public void SerialConnectionTest()
{
const double fd = 100;
const double dt = 1 / fd;
const double f0RC = 40;
const double f0CR = 5;
var RC = new LowPassRC(f0RC, dt);
var CR = new HighPassRC(f0CR, dt);
var filter = RC.ConnectionSerialTo(CR);
var A = filter.A;
var B = filter.B;
double[] expected_a =
{
1.53476636079571,
-0.33307051181674,
-0.568158087680825
};
double[] expected_b = { 1, 0, -1 };
CollectionAssert.AreEqual(expected_b, B);
CollectionAssert.AreEqual(expected_a, A, GetComparer(1e-15));
void CheckTransmissionCoefficient(double f)
{
var H = filter.GetTransmissionCoefficient(f, dt);
var HRC = RC.GetTransmissionCoefficient(f, dt);
var HCR = CR.GetTransmissionCoefficient(f, dt);
var delta = HRC * HCR - H;
const double eps = 1.25e-15;
Assert.That.Value(delta.Abs).IsEqual(0, eps);
}
CheckTransmissionCoefficient(0);
CheckTransmissionCoefficient(f0RC);
CheckTransmissionCoefficient(f0CR);
CheckTransmissionCoefficient(fd / 2);
var H0 = filter.GetTransmissionCoefficient(0, dt);
var Hf0RC = filter.GetTransmissionCoefficient(f0RC, dt);
var Hf0CR = filter.GetTransmissionCoefficient(f0CR, dt);
var Hfd05 = filter.GetTransmissionCoefficient(fd / 2, dt);
Assert.AreEqual(0, H0.Abs);
Assert.AreEqual(0, Hfd05.Abs, 1.89e-16);
Assert.AreEqual(0, H0.Arg);
Assert.AreEqual(-Math.PI / 2, Hfd05.Arg);
Assert.That.Value(Hf0RC.Abs).IsEqual(Consts.sqrt_2_inv, 9.35e-4);
Assert.That.Value(Hf0CR.Abs).IsEqual(Consts.sqrt_2_inv, 9.35e-4);
}
public void TransmissionCoefficientAtZeroFrequency()
{
const double fd = 100;
const double dt = 1 / fd;
const double f0 = 10;
//const double eps = 3.02e-4;
const double f = 0;
var rc = new LowPassRC(f0, dt);
var c = rc.GetTransmissionCoefficient(f, dt);
Assert.That.Value(c.Abs).IsEqual(1);
}
public void TransmissionCoefficientAtCutoffFrequency()
{
const double fd = 100;
const double dt = 1 / fd;
const double f0 = 10;
const double eps = 1e-14;
const double f = f0;
var rc = new LowPassRC(f0, dt);
var c = rc.GetTransmissionCoefficient(f, dt);
Assert.That.Value(c.Abs).IsEqual(sqrt_2_inv, eps);
Assert.That.Value(c.Arg * ToDeg).IsEqual(-45, eps);
}
public void ParallelConnectionTest()
{
const double fd = 100;
const double dt = 1 / fd;
const double f0RC = 40;
const double f0CR = 5;
var RC = new LowPassRC(f0RC, dt);
var CR = new HighPassRC(f0CR, dt);
var filter = RC.ConnectionParallelTo(CR);
var A = filter.A;
var B = filter.B;
double[] expected_a =
{
1.53476636079571,
-0.33307051181674,
-0.568158087680825
};
double[] expected_b =
{
1.241652068278721,
-0.16653525590837,
-0.758347931721279
};
CollectionAssert.AreEqual(expected_b, B, GetComparer(1e-15));
CollectionAssert.AreEqual(expected_a, A, GetComparer(1e-15));
void CheckTransmissionCoefficient(double f)
{
var H = filter.GetTransmissionCoefficient(f, dt);
var HRC = RC.GetTransmissionCoefficient(f, dt);
var HCR = CR.GetTransmissionCoefficient(f, dt);
var delta = (HRC + HCR) / 2 - H;
const double eps = 1.25e-15;
Assert.That.Value(delta.Abs).IsEqual(0, eps);
}
CheckTransmissionCoefficient(0);
CheckTransmissionCoefficient(f0RC);
CheckTransmissionCoefficient(f0CR);
CheckTransmissionCoefficient(fd / 2);
}
