(est);
+  });
+
   py::class_<SLM> slm(m, "cppSLM");
 
   slm.def_static("fromBiquads", [](const d fs, const d Lref, const us ds,

python_src/lasp/lasp_measurement.py

@@ -15,7 +15,7 @@ from scipy.io import wavfile
 import os, time, wave, logging
 from .lasp_common import SIQtys, Qty, getFreq
 from .lasp_version import LASP_VERSION_MAJOR, LASP_VERSION_MINOR
-from .lasp_cpp import Window, DaqChannel, AvPowerSpectra
+from .lasp_cpp import Window, DaqChannel, AvPowerSpectra, AvSweepPowerSpectra
 from typing import List
 from functools import lru_cache
 from .lasp_config import ones
@@ -814,9 +814,11 @@ class Measurement:
             channels = list(range(self.nchannels))
 
         nchannels = len(channels)
-        aps = AvPowerSpectra(nfft, window, overlap)
-        freq = getFreq(self.samplerate, nfft)
 
+        # aps = AvPowerSpectra(nfft, window, overlap)
+        aps = AvSweepPowerSpectra(nfft, window, overlap)
+        freq = getFreq(self.samplerate, nfft)
+        
         for data in self.iterData(channels, **kwargs):
             CS = aps.compute(data)
 
@@ -1005,7 +1007,8 @@ class Measurement:
 
         # Convert range to [-1, 1]
         # TODO: this is wrong for float data where full scale > 1
-        sensone = np.ones_like(self.sensitivity)
+        sensone = np.ones(data.shape[1])
+        
         data = scaleBlockSens(data, sensone)
 
         if dtype == "int16" or dtype == "int32":