Add unit tests for noise_bandwidth()

tests/dsp/filter/test_noise_bandwidth.py

@@ -0,0 +1,89 @@
+"""
+References:
+    - https://www.gaussianwaves.com/2020/09/equivalent-noise-bandwidth-enbw-of-window-functions/
+"""
+
+import pytest
+import scipy.signal
+
+import sdr
+
+
+def test_boxcar():
+    n = 128
+    h = scipy.signal.windows.get_window("boxcar", n)
+    fir = sdr.FIR(h)
+    B_n = fir.noise_bandwidth(n)
+    assert B_n == pytest.approx(1.000, rel=1e-3)
+
+
+def test_barthann():
+    n = 128
+    h = scipy.signal.windows.get_window("barthann", n)
+    fir = sdr.FIR(h)
+    B_n = fir.noise_bandwidth(n)
+    assert B_n == pytest.approx(1.456, rel=1e-3)
+
+
+def test_bartlett():
+    n = 128
+    h = scipy.signal.windows.get_window("bartlett", n)
+    fir = sdr.FIR(h)
+    B_n = fir.noise_bandwidth(n)
+    assert B_n == pytest.approx(1.333, rel=1e-3)
+
+
+def test_blackman():
+    n = 128
+    h = scipy.signal.windows.get_window("blackman", n)
+    fir = sdr.FIR(h)
+    B_n = fir.noise_bandwidth(n)
+    assert B_n == pytest.approx(1.727, rel=1e-3)
+
+
+def test_blackmanharris():
+    n = 128
+    h = scipy.signal.windows.get_window("blackmanharris", n)
+    fir = sdr.FIR(h)
+    B_n = fir.noise_bandwidth(n)
+    assert B_n == pytest.approx(2.004, rel=1e-3)
+
+
+def test_bohman():
+    n = 128
+    h = scipy.signal.windows.get_window("bohman", n)
+    fir = sdr.FIR(h)
+    B_n = fir.noise_bandwidth(n)
+    assert B_n == pytest.approx(1.786, rel=1e-3)
+
+
+def test_flattop():
+    n = 128
+    h = scipy.signal.windows.get_window("flattop", n)
+    fir = sdr.FIR(h)
+    B_n = fir.noise_bandwidth(n)
+    assert B_n == pytest.approx(3.770, rel=1e-3)
+
+
+def test_hamming():
+    n = 128
+    h = scipy.signal.windows.get_window("hamming", n)
+    fir = sdr.FIR(h)
+    B_n = fir.noise_bandwidth(n)
+    assert B_n == pytest.approx(1.363, rel=1e-3)
+
+
+def test_hann():
+    n = 128
+    h = scipy.signal.windows.get_window("hann", n)
+    fir = sdr.FIR(h)
+    B_n = fir.noise_bandwidth(n)
+    assert B_n == pytest.approx(1.500, rel=1e-3)
+
+
+def test_nuttall():
+    n = 128
+    h = scipy.signal.windows.get_window("nuttall", n)
+    fir = sdr.FIR(h)
+    B_n = fir.noise_bandwidth(n)
+    assert B_n == pytest.approx(1.976, rel=1e-3)