optimize testing when no interpolation is needed

amodem/dsp.py

@@ -112,9 +112,8 @@ class QAM(object):
 
 
 class Demux(object):
-    def __init__(self, src, freqs):
-        interp = sampling.Interpolator()
-        self.sampler = sampling.Sampler(src, interp)
+    def __init__(self, src, freqs, sampler=None):
+        self.sampler = sampling.Sampler(src) if sampler is None else sampler
         self.filters = [exp_iwt(-f, Nsym) / (0.5*Nsym) for f in freqs]
         self.filters = np.array(self.filters)
 

amodem/recv.py

@@ -12,6 +12,7 @@ log = logging.getLogger(__name__)
 
 from . import stream
 from . import dsp
+from . import sampling
 from . import train
 from . import common
 from . import config
@@ -205,7 +206,8 @@ def demodulate(symbols, filters, freqs, sampler):
 
 
 def receive(signal, freqs, gain=1.0):
-    symbols = dsp.Demux(signal, freqs)
+    sampler = sampling.Sampler(signal, sampling.Interpolator())
+    symbols = dsp.Demux(signal, freqs, sampler)
     symbols.sampler.gain = gain
 
     freq_err, offset_err = receive_prefix(symbols)

amodem/sampling.py

@@ -3,6 +3,8 @@ import numpy as np
 import itertools
 import logging
 
+from amodem import common
+
 log = logging.getLogger(__name__)
 
 
@@ -26,22 +28,27 @@ class Interpolator(object):
 
 
 class Sampler(object):
-    def __init__(self, src, interp):
+    def __init__(self, src, interp=None):
         self.freq = 1.0
-        self.interp = interp
-        self.resolution = self.interp.resolution
-        self.filt = self.interp.filt
-        self.width = self.interp.width
-
-        # TODO: explain indices arithmetic
-        padding = [0.0] * self.interp.width
-        self.src = itertools.chain(padding, src)
-        self.offset = self.interp.width + 1
-        self.buff = np.zeros(self.interp.coeff_len)
-        self.index = 0
         self.gain = 1.0
+        if interp is not None:
+            self.interp = interp
+            self.resolution = self.interp.resolution
+            self.filt = self.interp.filt
+            self.width = self.interp.width
 
-    def take(self, size):
+            # TODO: explain indices arithmetic
+            padding = [0.0] * self.interp.width
+            self.src = itertools.chain(padding, src)
+            self.offset = self.interp.width + 1
+            self.buff = np.zeros(self.interp.coeff_len)
+            self.index = 0
+            self.take = self._take
+        else:
+            # skip interpolation
+            self.take = lambda size: common.take(src, size)
+
+    def _take(self, size):
         frame = np.zeros(size)
         count = 0
         try: