diff options
| author | Nick Foster <nick@ettus.com> | 2012-04-19 18:11:01 -0700 |
|---|---|---|
| committer | Nick Foster <nick@ettus.com> | 2012-04-19 18:11:01 -0700 |
| commit | db89e68b8e5b40e478cfacf73f0f177066c6bfa7 (patch) | |
| tree | f0f57f82259573f942afaaaa2625f680c4e0dc21 | |
| parent | 01ac510c107684e952ef7b04dd68fbe9db6f8e41 (diff) | |
qtgui: move fftshift into its own fn
| -rw-r--r-- | gr-qtgui/lib/spectrumdisplayform.cc | 98 |
1 files changed, 57 insertions, 41 deletions
diff --git a/gr-qtgui/lib/spectrumdisplayform.cc b/gr-qtgui/lib/spectrumdisplayform.cc index 988ee7aa1f..adf633e5fb 100644 --- a/gr-qtgui/lib/spectrumdisplayform.cc +++ b/gr-qtgui/lib/spectrumdisplayform.cc @@ -135,6 +135,52 @@ SpectrumDisplayForm::setSystem( SpectrumGUIClass * newSystem, } } +/*********************************************************************** + * This is kind of gross because we're combining three operations: + * Conversion from float to double (which is what the plotter wants) + * Finding the peak and mean + * Doing the "FFT shift" to put 0Hz at the center of the plot + * I feel like this might want to be part of the sink block + **********************************************************************/ +static void fftshift_and_sum(double *outFFT, const float *inFFT, uint64_t num_points, double &sum_mean, double &peak_ampl, int &peak_bin) { + const float* inptr = inFFT+num_points/2; + double* outptr = outFFT; + + sum_mean = 0; + peak_ampl = -HUGE_VAL; + peak_bin = 0; + + // Run this twice to perform the fftshift operation on the data here as well + for(uint64_t point = 0; point < num_points/2; point++){ + float pt = (*inptr); + *outptr = pt; + if(*outptr > peak_ampl) { + peak_bin = point; + peak_ampl = *outptr; + } + sum_mean += *outptr; + + inptr++; + outptr++; + } + + // This loop takes the first half of the input data and puts it in the + // second half of the plotted data + inptr = inFFT; + for(uint64_t point = 0; point < num_points/2; point++){ + float pt = (*inptr); + *outptr = pt; + if(*outptr > peak_ampl) { + peak_bin = point; + peak_ampl = *outptr; + } + sum_mean += *outptr; + + inptr++; + outptr++; + } +} + void SpectrumDisplayForm::newFrequencyData( const SpectrumUpdateEvent* spectrumUpdateEvent) { @@ -156,64 +202,34 @@ SpectrumDisplayForm::newFrequencyData( const SpectrumUpdateEvent* spectrumUpdate // REMEMBER: The dataTimestamp is NOT valid when the repeat data flag is true... ResizeBuffers(numFFTDataPoints, numTimeDomainDataPoints); - const float* fftMagDataPointsPtr = fftMagDataPoints+numFFTDataPoints/2; - double* realFFTDataPointsPtr = _realFFTDataPoints; - - double sumMean = 0.0; - double localPeakAmplitude = -HUGE_VAL; - double localPeakFrequency = 0.0; const double fftBinSize = (_stopFrequency-_startFrequency) / static_cast<double>(numFFTDataPoints); - // Run this twice to perform the fftshift operation on the data here as well - for(uint64_t point = 0; point < numFFTDataPoints/2; point++){ - float pt = (*fftMagDataPointsPtr); - *realFFTDataPointsPtr = pt; - if(*realFFTDataPointsPtr > localPeakAmplitude) { - localPeakFrequency = static_cast<float>(point) * fftBinSize; - localPeakAmplitude = *realFFTDataPointsPtr; - } - sumMean += *realFFTDataPointsPtr; - - fftMagDataPointsPtr++; - realFFTDataPointsPtr++; - } - - // This loop takes the first half of the input data and puts it in the - // second half of the plotted data - fftMagDataPointsPtr = fftMagDataPoints; - for(uint64_t point = 0; point < numFFTDataPoints/2; point++){ - float pt = (*fftMagDataPointsPtr); - *realFFTDataPointsPtr = pt; - if(*realFFTDataPointsPtr > localPeakAmplitude) { - localPeakFrequency = static_cast<float>(point) * fftBinSize; - localPeakAmplitude = *realFFTDataPointsPtr; - } - sumMean += *realFFTDataPointsPtr; - - fftMagDataPointsPtr++; - realFFTDataPointsPtr++; - } + //this does the fftshift, conversion to double, and calculation of sum, peak amplitude, peak freq. + double sum_mean, peak_ampl; + int peak_bin; + fftshift_and_sum(_realFFTDataPoints, fftMagDataPoints, numFFTDataPoints, sum_mean, peak_ampl, peak_bin); + double peak_freq = peak_bin * fftBinSize; // Don't update the averaging history if this is repeated data if(!repeatDataFlag){ _AverageHistory(_realFFTDataPoints); // Only use the local info if we are not repeating data - _peakAmplitude = localPeakAmplitude; - _peakFrequency = localPeakFrequency; + _peakAmplitude = peak_ampl; + _peakFrequency = peak_freq; // calculate the spectral mean // +20 because for the comparison below we only want to throw out bins // that are significantly higher (and would, thus, affect the mean more) - const double meanAmplitude = (sumMean / numFFTDataPoints) + 20.0; + const double meanAmplitude = (sum_mean / numFFTDataPoints) + 20.0; // now throw out any bins higher than the mean - sumMean = 0.0; + sum_mean = 0.0; uint64_t newNumDataPoints = numFFTDataPoints; for(uint64_t number = 0; number < numFFTDataPoints; number++){ if (_realFFTDataPoints[number] <= meanAmplitude) - sumMean += _realFFTDataPoints[number]; + sum_mean += _realFFTDataPoints[number]; else newNumDataPoints--; } @@ -221,7 +237,7 @@ SpectrumDisplayForm::newFrequencyData( const SpectrumUpdateEvent* spectrumUpdate if (newNumDataPoints == 0) // in the odd case that all _noiseFloorAmplitude = meanAmplitude; // amplitudes are equal! else - _noiseFloorAmplitude = sumMean / newNumDataPoints; + _noiseFloorAmplitude = sum_mean / newNumDataPoints; } if(lastOfMultipleUpdatesFlag){ |