/// <summary>
/// <para>Computes the power spectrum of input time-domain signal.</para>
/// <para>Chinese Simplified: 计算输入信号的功率频谱。</para>
/// </summary>
/// <param name="waveform">
/// <para>input time-domain signal.</para>
/// <para>Chinese Simplified: 输入的时域波形。</para>
/// </param>
/// <param name="samplingRate">
/// <para>sampling rate of the input time-domain signal, in samples per second.</para>
/// <para>Chinese Simplified: 输入信号的采样率，以S/s为单位。</para>
/// </param>
/// <param name="spectrum">
/// <para>output sequence containing the power spectrum.</para>
/// <para>Chinese Simplified: 输出功率谱。</para>
/// </param>
/// <param name="df">
/// <para>the frequency resolution of the spectrum, in hertz.</para>
/// <para>Chinese Simplified: 功率谱的频谱间隔，以Hz为单位。</para>
/// </param>
/// <param name="unitSettings">
/// <para>unit settings of the output power spectrum</para>
/// <para>Chinese Simplified: 设置功率谱的单位。</para>
/// </param>
/// <param name="windowType">
/// <para>the time-domain window to apply to the time signal.</para>
/// <para>Chinese Simplified: 窗类型。</para>
/// </param>
/// <param name="windowPara">
/// <para>parameter for a Kaiser/Gaussian/Dolph-Chebyshev window, If window is any other window, this parameter is ignored</para>
/// <para>Chinese Simplified: 窗调整系数，仅用于Kaiser/Gaussian/Dolph-Chebyshev窗。</para>
/// </param>
public static void PowerSpectrum(double[] waveform, double samplingRate, ref double[] spectrum, out double df,
UnitConvSetting unitSettings, WindowType windowType, double windowPara)
{
int spectralLines = spectrum.Length; //谱线数是输出数组的大小
SpectralInfo spectralInfo = new SpectralInfo();
AdvanceComplexFFT(waveform, spectralLines, windowType, spectrum, ref spectralInfo);
double scale = 1.0 / spectralInfo.FFTSize;
CBLASNative.cblas_dscal(spectralLines, scale, spectrum, 1);
df = 0.5 * samplingRate / spectralInfo.spectralLines; //计算频率间隔
//Unit Conversion
UnitConversion(spectrum, df, SpectrumType.Amplitude, unitSettings, Window.WindowENBWFactor[(int)windowType]);
}
/// <summary>
/// <para>Computes the power spectrum of input time-domain signal.</para>
/// <para>Chinese Simplified: 计算输入信号的功率频谱。</para>
/// </summary>
/// <param name="waveform">
/// <para>input time-domain signal.</para>
/// <para>Chinese Simplified: 输入的时域波形。</para>
/// </param>
/// <param name="samplingRate">
/// <para>sampling rate of the input time-domain signal, in samples per second.</para>
/// <para>Chinese Simplified: 输入信号的采样率，以S/s为单位。</para>
/// </param>
/// <param name="spectrum">
/// <para>output sequence containing the power spectrum.</para>
/// <para>Chinese Simplified: 输出功率谱。</para>
/// </param>
/// <param name="df">
/// <para>the frequency resolution of the spectrum, in hertz.</para>
/// <para>Chinese Simplified: 功率谱的频谱间隔，以Hz为单位。</para>
/// </param>
/// <param name="unit">
/// <para>unit of the output power spectrum</para>
/// <para>Chinese Simplified: 设置功率谱的单位。</para>
/// </param>
/// <param name="windowType">
/// <para>the time-domain window to apply to the time signal.</para>
/// <para>Chinese Simplified: 窗类型。</para>
/// </param>
/// <param name="windowPara">
/// <para>parameter for a Kaiser/Gaussian/Dolph-Chebyshev window, If window is any other window, this parameter is ignored</para>
/// <para>Chinese Simplified: 窗调整系数，仅用于Kaiser/Gaussian/Dolph-Chebyshev窗。</para>
/// </param>
/// <param name="PSD">
/// <para>specifies whether the output power spectrum is converted to power spectral density.</para>
/// <para>Chinese Simplified: 输出的频谱是否为功率谱密度。</para>
/// </param>
public static void PowerSpectrum(double[] waveform, double samplingRate, ref double[] spectrum, out double df,
