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nxdn96 demodulation

This commit is contained in:
Max 2020-02-07 19:30:57 -05:00
parent e25e7be488
commit 3de2d3e440
1 changed files with 22 additions and 11 deletions
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29
op25/gr-op25_repeater/apps/p25_demodulator.py
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@ -2,7 +2,7 @@
# Copyright 2005,2006,2007 Free Software Foundation, Inc.
#
# OP25 Demodulator Block
# Copyright 2009, 2010, 2011, 2012, 2013, 2014, 2015 Max H. Parke KA1RBI
# Copyright 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020 Max H. Parke KA1RBI
#
# This file is part of GNU Radio and part of OP25
#
@ -62,7 +62,7 @@ def get_decim(speed):
for i_f in if_freqs:
if s % i_f != 0:
continue
q = s / i_f
q = int(s / i_f)
if q & 1:
continue
if q >= 40 and q & 3 == 0:
@ -71,7 +71,7 @@ def get_decim(speed):
else:
decim = q/2
decim2 = 2
return decim, decim2
return int(decim), int(decim2)
return None
class p25_demod_base(gr.hier_block2):
@ -92,14 +92,18 @@ class p25_demod_base(gr.hier_block2):
self.baseband_amp = blocks.multiply_const_ff(_def_bb_gain)
coeffs = op25_c4fm_mod.c4fm_taps(sample_rate=self.if_rate, span=9, generator=op25_c4fm_mod.transfer_function_rx).generate()
sps = self.if_rate / 4800
sps = self.if_rate / self.symbol_rate
if filter_type == 'rrc':
ntaps = 7 * sps
if ntaps & 1 == 0:
ntaps += 1
coeffs = filter.firdes.root_raised_cosine(1.0, if_rate, symbol_rate, excess_bw, ntaps)
if filter_type == 'nxdn':
coeffs = op25_c4fm_mod.c4fm_taps(sample_rate=self.if_rate, span=9, generator=op25_c4fm_mod.transfer_function_nxdn).generate()
coeffs = op25_c4fm_mod.c4fm_taps(sample_rate=self.if_rate, span=9, generator=op25_c4fm_mod.transfer_function_nxdn, symbol_rate=self.symbol_rate).generate()
gain_adj = 1.8 # for nxdn48 6.25 KHz
if self.symbol_rate == 4800:
gain_adj = 0.77 # nxdn96 12.5 KHz
coeffs = [x * gain_adj for x in coeffs]
if filter_type == 'gmsk':
# lifted from gmsk.py
_omega = sps
@ -248,6 +252,8 @@ class p25_demod_cb(p25_demod_base):
self.t_cache[0] = bpf_coeffs
fa = 6250
fb = self.if2 / 2
if filter_type == 'nxdn' and self.symbol_rate == 2400: # nxdn48 6.25 KHz
fa = 3125
lpf_coeffs = filter.firdes.low_pass(1.0, self.if1, (fb+fa)/2, fb-fa, filter.firdes.WIN_HAMMING)
self.bpf = filter.fir_filter_ccc(self.decim, bpf_coeffs)
self.lpf = filter.fir_filter_ccf(self.decim2, lpf_coeffs)
@ -259,7 +265,12 @@ class p25_demod_cb(p25_demod_base):
sys.stderr.write( 'Unable to use two-stage decimator for speed=%d\n' % (input_rate))
# local osc
self.lo = analog.sig_source_c (input_rate, analog.GR_SIN_WAVE, 0, 1.0, 0)
lpf_coeffs = filter.firdes.low_pass(1.0, input_rate, 7250, 1450, filter.firdes.WIN_HANN)
f1 = 7250
f2 = 1450
if filter_type == 'nxdn' and self.symbol_rate == 2400: # nxdn48 6.25 KHz
f1 = 3125
f2 = 625
lpf_coeffs = filter.firdes.low_pass(1.0, input_rate, f1, f2, filter.firdes.WIN_HANN)
decimation = int(input_rate / if_rate)
self.lpf = filter.fir_filter_ccf(decimation, lpf_coeffs)
resampled_rate = float(input_rate) / float(decimation) # rate at output of self.lpf
@ -319,7 +330,7 @@ class p25_demod_cb(p25_demod_base):
if sps == self.sps:
return
self.sps = sps
print 'set_omega %d %f' % (omega, sps)
print ('set_omega %d %f' % (omega, sps))
self.clock.set_omega(self.sps)
def set_relative_frequency(self, freq):
@ -363,7 +374,7 @@ class p25_demod_cb(p25_demod_base):
elif demod_type == 'cqpsk':
self.connect(self.if_out, self.cutoff, self.agc, self.clock, self.diffdec, self.to_float, self.rescale, self.slicer)
else:
print 'connect_chain failed, type: %s' % demod_type
print ('connect_chain failed, type: %s' % demod_type)
assert 0 == 1
if self.float_sink is not None:
self.connect_float(self.float_sink[1])
@ -385,7 +396,7 @@ class p25_demod_cb(p25_demod_base):
self.connect(self.fsk4_demod, sink)
self.float_sink = [self.fsk4_demod, sink]
else:
print 'connect_float: state error', self.connect_state
print ('connect_float: state error', self.connect_state)
assert 0 == 1
def connect_complex(self, src, sink):