public IList <Complex> FrequencyResponse()
{
ComplexFastFourierTransform transform = new ComplexFastFourierTransform();
List <Complex> coefficients = transform.Transform(new List <double>(ImpulseResponse()), FilterLength).FourierCoefficients;
return(coefficients);
}
public ActionResult <FrequencyDomain> FFT([FromBody] List <Double> value)
{
ComplexFastFourierTransform fft = new ComplexFastFourierTransform();
FrequencyDomain transform = fft.Transform(value);
return(Ok(transform));
}
private void ExportButton_Click(object sender, RoutedEventArgs e)
{
SaveFileDialog saveFileDialog = new SaveFileDialog();
saveFileDialog.Filter = $"{Properties.Resources.FILTER_IMPORT_EXPORT_FILE_EXTENSION} (*{Properties.Resources.FILTER_IMPORT_EXPORT_FILE_EXTENSION})|*{Properties.Resources.FILTER_IMPORT_EXPORT_FILE_EXTENSION}|{Properties.Resources.ALL_FILES} (*.*)|*.*";
if (saveFileDialog.ShowDialog() == true)
{
try
{
using (StreamWriter fileWriter = File.CreateText(saveFileDialog.FileName))
{
fileWriter.WriteLine(Properties.Resources.FILTER_CSV_HEADER);
List <double> summedFilterData = manager.ActiveWorkBook().CombinedFilterImpulseResponse(true);
ComplexFastFourierTransform cmplxFFT = new ComplexFastFourierTransform();
FrequencyDomain frequencyDomain = cmplxFFT.Transform(summedFilterData, manager.ActiveWorkBook().WindowedSyncFilters.Values.First().FilterLength);
var magPhaseList = ComplexFastFourierTransform.ToMagnitudePhaseList(frequencyDomain);
foreach (Tuple <double, double> coefficientMagPhase in magPhaseList)
{
fileWriter.WriteLine($"{coefficientMagPhase.Item1},{coefficientMagPhase.Item2}");
}
}
} catch (Exception ex)
{
Log.Warning(ex, ex.Message);
// TODO warn user
}
}
}
public void TestLoadFromFrequencyAmplitudes()
{
// low pass amplitude array
double[] amplitudes = { 1.0, 1.0, 1.0, 1.0, 1.0, 1.0,
1.0, 1.0, 1.0, 1.0, 1.0, 1.0,
0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
0.0, 0.0 };
List <double> frequencyDomain = new List <double>(amplitudes);
//FrequencyDomain frequencyDomain = ComplexFastFourierTransform.LoadFourierCoefficients(new List<double>(amplitudes));
ComplexFastFourierTransform synth = new ComplexFastFourierTransform();
FrequencyDomain timeDomain = synth.Transform(frequencyDomain, 2 * frequencyDomain.Count());
foreach (var value in timeDomain.FrequencyAmplitudes)
{
Console.WriteLine(value);
}
}
// 64 channel sample with padCount zeros padded right
public List <double> GetPaddedChannelSample(int sampleCount, int padCount)
{
int numSamplesToGet = (sampleCount - padCount);
int curIDX = _sampleIDX;
if (curIDX + numSamplesToGet >= _samples.Count)
{
numSamplesToGet = _samples.Count - curIDX;
if (numSamplesToGet <= 0)
{
// Roll over to the beginning
_sampleIDX = 0;
return(GetPaddedChannelSample(sampleCount, padCount));
}
}
_sampleIDX += numSamplesToGet;
_sliceSignal = _samples.GetRange(curIDX, numSamplesToGet);
List <double> paddedSignal = new List <double>(sampleCount);
paddedSignal.AddRange(_sliceSignal);
// Pad
int padLen = (sampleCount - numSamplesToGet);
for (int cnt = 0; cnt < padLen; cnt++)
{
paddedSignal.Add(0.0);
}
IDFT ff_transform = new ComplexFastFourierTransform();
IDFT cdf_tranform = new CorrelationFourierTransform();
//_frequencyDomain = DFT.CorrelationTransform(paddedSignal);
_frequencyDomain = ff_transform.Transform(paddedSignal);
return(_sliceSignal);
}
public IList <double> ImpulseResponse(bool normalize = false)
{
ComplexFastFourierTransform transform = new ComplexFastFourierTransform();
return(transform.Synthesize(FreqDomain));
}
public void TestComplexTransform()
{
//IDFT complexFourierTransform = new ComplexFastFourierTransform();
IDFT complexFourierTransform = new DSPGuideComplexDiscreteFourierTransform();
FrequencyDomain result;
List <double> recreatedSignal;
int sampleRate = 1000; // hz
List <double> timePoints = new List <double>(2 * sampleRate);
for (double timePointVal = 0; timePointVal < 2.0; timePointVal += (1.0 / sampleRate))
{
timePoints.Add(timePointVal);
}
List <double> signal = new List <double>(timePoints.Count);
foreach (double timePointVal in timePoints)
{
double signalValue = (2.5 * Math.Sin(2 * Math.PI * 4 * timePointVal)) + (1.5 * Math.Sin(2 * Math.PI * 6.5 * timePointVal));
signal.Add(signalValue);
}
result = complexFourierTransform.Transform(signal, sampleRate);
List <Tuple <double, double> > magPhaseList = ComplexFastFourierTransform.ToMagnitudePhaseList(result);
FrequencyDomain fromMagPhaseList = ComplexFastFourierTransform.FromMagnitudePhaseList(magPhaseList);
for (int idx = 0; idx < result.FourierCoefficients.Count; idx++)
{
double absDifference = Complex.Abs(result.FourierCoefficients[idx] - fromMagPhaseList.FourierCoefficients[idx]);
// Check that they are close, rounding error occurs, they wont be equal
Assert.IsTrue(absDifference < 1.0E-10);
}
// This file can be viewed in Excel for plotting of hz and amplitudes
StreamWriter amplitudeFile = new StreamWriter("frequencyAmplitudes.csv");
if (amplitudeFile != null)
{
amplitudeFile.WriteLine("HZ, Amplitude");
foreach (var frequencyAmplitude in result.FrequencyAmplitudes)
{
amplitudeFile.WriteLine($"{frequencyAmplitude.Key}, {frequencyAmplitude.Value}");
}
}
amplitudeFile.Close();
recreatedSignal = complexFourierTransform.Synthesize(result);
Assert.IsNotNull(result);
Assert.IsNotNull(recreatedSignal);
//double amplitude40 = result.FrequencyAmplitudes[4.0];
//double amplitude65 = result.FrequencyAmplitudes[6.5];
//Assert.IsTrue(Math.Abs(amplitude40 - 2.5) <= MaxAmplitudeDifference);
//Assert.IsTrue(Math.Abs(amplitude65 - 1.5) <= MaxAmplitudeDifference);
double maxDifference = 0.0;
for (int idx = 0; idx < recreatedSignal.Count; idx++)
{
double calculateDifference = Math.Abs(recreatedSignal[idx] - signal[idx]);
if (maxDifference < calculateDifference)
{
maxDifference = calculateDifference;
}
}
for (int idx = 0; idx < recreatedSignal.Count; idx++)
{
double calculateDifference = Math.Abs(recreatedSignal[idx] - signal[idx]);
Assert.IsTrue(calculateDifference <= MaxSignalDifference);
}
}
public ActionResult <List <Double> > InverseFFT([FromBody] FrequencyDomain fd)
{
ComplexFastFourierTransform transformer = new ComplexFastFourierTransform();
return(Ok(transformer.Synthesize(fd)));
}