SpectrumUnits unit = SpectrumUnits.V2, WindowType windowType = WindowType.Hanning,
double windowPara = double.NaN, bool PSD = false)
{
int spectralLines = spectrum.Length; //谱线数是输出数组的大小
SpectralInfo spectralInfo = new SpectralInfo();
AdvanceComplexFFT(waveform, spectralLines, windowType, spectrum, ref spectralInfo);
double scale = 1.0 / spectralInfo.FFTSize;
CBLASNative.cblas_dscal(spectralLines, scale, spectrum, 1);
df = 0.5 * samplingRate / spectralInfo.spectralLines; //计算频率间隔
//Unit Conversion
UnitConvSetting unitSettings = new UnitConvSetting(unit, PeakScaling.Rms, 50.00, PSD);
UnitConversion(spectrum, df, SpectrumType.Amplitude, unitSettings, Window.WindowENBWFactor[(int)windowType]);
}
/// <summary>
/// 频谱单位转换函数
/// </summary>
/// <param name="spectrum">输入频谱，单位转换后返回的序列也保存在里面</param>
/// <param name="spectrumType">输入频谱类型，功率谱或者幅度谱</param>
/// <param name="df">频谱间隔</param>
/// <param name="unitSetting">单位转换设置</param>
/// <param name="equivalentNoiseBw">计算频谱时，加窗所用窗函数的等效噪声带宽</param>
/// <returns></returns>
private static void UnitConversion(double[] spectrum, double df, SpectrumType spectrumType,
UnitConvSetting unitSetting, double equivalentNoiseBw)
{
double scale = 1.0;
int freq0Idx = 0, N = spectrum.Length;
//VMLNative.vdSqr(N, spectrum, spectrum);
if (unitSetting.PeakScaling == PeakScaling.Peak) //峰峰值要乘以2
{
switch (spectrumType)
{
case SpectrumType.Amplitude: // Sqrt2
scale *= Sqrt2;
break;
case SpectrumType.Power: // 2
scale *= 2;
break;
default:
throw new ArgumentOutOfRangeException(nameof(spectrumType), spectrumType, null);
}
CBLASNative.cblas_dscal(N, scale, spectrum, 1);
spectrum[0] /= scale; //零频不用
}
//根据设置的转换单位进行转换
switch (unitSetting.Unit)
{
case SpectrumUnits.V:
{
if (SpectrumType.Power == spectrumType)
{
VMLNative.vdSqrt(N, spectrum, spectrum);
}
break;
}
case SpectrumUnits.dBV:
{
if (SpectrumType.Power == spectrumType)
{
VMLNative.vdSqrt(N, spectrum, spectrum);
}
//lg
VMLNative.vdLog10(N, spectrum, spectrum);
scale = 20;
//20*lg
CBLASNative.cblas_dscal(N, scale, spectrum, 1);
break;
}
case SpectrumUnits.dBmV:
{
if (SpectrumType.Power == spectrumType)
{
VMLNative.vdSqrt(N, spectrum, spectrum);
}
CBLASNative.cblas_dscal(N, 1e3, spectrum, 1); //V To mV
VMLNative.vdLog10(N, spectrum, spectrum); //To Lg
scale = 20;
CBLASNative.cblas_dscal(N, scale, spectrum, 1); //To 20*Lg
break;
}
case SpectrumUnits.dBuV:
{
if (SpectrumType.Power == spectrumType)
{
VMLNative.vdSqrt(N, spectrum, spectrum);
}
CBLASNative.cblas_dscal(N, 1e6, spectrum, 1); //V To uV
VMLNative.vdLog10(N, spectrum, spectrum); //To Lg
scale = 20;
CBLASNative.cblas_dscal(N, scale, spectrum, 1); //To 20*Lg
break;
}
case SpectrumUnits.V2:
{
if (SpectrumType.Amplitude == spectrumType)
{
VMLNative.vdSqr(N, spectrum, spectrum);
}
break;
}
case SpectrumUnits.W:
case SpectrumUnits.dBW:
case SpectrumUnits.dBm:
{
if (SpectrumType.Amplitude == spectrumType)
{
VMLNative.vdSqr(N, spectrum, spectrum);
}
scale = 1.0 / unitSetting.Impedance; //1/R
CBLASNative.cblas_dscal(N, scale, spectrum, 1); //W = V^2/R
if (unitSetting.Unit == SpectrumUnits.dBW) //dBW = 20lgW
{
//lg
VMLNative.vdLog10(N, spectrum, spectrum);
scale = 20;
//20*lg
CBLASNative.cblas_dscal(N, scale, spectrum, 1);
}
else if (unitSetting.Unit == SpectrumUnits.dBm) // dBm = 10lg(W/1mW)
{
CBLASNative.cblas_dscal(N, 1e3, spectrum, 1); // W/1mW
//lg
VMLNative.vdLog10(N, spectrum, spectrum);
scale = 10;
//10*lg
CBLASNative.cblas_dscal(N, scale, spectrum, 1);
}
break;
}
default:
{
break;
}
}
if (!unitSetting.PSD)
{
return;
}
//谱密度计算
scale = 1.0 / (equivalentNoiseBw * df);
CBLASNative.cblas_dscal(N, scale, spectrum, 1);
}
