40kbps demo

common.py

@@ -7,8 +7,8 @@ log = logging.getLogger(__name__)
 Fs = 32e3
 Ts = 1.0 / Fs
 
-frequencies = (np.arange(4) + 8) * 1e3
-carrier_index = len(frequencies)/2
+frequencies = (np.arange(10) + 1) * 1e3
+carrier_index = 0
 Fc = frequencies[carrier_index]
 Tc = 1.0 / Fc
 

sigproc.py

@@ -51,7 +51,7 @@ class QAM(object):
             index = np.argmin(np.abs(s - self.points))
             yield self._dec[ self.points[index] ]
 
-modulator = QAM(bits_per_symbol=2, radii=[1.0])
+modulator = QAM(bits_per_symbol=4, radii=[1.0, 0.6])
 
 def clip(x, lims):
     return min(max(x, lims[0]), lims[1])

test.sh

@@ -3,7 +3,7 @@ set -u
 set -x
 set -e 
 
-dd if=/dev/urandom of=data.send bs=1024 count=8
+dd if=/dev/urandom of=data.send bs=1024 count=64
 python send.py
 python recv.py
 python errors.py data.* #python show.py tx.int16 rx.int16