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Use 4 carriers wit QAM16 to achieve 16kbps.

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Roman Zeyde
2014-06-21 12:55:36 +03:00
parent 5c6304823d
commit fbbc404b45
7 changed files with 71 additions and 49 deletions
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36
send.py
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@@ -29,13 +29,9 @@ def record(fname):
return p
log.info('MODEM Fc={}KHz, {} BAUD'.format(Fc/1e3, baud))
class Symbol(object):
t = np.arange(0, Nsym) * Ts
c0 = np.exp(2j * np.pi * F0 * t)
c1 = np.exp(2j * np.pi * F1 * t)
carrier = [ np.exp(2j * np.pi * F * t) for F in frequencies ]
sym = Symbol()
@@ -52,24 +48,30 @@ def train(sig, c):
sig.send(c*0, n=10)
sig.send(c*0, n=100)
def modulate(sig, bits):
symbols_iter = sigproc.modulator.encode(list(bits))
symbols_iter = itertools.chain(symbols_iter, itertools.repeat(0))
carriers = np.array(sym.carrier) / len(sym.carrier)
while True:
symbols = itertools.islice(symbols_iter, len(sym.carrier))
symbols = np.array(list(symbols))
sig.send(np.dot(symbols, carriers))
if all(symbols == 0):
break
if __name__ == '__main__':
bps = baud * sigproc.modulator.bits_per_symbol * len(sym.carrier)
log.info('Running MODEM @ {:.1f} kbps'.format(bps / 1e3))
with open('tx.int16', 'wb') as fd:
sig = Signal(fd)
start(sig, sym.c0)
train(sig, sym.c0)
train(sig, sym.c1)
carriers = [sym.c0, sym.c1]
start(sig, sym.carrier[carrier_index])
for c in sym.carrier:
train(sig, c)
bits = to_bits(pack(data))
symbols_iter = sigproc.modulator.encode(list(bits))
symbols_iter = itertools.chain(symbols_iter, itertools.repeat(0))
while True:
symbols = itertools.islice(symbols_iter, len(carriers))
symbols = np.array(list(symbols))
sig.send(np.dot(symbols, carriers))
if all(symbols == 0):
break
modulate(sig, bits)
r = record('rx.int16')