mirror of
https://github.com/hb9fxq/gr-digitalhf
synced 2024-12-22 23:19:59 +00:00
91 lines
3 KiB
Python
91 lines
3 KiB
Python
## -*- python -*-
|
|
|
|
import numpy as np
|
|
|
|
CONST_DTYPE=np.dtype([('points', np.complex64),
|
|
('symbols', np.int32)])
|
|
|
|
SYMB_SCRAMBLE_DTYPE=np.dtype([('symb', np.complex64),
|
|
('scramble', np.complex64),
|
|
('scramble_xor', np.uint8)])
|
|
|
|
def make_scr(s1, s2=None, s3=None):
|
|
a = np.zeros(len(s1), SYMB_SCRAMBLE_DTYPE)
|
|
a['symb'][:] = s1
|
|
if s2 is not None:
|
|
assert(len(s2) == len(s1))
|
|
a['scramble'][:] = s2
|
|
if s3 is not None:
|
|
assert(len(s3) == len(s1))
|
|
a['scramble_xor'][:] = s3
|
|
return a
|
|
|
|
def n_psk(n,x):
|
|
"""n-ary PSK constellation"""
|
|
return np.complex64(np.exp(2j*np.pi*x/n))
|
|
|
|
def freq_est(z):
|
|
"""Data-Aided Frequency Estimation for Burst Digital Transmission,
|
|
Umberto Mengali and M. Morelli, IEEE TRANSACTIONS ON COMMUNICATIONS,
|
|
VOL. 45, NO. 1, JANUARY 1997"""
|
|
L0 = len(z)
|
|
N = L0//2
|
|
R = np.zeros(N+1, dtype=np.complex64)
|
|
for i in range(N+1):
|
|
R[i] = 1.0/(L0-i)*np.sum(z[i:]*np.conj(z[0:L0-i])) ## eq (3)
|
|
m = np.arange(N+1, dtype=np.float32)
|
|
w = 3*((L0-m)*(L0-m+1)-N*(L0-N))/(N*(4*N*N - 6*N*L0 + 3*L0*L0-1)) ## eq (9)
|
|
mod_2pi = lambda x : np.mod(x-np.pi, 2*np.pi) - np.pi
|
|
return np.sum(w[1:] * mod_2pi(np.diff(np.angle(R)))) ## eq (8)
|
|
|
|
class Depuncturer(object):
|
|
def __init__(self, repeat=1, puncture_pattern=['1','1']):
|
|
assert(repeat >= 1)
|
|
self._repeat = repeat
|
|
self._num_patterns = num_patterns = len(puncture_pattern)
|
|
assert(num_patterns >= 2)
|
|
assert(all([len(puncture_pattern[0]) == len(p) for p in puncture_pattern[1:]]))
|
|
m = np.array([x=='1' for y in puncture_pattern for x in y])
|
|
self._num_unpacked = len(m)
|
|
self._num_packed = np.sum(m)
|
|
self._pattern = m.reshape(num_patterns, self._num_unpacked//num_patterns).transpose().reshape(1, self._num_unpacked)[0]
|
|
self._range_packed = np.arange(self._num_packed)
|
|
self._range_unpacked = np.arange(self._num_unpacked)
|
|
|
|
def process(self, x):
|
|
n = len(x)
|
|
assert(n%(self._num_packed * self._repeat) == 0)
|
|
## (1) unpack
|
|
xd = np.zeros(n * self._num_unpacked // self._num_packed, dtype=np.float64)
|
|
i = 0
|
|
j = 0
|
|
while i < len(xd):
|
|
xd[(i + self._range_unpacked)[self._pattern]] += x[j + self._range_packed]
|
|
j += self._num_packed
|
|
i += self._num_unpacked
|
|
assert(j == n)
|
|
assert(i == len(xd))
|
|
if self._repeat == 1:
|
|
return xd
|
|
|
|
## (2) combine repeated data
|
|
xu = np.zeros(len(xd) // self._repeat, dtype=np.float64)
|
|
i = 0
|
|
j = 0
|
|
m = self._num_patterns
|
|
r = np.arange(m)
|
|
while i < len(xu):
|
|
for k in range(self._repeat):
|
|
xu[i + r] += xd[j + r]
|
|
j += m
|
|
i += m
|
|
assert(i == len(xu))
|
|
assert(j == len(xd))
|
|
return xu
|
|
|
|
if __name__ == '__main__':
|
|
idx=np.arange(3)
|
|
z=np.exp(1j*idx*0.056+1j)
|
|
print(freq_est(z)/0.056)
|
|
|