2 # Copyright 2005,2006 Free Software Foundation, Inc.
4 # This file is part of GNU Radio
6 # GNU Radio is free software; you can redistribute it and/or modify
7 # it under the terms of the GNU General Public License as published by
8 # the Free Software Foundation; either version 2, or (at your option)
11 # GNU Radio is distributed in the hope that it will be useful,
12 # but WITHOUT ANY WARRANTY; without even the implied warranty of
13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 # GNU General Public License for more details.
16 # You should have received a copy of the GNU General Public License
17 # along with GNU Radio; see the file COPYING. If not, write to
18 # the Free Software Foundation, Inc., 51 Franklin Street,
19 # Boston, MA 02110-1301, USA.
22 # See gnuradio-examples/python/gmsk2 for examples
25 differential BPSK modulation and demodulation.
28 from gnuradio import gr, gru, modulation_utils
29 from math import pi, sqrt
33 from pprint import pprint
35 # default values (used in __init__ and add_options)
36 _def_samples_per_symbol = 2
42 _def_costas_alpha = 0.05
45 _def_omega_relative_limit = 0.005
48 # /////////////////////////////////////////////////////////////////////////////
50 # /////////////////////////////////////////////////////////////////////////////
52 class dbpsk_mod(gr.hier_block):
54 def __init__(self, fg,
55 samples_per_symbol=_def_samples_per_symbol,
56 excess_bw=_def_excess_bw,
57 gray_code=_def_gray_code,
61 Hierarchical block for RRC-filtered differential BPSK modulation.
63 The input is a byte stream (unsigned char) and the
64 output is the complex modulated signal at baseband.
68 @param samples_per_symbol: samples per baud >= 2
69 @type samples_per_symbol: integer
70 @param excess_bw: Root-raised cosine filter excess bandwidth
71 @type excess_bw: float
72 @param gray_code: Tell modulator to Gray code the bits
74 @param verbose: Print information about modulator?
76 @param log: Log modulation data to files?
81 self._samples_per_symbol = samples_per_symbol
82 self._excess_bw = excess_bw
83 self._gray_code = gray_code
85 if not isinstance(self._samples_per_symbol, int) or self._samples_per_symbol < 2:
86 raise TypeError, ("sbp must be an integer >= 2, is %d" % self._samples_per_symbol)
88 ntaps = 11 * self._samples_per_symbol
90 arity = pow(2,self.bits_per_symbol())
92 # turn bytes into k-bit vectors
94 gr.packed_to_unpacked_bb(self.bits_per_symbol(), gr.GR_MSB_FIRST)
97 self.symbol_mapper = gr.map_bb(psk.binary_to_gray[arity])
99 self.symbol_mapper = gr.map_bb(psk.binary_to_ungray[arity])
101 self.diffenc = gr.diff_encoder_bb(arity)
103 self.chunks2symbols = gr.chunks_to_symbols_bc(psk.constellation[arity])
105 # pulse shaping filter
106 self.rrc_taps = gr.firdes.root_raised_cosine(
107 self._samples_per_symbol, # gain (samples_per_symbol since we're
108 # interpolating by samples_per_symbol)
109 self._samples_per_symbol, # sampling rate
111 self._excess_bw, # excess bandwidth (roll-off factor)
114 self.rrc_filter = gr.interp_fir_filter_ccf(self._samples_per_symbol,
118 fg.connect(self.bytes2chunks, self.symbol_mapper, self.diffenc,
119 self.chunks2symbols, self.rrc_filter)
122 self._print_verbage()
125 self._setup_logging()
127 # Initialize base class
128 gr.hier_block.__init__(self, self._fg, self.bytes2chunks, self.rrc_filter)
130 def samples_per_symbol(self):
131 return self._samples_per_symbol
133 def bits_per_symbol(self=None): # static method that's also callable on an instance
135 bits_per_symbol = staticmethod(bits_per_symbol) # make it a static method. RTFM
137 def add_options(parser):
139 Adds DBPSK modulation-specific options to the standard parser
141 parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
142 help="set RRC excess bandwith factor [default=%default]")
143 parser.add_option("", "--no-gray-code", dest="gray_code",
144 action="store_false", default=True,
145 help="disable gray coding on modulated bits (PSK)")
146 add_options=staticmethod(add_options)
148 def extract_kwargs_from_options(options):
150 Given command line options, create dictionary suitable for passing to __init__
152 return modulation_utils.extract_kwargs_from_options(dbpsk_mod.__init__,
153 ('self', 'fg'), options)
154 extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
157 def _print_verbage(self):
158 print "bits per symbol = %d" % self.bits_per_symbol()
159 print "Gray code = %s" % self._gray_code
160 print "RRC roll-off factor = %.2f" % self._excess_bw
162 def _setup_logging(self):
163 print "Modulation logging turned on."
