public void Calibrate()
{
double[] envelopeAverage = null;
// create the envelope for each signal
for (int i = 0; i < m_rawSignals.Count; i++)
{
Signal signal = Signal.FromArray(m_rawSignals[i],
EchoTubeSensor.SampleRate, SampleFormat.Format32BitIeeeFloat);
LowPassFilter lowPassFilter = new LowPassFilter(100.0, EchoTubeSensor.SampleRate)
{
Alpha = 0.05f
};
Signal filteredSignal = lowPassFilter.Apply(signal);
// this is the filtered signal (and a single baseline)
float[] filteredRawSData = filteredSignal.ToFloat();
float[] processedData = new float[filteredRawSData.Length];
// now, shift and rectify the raw data
Parallel.For(0, processedData.Length, j =>
{
// shift & rectify
processedData[j] = Math.Abs(m_rawSignals[i][j] - filteredRawSData[j]);
});
Signal processedSignal = Signal.FromArray(processedData,
EchoTubeSensor.SampleRate, SampleFormat.Format32BitIeeeFloat);
// now, we can create the calibration envelope
EnvelopeFilter filter = new EnvelopeFilter(Sensor.EnvelopeAlpha);
Signal envelopedSignal = filter.Apply(processedSignal);
float[] envelopedData = envelopedSignal.ToFloat();
if (envelopeAverage == null)
{
envelopeAverage = new double[envelopedData.Length];
}
Parallel.For(0, envelopedData.Length, j =>
{
envelopeAverage[j] += envelopedData[j];
});
}
// now, we need to average over the envelope
if (m_rawSignals.Count > 0)
{
Parallel.For(0, envelopeAverage.Length, i =>
{
envelopeAverage[i] /= m_rawSignals.Count;
});
m_envelopedAvg = envelopeAverage.Select(x => (float)x).ToArray();
IsValid = true;
}
}
public float[] GetCalibratedSignal(float[] data)
{
Signal signal = Signal.FromArray(data, EchoTubeSensor.SampleRate, SampleFormat.Format32BitIeeeFloat);
EnvelopeFilter filter = new EnvelopeFilter(Sensor.EnvelopeAlpha);
Signal envelopedSignal = filter.Apply(signal);
float[] envelopedData = envelopedSignal.ToFloat();
if (IsValid)
{
Parallel.For(0, envelopedData.Length, i =>
{
/* if (Math.Abs(envelopedData[i] - m_envelopedAvg[i]) >= 200)
* Debug.WriteLine(envelopedData[i] + " :: " + m_envelopedAvg[i] + " :: " + i); */
// envelopedData[i] = Math.Abs(envelopedData[i] - m_envelopedAvg[i]);
envelopedData[i] = Math.Max(0.0f, envelopedData[i] - m_envelopedAvg[i]);
// envelopedData[i] = envelopedData[i] - m_envelopedAvg[i];
});
}
return(envelopedData);
}
private float[] PreprocessSignal(float[] rawData, bool amplify)
{
// preprocess the peaks
for (int i = 0; i < rawData.Length; i++)
{
if (i <= Sensor.StartCutOff)
{
rawData[i] *= i / (float)Sensor.StartCutOff;
}
else if (i >= rawData.Length - Sensor.EndCutOff)
{
rawData[i] *= (rawData.Length - i + 1) / (float)Sensor.EndCutOff;
}
// amplify the data
if (amplify)
{
// double factor = 2.0 * Math.Pow(Sensor.GetDistance(i), 3.0) + 1.0;
double factor = 4.0 * Math.Pow(Sensor.GetDistance(i), 2.0) + 1.0;
// rawData[i] *= 4.0f;
// factor *= 4.0;
rawData[i] *= (float)factor;
}
}
Signal signal = Signal.FromArray(rawData, EchoTubeSensor.SampleRate, SampleFormat.Format32BitIeeeFloat);
EnvelopeFilter filter = new EnvelopeFilter(Sensor.EnvelopeAlpha);
Signal envelopedSignal = filter.Apply(signal);
float[] currData = envelopedSignal.ToFloat();
/* float avg = currData.Average();
* rawData = rawData.Select(x => x - avg).ToArray();
* currData = currData.Select(x => x - avg).ToArray(); */
/* if (m_previousData == null)
* {
* m_previousData = new float[currData.Length];
* }
* else
* {
* if (checkPrevious)
* {
* double absDifference = 0.0;
* for (int i = 0; i < currData.Length; i++)
* {
* absDifference += Math.Abs(currData[i] - m_previousData[i]);
* }
* absDifference /= currData.Length;
*
* // Debug.WriteLine(absDifference);
* if (absDifference >= ErrorDetectionThreshold && false)
* {
* // this is a wrong signal
* // throw it away
* return null;
* }
* else
* {
* // signal was good, store the current as previous
* Array.Copy(currData, m_previousData, currData.Length);
* }
* }
* } */
return(currData);
}
