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Code Issues Releases Wiki Activity

fix for 2400bps modes

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This commit is contained in:
Christoph Mayer 2019-10-08 09:37:43 +02:00
parent b846571748
commit d5a5584271
1 changed files with 48 additions and 20 deletions
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68
python/physical_layer/STANAG_4285.py
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@ -8,31 +8,41 @@ from digitalhf.digitalhf_swig import viterbi27
class Deinterleaver(object):
"S4285 deinterleaver"
def __init__(self, incr):
self._dtype = np.float32
## incr = 12 -> L
## incr = 1 -> S
self._buf = [np.zeros(incr*(31-i) + 1) for i in range(32)]
self._buf = [np.zeros(incr*(31-i) + 1, dtype=self._dtype)
for i in range(32)]
def push(self, a):
assert(len(a) == 32)
for i in range(32):
self._buf[i][0] = a[i]
self._buf[i] = np.roll(self._buf[i],1)
return self.fetch()
def fetch(self):
return np.array([self._buf[(9*i)%32][0] for i in range(32)])
return np.array([self._buf[(9*i)%32][0] for i in range(32)],
dtype=self._dtype)
## ---- constellatios -----------------------------------------------------------
BPSK=np.array(zip(np.exp(2j*np.pi*np.arange(2)/2), [0,1]), common.CONST_DTYPE)
QPSK=np.array(zip(np.exp(2j*np.pi*np.arange(4)/4), [0,1,3,2]), common.CONST_DTYPE)
PSK8=np.array(zip(np.exp(2j*np.pi*np.arange(8)/8), [0,1,3,2,6,7,5,4]), common.CONST_DTYPE)
## ---- constellation indices ---------------------------------------------------
MODE_BPSK=0
MODE_QPSK=1
MODE_8PSK=2
MODES = { ## [BPS]['const'] [BPS]['punct'] [BPS]['repeat']
'2400': {'const': MODE_8PSK, 'punct': ['11', '10'] , 'repeat': 1, 'deintl_multiple': 4},
'1200': {'const': MODE_QPSK, 'punct': [ '1', '1'] , 'repeat': 1, 'deintl_multiple': 2},
'600': {'const': MODE_BPSK, 'punct': [ '1', '1'] , 'repeat': 1, 'deintl_multiple': 1},
'300': {'const': MODE_BPSK, 'punct': [ '1', '1'] , 'repeat': 2, 'deintl_multiple': 1},
'150': {'const': MODE_BPSK, 'punct': [ '1', '1'] , 'repeat': 4, 'deintl_multiple': 1},
'75': {'const': MODE_BPSK, 'punct': [ '1', '1'] , 'repeat': 8, 'deintl_multiple': 1}
'2400': {'const': MODE_8PSK, 'repeat': 1, 'deintl_multiple': 4},
'1200': {'const': MODE_QPSK, 'repeat': 1, 'deintl_multiple': 2},
'600': {'const': MODE_BPSK, 'repeat': 1, 'deintl_multiple': 1},
'300': {'const': MODE_BPSK, 'repeat': 2, 'deintl_multiple': 1},
'150': {'const': MODE_BPSK, 'repeat': 4, 'deintl_multiple': 1},
'75': {'const': MODE_BPSK, 'repeat': 8, 'deintl_multiple': 1}
}
DEINTERLEAVER_INCR = { 'S': 1, 'L': 12 }
@ -45,9 +55,7 @@ class PhysicalLayer(object):
self._sps = sps
self._frame_counter = 0
self._is_first_frame = True
self._constellations = [self.make_psk(2, [0,1]),
self.make_psk(4, [0,1,3,2]),
self.make_psk(8, [1,0,2,3,6,7,5,4])]
self._constellations = [BPSK,QPSK,PSK8]
self._preamble = self.get_preamble()
self._data = self.get_data()
self._viterbi_decoder = viterbi27(0x6d, 0x4f)
@ -61,8 +69,8 @@ class PhysicalLayer(object):
bps,intl = mode.split('/')
self._mode = MODES[bps]['const']
self._deinterleaver = Deinterleaver(DEINTERLEAVER_INCR[intl] * MODES[bps]['deintl_multiple'])
self._depuncturer = common.Depuncturer(repeat = MODES[bps]['repeat'],
puncture_pattern = MODES[bps]['punct'])
self._depuncturer = common.Depuncturer(repeat = MODES[bps]['repeat'])
self._repeat = MODES[bps]['repeat']
self._fault_counter = 0
def get_mode(self):
@ -128,15 +136,35 @@ class PhysicalLayer(object):
def decode_soft_dec(self, soft_dec):
n = len(soft_dec)
r = []
for i in range(0,n,32):
self._deinterleaver.push(soft_dec[i:i+32])
r.extend(self._deinterleaver.fetch().tolist())
rd = self._depuncturer.process(np.array(r, dtype=np.float32))
decoded_bits = self._viterbi_decoder.udpate(rd)
quality = 100.0*self._viterbi_decoder.quality()/(2*len(decoded_bits))
quality_correction = 4.0/3.5 if n==384 else 1.0
deintl = lambda x: np.concatenate([self._deinterleaver.push(x[i:i+32]) for i in range(0,len(x),32)])
rd = self._derepeat(deintl(self._depuncture(soft_dec)))
decoded_bits = self._viterbi_decoder.udpate(rd.tolist())
quality = 100.0*self._viterbi_decoder.quality()/(2*len(decoded_bits))*quality_correction
return decoded_bits,quality
def _derepeat(self, soft_dec):
if self._repeat == 1:
return soft_dec
n = len(soft_dec)
m = n//(2*self._repeat)
u = soft_dec.reshape(m, 2*self._repeat)
for i in range(1,self._repeat):
u[:,0] += u[:,2*i]
u[:,1] += u[:,2*i+1]
return np.reshape(u[:,0:2], 2*m)
def _depuncture(self, soft_dec):
if len(soft_dec) != 384:
return soft_dec
else:
u = np.zeros(512, dtype=soft_dec.dtype)
u[0::4] = soft_dec[0::3]
u[1::4] = soft_dec[1::3]
u[2::4] = soft_dec[2::3]
u[3::4] = 0.0 ## puncture
return u
@staticmethod
def get_preamble():
"""preamble symbols + scrambler(=1)"""