1
0
Fork 0
mirror of https://github.com/hb9fxq/gr-digitalhf synced 2024-12-22 23:19:59 +00:00
gr-digitalhf/python/physical_layer/STANAG_5511.py

183 lines
7.2 KiB
Python
Raw Normal View History

2019-05-23 18:37:32 +00:00
## -*- python -*-
from __future__ import print_function
import numpy as np
2020-02-19 14:07:50 +00:00
from . import common
2019-05-23 18:37:32 +00:00
from digitalhf.digitalhf_swig import viterbi27
2019-11-05 20:25:48 +00:00
## 192 = 6*32 0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,1 # 32
PREAMBLE = common.n_psk(8, np.array([7,0,3,4,1,1,1,0,2,6,1,5,1,7,0,3,5,4,2,2,6,1,2,2,0,4,5,4,1,2,2,6, # 1
7,0,7,0,1,1,5,4,2,6,5,1,1,7,4,7,5,4,6,6,6,1,6,6,0,4,1,0,1,2,6,2, # 2
7,4,7,4,1,5,5,0,2,2,5,5,1,3,4,3,5,0,6,2,6,5,6,2,0,0,1,4,1,6,6,6, # 3
7,0,3,4,5,5,5,4,2,6,1,5,5,3,4,7,5,4,2,2,2,5,6,6,0,4,5,4,5,6,6,2, # 4
7,4,3,0,1,5,1,4,2,2,1,1,1,3,0,7,5,0,2,6,6,5,2,6,0,0,5,0,1,6,2,2, # 5
7,4,3,0,5,1,5,0,2,2,1,1,5,7,4,3,5,0,2,6,2,1,6,2,0,0,5,0,5,2,6,6])) # 6
2019-05-23 18:37:32 +00:00
## ---- data scrambler -----------------------------------------------------------
class ScrambleData(object):
"""data scrambling sequence generator"""
def __init__(self):
self.reset()
def reset(self):
self._state = 0xBAD
self._counter = 0
def next(self):
if self._counter == 160:
self.reset()
for j in range(8):
self._advance()
self._counter += 1
return self._state&7
def _advance(self):
msb = self._state>>11
self._state = (self._state<<1)&4095
if msb:
self._state ^= 0x053
return self._state
## ---- constellation indices ---------------------------------------------------
MODE_BPSK=0
MODE_QPSK=1
## ---- physcal layer class -----------------------------------------------------
class PhysicalLayer(object):
"""Physical layer description for MIL-STD-188-110 Appendix D = STANAG 4539"""
def __init__(self, sps):
"""intialization"""
self._sps = sps
self._frame_counter = -1
self._constellations = [self.make_psk(2, [0,1]),
self.make_psk(4, [0,1,3,2])]
self._preamble = self.get_preamble()
self._scr_data = ScrambleData()
self._intl_idx = np.mod(17*np.arange(90, dtype=np.uint32), 90)
self._viterbi_decoder = viterbi27(0x6d, 0x4f)
self._viterbi_decoder2 = viterbi27(0x67, 0x5d)
##self._data = self.get_data()
def get_constellations(self):
return self._constellations
def get_next_frame(self, symbols):
"""returns a tuple describing the frame:
[0] ... known+unknown symbols and scrambling
[1] ... modulation type after descrambling
[2] ... a boolean indicating if the processing should continue
[3] ... a boolean indicating if the soft decision for the unknown
symbols are saved"""
print('-------------------- get_frame --------------------',
self._frame_counter)
success = True
if len(symbols) == 0:
self._frame_counter = -1
self._scr_data.reset()
if self._frame_counter == -1:
self._frame_counter += 1
return [self.get_preamble(),MODE_BPSK,success,False]
else:
z = np.mean(symbols[-19:])
print('CHECK:', z)
success = np.real(z) > 0.5 and np.abs(np.imag(z)) < 0.5
a = np.zeros(64, dtype=common.SYMB_SCRAMBLE_DTYPE)
a['scramble'] = common.n_psk(8, np.array([self._scr_data.next() for _ in range(64)]))
a['symb'][-19:] = a['scramble'][-19:]
self._frame_counter += 1
return [a,MODE_QPSK,success,success]
def get_doppler(self, iq_samples):
