public void TestLowPass16()
{
const int order = 16;
const double fs = 31250d;
const double cutoffFrequency = 300d;
const double error = 1e-4;
var coeff = new LowPassChebyshevIICoefficients(order, fs, cutoffFrequency, 48);
var chain = coeff.Calculate();
var expected = Helpers.LoadCsv(
@"0.003088, -0.005107, 0.003088, 1.000000, -1.733557, 0.752389
1.000000, -1.957258, 1.000000, 1.000000, -1.814016, 0.827649
1.000000, -1.983684, 1.000000, 1.000000, -1.885766, 0.894795
1.000000, -1.990975, 1.000000, 1.000000, -1.929719, 0.935987
1.000000, -1.993917, 1.000000, 1.000000, -1.955793, 0.960505
1.000000, -1.995325, 1.000000, 1.000000, -1.972269, 0.976106
1.000000, -1.996028, 1.000000, 1.000000, -1.983739, 0.987102
1.000000, -1.996328, 1.000000, 1.000000, -1.992751, 0.995910").ToList();
var expectedGain = 3.444463173412853e-25;
Assert.AreEqual(expected.Count, chain.Count);
for (int i = 0; i < expected.Count; i++)
{
Helpers.ValidateBiquad(expected[i], chain[i], error);
}
}
public void TestLowPassChebyshevIIFiltering()
{
const int order = 16;
const int fs = 44100;
const double cutoffFrequency = 2000d;
const int cycles = 10;
double[] frequencies = { 770, 5830 };
var validFrequencies = frequencies.TakeWhile(f => f < cutoffFrequency);
var coeff = new LowPassChebyshevIICoefficients(order, fs, cutoffFrequency, 48);
TestFilter(order, fs, cycles, coeff, frequencies, validFrequencies);
}
public void TestLowPass08()
{
const int order = 8;
const double fs = 44100d;
const double cutoffFrequency = 500d;
const double error = 1e-4;
var coeff = new LowPassChebyshevIICoefficients(order, fs, cutoffFrequency, 48);
var chain = coeff.Calculate();
var expected = Helpers.LoadCsv(
@"0.003542, -0.006627, 0.003542, 1.000000, -1.850372, 0.856450
1.000000, -1.983612, 1.000000, 1.000000, -1.902676, 0.907306
1.000000, -1.992667, 1.000000, 1.000000, -1.950079, 0.953551
1.000000, -1.994727, 1.000000, 1.000000, -1.983090, 0.986058
").ToList();
Assert.AreEqual(expected.Count, chain.Count);
for (int i = 0; i < expected.Count; i++)
{
Helpers.ValidateBiquad(expected[i], chain[i], error);
}
}
public void TestLowPass12()
{
const int order = 12;
const double fs = 32000d;
const double cutoffFrequency = 2000d;
const double error = 1e-2;
var coeff = new LowPassChebyshevIICoefficients(order, fs, cutoffFrequency, 48);
var chain = coeff.Calculate();
var expected = Helpers.LoadCsv(
@"0.004224, 0.003363, 0.004224, 1.000000, -0.961310, 0.242000
1.000000, -1.149174, 1.000000, 1.000000, -1.179991, 0.413183
1.000000, -1.614136, 1.000000, 1.000000, -1.428074, 0.609010
1.000000, -1.763423, 1.000000, 1.000000, -1.615363, 0.760065
1.000000, -1.822796, 1.000000, 1.000000, -1.745316, 0.870017
1.000000, -1.845222, 1.000000, 1.000000, -1.840403, 0.958141").ToList();
Assert.AreEqual(expected.Count, chain.Count);
for (int i = 0; i < expected.Count; i++)
{
Helpers.ValidateBiquad(expected[i], chain[i], error);
}
}