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 QPSK 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 = None
45 _def_omega_relative_limit = 0.005
48 # /////////////////////////////////////////////////////////////////////////////
50 # /////////////////////////////////////////////////////////////////////////////
52 class dqpsk_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 QPSK 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 symbol >= 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 debug: Print modualtion 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(samples_per_symbol, int) or samples_per_symbol < 2:
86 raise TypeError, ("sbp must be an integer >= 2, is %d" % samples_per_symbol)
88 ntaps = 11 * 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)
104 rotated_const = map(lambda pt: pt * rot, psk.constellation[arity])
105 self.chunks2symbols = gr.chunks_to_symbols_bc(rotated_const)
107 # pulse shaping filter
108 self.rrc_taps = gr.firdes.root_raised_cosine(
109 self._samples_per_symbol, # gain (sps since we're interpolating by sps)
110 self._samples_per_symbol, # sampling rate
112 self._excess_bw, # excess bandwidth (roll-off factor)
115 self.rrc_filter = gr.interp_fir_filter_ccf(self._samples_per_symbol, self.rrc_taps)
118 self._print_verbage()
121 self._setup_logging()
123 # Connect & Initialize base class
124 self._fg.connect(self.bytes2chunks, self.symbol_mapper, self.diffenc,
125 self.chunks2symbols, self.rrc_filter)
126 gr.hier_block.__init__(self, self._fg, self.bytes2chunks, self.rrc_filter)
128 def samples_per_symbol(self):
129 return self._samples_per_symbol
131 def bits_per_symbol(self=None): # staticmethod that's also callable on an instance
133 bits_per_symbol = staticmethod(bits_per_symbol) # make it a static method. RTFM
135 def _print_verbage(self):
136 print "bits per symbol = %d" % self.bits_per_symbol()
137 print "Gray code = %s" % self._gray_code
138 print "RRS roll-off factor = %f" % self._excess_bw
140 def _setup_logging(self):
141 print "Modulation logging turned on."
142 self._fg.connect(self.bytes2chunks,
143 gr.file_sink(gr.sizeof_char, "bytes2chunks.dat"))
144 self._fg.connect(self.symbol_mapper,
145 gr.file_sink(gr.sizeof_char, "graycoder.dat"))
146 self._fg.connect(self.diffenc,
147 gr.file_sink(gr.sizeof_char, "diffenc.dat"))
148 self._fg.connect(self.chunks2symbols,
149 gr.file_sink(gr.sizeof_gr_complex, "chunks2symbols.dat"))
150 self._fg.connect(self.rrc_filter,
151 gr.file_sink(gr.sizeof_gr_complex, "rrc_filter.dat"))
153 def add_options(parser):
155 Adds QPSK modulation-specific options to the standard parser
157 parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
158 help="set RRC excess bandwith factor [default=%default] (PSK)")
159 parser.add_option("", "--no-gray-code", dest="gray_code",
160 action="store_false", default=_def_gray_code,
161 help="disable gray coding on modulated bits (PSK)")
162 add_options=staticmethod(add_options)
165 def extract_kwargs_from_options(options):
167 Given command line options, create dictionary suitable for passing to __init__
169 return modulation_utils.extract_kwargs_from_options(dqpsk_mod.__init__,
170 ('self', 'fg'), options)
171 extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
174 # /////////////////////////////////////////////////////////////////////////////
177 # Differentially coherent detection of differentially encoded qpsk
178 # /////////////////////////////////////////////////////////////////////////////
180 class dqpsk_demod(gr.hier_block):
