Question

Blockquote 我生成了2个正弦波，并将其分成2个数组。我汇总第一个指标数组与第二个数组的每个索引并获得第三个数组（总信号）之后，我想从totalsignal第二个数组中筛选出第一个数组。但是结果上的正弦图看起来不一样。该行的开头是平坦的，幅度为300（在原始正弦图中，幅度为10）。 graph after filter >

     public Form1()
        {
                InitializeComponent();
                plot();
            }

            public void plot()
            {
                string TestName = "chart name";
                string field = "Amplitude";
            string x_axis = "Time";
            string xTitle = "Time [Sec]";
            string yTitle = "Amplitude";
            Color[] colors = new Color[] { Color.Red, Color.Green, Color.Blue, Color.Yellow, Color.Brown };
            bool show_graph_as_line = true;

            int freq1 = 10;
            int freq2 = 50;

            int amplitude1 = 10;
            int amplitude2 = 20;

            //samples per second
            int sampleRate = 10000; 


            double[] totalSignal;
            int idx = 0;

            //size of arrays
            int size = 10000;

            double[] signal_1_xAxis = new double[size];
            double[] signal_2_xAxis = new double[size];

            double[] signal_1_yAxis = new double[size];
            double[] signal_2_yAxis = new double[size];


            signal_1_yAxis = GenerateSineWave(freq1, amplitude1, sampleRate, size);

            signal_2_yAxis = GenerateSineWave(freq2, amplitude2, sampleRate, size);

            double dt = 1.0 / sampleRate;

            for (int i = 1; i < size; i++)
            {
                signal_1_xAxis[i] = i * dt;
                signal_2_xAxis[i] = i * dt;
            }


            totalSignal = SumOfSignals(signal_1_yAxis, signal_2_yAxis);

            MathNet.Filtering.OnlineFilter bandPass = MathNet.Filtering.OnlineFilter.CreateLowpass(MathNet.Filtering.ImpulseResponse.Finite, sampleRate, 15);

            var Result = bandPass.ProcessSamples(totalSignal);

        }

        public static double[] GenerateSineWave(
            double frequency,
            double amplitude,
            double sampleRate,
            double samplesPerBuffer)
        {
            double deltaT = 1 / sampleRate; // sec./samp
            int intSamplesPerBuffer = (int)samplesPerBuffer;

            double[] rVal = new double[intSamplesPerBuffer];

            for (int i = 0; i < intSamplesPerBuffer; i++)
                rVal[i] = amplitude * Math.Sin((2.0 * Math.PI) * frequency * (i * deltaT));

            return rVal;
        }

        public double[] SumOfSignals(double[] signal_1, double[] signal_2)
        {
            double[] sumSig = new double[10000];

            for (int i = 0; i < signal_1.Length; i++)
            {
                sumSig[i] = signal_1[i] + signal_2[i];
            }


            return sumSig;
        }


    }
}


  [1]: https://i.stack.imgur.com/Pbktt.jpg

低通滤波器无法提供预期的结果

0 个答案: