SignalShaping.cxx

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#include "lardata/Utilities/SignalShaping.h"
#include "cetlib_except/exception.h"
#include <cmath>

//----------------------------------------------------------------------
// Constructor.
//
util::SignalShaping::SignalShaping() : fResponseLocked(false), fFilterLocked(false), fNorm(true) {}

//----------------------------------------------------------------------
// Destructor.
//
util::SignalShaping::~SignalShaping() {}

// void util::SignalShaping::ResetDecon()
// {
//   fResponseLocked = false;
//   fFilterLocked = false;
//   fResponse.clear();
//   fConvKernel.clear();
//   fFilter.clear();
//   fDeconvKernel.clear();
//   //Set deconvolution polarity to + as default
//   fDeconvKernelPolarity = +1;
// }

//----------------------------------------------------------------------
// Reset this class to its default-constructed state.
void util::SignalShaping::Reset()
{
  fResponseLocked = false;
  fFilterLocked = false;
  fResponse.clear();
  fConvKernel.clear();
  fFilter.clear();
  fDeconvKernel.clear();
  //Set deconvolution polarity to + as default
  fDeconvKernelPolarity = +1;
}

//----------------------------------------------------------------------
// Add a time domain response function.
void util::SignalShaping::AddResponseFunction(const std::vector<double>& resp, bool ResetResponse)
{
  // Make sure configuration is not locked.

  if (fResponseLocked) throw cet::exception("SignalShaping") << "Configuration locked.\n";

  // Get FFT service.

  art::ServiceHandle<util::LArFFT> fft;
  int nticks = fft->FFTSize();

  // Copy new response function into fResponse attribute, and pad or
  // truncate to correct size.

  fResponse = resp;
  fResponse.resize(nticks, 0.);

  // Is this the first response function?

  if (fConvKernel.size() == 0 || ResetResponse) {

    // This is the first response function.
    // Just calculate the fourier transform.

    fConvKernel.resize(nticks / 2 + 1);
    fft->DoFFT(fResponse, fConvKernel);
  }
  else {

    // Not the first response function.
    // Calculate the fourier transform of new response function.

    std::vector<TComplex> kern(nticks / 2 + 1);
    fft->DoFFT(fResponse, kern);

    // Update overall convolution kernel.

    if (kern.size() != fConvKernel.size()) {
      throw cet::exception("SignalShaping") << __func__ << ": inconsistent kernel size, "
                                            << kern.size() << " vs. " << fConvKernel.size();
    }
    for (unsigned int i = 0; i < kern.size(); ++i)
      fConvKernel[i] *= kern[i];

    // Recalculate overall response function.

    fft->DoInvFFT(fConvKernel, fResponse);
  }
}

//----------------------------------------------------------------------
// Shift the response function and convolution kernel by the specified
// number of ticks.
void util::SignalShaping::ShiftResponseTime(double ticks)
{
  // Make sure configuration is not locked.

  if (fResponseLocked) throw cet::exception("SignalShaping") << "Configuration locked.\n";

  // Get FFT service.

  art::ServiceHandle<util::LArFFT> fft;

  // Update convolution kernel.

  fft->ShiftData(fConvKernel, ticks);

  // Recalculate overall response functiion.

  fft->DoInvFFT(fConvKernel, fResponse);
}

//----------------------------------------------------------------------
// Set the peak response time to be at the specified tick.
void util::SignalShaping::SetPeakResponseTime(double tick)
{
  // Make sure configuration is not locked.

  if (fResponseLocked) throw cet::exception("SignalShaping") << "Configuration locked.\n";

  // Get FFT service.

  art::ServiceHandle<util::LArFFT> fft;

  // Construct a delta-function response centered at tick zero.

  std::vector<double> delta(fft->FFTSize(), 0.);
  delta[0] = 1.;

  // Figure out peak of current overall response.

  double peak = fft->PeakCorrelation(delta, fResponse);

  // Shift peak response to desired tick.

  ShiftResponseTime(tick - peak);
}

//----------------------------------------------------------------------
// Add a frequency domain filter function to cumulative filter function.
void util::SignalShaping::AddFilterFunction(const std::vector<TComplex>& filt)
{
  // Make sure configuration is not locked.

  if (fFilterLocked) throw cet::exception("SignalShaping") << "Configuration locked.\n";

  // Get FFT service.

  art::ServiceHandle<util::LArFFT const> fft;

  // If this is the first filter function, just copy the filter function.
  // Otherwise, update the overall filter function.

  if (fFilter.size() == 0) {
    fFilter = filt;
    fFilter.resize(fft->FFTSize() / 2 + 1);
  }
  else {
    unsigned int n = std::min(fFilter.size(), filt.size());
    for (unsigned int i = 0; i < n; ++i)
      fFilter[i] *= filt[i];
    for (unsigned int i = n; i < fFilter.size(); ++i)
      fFilter[i] = 0.;
  }
}

