mirror of
https://github.com/hb9fxq/gr-digitalhf
synced 2024-11-05 05:55:53 +00:00
81 lines
3.1 KiB
Python
81 lines
3.1 KiB
Python
## -*- python -*-
|
|
|
|
import numpy as np
|
|
from gnuradio import digital
|
|
|
|
class PhysicalLayer(object):
|
|
"""Physical layer description for STANAG 4285"""
|
|
|
|
def __init__(self, mode=0):
|
|
"""For STANAG 4258 the mode has to be set manually: mode=0 -> BPSK, mode=1 -> QPSK, mode=2 -> 8PSK"""
|
|
self._constellations = [PhysicalLayer.make_psk(2, [0,1]),
|
|
PhysicalLayer.make_psk(4, [0,1,3,2]),
|
|
PhysicalLayer.make_psk(8, [1,0,2,3,6,7,5,4])]
|
|
self._preamble = [PhysicalLayer.get_preamble(), 0] ## BPSK
|
|
self._data = [PhysicalLayer.get_data(), mode] ## according to the mode
|
|
self._counter = 0
|
|
|
|
def set_mode(self):
|
|
"""For STANAG 4258 the mode has to be set manually: mode=0 -> BPSK, mode=1 -> QPSK, mode=2 -> 8PSK"""
|
|
self._data[1] = mode
|
|
|
|
def get_constellations(self):
|
|
return self._constellations
|
|
|
|
def get_frame(self):
|
|
"""returns the known+unknown symbols and scrambling"""
|
|
if self._counter == 0:
|
|
return self._preamble
|
|
else:
|
|
return self._data
|
|
|
|
def get_doppler(self): ## symbols
|
|
"""used for doppler shift update, for determining which frame to provide next,
|
|
and for stopping at end of data/when the signal quality is too low"""
|
|
self._counter = (self._counter+1)&1
|
|
## TODO: doppler calculations
|
|
doppler = 0.1234
|
|
return [True, doppler]
|
|
|
|
@staticmethod
|
|
def get_preamble():
|
|
"""preamble symbols + scrambler(=1)"""
|
|
state = np.array([1,1,0,1,0], dtype=np.bool)
|
|
taps = np.array([0,0,1,0,1], dtype=np.bool)
|
|
p = np.zeros(80, dtype=np.uint8)
|
|
for i in range(80):
|
|
p[i] = state[-1]
|
|
state = np.concatenate(([np.sum(state&taps)&1], state[0:-1]))
|
|
a = np.zeros(80, dtype=[('symb',np.complex64), ('scramble', np.complex64)])
|
|
## BPSK modulation
|
|
constellation = PhysicalLayer.make_psk(2,range(2))['points']
|
|
a['symb'] = constellation[p,]
|
|
a['scramble'] = 1
|
|
return a
|
|
|
|
@staticmethod
|
|
def get_data():
|
|
"""data symbols + scrambler; for unknown symbols 'symb'=0"""
|
|
state = np.array([1,1,1,1,1,1,1,1,1], dtype=np.bool)
|
|
taps = np.array([0,0,0,0,1,0,0,0,1], dtype=np.bool)
|
|
p = np.zeros(176, dtype=np.uint8)
|
|
for i in range(176):
|
|
p[i] = np.sum(state[-3:]*[4,2,1])
|
|
for j in range(3):
|
|
state = np.concatenate(([np.sum(state&taps)&1], state[0:-1]))
|
|
a=np.zeros(176, dtype=[('symb',np.complex64), ('scramble', np.complex64)])
|
|
## PSK-8 modulation
|
|
constellation = PhysicalLayer.make_psk(8,range(8))['points']
|
|
a['scramble'] = constellation[p,]
|
|
a['symb'][ 32: 48] = 1 ## mini-probe 1
|
|
a['symb'][ 80: 96] = 1 ## mini-probe 2
|
|
a['symb'][128:144] = 1 ## mini-probe 3
|
|
return a
|
|
|
|
@staticmethod
|
|
def make_psk(n, gray_code):
|
|
c = np.zeros(n, dtype=[('points', np.complex64), ('symbols', np.uint8)])
|
|
c['points'] = np.exp(2*np.pi*1j*np.array(range(n))/n)
|
|
c['symbols'] = gray_code
|
|
return c
|