Fix lag calculator and add test

1 files changed, 36 insertions, 0 deletions

diff --git a/src/dab_util_test.py b/src/dab_util_test.py
new file mode 100644
index 0000000..83813a9
--- /dev/null
+++ b/src/dab_util_test.py
@@ -0,0 +1,36 @@
+from scipy import signal
+import numpy as np
+import src.gen_source as gs
+reload(gs)
+import src.dab_util as du
+reload(du)
+
+def gen_test_signals(oversampling=4, sample_offset_float=0):
+    off = int(sample_offset_float)
+    phi_samples = sample_offset_float - off
+    phi = phi_samples*360/oversampling
+
+    s1 = np.zeros((1024))
+    s1[256:768] = gs.gen_sin(512, oversampling, 0)
+    s2 = np.zeros((1024))
+    s2[256+off:768+off] = gs.gen_sin(512, oversampling, phi)
+
+    return s1, s2
+
+def test_phase_offset(lag_function, tol):
+    def r():
+        return np.random.rand(1)*100-50
+    res = []
+    for i in range(100):
+        off = r()
+        s1, s2 = gen_test_signals(
+            oversampling=4, sample_offset_float=off)
+
+        off_meas = lag_function(s2, s1)
+        res.append(np.abs(off-off_meas)<tol)
+    return np.mean(res)
+
+for n_up in [1, 2, 3, 4, 7, 8, 16]:
+   correct_ratio = test_phase_offset(lambda x,y: du.lag_upsampling(x,y,n_up), tol=1./n_up)
+   print("%.1f%% of the tested offsets were measured within tolerance %.4f for n_up = %d" % (correct_ratio * 100, 1./n_up, n_up))
+