diff --git a/amodem/loop.py b/amodem/loop.py
deleted file mode 100644
index beef6cb..0000000
--- a/amodem/loop.py
+++ /dev/null
@@ -1,37 +0,0 @@
-import numpy as np
-import itertools
-
-from . import sampling
-from . import sigproc
-from . import common
-
-
-class Filter(object):
-    def __init__(self, b, a=()):
-        self.b = b
-        self.a = a
-        self.x = [0] * len(b)
-        self.y = [0] * len(a)
-
-    def __call__(self, x):
-        self.x = [x] + self.x
-        self.x = self.x[:len(self.b)]
-        self.y = self.y[:len(self.a)]
-        y = np.dot(self.x, self.b) + np.dot(self.y, self.a)
-        self.y = [y] + self.y
-        return y
-
-
-class FreqLoop(object):
-    def __init__(self, src, freqs):
-        interp = sampling.Interpolator()
-        self.sampler = sampling.Sampler(src, interp)
-        self.gens = []
-
-        samplers = itertools.tee(self.sampler, len(freqs))
-        for freq, generator in zip(freqs, samplers):
-            gen = sigproc.extract_symbols(generator, freq)
-            self.gens.append(gen)
-
-    def __iter__(self):
-        return common.izip(*self.gens)
diff --git a/amodem/recv.py b/amodem/recv.py
index d47fcba..77d9a8a 100755
--- a/amodem/recv.py
+++ b/amodem/recv.py
@@ -14,7 +14,6 @@ log = logging.getLogger(__name__)
 
 from . import stream
 from . import sigproc
-from . import loop
 from . import train
 from . import common
 from . import config
@@ -212,7 +211,7 @@ def demodulate(symbols, filters, freqs, sampler):
 
 
 def receive(signal, freqs, gain=1.0):
-    signal = loop.FreqLoop(signal, freqs)
+    signal = sigproc.FreqLoop(signal, freqs)
     signal.sampler.gain = gain
     symbols = iter(signal)
 
diff --git a/amodem/sigproc.py b/amodem/sigproc.py
index 91b8f33..0d53e89 100644
--- a/amodem/sigproc.py
+++ b/amodem/sigproc.py
@@ -1,6 +1,8 @@
 import numpy as np
 from numpy import linalg
+import itertools
 
+from . import sampling
 from . import common
 from .config import Ts, Nsym
 
@@ -58,6 +60,21 @@ class QAM(object):
             yield self._dec[S]
 
 
+class FreqLoop(object):
+    def __init__(self, src, freqs):
+        interp = sampling.Interpolator()
+        self.sampler = sampling.Sampler(src, interp)
+        self.gens = []
+
+        samplers = itertools.tee(self.sampler, len(freqs))
+        for freq, generator in zip(freqs, samplers):
+            gen = extract_symbols(generator, freq)
+            self.gens.append(gen)
+
+    def __iter__(self):
+        return common.izip(*self.gens)
+
+
 class MODEM(object):
     def __init__(self, config):
         self.qam = QAM(config.symbols)