public void CreationTest()
{
const double fd = 100;
const double dt = 1 / fd;
const double f0 = 10;
var rc = new HighPassRC(f0, dt);
var a = rc.A;
var b = rc.B;
Assert.AreEqual(2, a.Count);
Assert.AreEqual(2, b.Count);
var a0 = a[0];
var a1 = a[1];
var b0 = b[0];
var b1 = b[1];
var w0 = Tan(PI * f0 * dt);
Assert.AreEqual(1 / (w0 + 1), b0 / a0);
Assert.AreEqual(-1 / (w0 + 1), b1 / a0);
//Assert.AreEqual(1, a0 / a0);
Assert.AreEqual((w0 - 1) / (w0 + 1), a1 / a0);
Assert.That.Value(b0).IsEqual(1);
Assert.That.Value(b1).IsEqual(-1);
Assert.That.Value(a0).IsEqual(w0 + 1);
Assert.That.Value(a1).IsEqual(w0 - 1);
}
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 TransmissionCoefficientAtZerroFrequency()
{
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 HighPassRC(f0, dt);
var c = rc.GetTransmissionCoefficient(f, dt);
Assert.That.Value(c.Abs).IsEqual(0);
}
public void TransmissionCoefficientAtCutoffFrequency()
{
const double fd = 100;
const double dt = 1 / fd;
const double f0 = 10;
//const double eps = 3.02e-4;
const double f = f0;
var rc = new HighPassRC(f0, dt);
var c = rc.GetTransmissionCoefficient(f, dt);
Assert.That.Value(c.Abs).IsEqual(Consts.sqrt_2_inv, 1e-14);
Assert.That.Value(c.Arg * Consts.ToDeg).IsEqual(45);
}
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);
}
public void ProcessSignalAtCutOffFrequencyTestTest()
{
const double fd = 100;
const double dt = 1 / fd;
const double f0 = 10;
const double eps = 3.02e-4;
const double A0 = Consts.sqrt_2;
var x0 = new SamplesDigitalSignal(dt, 1024, t => A0 * Cos(2 * PI * f0 * t));
var x0_power = x0.Power;
Assert.AreEqual(1, x0_power, eps);
var rc = new HighPassRC(f0, dt);
var y0 = rc.Process(x0);
var y0_power = y0.Power;
Assert.AreEqual(x0_power / 2, y0_power, eps);
}
public void ImpulseResponseTest()
{
const double fd = 100;
const double dt = 1 / fd;
const double f0 = 10;
var rc = new HighPassRC(f0, dt);
var a = rc.A;
var b = rc.B;
var a0 = a[0];
var a1 = a[1] / a0;
var b0 = b[0] / a0;
var b1 = b[1] / a0;
var expected_impulse_response = new List <double>
{
b0,
b0 * -a1 + b1,
b0 * -a1 * -a1 + b1 * -a1,
b0 * -a1 * -a1 * -a1 + b1 * -a1 * -a1,
b0 * -a1 * -a1 * -a1 * -a1 + b1 * -a1 * -a1 * -a1,
b0 * -a1 * -a1 * -a1 * -a1 * -a1 + b1 * -a1 * -a1 * -a1 * -a1,
};
var delta = new double[expected_impulse_response.Count];
delta[0] = 1;
var impulse_response = rc.Process(delta).ToArray();
const double eps = 1.11023e-16;
CollectionAssert.AreEqual(expected_impulse_response, impulse_response, GetComparer(eps));
}