//----------------------------------------------------------------------
// Add a DeconvKernel Polarity Flag to decide how to normalize
void util::SignalShaping::SetDeconvKernelPolarity(int pol)
{

  if ((pol != 1) and (pol != -1)) {
    throw cet::exception("SignalShaping")
      << __func__ << ": DeconvKernelPolarity should be +1 or -1 (got " << pol
      << "). Setting to +1\n";
    fDeconvKernelPolarity = +1;
  }

  else
    fDeconvKernelPolarity = pol;
}

//----------------------------------------------------------------------
// Test and lock the response and convolution kernel.
void util::SignalShaping::LockResponse() const
{
  // Do nothing if the response is already locked.

  if (!fResponseLocked) {

    // Get FFT service.

    art::ServiceHandle<util::LArFFT const> fft;

    // Make sure response has been configured.

    if (fResponse.size() == 0)
      throw cet::exception("SignalShaping") << "Response has not been configured.\n";

    // Make sure response and convolution kernel have the correct
    // size (should always be the case if we get here).

    unsigned int n = fft->FFTSize();
    if (fResponse.size() != n)
      throw cet::exception("SignalShaping")
        << __func__ << ": inconsistent kernel size, " << fResponse.size() << " vs. " << n << "\n";
    if (2 * (fConvKernel.size() - 1) != n)
      throw cet::exception("SignalShaping")
        << __func__ << ": unexpected FFT size, " << n << " vs. expected "
        << (2 * (fConvKernel.size() - 1)) << "\n";

    // Set the lock flag.

    fResponseLocked = true;
  }
}

//----------------------------------------------------------------------
// Calculate the deconvolution kernel as the ratio
// of the filter function and convolution kernel.
void util::SignalShaping::CalculateDeconvKernel() const
{
  // Make sure configuration is not locked.

  if (fFilterLocked) throw cet::exception("SignalShaping") << "Configuration locked.\n";

  // Lock response configuration.

  LockResponse();

  // Get FFT service.

  art::ServiceHandle<util::LArFFT> fft;

  // Make sure filter function has been configured.

  if (fFilter.size() == 0)
    throw cet::exception("SignalShaping") << "Filter function has not been configured.\n";

  // Make sure filter function has the correct size.
  // (Should always be the case if we get here.)

  unsigned int n = fft->FFTSize();
  if (2 * (fFilter.size() - 1) != n)
    if (fFilter.size() != fConvKernel.size()) {
      throw cet::exception("SignalShaping") << __func__ << ": inconsistent size, " << fFilter.size()
                                            << " vs. " << fConvKernel.size() << "\n";
    }

  // Calculate deconvolution kernel as the ratio of the
  // filter function and the convolution kernel.

  fDeconvKernel = fFilter;
  for (unsigned int i = 0; i < fDeconvKernel.size(); ++i) {
    if (std::abs(fConvKernel[i].Re()) <= 0.0001 && std::abs(fConvKernel[i].Im()) <= 0.0001) {
      fDeconvKernel[i] = 0.;
    }
    else {
      fDeconvKernel[i] /= fConvKernel[i];
    }
  }

  // Normalize the deconvolution kernel.

  // Calculate the unnormalized deconvoluted response
  // (inverse FFT of filter function).

  std::vector<double> deconv(n, 0.);
  fft->DoInvFFT(const_cast<std::vector<TComplex>&>(fFilter), deconv);

  if (fNorm) {
    // Find the peak value of the response
    // Should normally be at zero, but don't assume that.
    // Use DeconvKernelPolairty to find what to normalize to
    double peak_response = 0;
    if (fDeconvKernelPolarity == -1) peak_response = 4096;
    for (unsigned int i = 0; i < fResponse.size(); ++i) {
      if ((fResponse[i] > peak_response) and (fDeconvKernelPolarity == 1))
        peak_response = fResponse[i];
      else if ((fResponse[i] < peak_response) and (fDeconvKernelPolarity == -1))
        peak_response = fResponse[i];
    }
    if (fDeconvKernelPolarity == -1) peak_response *= -1;
    if (peak_response <= 0.) {
      throw cet::exception("SignalShaping")
        << __func__ << ": peak should always be positive (got " << peak_response << ")\n";
    }

    // Find the peak value of the deconvoluted response
    // Should normally be at zero, but don't assume that.

    double peak_deconv = 0.;
    for (unsigned int i = 0; i < deconv.size(); ++i) {
      if (deconv[i] > peak_deconv) peak_deconv = deconv[i];
    }
    if (peak_deconv <= 0.) {
      throw cet::exception("SignalShaping")
        << __func__ << ": deconvolution peak should always be positive (got " << peak_deconv
        << ")\n";
    }

    // Multiply the deconvolution kernel by a factor such that
    // (Peak of response) = (Peak of deconvoluted response).

    double ratio = peak_response / peak_deconv;
    for (unsigned int i = 0; i < fDeconvKernel.size(); ++i)
      fDeconvKernel[i] *= ratio;
  }
  // Set the lock flag.

  fFilterLocked = true;
}