refactor equalizer to use original signal, instead of symbols

tests/test_equalizer.py

@@ -1,4 +1,5 @@
 from numpy.linalg import norm
+from numpy.random import RandomState
 import numpy as np
 
 from amodem import dsp
@@ -41,7 +42,7 @@ def test_modem():
     assert_approx(sent, received)
 
 
-def test_isi():
+def test_symbols():
     length = 100
     gain = float(config.Nfreq)
 
@@ -54,10 +55,31 @@ def test_isi():
     y = dsp.lfilter(x=x, b=num, a=den)
 
     lookahead = 2
-    h = equalizer.equalize(y, symbols, order=len(den), lookahead=lookahead)
+    h = equalizer.equalize_symbols(
+        signal=y, symbols=symbols, order=len(den), lookahead=lookahead
+    )
     assert norm(h[:lookahead]) < 1e-12
     assert_approx(h[lookahead:], den / num)
 
     y = dsp.lfilter(x=y, b=h[lookahead:], a=[1])
     z = equalizer.demodulator(y, size=length)
     assert_approx(z, symbols)
+
+
+def test_signal():
+    length = 100
+    x = np.sign(RandomState(0).normal(size=length))
+    den = np.array([1, -0.6, 0.1])
+    num = np.array([0.5])
+    y = dsp.lfilter(x=x, b=num, a=den)
+
+    lookahead = 2
+    h = equalizer.equalize_signal(
+        signal=y, expected=x, order=len(den), lookahead=lookahead)
+    assert norm(h[:lookahead]) < 1e-12
+
+    h = h[lookahead:]
+    assert_approx(h, den / num)
+
+    x_ = dsp.lfilter(x=y, b=h, a=[1])
+    assert_approx(x_, x)