从FFT获取RMS

我得到了一组数据电压，我希望从之前应用的FFT中获得RMS值到该数据。 我已经看到时域中的RMS应该等于Parseval定理的RMS（fft）/ sqrt（nFFT），但给出了不同的结果。 我正在使用这些function：1）FFT

public static VectorDPoint FFT(double[] trama, double samplingFreq) { double fs = samplingFreq; // Sampling frequency double t1 = 1 / fs; // Sample time int l = trama.Length; // Length of signal // Time vector //Vector t = Normal(0, l, 1) * t1; //// Values vector //Vector y = new Vector(trama); // We just use half of the data as the other half is simetric. The middle is found in NFFT/2 + 1 int nFFT = (int)Math.Pow(2, NextPow2(l)); if (nFFT > 655600) { } // Create complex array for FFT transformation. Use 0s for imaginary part Complex[] samples = new Complex[nFFT]; for (int i = 0; i = trama.Length) { samples[i] = new MathNet.Numerics.Complex(0, 0); } else { samples[i] = new MathNet.Numerics.Complex(trama[i], 0); } } ComplexFourierTransformation fft = new ComplexFourierTransformation(TransformationConvention.Matlab); fft.TransformForward(samples); ComplexVector s = new ComplexVector(samples); s = s / l; Vector f = (fs / 2.0) * Linspace(0, 1, (nFFT / 2) + 1); VectorDPoint result = new VectorDPoint(); for (int i = 0; i < (nFFT / 2) + 1; i++) { result.Add(new DPoint(f[i], 2 * s[i].Modulus)); } s = null; f = null; samples = null; return result; 

2）RMS

  public static double RMSCalculate(double[] channelValues, int samplesNumber, double sampleRate, DateTime currentDate) { double[] times = new double[channelValues.Length]; double sampleTime = 0.0; double period = 0; times[0] = currentDate.Second + currentDate.Millisecond / 1000.0; sampleTime = 1 / sampleRate; //s // Limited samples for (int i = 1; i < channelValues.Length; i++) { times[i] = times[i - 1] + sampleTime; } DPoint RMSValues = new DPoint(); RMSValues.Y = 0; if (channelValues.Length == 1) { double x = channelValues[0]; double y = channelValues[0]; RMSValues = new DPoint(x, Math.Abs(y)); } else { for (int i = 0; i < times.Length - 1; i++) { period = 0; if (i + 1 < times.Length) { RMSValues.Y += channelValues[i + 1] * channelValues[i + 1] * (times[i + 1] - times[i]); } } period = times[times.Length - 1] - times[0]; RMSValues.Y = RMSValues.Y / period; RMSValues.Y = Math.Sqrt(RMSValues.Y); } return RMSValues.Y; }