164 self._fg.connect(self.bytes2chunks,
165 gr.file_sink(gr.sizeof_char, "bytes2chunks.dat"))
166 self._fg.connect(self.symbol_mapper,
167 gr.file_sink(gr.sizeof_char, "graycoder.dat"))
168 self._fg.connect(self.diffenc,
169 gr.file_sink(gr.sizeof_char, "diffenc.dat"))
170 self._fg.connect(self.chunks2symbols,
171 gr.file_sink(gr.sizeof_gr_complex, "chunks2symbols.dat"))
172 self._fg.connect(self.rrc_filter,
173 gr.file_sink(gr.sizeof_gr_complex, "rrc_filter.dat"))
176 # /////////////////////////////////////////////////////////////////////////////
179 # Differentially coherent detection of differentially encoded BPSK
180 # /////////////////////////////////////////////////////////////////////////////
182 class dbpsk_demod(gr.hier_block):
184 def __init__(self, fg,
185 samples_per_symbol=_def_samples_per_symbol,
186 excess_bw=_def_excess_bw,
187 costas_alpha=_def_costas_alpha,
188 gain_mu=_def_gain_mu,
190 omega_relative_limit=_def_omega_relative_limit,
191 gray_code=_def_gray_code,
192 verbose=_def_verbose,
195 Hierarchical block for RRC-filtered differential BPSK demodulation
197 The input is the complex modulated signal at baseband.
198 The output is a stream of bits packed 1 bit per byte (LSB)
200 @param fg: flow graph
202 @param samples_per_symbol: samples per symbol >= 2
203 @type samples_per_symbol: float
204 @param excess_bw: Root-raised cosine filter excess bandwidth
205 @type excess_bw: float
206 @param costas_alpha: loop filter gain
207 @type costas_alphas: float
208 @param gain_mu: for M&M block
210 @param mu: for M&M block
212 @param omega_relative_limit: for M&M block
213 @type omega_relative_limit: float
214 @param gray_code: Tell modulator to Gray code the bits
215 @type gray_code: bool
216 @param verbose: Print information about modulator?
218 @param debug: Print modualtion data to files?
223 self._samples_per_symbol = samples_per_symbol
224 self._excess_bw = excess_bw
225 self._costas_alpha = costas_alpha
226 self._gain_mu = gain_mu
228 self._omega_relative_limit = omega_relative_limit
229 self._gray_code = gray_code
231 if samples_per_symbol < 2:
232 raise TypeError, "samples_per_symbol must be >= 2, is %r" % (samples_per_symbol,)
234 arity = pow(2,self.bits_per_symbol())
236 # Automatic gain control
237 scale = (1.0/16384.0)
238 self.pre_scaler = gr.multiply_const_cc(scale) # scale the signal from full-range to +-1
239 #self.agc = gr.agc2_cc(0.6e-1, 1e-3, 1, 1, 100)
240 self.agc = gr.feedforward_agc_cc(16, 1.0)
243 # Costas loop (carrier tracking)
244 # FIXME: need to decide how to handle this more generally; do we pull it from higher layer?