"""returns a tuple
[0] ... quality flag
[1] ... doppler estimate (rad/symbol) if available"""
print('-------------------- get_doppler --------------------',
self._frame_counter,len(iq_samples))
2019-11-05 20:25:48 +00:00
r = {'success': False, ## -- quality flag
'use_amp_est': False, ##self._frame_counter < 0,
'doppler': 0} ## -- doppler estimate (rad/symb)
2019-05-23 18:37:32 +00:00
sps = self._sps
_,zp = self.get_preamble_z()
wlen = 32
2019-11-05 20:25:48 +00:00
cc = np.correlate(iq_samples, zp[0:wlen])
2019-05-23 18:37:32 +00:00
imax = np.argmax(np.abs(cc[0:wlen*sps]))
idx = np.arange(wlen*sps)
2019-11-05 20:25:48 +00:00
pks = [np.vdot(zp[ i*wlen*sps+idx],
iq_samples[imax+i*wlen*sps+idx])
2019-05-23 18:37:32 +00:00
for i in range((len(iq_samples)-imax) // (wlen*sps))]
print('get_doppler pks: ', pks, np.angle(pks))
2019-11-05 20:25:48 +00:00
r['doppler'] = common.freq_est(pks)/(wlen*sps)
print('get_doppler doppler: ', r['doppler'])
r['success'] = True
return r
2019-05-23 18:37:32 +00:00
def set_mode(self, mode):
pass
def decode_soft_dec(self, soft_dec):
print('decode_soft_dec', self._frame_counter)
assert(len(soft_dec) == 90)
deintl_soft_dec = np.zeros(90, dtype=np.float64)
deintl_soft_dec[self._intl_idx] = soft_dec
print('decode_soft_dec', deintl_soft_dec)
2019-11-05 20:25:48 +00:00
decoded_bits = []
quality = 0.0
2019-05-23 18:37:32 +00:00
if self._frame_counter == 2:
self._viterbi_decoder.reset()
decoded_bits = self._viterbi_decoder.udpate(deintl_soft_dec)
2019-11-05 20:25:48 +00:00
quality = 100.0*self._viterbi_decoder.quality()/(2*len(decoded_bits))
print('bits=', len(decoded_bits), decoded_bits)
print('quality={}% ({},{})'.format(quality,
2019-05-23 18:37:32 +00:00
self._viterbi_decoder.quality(),
len(decoded_bits)))
else:
depunct_deintl_soft_dec = np.zeros(90//3*4, dtype=np.float64)
depunct_deintl_soft_dec[0::4] = deintl_soft_dec[0::3]
depunct_deintl_soft_dec[1::4] = deintl_soft_dec[1::3]
depunct_deintl_soft_dec[2::4] = deintl_soft_dec[2::3]
depunct_deintl_soft_dec[3::4] = 0
self._viterbi_decoder2.reset()
decoded_bits = self._viterbi_decoder2.udpate(depunct_deintl_soft_dec)
2019-11-05 20:25:48 +00:00
quality = 100.0*4/3.5*self._viterbi_decoder2.quality()/(2*len(decoded_bits))
print('bits=', len(decoded_bits), decoded_bits)
print('quality={}% ({},{})'.format(quality,
2019-05-23 18:37:32 +00:00
self._viterbi_decoder2.quality(),
len(decoded_bits)))
2019-11-05 20:25:48 +00:00
if quality > 90:
return decoded_bits,quality
else:
return [],0.0
2019-05-23 18:37:32 +00:00
def get_preamble(self):
"""preamble symbols + scrambler"""
2019-11-05 20:25:48 +00:00
return common.make_scr(PREAMBLE,PREAMBLE)
2019-05-23 18:37:32 +00:00
def get_preamble_z(self):
"""preamble symbols for preamble correlation"""
a = self.get_preamble()
return 2,np.array([z for z in a['symb'] for _ in range(self._sps)])
@staticmethod
def make_psk(n, gray_code):
"""generates n-PSK constellation data"""
c = np.zeros(n, dtype=common.CONST_DTYPE)
c['points'] = common.n_psk(n,np.arange(n))
c['symbols'] = gray_code
return c
if __name__ == '__main__':
print(PREAMBLE)
z = common.n_psk(8,PREAMBLE)
cc = [np.sum(z[0:32]*np.conj(z[32*i:32*i+32])) for i in range(6)]
print(np.abs(cc))
print(np.angle(cc)/np.pi*4)
print(z)