182 def __init__(self, fg,
183 samples_per_symbol=_def_samples_per_symbol,
184 excess_bw=_def_excess_bw,
185 costas_alpha=_def_costas_alpha,
186 gain_mu=_def_gain_mu,
188 omega_relative_limit=_def_omega_relative_limit,
189 gray_code=_def_gray_code,
190 verbose=_def_verbose,
193 Hierarchical block for RRC-filtered DQPSK demodulation
195 The input is the complex modulated signal at baseband.
196 The output is a stream of bits packed 1 bit per byte (LSB)
198 @param fg: flow graph
200 @param samples_per_symbol: samples per symbol >= 2
201 @type samples_per_symbol: float
202 @param excess_bw: Root-raised cosine filter excess bandwidth
203 @type excess_bw: float
204 @param costas_alpha: loop filter gain
205 @type costas_alphas: float
206 @param gain_mu: for M&M block
208 @param mu: for M&M block
210 @param omega_relative_limit: for M&M block
211 @type omega_relative_limit: float
212 @param gray_code: Tell modulator to Gray code the bits
213 @type gray_code: bool
214 @param verbose: Print information about modulator?
216 @param debug: Print modualtion data to files?
221 self._samples_per_symbol = samples_per_symbol
222 self._excess_bw = excess_bw
223 self._costas_alpha = costas_alpha
224 self._gain_mu = gain_mu
226 self._omega_relative_limit = omega_relative_limit
227 self._gray_code = gray_code
229 if samples_per_symbol < 2:
230 raise TypeError, "sbp must be >= 2, is %d" % samples_per_symbol
232 arity = pow(2,self.bits_per_symbol())
234 # Automatic gain control
235 scale = (1.0/16384.0)
236 self.pre_scaler = gr.multiply_const_cc(scale) # scale the signal from full-range to +-1
237 #self.agc = gr.agc2_cc(0.6e-1, 1e-3, 1, 1, 100)
238 self.agc = gr.feedforward_agc_cc(16, 1.0)
240 # Costas loop (carrier tracking)
241 if self._costas_alpha is None: # If no alpha value was specified by the user
242 alpha_dir = {2:0.075, 3:0.075, 4:0.105, 5:0.105, 6:0.125, 7:0.130}
243 self._costas_alpha = alpha_dir[self._samples_per_symbol]
246 # The value of beta is now set to be overdamped; this value can have a huge impact on the
247 # performance of QPSK. Set to 0.25 for critically damped or higher for underdamped responses.
248 beta = .15 * self._costas_alpha * self._costas_alpha
249 self.costas_loop = gr.costas_loop_cc(self._costas_alpha, beta, 0.02, -0.02, costas_order)
252 ntaps = 11 * samples_per_symbol
253 self.rrc_taps = gr.firdes.root_raised_cosine(
254 self._samples_per_symbol, # gain
255 self._samples_per_symbol, # sampling rate
257 self._excess_bw, # excess bandwidth (roll-off factor)
260 self.rrc_filter=gr.fir_filter_ccf(1, self.rrc_taps)
262 # symbol clock recovery
263 omega = self._samples_per_symbol
264 gain_omega = .25 * self._gain_mu * self._gain_mu
265 self.clock_recovery=gr.clock_recovery_mm_cc(omega, gain_omega,
266 self._mu, self._gain_mu,
267 self._omega_relative_limit)
269 self.diffdec = gr.diff_phasor_cc()
270 #self.diffdec = gr.diff_decoder_bb(arity)
272 # find closest constellation point
275 rotated_const = map(lambda pt: pt * rot, psk.constellation[arity])
276 #print "rotated_const = %s" % rotated_const
278 self.slicer = gr.constellation_decoder_cb(rotated_const, range(arity))
281 self.symbol_mapper = gr.map_bb(psk.gray_to_binary[arity])
283 self.symbol_mapper = gr.map_bb(psk.ungray_to_binary[arity])
286 # unpack the k bit vector into a stream of bits
287 self.unpack = gr.unpack_k_bits_bb(self.bits_per_symbol())
290 self._print_verbage()
293 self._setup_logging()
295 # Connect & Initialize base class
296 self._fg.connect(self.pre_scaler, self.agc, self.costas_loop,
297 self.rrc_filter, self.clock_recovery,
298 self.diffdec, self.slicer, self.symbol_mapper,
300 gr.hier_block.__init__(self, self._fg, self.pre_scaler, self.unpack)
302 def samples_per_symbol(self):
303 return self._samples_per_symbol
305 def bits_per_symbol(self=None): # staticmethod that's also callable on an instance
307 bits_per_symbol = staticmethod(bits_per_symbol) # make it a static method. RTFM
309 def _print_verbage(self):
310 print "bits per symbol = %d" % self.bits_per_symbol()
311 print "Gray code = %s" % self._gray_code
312 print "RRC roll-off factor = %.2f" % self._excess_bw
313 print "Costas Loop alpha = %.5f" % self._costas_alpha
314 print "M&M symbol sync gain = %.5f" % self._gain_mu
315 print "M&M symbol sync mu = %.5f" % self._mu
316 print "M&M omega relative limit = %.5f" % self._omega_relative_limit
319 def _setup_logging(self):
320 print "Modulation logging turned on."
