def sync_symbol(filtertype, alpha, K, n_mod, N):
"""
Generate Schmidls Training Symbols to achieve Receiver Synchronisation
K: should be an odd number
Process:
* First Symbol: Transmit PN-Sequence on all even frequencies while zeros on the odd
frequencies. Constant signal energy -> Multiply every Symbol with sqrt(2)
* Second Symbol: Transmit PN-Sequence on all odd frequencies and another PN-Sequence
on the even frequencies
"""
pn_order = 14
pn_seed = "00101101010010"
pn_mask = "01001110100111"
if int(np.floor(K / 2.0)) % 2:
n_even_freq = int(np.floor(K / 2.0))
else:
n_even_freq = int(np.ceil(K / 2.0))
seq_length = n_even_freq * n_mod
sym_sequence = np.zeros(K, dtype="complex")
pn_sequence = cp.pnsequence(pn_order, pn_seed, pn_mask, seq_length)
qam_mod = cp.modulation.QAMModem(2**n_mod)
qam_sequence = qam_mod.modulate(pn_sequence)
for i in range(len(sym_sequence)):
if not i % 2:
sym_sequence[i] = qam_sequence[i / 2]
ifft_sequence = np.fft.ifftshift(sym_sequence)
output = gfdm_tx(ifft_sequence, filtertype, alpha, 1, K, N)
# output = np.fft.ifft(np.sqrt(2)*ifft_sequence)
return output
def sync_symbol(filtertype, alpha, K, n_mod, N):
'''
Generate Schmidls Training Symbols to achieve Receiver Synchronisation
K: should be an odd number
Process:
* First Symbol: Transmit PN-Sequence on all even frequencies while zeros on the odd
frequencies. Constant signal energy -> Multiply every Symbol with sqrt(2)
* Second Symbol: Transmit PN-Sequence on all odd frequencies and another PN-Sequence
on the even frequencies
'''
pn_order = 14
pn_seed = '00101101010010'
pn_mask = '01001110100111'
if int(np.floor(K/2.0)) % 2:
n_even_freq = int(np.floor(K/2.0))
else:
n_even_freq = int(np.ceil(K/2.0))
seq_length = n_even_freq*n_mod
sym_sequence = np.zeros(K, dtype='complex')
pn_sequence = cp.pnsequence(pn_order, pn_seed, pn_mask, seq_length)
qam_mod = cp.modulation.QAMModem(2**n_mod)
qam_sequence = qam_mod.modulate(pn_sequence)
for i in xrange(len(sym_sequence)):
if not i % 2:
sym_sequence[i] = qam_sequence[i/2]
ifft_sequence = np.fft.ifftshift(sym_sequence)
output = gfdm_tx(ifft_sequence, filtertype, alpha, 1, K, N)
# output = np.fft.ifft(np.sqrt(2)*ifft_sequence)
return output
def sync_symbol2(filtertype, alpha, K, L, n_mod):
pn_order = 14
pn_seed = '01001000111011'
pn_mask = '01001101001110'
seq_length = K*n_mod
pn_sequence = cp.pnsequence(pn_order, pn_seed, pn_mask, seq_length)
qam_mod = cp.modulation.QAMModem(2**n_mod)
qam_sequence = qam_mod.modulate(pn_sequence)
output = gfdm_tx_fft2(np.tile(qam_sequence, 2), filtertype, alpha, 2, K, 2, 1)
return output
def sync_symbol2(filtertype, alpha, K, L, n_mod):
pn_order = 14
pn_seed = '01001000111011'
pn_mask = '01001101001110'
seq_length = K * n_mod
pn_sequence = cp.pnsequence(pn_order, pn_seed, pn_mask, seq_length)
qam_mod = cp.modulation.QAMModem(2 ** n_mod)
qam_sequence = qam_mod.modulate(pn_sequence)
output = gfdm_tx_fft2(np.tile(qam_sequence, 2), filtertype, alpha, 2, K, 2, 1)
return output