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75 lines
1.5 KiB
Python
75 lines
1.5 KiB
Python
import numpy as np
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import hashlib
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import struct
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import logging
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log = logging.getLogger(__name__)
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Fs = 32e3
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Ts = 1.0 / Fs
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frequencies = (np.arange(4) + 8) * 1e3
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carrier_index = len(frequencies)/2
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Fc = frequencies[carrier_index]
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Tc = 1.0 / Fc
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Tsym = 1e-3
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Nsym = int(Tsym / Ts)
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baud = int(1/Tsym)
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scaling = 32000.0 # out of 2**15
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SATURATION_THRESHOLD = 1.0
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LENGTH_FORMAT = '<I'
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def pack(data):
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log.info('Sending {} bytes'.format(len(data)))
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return data
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def unpack(data):
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log.info('Received {} bytes'.format(len(data)))
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return data
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def to_bits(chars):
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for c in chars:
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val = ord(c)
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for i in range(8):
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mask = 1 << i
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yield (1 if (val & mask) else 0)
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def to_bytes(bits):
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assert len(bits) == 8
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byte = sum(b << i for i, b in enumerate(bits))
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return chr(byte)
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def load(fname):
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x = np.fromfile(open(fname, 'rb'), dtype='int16')
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x = x / scaling
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t = np.arange(len(x)) / Fs
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return t, x
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class Signal(object):
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def __init__(self, fd):
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self.fd = fd
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def send(self, sym, n=1):
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sym = sym.imag * scaling
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sym = sym.astype('int16')
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for i in range(n):
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sym.tofile(self.fd)
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if __name__ == '__main__':
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import pylab
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def plot(f):
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t = pylab.linspace(0, Tsym, 1e3)
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x = pylab.sin(2 * pylab.pi * f * t)
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pylab.plot(t / Tsym, x)
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t = pylab.linspace(0, Tsym, Nsym + 1)
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x = pylab.sin(2 * pylab.pi * f * t)
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pylab.plot(t / Tsym, x, '.k')
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plot(Fc)
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plot(F0)
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plot(F1)
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pylab.show()
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