246 beta = .25 * self._costas_alpha * self._costas_alpha
247 self.costas_loop = gr.costas_loop_cc(self._costas_alpha, beta, 0.002, -0.002, costas_order)
250 ntaps = 11 * self._samples_per_symbol
251 self.rrc_taps = gr.firdes.root_raised_cosine(
253 self._samples_per_symbol, # sampling rate
255 self._excess_bw, # excess bandwidth (roll-off factor)
258 self.rrc_filter=gr.fir_filter_ccf(1, self.rrc_taps)
260 # symbol clock recovery
261 omega = self._samples_per_symbol
262 gain_omega = .25 * self._gain_mu * self._gain_mu
263 self.clock_recovery=gr.clock_recovery_mm_cc(omega, gain_omega,
264 self._mu, self._gain_mu,
265 self._omega_relative_limit)
267 # find closest constellation point
269 rotated_const = map(lambda pt: pt * rot, psk.constellation[arity])
270 #print "rotated_const =", rotated_const
272 self.diffdec = gr.diff_phasor_cc()
273 #self.diffdec = gr.diff_decoder_bb(arity)
275 self.slicer = gr.constellation_decoder_cb(rotated_const, range(arity))
278 self.symbol_mapper = gr.map_bb(psk.gray_to_binary[arity])
280 self.symbol_mapper = gr.map_bb(psk.ungray_to_binary[arity])
282 # unpack the k bit vector into a stream of bits
283 self.unpack = gr.unpack_k_bits_bb(self.bits_per_symbol())
286 self._print_verbage()
289 self._setup_logging()
291 # Connect and Initialize base class
292 self._fg.connect(self.pre_scaler, self.agc, self.costas_loop,
293 self.rrc_filter, self.clock_recovery, self.diffdec,
294 self.slicer, self.symbol_mapper, self.unpack)
296 gr.hier_block.__init__(self, self._fg, self.pre_scaler, self.unpack)
298 def samples_per_symbol(self):
299 return self._samples_per_symbol
301 def bits_per_symbol(self=None): # staticmethod that's also callable on an instance
303 bits_per_symbol = staticmethod(bits_per_symbol) # make it a static method. RTFM
305 def _print_verbage(self):
306 print "bits per symbol = %d" % self.bits_per_symbol()
307 print "Gray code = %s" % self._gray_code
308 print "RRC roll-off factor = %.2f" % self._excess_bw
309 print "Costas Loop alpha = %.5f" % self._costas_alpha
310 print "M&M symbol sync gain = %.5f" % self._gain_mu
311 print "M&M symbol sync mu = %.5f" % self._mu
312 print "M&M omega relative limit = %.5f" % self._omega_relative_limit
314 def _setup_logging(self):
315 print "Modulation logging turned on."
316 self._fg.connect(self.pre_scaler,
317 gr.file_sink(gr.sizeof_gr_complex, "prescaler.dat"))
318 self._fg.connect(self.agc,
319 gr.file_sink(gr.sizeof_gr_complex, "agc.dat"))
320 self._fg.connect(self.costas_loop,
321 gr.file_sink(gr.sizeof_gr_complex, "costas_loop.dat"))
322 self._fg.connect((self.costas_loop,1),
323 gr.file_sink(gr.sizeof_gr_complex, "costas_error.dat"))
324 self._fg.connect(self.rrc_filter,
325 gr.file_sink(gr.sizeof_gr_complex, "rrc_filter.dat"))
326 self._fg.connect(self.clock_recovery,
327 gr.file_sink(gr.sizeof_gr_complex, "clock_recovery.dat"))
328 self._fg.connect((self.clock_recovery,1),
329 gr.file_sink(gr.sizeof_gr_complex, "clock_recovery_error.dat"))
330 self._fg.connect(self.diffdec,
331 gr.file_sink(gr.sizeof_gr_complex, "diffdec.dat"))
332 self._fg.connect(self.slicer,
333 gr.file_sink(gr.sizeof_char, "slicer.dat"))
334 self._fg.connect(self.symbol_mapper,
335 gr.file_sink(gr.sizeof_char, "symbol_mapper.dat"))
336 self._fg.connect(self.unpack,
337 gr.file_sink(gr.sizeof_char, "unpack.dat"))
339 def add_options(parser):
341 Adds DBPSK demodulation-specific options to the standard parser
343 parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
344 help="set RRC excess bandwith factor [default=%default] (PSK)")
345 parser.add_option("", "--no-gray-code", dest="gray_code",
346 action="store_false", default=_def_gray_code,
347 help="disable gray coding on modulated bits (PSK)")
348 parser.add_option("", "--costas-alpha", type="float", default=None,
349 help="set Costas loop alpha value [default=%default] (PSK)")
350 parser.add_option("", "--gain-mu", type="float", default=_def_gain_mu,
351 help="set M&M symbol sync loop gain mu value [default=%default] (GMSK/PSK)")
352 parser.add_option("", "--mu", type="float", default=_def_mu,
353 help="set M&M symbol sync loop mu value [default=%default] (GMSK/PSK)")
354 parser.add_option("", "--omega-relative-limit", type="float", default=_def_omega_relative_limit,
355 help="M&M clock recovery omega relative limit [default=%default] (GMSK/PSK)")
356 add_options=staticmethod(add_options)
358 def extract_kwargs_from_options(options):
360 Given command line options, create dictionary suitable for passing to __init__
362 return modulation_utils.extract_kwargs_from_options(
363 dbpsk_demod.__init__, ('self', 'fg'), options)
364 extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
367 # Add these to the mod/demod registry
369 modulation_utils.add_type_1_mod('dbpsk', dbpsk_mod)
370 modulation_utils.add_type_1_demod('dbpsk', dbpsk_demod)