def make_non_differential_constellation(m, gray_coded):
side = int(pow(m, 0.5))
if (not isinstance(m, int) or m < 4 or not is_power_of_four(m)):
raise ValueError("m must be a power of 4 integer.")
# Each symbol holds k bits.
k = int(log(m) / log(2.0))
if gray_coded:
# Number rows and columns using gray codes.
gcs = gray_code(side)
# Get inverse gray codes.
i_gcs = mod_codes.invert_code(gcs)
else:
i_gcs = range(0, side)
# The distance between points is found.
step = 2.0/(side-1)
gc_to_x = [-1 + i_gcs[gc]*step for gc in range(0, side)]
# First k/2 bits determine x position.
# Following k/2 bits determine y position.
const_map = []
for i in range(m):
y = gc_to_x[get_bits(i, 0, k/2)]
x = gc_to_x[get_bits(i, k/2, k/2)]
const_map.append(complex(x,y))
return const_map
def psk_constellation(m=_def_constellation_points, mod_code=_def_mod_code):
"""
Creates a PSK constellation object.
"""
k = log(m) / log(2.0)
if (k != int(k)):
raise StandardError('Number of constellation points must be a power of two.')
points = [exp(2*pi*(0+1j)*i/m) for i in range(0,m)]
pre_diff_code, post_diff_code = create_encodings(mod_code, m)
if post_diff_code is not None:
inverse_post_diff_code = mod_codes.invert_code(post_diff_code)
points = [points[x] for x in inverse_post_diff_code]
constellation = digital.constellation_psk(points, pre_diff_code, m)
return constellation
def __init__(self, constellation,
samples_per_symbol=_def_samples_per_symbol,
differential=_def_differential,
excess_bw=_def_excess_bw,
gray_coded=True,
freq_bw=_def_freq_bw,
timing_bw=_def_timing_bw,
phase_bw=_def_phase_bw,
verbose=_def_verbose,
log=_def_log):
"""
Hierarchical block for RRC-filtered differential generic demodulation.
The input is the complex modulated signal at baseband.
The output is a stream of bits packed 1 bit per byte (LSB)
@param constellation: determines the modulation type
@type constellation: gnuradio.digital.gr_constellation
@param samples_per_symbol: samples per symbol >= 2
@type samples_per_symbol: float
@param excess_bw: Root-raised cosine filter excess bandwidth
@type excess_bw: float
@param gray_coded: turn gray coding on/off
@type gray_coded: bool
@param freq_bw: loop filter lock-in bandwidth
@type freq_bw: float
@param timing_bw: timing recovery loop lock-in bandwidth
@type timing_bw: float
@param phase_bw: phase recovery loop bandwidth
@type phase_bw: float
@param verbose: Print information about modulator?
@type verbose: bool
@param debug: Print modualtion data to files?
@type debug: bool
"""
gr.hier_block2.__init__(self, "generic_demod",
gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature
gr.io_signature(1, 1, gr.sizeof_char)) # Output signature
self._constellation = constellation.base()
self._samples_per_symbol = samples_per_symbol
self._excess_bw = excess_bw
self._phase_bw = phase_bw
self._freq_bw = freq_bw
self._timing_bw = timing_bw
self._timing_max_dev= _def_timing_max_dev
self._differential = differential
if self._samples_per_symbol < 2:
raise TypeError, ("sbp must be >= 2, is %d" % self._samples_per_symbol)
arity = pow(2,self.bits_per_symbol())
nfilts = 32
ntaps = 11 * int(self._samples_per_symbol*nfilts)
# Automatic gain control
self.agc = gr.agc2_cc(0.6e-1, 1e-3, 1, 1, 100)
# Frequency correction
fll_ntaps = 55
self.freq_recov = digital.fll_band_edge_cc(self._samples_per_symbol, self._excess_bw,
fll_ntaps, self._freq_bw)
# symbol timing recovery with RRC data filter
taps = gr.firdes.root_raised_cosine(nfilts, nfilts*self._samples_per_symbol,
1.0, self._excess_bw, ntaps)
self.time_recov = digital.pfb_clock_sync_ccf(self._samples_per_symbol,
self._timing_bw, taps,
nfilts, nfilts//2, self._timing_max_dev)
fmin = -0.25
fmax = 0.25
self.receiver = digital.constellation_receiver_cb(
self._constellation, self._phase_bw,
fmin, fmax)
# Do differential decoding based on phase change of symbols
if differential:
self.diffdec = digital.diff_decoder_bb(arity)
if gray_coded:
self.symbol_mapper = digital.map_bb(
mod_codes.invert_code(self._constellation.pre_diff_code()))
# unpack the k bit vector into a stream of bits
self.unpack = gr.unpack_k_bits_bb(self.bits_per_symbol())
if verbose:
self._print_verbage()
if log:
self._setup_logging()
# Connect and Initialize base class
blocks = [self, self.agc, self.freq_recov,
self.time_recov, self.receiver]
if differential:
blocks.append(self.diffdec)
if self._constellation.apply_pre_diff_code():
blocks.append(self.symbol_mapper)
blocks += [self.unpack, self]
self.connect(*blocks)
