fix carriers initialization

make sure tested process won't exit before killing it

amodem/dsp.py

@@ -137,6 +137,10 @@ class MODEM(object):
         self.freqs = config.frequencies
         self.bits_per_baud = self.qam.bits_per_symbol * len(self.freqs)
         self.modem_bps = self.baud * self.bits_per_baud
+        self.carriers = np.array([
+            np.exp(2j * np.pi * freq * np.arange(0, Nsym) * Ts)
+            for freq in self.freqs
+        ])
 
 
 def power(x):

amodem/equalizer.py

@@ -1,12 +1,13 @@
 import numpy as np
 from numpy.linalg import lstsq
 
-from amodem import dsp, config, send
+from amodem import dsp, config
 
 import itertools
 import random
 
 _constellation = [1, 1j, -1, -1j]
+modem = dsp.MODEM(config)
 
 
 def train_symbols(length, seed=0, Nfreq=config.Nfreq):
@@ -15,7 +16,7 @@ def train_symbols(length, seed=0, Nfreq=config.Nfreq):
     return np.array([choose() for i in range(length)])
 
 
-def modulator(symbols, carriers=send.sym.carrier):
+def modulator(symbols, carriers=modem.carriers):
     gain = 1.0 / len(carriers)
     result = []
     for s in symbols:
@@ -34,7 +35,7 @@ def demodulator(signal, size):
 def equalize(signal, symbols, order):
     Nsym = config.Nsym
     Nfreq = config.Nfreq
-    carriers = send.sym.carrier
+    carriers = modem.carriers
 
     assert symbols.shape[1] == Nfreq
     length = symbols.shape[0]

amodem/send.py

@@ -17,14 +17,6 @@ from . import ecc
 modem = dsp.MODEM(config)
 
 
-class Symbol(object):
-    def __init__(self):
-        t = np.arange(0, config.Nsym) * config.Ts
-        self.carrier = [np.exp(2j * np.pi * F * t) for F in modem.freqs]
-
-sym = Symbol()
-
-
 class Writer(object):
     def __init__(self):
         self.last = time.time()
@@ -55,9 +47,9 @@ def training(fd, c):
 def modulate(fd, bits):
     symbols_iter = modem.qam.encode(bits)
     symbols_iter = itertools.chain(symbols_iter, itertools.repeat(0))
-    carriers = np.array(sym.carrier) / len(sym.carrier)
+    carriers = modem.carriers / config.Nfreq
     while True:
-        symbols = itertools.islice(symbols_iter, len(sym.carrier))
+        symbols = itertools.islice(symbols_iter, config.Nfreq)
         symbols = np.array(list(symbols))
         writer.write(fd, np.dot(symbols, carriers))
         if all(symbols == 0):  # EOF marker
@@ -70,8 +62,8 @@ def main(args):
     # padding audio with silence
     writer.write(args.output, np.zeros(int(config.Fs * args.silence_start)))
 
-    start(args.output, sym.carrier[config.carrier_index])
-    for c in sym.carrier:
+    start(args.output, modem.carriers[config.carrier_index])
+    for c in modem.carriers:
         training(args.output, c)
     training_size = writer.offset
     log.info('%.3f seconds of training audio',

tests/test_equalizer.py

@@ -1,7 +1,7 @@
 from numpy.linalg import norm
 import numpy as np
 
-from amodem import train, dsp, config, send
+from amodem import train, dsp, config
 from amodem import equalizer
 
 
@@ -57,7 +57,7 @@ def test_commutation():
 def test_modem():
     L = 1000
     sent = equalizer.train_symbols(L)
-    gain = len(send.sym.carrier)
+    gain = config.Nfreq
     x = equalizer.modulator(sent) * gain
     received = equalizer.demodulator(x, L)
     assert_approx(sent, received)