321 self._fg.connect(self.pre_scaler,
322 gr.file_sink(gr.sizeof_gr_complex, "prescaler.dat"))
323 self._fg.connect(self.agc,
324 gr.file_sink(gr.sizeof_gr_complex, "agc.dat"))
325 self._fg.connect(self.costas_loop,
326 gr.file_sink(gr.sizeof_gr_complex, "costas_loop.dat"))
327 self._fg.connect((self.costas_loop,1),
328 gr.file_sink(gr.sizeof_gr_complex, "costas_error.dat"))
329 self._fg.connect(self.rrc_filter,
330 gr.file_sink(gr.sizeof_gr_complex, "rrc_filter.dat"))
331 self._fg.connect(self.clock_recovery,
332 gr.file_sink(gr.sizeof_gr_complex, "clock_recovery.dat"))
333 self._fg.connect((self.clock_recovery,1),
334 gr.file_sink(gr.sizeof_gr_complex, "clock_recovery_error.dat"))
335 self._fg.connect(self.diffdec,
336 gr.file_sink(gr.sizeof_gr_complex, "diffdec.dat"))
337 self._fg.connect(self.slicer,
338 gr.file_sink(gr.sizeof_char, "slicer.dat"))
339 self._fg.connect(self.symbol_mapper,
340 gr.file_sink(gr.sizeof_char, "gray_decoder.dat"))
341 self._fg.connect(self.unpack,
342 gr.file_sink(gr.sizeof_char, "unpack.dat"))
344 def add_options(parser):
346 Adds modulation-specific options to the standard parser
348 parser.add_option("", "--excess-bw", type="float", default=_def_excess_bw,
349 help="set RRC excess bandwith factor [default=%default] (PSK)")
350 parser.add_option("", "--no-gray-code", dest="gray_code",
351 action="store_false", default=_def_gray_code,
352 help="disable gray coding on modulated bits (PSK)")
353 parser.add_option("", "--costas-alpha", type="float", default=None,
354 help="set Costas loop alpha value [default=%default] (PSK)")
355 parser.add_option("", "--gain-mu", type="float", default=_def_gain_mu,
356 help="set M&M symbol sync loop gain mu value [default=%default] (PSK)")
357 parser.add_option("", "--mu", type="float", default=_def_mu,
358 help="set M&M symbol sync loop mu value [default=%default] (PSK)")
359 add_options=staticmethod(add_options)
361 def extract_kwargs_from_options(options):
363 Given command line options, create dictionary suitable for passing to __init__
365 return modulation_utils.extract_kwargs_from_options(
366 dqpsk_demod.__init__, ('self', 'fg'), options)
367 extract_kwargs_from_options=staticmethod(extract_kwargs_from_options)
371 # Add these to the mod/demod registry
373 modulation_utils.add_type_1_mod('dqpsk', dqpsk_mod)
374 modulation_utils.add_type_1_demod('dqpsk', dqpsk_demod)